Research Article Structural and Antioxidant Properties of ...downloads.hindawi.com/journals/bca/2016/8636409.pdf · with the - +G(d,p) and - G(d) Pople-style basis sets on the atoms

Research ArticleStructural and Antioxidant Properties of Compounds Obtainedfrom Fe2+ Chelation by Juglone and Two of Its Derivatives DFTQTAIM and NBO Studies

Aymard Didier Tamafo Fouegue1 Julius Numbonui Ghogomu1 Deacutesireacute Bikeacuteleacute Mama2

Nyiang Kennet Nkungli1 and Elie Younang3

1Department of Chemistry Faculty of Science University of Dschang PO Box 67 Dschang Cameroon2Department of Chemistry Faculty of Science University of Douala PO Box 24157 Douala Cameroon3Department of Inorganic Chemistry Faculty of Science University of Yaounde I PO Box 812 Yaounde Cameroon

Correspondence should be addressed to Julius Numbonui Ghogomu ghogsjujuhotmailcom

Received 22 June 2016 Revised 23 August 2016 Accepted 28 August 2016

Academic Editor Konstantinos Tsipis

Copyright copy 2016 Aymard Didier Tamafo Fouegue et al This is an open access article distributed under the Creative CommonsAttribution License which permits unrestricted use distribution and reproduction in any medium provided the original work isproperly cited

The chelating ability of juglone and two of its derivatives towards Fe2+ion and the antioxidant activity (AOA) of the resulting chelatesand complexes (in the presence of H

2O and CH

3OH as ligands) in gas phase is reported via bond dissociation enthalpy ionization

potential proton dissociation enthalpy proton affinity and electron transfer enthalpy The DFTB3LYP level of theory associatedwith the 6-31+G(dp) and 6-31G(d) Pople-style basis sets on the atoms of the ligands and the central Fe(II) respectively was usedNegative chelation free energies obtained revealed that juglone derivatives possessing the O-H substituent (L

2) have the greatest

ability to chelate Fe2+ ion Apart from 1B thermodynamic descriptors of the AOA showed that the direct hydrogen atom transfer isthe preferred mechanism of the studied molecules NBO analysis showed that the Fe-ligand bonds are all formed through metal toligand charge transfer QTAIM studies revealed that among all the Fe-ligand bonds the O

1-Fe bond of 1A is purely covalent The

aforementioned results show that the ligands can be used to fight against Fe(II) toxicity thus preserving human health and fightagainst the deterioration of industrial products In addition most of the complexes studied have shown a better AOA than theircorresponding ligands

1 Introduction

Juglone (5-hydroxy-14-naphthoquinone) is a phenolic alle-lochemical responsible for walnut allelopathy and theinhibitory effect of black walnut (Juglans nigra) in associatedplant species [1 2] It is a natural product that has showna multitude of properties that are deemed beneficial in thefields of medicine farming and aquaculture [3] In the field ofmedicine juglone has been shown to possess good antifungalproperties which are similar to those of some commerciallyavailable antifungal agents [4 5] In addition it has beenshown that juglone could be a promising chemopreventiveagent for human intestinal neoplasia [6] Furthermore itsantitumour [7ndash11] and antibacterial properties [5 12] havebeen reported Some experimental and theoretical studies

have also emphasized the ability of juglone and its derivativesto inhibit the degradation of cells and foods by offeringresistance to oxygen and its reactive species (known asantioxidant activity (AOA)) [10 13 14]

Antioxidants are capable of chelating transition metalions (especially Fe2+ andCu+) leading to the formation of sta-ble complexes thereby preventing these metals from partici-pating in free radical generation [15ndash18] but the mechanismhas not been studied exhaustively The production of freeradicals can lead to lipid peroxidation protein modificationand DNA damage Among the transition metals iron is themost dangerous lipid oxidation prooxidant due to its highreactivity In fact the ferrous state of iron accelerates lipidoxidation by breaking down hydrogen and lipid peroxidesto reactive free radicals via the Fenton reaction [19] thus

Hindawi Publishing CorporationBioinorganic Chemistry and ApplicationsVolume 2016 Article ID 8636409 13 pageshttpdxdoiorg10115520168636409

2 Bioinorganic Chemistry and Applications

degrading the quality of foods and causing several diseases[20] Antioxidants are well known radical scavengers that arelargely used to fight against these negative effects of free rad-icals via the above mentioned mechanism Besides removalof the metals metal-chelating compounds can also alter theirredox potentials rendering them inactive The use of naturalmetal chelators instead of the synthetic counterparts whichmay present some toxicity problems should be encouraged[21] Several experimental and theoretical studies have beendevoted to the elucidation of the metal-chelation mechanismof AOA [19 21ndash25]

It has been demonstrated experimentally that depro-tonated juglone has the capacity to chelate Fe2+ [13] ATheoretical study to complement this experimental resultis warranted To the best of our knowledge no such the-oretical work exists in the literature In this paper we aimto investigate the Fe2+ chelating ability of neutral jugloneand two of its derivatives (shown in Figure 1) as well asevaluate theAOAof the resulting compounds by themeans ofdensity functional theory (DFT) [26] This work is thereforeexpected to contribute toward the development of newantioxidants which has been the ambition that has attracteda great deal of researchersrsquo attention in recent years owingto the significance of antioxidants in biological processesas well as the processes in the food pharmaceutical andmaterial industries Specifically the chelation of Fe2+ by threeantioxidants in their neutral forms is studied at DFTB3LYPlevel theory The main antioxidant studied is juglone (L

1)

and the rest are its derivatives obtained by replacing thehydrogen atom ortho to the hydroxyl group of juglone eitherbyOH (L

2) or byCN (L

3) groups which are electron donating

(EDG) and withdrawing (EWG) groups respectively Thestructural and electronic parameters of the resulting chelatesor complexes have been analyzed followed by the evaluationof the AOA of all compounds studied (Figure 1) by means ofbond dissociation enthalpy (BDE) ionization potential (IP)proton dissociation enthalpy (PDE) proton affinity (PA) andelectron transfer enthalpy (ETE) [17 18] Our main objectivehere is to study the effect of iron(II) chelation on the AOA ofthe three ligands (L

1 L2 and L

3)

2 Computational Details andTheoretical Background

21 Computational Details All calculations were carried outusingGaussian 09W [27]The input structures were preparedusing the GaussView 508 program [28] The DFT methodwhich was designed especially for the study of coordinationcompounds [24] was associated with the B3LYP hybridfunctional in this research endeavor [29] In addition DFThas been chosen because it has been used successfully tostudy radical scavenging activities of phenolic compounds[30ndash32] Also when compared to ab initio methods DFT isvery rapid and is often said to ally precision and the rapidity[33] Faced with limited computational resources and largemolecular sizes we used a mixed basis set comprising the6-31Glowast basis for the central metal ion and the 6-31+Glowastlowastbasis for every other element in the molecules studied Inaddition mixed basis sets have been recently employed for

many studies on complexes and have been shown to speed upcalculations without altering the quality of theoretical results[21 34 35] All computations on the closed shell systems wereperformed using the Restricted Kohn-Sham formalism whilethe Unrestricted Kohn-Sham formalismwas adopted in openshell systems in order to reduce spin contamination [36]Ground-state geometries for all complexes have been fullyoptimized without any symmetry constraints Vibrationalfrequency calculations have further been undertaken on theoptimized geometries in order to confirm that the resultingequilibriumgeometrieswereminima (nonegative frequency)on the potential energy surface Central metal-ligand chargetransfer was evaluated by means of Natural Bond Orbital(NBO) analysis [37] as implemented in Gaussian 09 TheQuantum Theory of Atom in Molecules (QTAIM) proposedby Bader [38] was used to evaluate the nature of all metal-ligand bonds with the aim of determining their degree ofcovalency QTAIM analysis was performed as implementedin multiwfn [39]

22 Theoretical Background The chelates [FeL119894]2+ (119894 = 1 2

and 3) (Figure 1) optimized in this work are presumed to beformed according to

Fe2+ + L119894997888rarr [FeL

119894]2+ (1)

The complexes [FeL119894(X)4]2+ (119894 = 1 2 and 3 and X =H

2O or

CH3OH) are presumed to be formed according to

Fe2+ + L119894+ 4X 997888rarr [FeL

119894(X)4]2+ (2)

The use of water and methanol molecules as other ligands isbecause of the difficulty to find isolated form of Fe2+ and theabundance of such polar molecules in organisms [23]

The effect of multiplicity on the stability of all the ninechelates and complexes resulting from both (1) and (2) aspresented in Figure 1 was first investigated This was donevia geometry optimizations of all the input structures inthe singlet and quintet states based on the possible numberof unpaired electrons of the central Fe2+ ion in orderto determine the geometry with the lowest ground-stateenergy The binding energies (Δ119864int) free energies (Δ119866) andenthalpies (Δ119867) of formation of the most stable geometriesat standard conditions were calculated as follows

Δ119864int = 119864comp minus 119864L minus 4119864X minus 119864Fe2+ (3)

Δ119867 = 119867comp minus 119867L minus 4119867X minus 119867Fe2+ (4)


In these equations119864119867 and119866 stand for the thermal energiesenthalpies and free energies of formation of the respectivespecies Due to the absence of X ligands in the chelates 119864X119867X and 119866X terms are nonexistent in their expressions forΔ119864int Δ119867 and Δ119866

Using the most stable optimized geometry of each com-pound the usual schemes of hydrogen transfer by antiox-idants and the related parameters were calculated Theseinclude the following

Bioinorganic Chemistry and Applications 3

22

2

2

112 1

1

1

3A

3B2B

2A1A

1B

1C

2

2

1

1

3C2C

2

2

1

1

X1

X2

X3

X4

X4

X4

X1

X1

X2

X3

X4

X1

X2

X3

X4

X1

X2X3

X2

X3

X4

X1

X2X3

Figure 1 Optimized geometries of the studied molecules obtained by applying the B3LYP6-31G(d)(Fe)U6-31+G(dp)(E) level of theory

(i) The Direct Hydrogen Atom Transfer (HAT) The directhydrogen atom transfer (HAT) is themechanism inwhich thephenolic H atom is transferred in one step by the antioxidantBDE which is the parameter used to evaluate HAT is thereaction enthalpy for the mechanism This parameter hasbeen evaluated on all the hydroxyl groups of juglone andits two derivatives studied The lower the BDE the easierthe dissociation of the phenolic O-H bond as elucidated in(6) and (7) where X-H represents the ligands chelates orcomplexes and X∙ is the radical compound resulting from theH atom abstraction

X-H 997888rarr X∙ +H∙ (6)

BDE = HH∙ +HX∙ minusHX-H (7)

(ii)The Sequential Electron Transfer Proton Transfer (SETPT)Here an electron abstraction from X-H (characterized bythe ionization potential (IP) of X-H) is followed by a protontransfer (characterized by the proton dissociation enthalpy(PDE) of the cationic radical X-H+∙) as shown in the follow-ing

X-H 997888rarr X-H+∙ + eminus (8)

IP = HX-H+∙ +Heminus minusHX-H (9)

X-H+∙ 997888rarr X∙ +H+ (10)

PDE = HX∙ +HH+ minusHX-H+∙ (11)

(iii) The Sequential Proton Loss Electron Transfer (SPLET)Here a proton loss is followed by an electron transfer Thereaction enthalpy of the first step in the SPLET mechanismcorresponds to the proton affinity (PA) of Xminus The reactionenthalpy of the next step the transfer of an electron by Xminus isdenoted as electron transfer enthalpy (ETE) and is calculatedusing the following equations

X-H 997888rarr Xminus +H+ (12)

PA = HXminus +HH+ minusHX-H (13)

Xminus 997888rarr X∙ + eminus (14)

ETE = HX∙ +Heminus minusHXminus (15)

The free energies of all aforementioned descriptors havealso been calculated and denoted BDFE (bond dissociationfree energy) IPFE (ionization potential free energy) PDFE(proton dissociation free energy) PAFE (proton affinity freeenergy) and ETFE (electron transfer free energy)

3 Results and Discussion

31 Effect of Multiplicity on Electronic Energies Owing to theintrinsic relationship between spin multiplicity and ligandfield the effect of multiplicity on the total energies of thechelates and complexes studied (Figure 1) has been inves-tigated This was done in order to select the multiplicitiesof the molecules studied that correspond to their lowest


Table 1 Energies (Hartree) of the compounds related to theirmultiplicities obtained from B3LYP6-31G(d)(Fe)U6-31+G(dp)(E)

Spin multiplicity Singlet Quintet[Fe(L

1)]2+ 1A minus187321293208 minus187312426700

[Fe(L1)(OH

2)4]2+ 1B minus217923172776 minus217898173479

[Fe(L1)(CH3OH)4]2+ 1C minus233610729027 minus233615725602

[Fe(L2)]2+ 2A minus194845209999 minus194833220631

[Fe(L2)(OH

2)4]2+ 2B minus225413720775 minus225418434320

[FeL2(CH3OH)4]2+ 2C minus241168291413 minus241172799125

[Fe(L3)]2+ 3A minus196522170297 minus196531620465

[Fe(L3)(OH

2)4]2+ 3B minus227113120555 minus227117906337


energy (or most stable) geometries In this regard the singletand quintet states corresponding to geometries in which thecentral Fe2+ ion has no unpaired electron and four unpairedelectrons respectively were investigated for each chelate andcomplex ⟨1198782⟩ values calculated for all quintet states are inthe range of 60001ndash60006 which is close to the value of6000 corresponding to the pure quintet wave function Thetotal energies of the said states are displayed in Table 1 Inthis table the complexes of L

1(juglone) L

2(the derivative

with the OH group) and L3(the derivative with the CN

group) are denoted by 1 2 and 3 respectivelyThe chelates arerepresented by the symbolYA (whereY = 1 2 or 3) Similarlythe complexes containing the ligands H

2O and MeOH are

respectively represented by YB and YCIt can be seen from Table 1 that the singlet state of 1A and

1B which are complexes of L1 are the most stable whereas

the quintet state is instead the most stable in the case of itsMeOH containing complex (1C) It is obvious from the tablethat among the complexes of L

2 2A has the lowest energy

singlet state while 2B and 2C containing H2O and MeOH

ligands respectively are constrained to the quintet state Thethree complexes of L

3(3A 3B and 3C) are restricted to the

quintet state From the foregoing observations the rest of thiswork has been limited to the singlet states of 1A 1B and 2Aand the quintet states of 1C 2B 2C 3A 3B and 3C

32 Iron(II) Chelation Capacity of the Ligands The capacityof juglone and its derivatives to chelate Fe(II) has beenevaluated at 29815 K and 1 atm via Gibbs free energy offormation calculations on the complexes as shown in (5)The enthalpies of formation of the complexes as well as theirbinding energies were also calculated and the results arepresented in Table 2

By inspection of Table 2 it can be seen that the freeenergies of formation of the three chelates (1A 2A and 3A)are negative meaning that their formation is spontaneousAmong the chelates the computed free energies increase inthe order 2A lt 1A lt 3A showing that L

2has the highest

Fe2+ ion binding capacity and L3has the lowest This result

is attributable to the fact that the presence of the EDG(the -OH group of L

2) increases the electron density on

the ligating oxygen atoms thus increasing the metal-ligandinteractionThe reverse is observed in presence of -CN (3A)

Table 2 Binding energy (Δ119864int) enthalpy (Δ119867) and free energychange (Δ119866) of formation of the complexes all in kJmol obtainedfrom B3LYP6-31G(d)(Fe)U6-31+G(dp)(E)

Molecule Δ119867 Δ119866 Δ119864int

1A minus100008 minus96377 minus997601B minus433208 minus150067 minus4319691C minus623060 minus77445 minus6218192A minus890034 minus98677 minus8897862B minus1148396 minus79141 minus11471562C minus1500490 minus167743 minus14992503A minus1639551 minus60987 minus16393043B minus1932320 minus75795 minus19310813C minus2188049 minus66861 minus2186809

The presence of H2O ligands decreases Δ119866 of formation of

1A while the MeOH ligands rather result in its incrementIn the case of 2A the opposite of the previous observationis evidenced in Table 2 implying that while the presence ofwater ligands increases Δ119866 of formation of 2A the presenceof the methanol ligands instead leads to its reduction Thepresence of H

2O and MeOH ligands in 3A decreases its Δ119866

by 148 and 58 kJmol respectivelyThe negative values of the binding energies have proven

that the complexes investigated are stable [25] corroboratingthe fact that their formation is thermodynamically feasibleThe values of the enthalpies of formation of all complexes arealso negative showing that their formation is exothermic at29815 K and under 1 atm

33 Geometric Parameters This section is dedicated to Fe-ligand and O

1-H bond lengths obtained from the optimized

geometries of the complexes presented in Figure 1 It is clearfrom this figure that the chelates 1A 2A and 3A are perfectlyplanar and the complexes 2B 2C 3B and 3C are octahedralThe values of the bond lengths around the central metal arepresented in Table 3

The atomic numbering adopted in Table 3 is as presentedin Figure 1 The length of the O

1-Fe bond in each chelate

increases in the order 2A lt 1A lt 3A which is the same orderof their Δ119866 of formation Hence the values of Δ119866 and theO1-Fe bond lengths for the chelates are directly proportional

It can also be observed from Table 3 that the presence ofH2O and MeOH ligands increases the values of the O

1-Fe

bond lengths in all the chelates Some discrepancies betweenthe O

1-Fe bond lengths in 1A 2A 3A relative to those in

the corresponding methanol complexes of 0315 0358 and0225gt respectively have been observed

The O2-Fe bond lengths have been found to be shorter

than the O1-Fe counterparts in all chelates investigated The

lengths of the former have also been found to increase inpresence of H

2O and MeOH as ligands Our results are in

good agreement with those in the literature for similar studieson three naturally occurring phenolic antioxidants [23]

The lengths of all the Xn-Fe bonds (119899 = 1 2 3 and4 X = H

2O or MeOH) are larger than 2gt Among the

complexes of juglone that possessingMeOH ligands (1C) has


Table 3 Metal-ligand and O-H bond lengths (gt) of the complexes obtained from B3LYP6-31G(d)(Fe)U6-31+G(dp)(E)

O1-H O

1-Fe O

2-Fe X

1-Fe X

2-Fe X

3-Fe X

4-Fe

1A 0979 1870 1785 mdash mdash mdash mdash1B 0971 1982 1898 2029 2021 2023 20241C 0977 2185 1991 2140 2080 2187 2111

2A 09930972lowast 1863 1796 mdash mdash mdash mdash

2B 09910976lowast 2145 1994 2088 2145 2140 2139

2C 09770969lowast 2221 2010 2196 2117 2186 2137


the longest Xn-Fe bond and its formation is found to be theleast spontaneous

From inspection of the O1-H bonds of the three chelates

the ranking 1Alt 2Alt 3A can bemade showing that the bondis the longest in 3Awith a length of 0997gtThis is surprisingbecause the O

1-H group of 2A is involved in hydrogen

bonding as depicted in Figure 1 which should elongate itsO1-H bond rendering it the longest relative to those of the

other chelates Since the AOA is greatly influenced by thelength of the phenolic O-H bond these differences in O

1-

H bond lengths could have great consequences on the valuesof associated thermodynamic descriptors of AOA Still fromthese findings it can be predicted that among the chelates1A which has the shortest O

1-H bond length should have the

highest associated BDE value The presence of the H2O and

MeOH ligands is found to slightly decrease the length of thesaid bond The presence of the methanol ligands has a moresignificant effect on the O

1-H bond length of 2A Indeed the

presence of the methanol ligand is found to reduce the lengthof the bond by 0016gt This is attributable to hydrogen bondstrength reduction in 2B The presence of the water ligandsin 2A has virtually no effect on the length of the O

1-H bond

The presence of both ligands individually reduces the lengthof the hydroxyl link of 3A by 0011 and 0013gt respectively

The lengths of the hydrogen bonds of 1B 2B and 3Bare respectively 1909 1920 and 1961gt which are ingood agreement with those of the O

1-H groups of the said

molecules since they are inversely proportional to the O1-H

bond length The lengths of the additional O-H bonds in 2A2B and 2C (marked in Table 3 with lowast) are shorter than thoseof O1-H groups due to the fact that they are not engaged in

any hydrogen bond

34 Thermodynamic Descriptors of Antioxidant Properties341 HAT Mechanism The calculated gas phase BDE valuesof the molecules investigated are presented in Table 4

It is evident in Table 2 that the BDEs of the O1-H bond

for the chelates increase in the order 2A lt 3A lt 1A Thefact that the BDE of O

1-H is the lowest in 2A suggests

that the hydrogen bond in which this group is engaged

weakens the O1-H bond in this molecule In addition the

phenoxy radical formed due to HAT by 2A is stabilizedby an O-Hsdot sdot sdotO

1hydrogen bond further strengthening the

AOA of 2A The low BDE of 3A relative to that of 1Acan be explained by the fact that its O

1-H bond is longer

and therefore weaker than that of 1A From the foregoingobservations it can be concluded that the addition of the OHor CN groups to 1A reduces the BDE value of its hydroxylgroup

It is also clear fromTable 4 that the BDEof theO1-H bond

of juglone (L1) is lower than that of 1A by 191 kJmol implying

that Fe(II) chelation by juglone leads to an increase in theBDE of its O-H groupThe presence of the water ligands in 1Bresults in a BDE value increment of 397 kJmol relative to thatof 1A which contains no H

2O ligandsThis can be attributed

to the reduction in the O1-H bond length due to the presence

of H2O ligands as previously observed in Section 33 On

the contrary the introduction of the MeOH ligands into 1Adecreases its BDE value

It can be seen from Table 4 that the O1-H BDE of 2A is

lower than that of L2by 269 kJmol Among the compounds

studied 2A has been found to exhibit the lowest O1-H

BDE showing that the HAT mechanism is most favorablein this molecule Besides the electron donating ability of thehydroxyl substituent of 2A the hydrogen bond in its phenoxyradical could have a great stabilizing effect that lowers its BDEvalue The BDE value of 2B lies between those of 2A and L

2

On the other hand the BDE value of 2C is much higher thanthose of both 2A and L

2 Among the molecules investigated

in this work the highest BDE value (1240 kJmol) has beenrecorded for 2C This is probably due to the fact that thehydrogen bond in 2C that involves the O

1-H group is weaker

than similar bonds in 2A and 2B From these results it can beconcluded that Fe(II) chelation by L

2decreases its BDE value

as opposed to the presence of MeOH ligands which greatlyincreases the BDE value

Fe (II) chelation by L3is found to decrease its BDE value

by 128 kJmol It has been found that theBDEvalues of 3B and3C are lower than that of 3A by 35 and 49 kJmol respectivelyGenerally our results have shown that the BDEs of the O

1-H

bonds of the species currently investigated increases in the


Table 4 Values of BDE BDFE IP IPFE PDE PDFE PA PAFE ETE and ETFE of the compounds studied all in kJmol obtained fromB3LYP6-31G(d)(Fe)U6-31+G(dp)(E)

BDE BDFE IP IPFE PDE PDFE PA PAFE ETE ETFEL1 417 377 834 824 899 864 1422 1386 312 309

1A 608 575 1919 1917 6 minus23 1014 910 1041 10381B 1001 977 2132 2142 186 154 793 629 1710 17201C 233 211 1299 1309 251 222 898 679 897 904

L2

380359lowast

341323lowast 805 795 892 874 1377

1361lowast13661330lowast

319314lowast

315312lowast

2A 111798lowast

74765lowast 1967 1967 minus539 minus574 1150


4141107lowast

4071104lowast

2B 271358lowast

250327lowast 1338 1351 251 218 868


9281016lowast

9371009lowast

2C 12401324lowast

12171301lowast 2255 2273 245 262 1904


908993lowast

910994lowast

L3 421 381 874 863 864 828 1366 1353 371 368

3A 283 250 1833 1979 minus233 minus410 570 447 1176 11753B 248 232 1375 1394 191 157 829 641 953 9633C 234 211 1308 1319 243 211 881 653 924 930lowast refers to the parameters related to the O-H substituent present on L2

order 2A lt 1C lt 3C lt 3B lt 2B lt 3A lt L2lt L1lt L3lt 1A lt

1B lt 2CThe BDE value of the additional O-H substituent in L

2

designated by an asterisk (lowast) in Table 3 is found to be lowerthan that of the O

1-H bond whereas the reverse is observed

for its complexesTherefore the H atom of the O1-H bond in

the complexes is more available for a radical attackThe trend in the BDFE values of the molecules studied is

similar to that of the BDEvalues As a general observation theBDFE values are found to be lower than the correspondingBDE values The differences between the values of thesedescriptors are in the range 21ndash37 kJmol for the complexesstudied Furthermore the BDFEs are all positive signifyingthat the HAT mechanism is not spontaneous for all thecomplexes and ligands studied These results are in goodagreement with those found in the literature [23 40]

342 SETPT Mechanism The first and the determining stepin this mechanism is electron transfer which is characterizedby the associated IP of the antioxidants The calculatedadiabatic IP values of the complexes and ligands are presentedin Table 4 It is clear in Table 4 that Fe2+ chelation leads to anincrease in the IPs of L

1 L2 and L

3 This result is in good

agreement with some literature findings [21] The IP valuesof the chelates have been found to increase in the order 3Alt 1A lt 2A Surprisingly from this ranking 3A possessingEWG exhibits the greatest electron transfer capability while2A containing EDG togetherwith a hydrogen bond shows theleast electron transferability

While the presence of water ligands increases the IP of1A the MeOH ligands instead lead to its reduction Theseligands have been found to have a similar effect on the BDEof 1A as explained in Section 341 In the case of 2A theopposite trend is observed wherein the presence of the waterligands instead leads to a reduction in its IP whereas the

MeOH ligands result in its increment The introduction ofeither water or MeOH ligands reduces the IP value of 3A inwhich case the effect of the MeOH is found to be the greatestThe presence of these ligands similarly affects the BDE of 3Aand its complexes

Unlike BDFE the values of IPFE for the complexes aregenerally found to be slightly higher than their IP as shownin Table 4 The only exceptions to this trend are the IPFEs of1A and 2A which are lower than IP (by 2 kJmol) and equalto IP respectively

The PDE values of the complexes displayed in Table 4 areall lower than those of the ligands We have attributed this tothe fact that the cation radicals of the complexes are less stableand are therefore more reactive than those of the ligands asshownby the IP values presented in this tableThePDEvaluesof the chelates are smaller than those of the free ligands aswellas those of complexes The PDE values of 2A (minus539 kJmol)and 3A (minus233 kJmol) are negative which is an indicationthat the proton transfer process of their cation radicals isexothermic Since the PDFE values of the chelates (1A 2Aand 3A) are all negative it can be concluded that the protontransfer process by their cation radicals is spontaneous whichis not the case for the rest of the compounds in Table 4

343 SPTET Mechanism This mechanism begins with thetransfer of a proton designated as PA This is followed byan electron transfer from the resulting anion also designatedas ETE The values of PA and ETE for the ligands and theircomplexes as well as their free energies (PAFE and ETFE)calculated in this work are presented in Table 4 This tableshows that apart from 2C the chelates and complexes havelower PA values than their respective ligands Like the IPvalues the PAs of the chelates can be classified in the order3A lt 1A lt 2A This can be explained by the fact that EWG(-CN) increases the acidity of the H atom of the hydroxyl


1A 1B 1C 2A 2B 2C 3A 3B 3CMolecules

BDFEIPFEPAFE

L1 L2

0200400600800

10001200140016001800200022002400

Ther

mod

ynam

ic p

aram

eter

s (kJ

mol

)

L3

Figure 2 Superposition of BDFE IPFE and PAFE of juglone its derivatives and their complexes

group whereas EDG (-OH) reduces the hydroxyl H atomrsquosacidity The presence of water and MeOH ligands reducesthe PA of 1A the latter having the least effect Like thecase with IP the presence of H

2O ligands reduces the PA

of 2A while the presence of MeOH ligands increases thatPA The presence of water and MeOH ligands is observedto increase the PA of 3A with the latter having the greatesteffect

The hydrogen of the O-H substituent is more acidic thatthat of the O

1-H group of all L

2complexes since the PAlowast

and PAFElowast of the former are lower than PA and PAFE of thelatter as shown in Table 4 It can be seen from Table 4 thatthe values of PAFE and PA for the chelates and complexesfollow the same trend even though the PAFEs are lower thanPAs In fact the differences between these PAs and PAFEsfor the molecules studied range from 104 to 228 kJmol for1A and 3C respectively However both the PAs and PAFEsare higher than the PDEs and PDFEs respectively due tothe high reactivity of the cationic radicals As evidenced inTable 4 the values of ETE and ETFEs are respectively lowerthan those of IP and IPFEs

344 Thermodynamically Preferred Mechanism In order toselect the thermodynamically preferred mechanism amongthe antioxidant mechanisms studied the free energies ofthe first step of each mechanism have been compared Tofacilitate this process free energies for all the moleculesinvestigated were plotted on the same axes as shown inFigure 2

It is clear from this figure that the preferred mechanismfor all the ligands as well as their chelates and complexes isthe HAT since each of these compounds exhibits the lowestfree energy for this process In the case of 1B the SPLET isthe most preferred mechanism since the free energy for PAis lower than that for direct HATWhile the second preferredantioxidant mechanism for the ligands is SETPT that for the

chelates and complexes is SPLET In the case of 1B the secondpreferred mechanism is HAT

345 Spin Density Analysis The spin density is the mostimportant parameter that correlates with the AOA of antiox-idants [41] It characterizes the stability of free radicals sincethe energy of a free radical can be efficiently decreased ifthe unpaired electrons are highly delocalized through theconjugated system after hydrogen abstraction [5] In Figure 3the Mulliken spin density values on selected atoms of thechelates and complexes studied are presented

Analyses of the structures in this figure have revealeda huge concentration on Fe(II) and the oxygen atom fromwhich the H atom transferred is abstracted Among theradicals formed from the chelates that of 2A the chelate withthe lowest BDE (111 kJmol) is found to have the lowest spindensity value on the central metal (199) On the other handthe complex 1B among all the compounds studied has shownthe lowest spin density value on the central metal (093)As a general observation for the rest of the complexes thespin densities on the central Fe2+ ions are in the range 390ndash430 The spin density delocalization in all molecules studieshas been greatly contributed by the carbon atoms in the tworings of juglone and its derivatives As such these carbonatoms significantly contribute to the stabilization of theradicals

35 NBO Analysis Natural Bond Orbital (NBO) refers toa suite of mathematical algorithms for analyzing electronicwave functions in terms of localized Lewis-like chemicalbonds [37 38] In the current study the strength of metal-ligand interactions has been estimated by means of thesecond-order perturbation theory as applied in NBO anal-ysis For each chelate and complex the stabilization energyor second-order perturbation energy 119864(2) associated with the


O

O

O

CN

Fe

O

O

OH

O

Fe

O

O

O

Fe

O

O

O

OH

Fe

OO

O

Fe

OO

O

Fe

OH

OO

OH

Fe

O

OO

O

Fe

OO

O

Fe

OH

OO

O

Fe

CN

028

032017

009

015

026

207

009008

008

199

018003

017 002

384

031010

029

016

020

011006 015022

010

003001

004

206

077

010

025

018009

016021

011003

093

006

001

004

003

004

004

001

407

022 0

02

006

011

025

004

002

008

004

001

001

430

007

005

006

004

001

002

003

010

025

005

004

004

004

390

013

020

012029

015

024

002006 001009

004

002

001

001

001064

009

428

007

005

006

001 011

027

003

005

005

005

005

003

005

423

008

025005

003008

002

004

009 008

004

004

004

004

004

OO

O

Fe

CN

004

004

004

003

427

010

006

008001

008

005

002

011

029

002

004

1A 2A 3A

1B 2B

2C 3A

OO

OH

Fe

O

390

0 10028

024

015

003

040

018

009

002

002014

005

044

001

002

002

002

3B

3C

2Alowast

2Blowast

3Blowast

OH2

OH2

OH2

OH2

OH2

OH2

OH2

OH2

OH2

OH2

OH2

OH2

OH2

OH2

OH2

OH2

HOCH3

HOCH3

HOCH3

HOCH3

HOCH3

OHCH3

OHCH3

OHCH3OHCH3

OHCH3OHCH3

HOCH3

OHCH3

HOCH3

OHCH3

HOCH3

Figure 3 Mulliken spin densities of the radicals of the chelates and complexes studied

delocalization from 119894 rarr 119895 ((119894) and (119895) being the donor andacceptor orbitals resp) was estimated using

119864(2)= minus119902119894

(119865119894119895)

120576119895minus 120576119894

(16)

Here 119902119894is the orbital occupancy 120576

119894 120576119895are diagonal elements

and 119865119894119895is the off-diagonal NBO Fock matrix element Values

of119864(2) are proportional to the intensities of NBO interactionsand the greater the electron donating tendency from donor

to acceptor NBOs the larger the 119864(2) values and the moreintensive the interaction between the electron donors and theelectron acceptors [42 43]

In Table 5 the values of 119864(2) (greater than 5 kJmol)for the ligand-metal charge transfer are reported as wellas the NPA charges of the central metal ions It is worthnoting that the values of 119864(2) are lower than 3 kJmol formetal-ligand charge transfer signifying that these inter-actions are very weak and therefore ignored in thispaper


Table 5 NBO analysis of the metal-ligand bonds and NPA atomic charge of the central Fe in the chelates and complexes obtained fromB3LYP6-31G(d)(Fe)U6-31+G(dp)(E)

NPA atomic charge Fe (e) Donor (119894) Acceptor (119895) 119864(2) (kJmol) Donor (119894) Acceptor (119895) 119864

(2) (kJmol)

1A 145 LP(2) O1

LPlowast(4) Fe 7183 LP(1) O2

LPlowast(6) Fe 2702LP(2) O

1LPlowast(6) Fe 1187 LP(2) O

2LPlowast(5) Fe 1216

1B 117

LP(2) O1

LPlowast(4) Fe 6990 LP(2) X1


1LPlowast(7) Fe 2677 LP(2) X


LP(2) O2





1C 146

LP(2) O1





LP(2) O2





2A 133LP(2) O


2LPlowast(6) Fe 873

LP(2) O2





2B 143

LP(2) O1





LP(1) O2





2C 151

LP(2) O1





LP(1) O2





3A 166 LP(2) O1



2LPlowast(2) Fe 2540 mdash mdash mdash

3B 117

LP(2) O2





LP(1) O1





3C 120

LP(2) O2




2LPlowast(5) Fe 953

LP(1) O1




4LPlowast(2) Fe 793

It can be observed from 119864(2) values in Table 5 that withthe exception of 1A the interactions between the lone pairson O2and the antibonding LPlowast on the metal ion are stronger

than those between the lone pairs on O1and the antibonding

LPlowast on Fe In addition the presence of water and methanolligands which also interact strongly with Fe strengthens theseligand-metal interactions thus accounting for the incrementin the absolute values of the interaction energies as previouslyobserved in Section 32 (Table 2) Among the compoundsinvestigated the strongest NBO interaction (that with thehighest energy) is LP(2) O

1rarr LPlowast(4) Fe in 1A with a

stabilization energy of 7183 kJmolThe atomic charges on Fe (Table 5) in themolecules under

investigation have shown that ligand-metal charge transferis effective since the metalrsquos formal charge of +2 now liesbetween 117 and 166 The highest atomic charge on Fe (166)is obtained in 3A while the lowest value (117) is found in 1Band 3B

36 Analysis of Metal-Ligand Bonds by the QTAIM QTAIMis nowadays a strong tool used by quantum chemists toanalyze the nature and strength of weak interactions [38]In this work the analysis of electron density (120588(119903)) andits Laplacian (nabla2120588(119903)) for the metal-ligand bonds has beenperformed by the means of the Bader QTAIM as imple-mented in multiwfn According to this theory the sign ofthe Laplacian of the electron density (nabla2120588(119903)) at a bondcritical point reveals whether charge is concentrated as incovalent bond interactions (nabla2120588(119903) lt 0) or depleted as inclosed shell (electrostatic) interactions (nabla2120588(119903) gt 0) [41]Specifically for nonpolar and weakly polar covalent bondsnabla2120588(119903) lt 0 andminus119866(119903)V(119903) lt 1 For intermediate interactions

we have nabla2120588(119903) gt 0 but minus119866(119903)V(119903) lt 1 and for closedshell interactions nabla2120588(119903) gt 0 and minus119866(119903)V(119903) gt 1 Here119866(119903) is the kinetic energy density at the critical point (alwayspositive) while V(119903) is the potential energy density at thecritical point (always negative) by definition [44] The values


Table 6 Topological analysis of the metal-ligand and O-H bonds of the complexes

Parameter O1-H1

O1-Fe O

2-Fe X

1-Fe X

2-Fe X

3-Fe X

4-Fe

1A120588(119903) 0342 0228 0132 mdash mdash mdash mdashnabla2120588(119903) minus0211 minus0108 0894 mdash mdash mdash mdash

minus119866(119903)V(119903) 0088 0477 0941 mdash mdash mdash mdash

1B120588(119903) 0353 0637 0354 0056 0057 0058 0058nabla2120588(119903) minus2123 0541 0061 0436 0454 0440 0446

minus119866(119903)V(119903) 0097 1071 0506 1061 1069 1056 1060

1C120588(119903) 0327 0048 0075 0054 0062 0049 0058nabla2120588(119903) minus1576 0213 0464 0278 0313 0227 0297

minus119866(119903)V(119903) 0116 0093 0987 0949 0960 0922 0947

2A

120588(119903)0326 0110 0337 mdash mdash mdash mdash0348lowast

nabla2120588(119903)

minus2022 0699 0025 mdash mdash mdash mdashminus2214lowast

minus119866(119903)V(119903) 0088 0963 0503 mdash mdash mdash mdash0093lowast

2B

120588(119903)0310 0052 0076 0060 0053 0053 00530388lowast

nabla2120588(119903)

minus1148 0258 0441 0328 0282 0283 0263minus1676lowast

minus119866(119903)V(119903) 0113 0951 0980 0972 0956 0956 09500004lowast

2C

120588(119903)0347 0044 0073 0047 0057 0048 00540355lowast

nabla2120588(119903)


minus119866(119903)V(119903) 0099 0918 0981 0925 0946 0926 09460099lowast

3A120588(119903) 0300 0084 0110 mdash mdash mdash mdashnabla2120588(119903) minus1431 0481 0730 mdash mdash mdash mdash


3B120588(119903) 0316 0050 0077 0060 0053 0054 0053nabla2120588(119903) minus1511 0239 0451 0328 0239 0286 0284

minus119866(119903)V(119903) 0117 0943 0983 0972 0950 0958 0957

3C120588(119903) 0320 0047 0323 0078 0194 0050 0059nabla2120588(119903) minus1532 0211 minus0341 0031 0172 0238 0311

minus119866(119903)V(119903) 0117 0934 0453 1214 0436 0929 0956lowast refers to the parameters related to the O-H substituent present on L2

of 120588(119903)nabla2120588(119903) andminus119866(119903)V(119903) for all themetal-ligand bondsas well as for the O-H bonds are presented in Table 6

From Table 6 it can be seen that each Fe-O bond has apositive nabla2120588(119903) value except that of the O

1-Fe bond of 1A

which is negative (minus0108) This implies that the said O1-Fe

bond is covalent in nature while the rest of the Fe-O bondsare noncovalent The covalent character of the O

1-Fe bond

of 1A provides a probable explanation to the fact that theperturbation energy (119864(2) = 7183 kJmol) corresponding tothe interaction between O

1and Fe is the largest among the

metal-ligand interactionsThe values of minus119866(119903)V(119903) for theO

119894-Fe (119894 = 1 and 2) bonds

are all less than unity (except for the O1-Fe bond of 1Bwhich

is a weak or closed shell interaction) meaning that thesebonds are intermediate type interactions Based on the valuesof minus119866(119903)V(119903) it can be concluded that the Xi-Fe (119894 = 1 2 3and 4) bonds of 1C 2B 2C 3B and 3C (except the weak X

1-

Fe interaction of 3C) are also intermediate type interactionsOn the contrary Xi-Fe (119894 = 1 2 3 and 4) bonds of 1B resultfromweak interactionsThe negative values ofnabla2120588(119903) and thelow values of minus119866(119903)V(119903) as presented in Table 6 have clearlyshown that the O-H bonds are all covalent

The topological analyses of the complexes of L2have

confirmed the hydrogen bond O1-Hsdot sdot sdotO earlier observed

in their optimized geometries (Figure 1) Surprisingly thetopological analysis of the complexes of L

3revealed the


Figure 4 Molecular graph of 3A bond critical points (small redspheres) ring critical points (small yellow sphere) bond paths(green lines) and O-Hsdot sdot sdotCN VDW interaction (orange line)

existence of a Van der Waals (VDW) interaction between thehydrogen atom of the O-H group and the carbon atom of the-CN group as illustrated in Figure 4 This VDW interactionjustifies the large O

1-H bond length for the complexes of

L3(see Table 3) Hence the VDW interaction has caused

the elongation and weakening of the O-H resulting in therelatively low BDE values observed for these complexes

4 Conclusion

A DFTB3LYP study has been performed herein in order todetermine the chelating ability of neutral juglone and twoof its derivatives towards Fe2+ The AOA of the resultingchelates and mixed ligand complexes with either H

2O or

CH3OH as another ligand were also evaluated Precisely

the Gibbs free energies the binding energies and NBOanalysis were used to evaluate the ability of L

1 L2 and L

3

to chelate Fe(II) ions QTAIM was also used to investigatethe degree of covalency of the metal-ligand bonds The usualthermodynamic parameters BDE IP PDE PA and ETE andtheir free energies used in predicting the radical scavengingactivities of antioxidants were used to study the effect ofFe2+ chelation on the AOA of the ligands chelates andcomplexes

The negative values of Δ119866 and Δ119864int have indicated thatthe three ligands are capable of chelating the ferrous stateof iron These parameters have been relatively modified bythe presence of H

2O or CH

3OH ligands in the complexes

NBO analysis has showed that metal-ligand bonds in thechelates and complexes result from metal-to-ligand chargetransfer Moreover the second-order perturbation energycorresponding to the O

2-Fe bonds of all the molecules with

the exception of 1A have been found to be higher than thoseof the O

1-Fe bond indicating that the former bonds are

relatively stronger than the latter QTAIM showed that apartfrom the O

1-Fe bond in 1A which is purely covalent nearly

all the O1-Fe and O

2-Fe bonds of the rest of the molecules

are intermediate type interactions Also the Xi-Fe (119894 = 1 23 and 4) bonds in 1C 2B 2C 3B and 3C (except the weakX1-Fe interaction in 3C) are intermediate type interactions

whereas the Xi-Fe (119894 = 1 2 3 and 4) bonds of 1B result fromweak interactions

Our results also revealed that while the chelation of Fe(II)reduces the BDE of L

2and L

3 that of L

1instead increases

Furthermore the reduction in the O1-H bond length in 1B

and the presence of H2O ligands lead to an increase in the

BDE of the chelate while the addition of four CH3OH ligands

to 1A instead decreases its BDE The presence of H2O and

CH3OH ligands increases the BDE of 2A but decreases that

of 3A QTAIM has revealed a VDW interaction betweenthe H atom of the hydroxyl group of L

3and the C atom

of its CN group which elongates and weakens the O-Hbond of the complexes of L

3 conferring them relatively low

BDEs On the other hand BDE of 2B has been found tobe the lowest owing to the presence of a hydrogen bondwhich stabilizes its radical The IPs of the three ligands havebeen found to increase following their chelation of Fe2+ anobservation which agrees with those in the literature Withthe exception of 2C the PA values of all the complexes andchelates studied have been found to be lower than those oftheir corresponding ligands Analyses of the free energies ofthe first step of each hydrogen transfer mechanism revealedthat the direct HAT is the preferred mechanism of the radicalscavenging activity of nearly all the molecules studied in thepresent work Solvent effects are going to be addressed in asubsequent article

Competing Interests

The authors declare that there is no conflict of interestsregarding the publication of this paper

Acknowledgments

The authors gratefully acknowledge the support of this workby the Research Laboratory of Noxious Chemistry andEnvironmental Engineering of the University of DschangIt also benefited from the financial assistance of the Min-istry of External Affairs of India and FICCI (Federation ofIndian Chambers of Commerce and Industry) through a CVRaman International Fellowship award (Grant no 101F102)for African Researchers that was realized at IIT KanpurKanpur India

References

[1] E F Davis ldquoThe toxic principle of Juglans nigraas identifiedwith synthetic juglone and its toxic effects on tomato and alfalfaplantsrdquo American Journal of Botanics vol 15 p 620 1928

[2] W J Rietveld ldquoAllelopathic effects of juglone on germinationand growth of several herbaceous and woody speciesrdquo Journalof Chemical Ecology vol 9 no 2 pp 295ndash308 1983

[3] M P Strugstad and S Despotovski ldquoA summary of extractionsynthesis properties and potential uses of juglone a literaturereviewrdquo Journal of Ecosystems and Management vol 13 no 3pp 1ndash16 2012

[4] A M Clark T M Jurgens and C D Hufford ldquoAntimicrobialactivity of juglonerdquo Phytotherapy Research vol 4 no 1 pp 11ndash14 1990


[5] S Drage D Engelmeier G Bachmann A Sessitsch B Mitterand F Hadacek ldquoCombining microdilution with MicroRespmicrobial substrate utilization antimicrobial susceptibility andrespirationrdquo Journal of Microbiological Methods vol 88 no 3pp 399ndash412 2012

[6] S Sugie KOkamotoKMWRahman et al ldquoInhibitory effectsof plumbagin and juglone on azoxymethane-induced intestinalcarcinogenesis in ratsrdquo Cancer Letters vol 127 no 1-2 pp 177ndash183 1998

[7] U C Bhargava and B AWestfall ldquoAntitumor activity of Juglansnigra (black walnut) extractivesrdquo Journal of PharmaceuticalSciences vol 57 no 10 pp 1674ndash1677 1968

[8] P J OrsquoBrien ldquoMolecular mechanisms of quinone cytotoxicityrdquoChemico-Biological Interactions vol 80 no 1 pp 1ndash41 1991

[9] M T Paulsen and M Ljungman ldquoThe natural toxin juglonecauses degradation of p53 and induces rapid H2AX phospho-rylation and cell death in human fibroblastsrdquo Toxicology andApplied Pharmacology vol 209 no 1 pp 1ndash9 2005

[10] S Reese A Vidyasagar L Jacobson et al ldquoThe Pin 1 inhibitorjuglone attenuates kidney fibrogenesis via Pin 1-independentmechanisms in the unilateral ureteral occlusion modelrdquo Fibro-genesis amp Tissue Repair vol 3 article 1 2010

[11] H-L Xu X-F Yu S-C Qu et al ldquoAnti-proliferative effect ofJuglone from Juglans mandshurica Maxim on human leukemiacell HL-60 by inducing apoptosis through the mitochondria-dependent pathwayrdquo European Journal of Pharmacology vol645 no 1ndash3 pp 14ndash22 2010

[12] F Zakavi L G Hagh A Daraeighadikolaei A F Sheikh ADaraeighadikolaei and Z L Shooshtari ldquoAntibacterial effectof Juglans regia bark against oral pathologic bacteriardquo Interna-tional Journal of Dentistry vol 2013 Article ID 854765 5 pages2013

[13] V Chobot and FHadacek ldquoMilieu-dependent pro- and antioxi-dant activity of juglonemay explain linear and nonlinear effectson seedling developmentrdquo Journal of Chemical Ecology vol 35no 3 pp 383ndash390 2009

[14] R Jin ldquoADFT study on the radical scavenging activity of jugloneand its derivativesrdquo Journal of Molecular Structure vol 939 no1ndash3 pp 9ndash13 2010

[15] A L A Bentes R S Borges W R Monteiro L G M DeMacedo and C N Alves ldquoStructure of dihydrochalcones andrelated derivatives and their scavenging and antioxidant activityagainst oxygen and nitrogen radical speciesrdquoMolecules vol 16no 2 pp 1749ndash1760 2011

[16] M Leopoldini T Marino N Russo and M Toscano ldquoAntiox-idant properties of phenolic compounds H-atom versus elec-tron transfer mechanismrdquo Journal of Physical Chemistry A vol108 no 22 pp 4916ndash4922 2004

[17] M Leopoldini N Russo andM Toscano ldquoThemolecular basisof working mechanism of natural polyphenolic antioxidantsrdquoFood Chemistry vol 125 no 2 pp 288ndash306 2011

[18] A Galano G Mazzone R Alvarez-Diduk T Marino J RAlvarez-Idaboy andN Russo ldquoThe food antioxidants chemicalinsights at the molecular levelrdquo Annual Review of Food Scienceand Technology vol 7 no 1 pp 335ndash352 2016

[19] I Gulcin Z Huyut E Mahfuz and Y A Hassan ldquoRadicalscavenging and antioxidant activity of tannic acidrdquo ArabianJournal of Chemistry vol 3 no 1 pp 43ndash53 2010

[20] E A Decker J E Ryan and D J McClements Oxidation inFoods Andbeverages and Antioxidant Applications WoodheadPublishing Limited New Dehli India 2010

[21] M Leopoldini N Russo S Chiodo and M Toscano ldquoIronchelation by the powerful antioxidant flavonoid quercetinrdquoJournal of Agricultural and Food Chemistry vol 54 no 17 pp6343ndash6351 2006

[22] J J Fifen M Nsangou Z Dhaouadi O Motapon and SLahmar ldquoSingle or double hydrogen atom transfer in thereaction of metalmdashassociated phenolic acids with ∙OH radicalDFT studyrdquo Journal of Molecular Structure THEOCHEM vol901 no 1ndash3 pp 49ndash55 2009

[23] O Holtomo M Nsangou J J Fifen and O Motapon ldquoAntiox-idative potency and UV-Vis spectra features of the compoundsresulting from the chelation of Fe2+ by caffeic acid phenethylester and two of its derivativesrdquo Computational and TheoreticalChemistry vol 1067 pp 135ndash147 2015

[24] M Szeląg A Urbaniak and H A R Bluyssen ldquoA theoreti-cal antioxidant pharmacophore for natural hydroxycinnamicacidsrdquo Open Chemistry vol 13 no 1 pp 17ndash31 2015

[25] MMKabanda V T Tran KM Seema et al ldquoConformationalelectronic and antioxidant properties of lucidone linderone andmethyllinderone DFT QTAIM and NBO studiesrdquo MolecularPhysics vol 113 no 7 pp 683ndash697 2015

[26] E Lewars Computational Chemistry Introduction to theTheoryand Applications ofMolecular and QuantumMechanics KlumerAcademy Publishers New York NY USA 2003

[27] M J Frisch G W Trucks H B Schlegel et al Gaussian 09Revision A02 Gaussian Wallingford Conn USA 2009

[28] D D Roy A K Todd and M M John Gauss View 508Gaussian Wallingford Conn USA 2009

[29] F Jensen Introduction to Computational Chemistry JohnWileyamp Sons New York NY USA 1999

[30] J J Fifen M Nsangou Z Dhaouadi O Motapon and NJaidane ldquoSolvent effect on the antioxidant activity of 34-dihydroxyphenylpyruvic acid DFT and TD-DFT studyrdquo Jour-nal of Molecular Structure vol 966 pp 232ndash243 2011

[31] E Klein J Rimarcık and L Vladimır ldquoDFTB3LYP study ofthe OndashH bond dissociation enthalpies and proton affinities ofpara- andmeta-substituted phenols in water and benzenerdquoActaChimica Slovaca vol 2 no 2 pp 37ndash51 2009

[32] G Wang Y Xue L An et al ldquoTheoretical study on the struc-tural and antioxidant properties of some recently synthesised245-trimethoxy chalconesrdquo Food Chemistry vol 171 pp 89ndash97 2014

[33] K I Ramachandran G Deepa and K Namboori Com-putational Chemistryand Molecular Modeling Principles andApplications Springer Berlin Germany 2008

[34] X Gu T Fei H Zhang et al ldquoTheoretical studies of blue-emitting iridium complexes with different ancillary ligandsrdquoJournal of Physical Chemistry A vol 112 no 36 pp 8387ndash83932008

[35] F Zhao J-X Wang and Y-B Wang ldquoDFTTDDFT theoreticalstudies on electronic structures and spectral properties ofrhenium(I) phenanthrolineimidazo complexesrdquoComputationaland Theoretical Chemistry vol 973 no 1ndash3 pp 40ndash46 2011

[36] D C Young Computational Chemistry A Practical Guide forApplying Techniques to Real-World Problems John Wiley ampSons New York NY USA 2001

[37] E D Glendening R L Clark and F Weinhold ldquoNatural bondorbital methodsrdquoWIREs Computational Molecular Science vol2 pp 1ndash42 2012

[38] R F W Bader Atoms in Molecules A QuantumTheory OxfordUniversity Press Oxford UK 1990


[39] T Lu and F Chen ldquoCalculation of molecular orbital composi-tionrdquo Acta Chimica Sinica vol 69 no 20 pp 2393ndash2406 2011

[40] J Rimarcık V Lukes E Klein and M Ilcin ldquoStudy ofthe solvent effect on the enthalpies of homolytic and het-erolytic NndashH bond cleavage in p-phenylenediamine and te-tracyano-p-phenylenediaminerdquo Journal of Molecular StructureTHEOCHEM vol 952 no 1ndash3 pp 25ndash30 2010

[41] DMikulski K Eder andMMolski ldquoQuantum-chemical studyon relationship between structure and antioxidant properties ofhepatoprotective compounds occurring inCynara scolymus andSilybum marianumrdquo Journal of Theoretical and ComputationalChemistry vol 13 no 1 Article ID 1450004 pp 1ndash24 2014

[42] R Renjith Y S Mary C Y Panicker et al ldquoSpectroscopic (FT-IR FT-Raman) first order hyperpolarizability NBO analysisHOMO and LUMO analysis of 1789-tetrachloro-1010-dime-thoxy-4-[3-(4-phenylpiperazin-1-yl)propyl]-4-azatricyclo[521026]dec-8-ene-35- dione by density functional methodsrdquoSpectrochimica ActamdashPart A Molecular and Biomolecular Spec-troscopy vol 124 pp 500ndash513 2014

[43] M Martınez-Cifuentes B E Weiss-Lopez L S Santos and RAraya-Maturana ldquoIntramolecular hydrogen bond in biologi-cally active O-carbonyl hydroquinonesrdquo Molecules vol 19 no7 pp 9354ndash9368 2014

[44] G V Baryshnikov B F Minaev V A Minaeva A T Podgor-naya and H Agren ldquoApplication of Baderrsquos atoms in moleculestheory to the description of coordination bonds in the complexcompounds of Ca2+ andMg2+ withmethylidene rhodanine andits anionrdquo Russian Journal of General Chemistry vol 82 no 7pp 1254ndash1262 2012

Submit your manuscripts athttpwwwhindawicom

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Inorganic ChemistryInternational Journal of

Hindawi Publishing Corporation httpwwwhindawicom Volume 2014

International Journal ofPhotoenergy


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Chemistry


Advances in

Physical Chemistry

Hindawi Publishing Corporationhttpwwwhindawicom

Analytical Methods in Chemistry

Journal of

Volume 2014

Bioinorganic Chemistry and ApplicationsHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

SpectroscopyInternational Journal of


The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Medicinal ChemistryInternational Journal of


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Applied ChemistryJournal of



Theoretical ChemistryJournal of


Journal of

Spectroscopy

Analytical ChemistryInternational Journal of


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Organic Chemistry International

ElectrochemistryInternational Journal of



CatalystsJournal of


degrading the quality of foods and causing several diseases[20] Antioxidants are well known radical scavengers that arelargely used to fight against these negative effects of free rad-icals via the above mentioned mechanism Besides removalof the metals metal-chelating compounds can also alter theirredox potentials rendering them inactive The use of naturalmetal chelators instead of the synthetic counterparts whichmay present some toxicity problems should be encouraged[21] Several experimental and theoretical studies have beendevoted to the elucidation of the metal-chelation mechanismof AOA [19 21ndash25]

It has been demonstrated experimentally that depro-tonated juglone has the capacity to chelate Fe2+ [13] ATheoretical study to complement this experimental resultis warranted To the best of our knowledge no such the-oretical work exists in the literature In this paper we aimto investigate the Fe2+ chelating ability of neutral jugloneand two of its derivatives (shown in Figure 1) as well asevaluate theAOAof the resulting compounds by themeans ofdensity functional theory (DFT) [26] This work is thereforeexpected to contribute toward the development of newantioxidants which has been the ambition that has attracteda great deal of researchersrsquo attention in recent years owingto the significance of antioxidants in biological processesas well as the processes in the food pharmaceutical andmaterial industries Specifically the chelation of Fe2+ by threeantioxidants in their neutral forms is studied at DFTB3LYPlevel theory The main antioxidant studied is juglone (L

1)

and the rest are its derivatives obtained by replacing thehydrogen atom ortho to the hydroxyl group of juglone eitherbyOH (L

2) or byCN (L

3) groups which are electron donating

(EDG) and withdrawing (EWG) groups respectively Thestructural and electronic parameters of the resulting chelatesor complexes have been analyzed followed by the evaluationof the AOA of all compounds studied (Figure 1) by means ofbond dissociation enthalpy (BDE) ionization potential (IP)proton dissociation enthalpy (PDE) proton affinity (PA) andelectron transfer enthalpy (ETE) [17 18] Our main objectivehere is to study the effect of iron(II) chelation on the AOA ofthe three ligands (L

1 L2 and L

3)

2 Computational Details andTheoretical Background

21 Computational Details All calculations were carried outusingGaussian 09W [27]The input structures were preparedusing the GaussView 508 program [28] The DFT methodwhich was designed especially for the study of coordinationcompounds [24] was associated with the B3LYP hybridfunctional in this research endeavor [29] In addition DFThas been chosen because it has been used successfully tostudy radical scavenging activities of phenolic compounds[30ndash32] Also when compared to ab initio methods DFT isvery rapid and is often said to ally precision and the rapidity[33] Faced with limited computational resources and largemolecular sizes we used a mixed basis set comprising the6-31Glowast basis for the central metal ion and the 6-31+Glowastlowastbasis for every other element in the molecules studied Inaddition mixed basis sets have been recently employed for

many studies on complexes and have been shown to speed upcalculations without altering the quality of theoretical results[21 34 35] All computations on the closed shell systems wereperformed using the Restricted Kohn-Sham formalism whilethe Unrestricted Kohn-Sham formalismwas adopted in openshell systems in order to reduce spin contamination [36]Ground-state geometries for all complexes have been fullyoptimized without any symmetry constraints Vibrationalfrequency calculations have further been undertaken on theoptimized geometries in order to confirm that the resultingequilibriumgeometrieswereminima (nonegative frequency)on the potential energy surface Central metal-ligand chargetransfer was evaluated by means of Natural Bond Orbital(NBO) analysis [37] as implemented in Gaussian 09 TheQuantum Theory of Atom in Molecules (QTAIM) proposedby Bader [38] was used to evaluate the nature of all metal-ligand bonds with the aim of determining their degree ofcovalency QTAIM analysis was performed as implementedin multiwfn [39]

22 Theoretical Background The chelates [FeL119894]2+ (119894 = 1 2

and 3) (Figure 1) optimized in this work are presumed to beformed according to

Fe2+ + L119894997888rarr [FeL

119894]2+ (1)

The complexes [FeL119894(X)4]2+ (119894 = 1 2 and 3 and X =H

2O or

CH3OH) are presumed to be formed according to

Fe2+ + L119894+ 4X 997888rarr [FeL

119894(X)4]2+ (2)

The use of water and methanol molecules as other ligands isbecause of the difficulty to find isolated form of Fe2+ and theabundance of such polar molecules in organisms [23]

The effect of multiplicity on the stability of all the ninechelates and complexes resulting from both (1) and (2) aspresented in Figure 1 was first investigated This was donevia geometry optimizations of all the input structures inthe singlet and quintet states based on the possible numberof unpaired electrons of the central Fe2+ ion in orderto determine the geometry with the lowest ground-stateenergy The binding energies (Δ119864int) free energies (Δ119866) andenthalpies (Δ119867) of formation of the most stable geometriesat standard conditions were calculated as follows

Δ119864int = 119864comp minus 119864L minus 4119864X minus 119864Fe2+ (3)



In these equations119864119867 and119866 stand for the thermal energiesenthalpies and free energies of formation of the respectivespecies Due to the absence of X ligands in the chelates 119864X119867X and 119866X terms are nonexistent in their expressions forΔ119864int Δ119867 and Δ119866

Using the most stable optimized geometry of each com-pound the usual schemes of hydrogen transfer by antiox-idants and the related parameters were calculated Theseinclude the following


22

2

2

112 1

1

1

3A

3B2B

2A1A

1B

1C

2

2

1

1

3C2C

2

2

1

1

X1

X2

X3

X4

X4

X4

X1

X1

X2

X3

X4

X1

X2

X3

X4

X1

X2X3

X2

X3

X4

X1

X2X3



X-H 997888rarr X∙ +H∙ (6)





X-H+∙ 997888rarr X∙ +H+ (10)













1)]2+ 1A minus187321293208 minus187312426700

[Fe(L1)(OH

2)4]2+ 1B minus217923172776 minus217898173479


[Fe(L2)]2+ 2A minus194845209999 minus194833220631

[Fe(L2)(OH

2)4]2+ 2B minus225413720775 minus225418434320


[Fe(L3)]2+ 3A minus196522170297 minus196531620465

[Fe(L3)(OH

2)4]2+ 3B minus227113120555 minus227117906337



1(juglone) L

2(the derivative



2O and MeOH are











2has the highest




















1-Fe














O1-H O

1-Fe O

2-Fe X

1-Fe X

2-Fe X

3-Fe X

4-Fe



2B 09910976lowast 2145 1994 2088 2145 2140 2139

2C 09770969lowast 2221 2010 2196 2117 2186 2137








1-







1-H bond






any hydrogen bond










1-H bond is longer













2




1-H group is weaker






1-H





1A 608 575 1919 1917 6 minus23 1014 910 1041 10381B 1001 977 2132 2142 186 154 793 629 1710 17201C 233 211 1299 1309 251 222 898 679 897 904

L2

380359lowast

341323lowast 805 795 892 874 1377


319314lowast

315312lowast

2A 111798lowast



4141107lowast

4071104lowast

2B 271358lowast

250327lowast 1338 1351 251 218 868


9281016lowast

9371009lowast

2C 12401324lowast

12171301lowast 2255 2273 245 262 1904


908993lowast

910994lowast

L3 421 381 874 863 864 828 1366 1353 371 368




2







1 L2 and L










BDFEIPFEPAFE

L1 L2

0200400600800

10001200140016001800200022002400

Ther

mod

ynam

ic p

aram

eter

s (kJ

mol

)

L3






1-H group of all L










O

O

O

CN

Fe

O

O

OH

O

Fe

O

O

O

Fe

O

O

O

OH

Fe

OO

O

Fe

OO

O

Fe

OH

OO

OH

Fe

O

OO

O

Fe

OO

O

Fe

OH

OO

O

Fe

CN

028

032017

009

015

026

207

009008

008

199

018003

017 002

384

031010

029

016

020

011006 015022

010

003001

004

206

077

010

025

018009

016021

011003

093

006

001

004

003

004

004

001

407

022 0

02

006

011

025

004

002

008

004

001

001

430

007

005

006

004

001

002

003

010

025

005

004

004

004

390

013

020

012029

015

024

002006 001009

004

002

001

001

001064

009

428

007

005

006

001 011

027

003

005

005

005

005

003

005

423

008

025005

003008

002

004

009 008

004

004

004

004

004

OO

O

Fe

CN

004

004

004

003

427

010

006

008001

008

005

002

011

029

002

004

1A 2A 3A

1B 2B

2C 3A

OO

OH

Fe

O

390

0 10028

024

015

003

040

018

009

002

002014

005

044

001

002

002

002

3B

3C

2Alowast

2Blowast

3Blowast

OH2

OH2

OH2

OH2

OH2

OH2

OH2

OH2

OH2

OH2

OH2

OH2

OH2

OH2

OH2

OH2

HOCH3

HOCH3

HOCH3

HOCH3

HOCH3

OHCH3

OHCH3

OHCH3OHCH3

OHCH3OHCH3

HOCH3

OHCH3

HOCH3

OHCH3

HOCH3



119864(2)= minus119902119894

(119865119894119895)

120576119895minus 120576119894

(16)










(2) (kJmol)

1A 145 LP(2) O1





1B 117

LP(2) O1





LP(2) O2





1C 146

LP(2) O1





LP(2) O2





2A 133LP(2) O


2LPlowast(6) Fe 873

LP(2) O2





2B 143

LP(2) O1





LP(1) O2





2C 151

LP(2) O1





LP(1) O2





3A 166 LP(2) O1




3B 117

LP(2) O2





LP(1) O1





3C 120

LP(2) O2




2LPlowast(5) Fe 953

LP(1) O1




4LPlowast(2) Fe 793











Parameter O1-H1

O1-Fe O

2-Fe X

1-Fe X

2-Fe X

3-Fe X

4-Fe



1B120588(119903) 0353 0637 0354 0056 0057 0058 0058nabla2120588(119903) minus2123 0541 0061 0436 0454 0440 0446

minus119866(119903)V(119903) 0097 1071 0506 1061 1069 1056 1060

1C120588(119903) 0327 0048 0075 0054 0062 0049 0058nabla2120588(119903) minus1576 0213 0464 0278 0313 0227 0297

minus119866(119903)V(119903) 0116 0093 0987 0949 0960 0922 0947

2A


nabla2120588(119903)



2B

120588(119903)0310 0052 0076 0060 0053 0053 00530388lowast

nabla2120588(119903)


minus119866(119903)V(119903) 0113 0951 0980 0972 0956 0956 09500004lowast

2C

120588(119903)0347 0044 0073 0047 0057 0048 00540355lowast

nabla2120588(119903)


minus119866(119903)V(119903) 0099 0918 0981 0925 0946 0926 09460099lowast



3B120588(119903) 0316 0050 0077 0060 0053 0054 0053nabla2120588(119903) minus1511 0239 0451 0328 0239 0286 0284

minus119866(119903)V(119903) 0117 0943 0983 0972 0950 0958 0957





1-Fe bond of 1A



1-Fe bond




119894-Fe (119894 = 1 and 2) bonds



1-





3revealed the







4 Conclusion


2O or



1 L2 and L

3



2O or CH








all the O1-Fe and O





2and L

3 that of L

1instead increases







3and the C atom




Competing Interests


Acknowledgments


References
























































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of


22

2

2

112 1

1

1

3A

3B2B

2A1A

1B

1C

2

2

1

1

3C2C

2

2

1

1

X1

X2

X3

X4

X4

X4

X1

X1

X2

X3

X4

X1

X2

X3

X4

X1

X2X3

X2

X3

X4

X1

X2X3



X-H 997888rarr X∙ +H∙ (6)





X-H+∙ 997888rarr X∙ +H+ (10)













1)]2+ 1A minus187321293208 minus187312426700

[Fe(L1)(OH

2)4]2+ 1B minus217923172776 minus217898173479


[Fe(L2)]2+ 2A minus194845209999 minus194833220631

[Fe(L2)(OH

2)4]2+ 2B minus225413720775 minus225418434320


[Fe(L3)]2+ 3A minus196522170297 minus196531620465

[Fe(L3)(OH

2)4]2+ 3B minus227113120555 minus227117906337



1(juglone) L

2(the derivative



2O and MeOH are











2has the highest




















1-Fe














O1-H O

1-Fe O

2-Fe X

1-Fe X

2-Fe X

3-Fe X

4-Fe



2B 09910976lowast 2145 1994 2088 2145 2140 2139

2C 09770969lowast 2221 2010 2196 2117 2186 2137








1-







1-H bond






any hydrogen bond










1-H bond is longer













2




1-H group is weaker






1-H





1A 608 575 1919 1917 6 minus23 1014 910 1041 10381B 1001 977 2132 2142 186 154 793 629 1710 17201C 233 211 1299 1309 251 222 898 679 897 904

L2

380359lowast

341323lowast 805 795 892 874 1377


319314lowast

315312lowast

2A 111798lowast



4141107lowast

4071104lowast

2B 271358lowast

250327lowast 1338 1351 251 218 868


9281016lowast

9371009lowast

2C 12401324lowast

12171301lowast 2255 2273 245 262 1904


908993lowast

910994lowast

L3 421 381 874 863 864 828 1366 1353 371 368




2







1 L2 and L










BDFEIPFEPAFE

L1 L2

0200400600800

10001200140016001800200022002400

Ther

mod

ynam

ic p

aram

eter

s (kJ

mol

)

L3






1-H group of all L










O

O

O

CN

Fe

O

O

OH

O

Fe

O

O

O

Fe

O

O

O

OH

Fe

OO

O

Fe

OO

O

Fe

OH

OO

OH

Fe

O

OO

O

Fe

OO

O

Fe

OH

OO

O

Fe

CN

028

032017

009

015

026

207

009008

008

199

018003

017 002

384

031010

029

016

020

011006 015022

010

003001

004

206

077

010

025

018009

016021

011003

093

006

001

004

003

004

004

001

407

022 0

02

006

011

025

004

002

008

004

001

001

430

007

005

006

004

001

002

003

010

025

005

004

004

004

390

013

020

012029

015

024

002006 001009

004

002

001

001

001064

009

428

007

005

006

001 011

027

003

005

005

005

005

003

005

423

008

025005

003008

002

004

009 008

004

004

004

004

004

OO

O

Fe

CN

004

004

004

003

427

010

006

008001

008

005

002

011

029

002

004

1A 2A 3A

1B 2B

2C 3A

OO

OH

Fe

O

390

0 10028

024

015

003

040

018

009

002

002014

005

044

001

002

002

002

3B

3C

2Alowast

2Blowast

3Blowast

OH2

OH2

OH2

OH2

OH2

OH2

OH2

OH2

OH2

OH2

OH2

OH2

OH2

OH2

OH2

OH2

HOCH3

HOCH3

HOCH3

HOCH3

HOCH3

OHCH3

OHCH3

OHCH3OHCH3

OHCH3OHCH3

HOCH3

OHCH3

HOCH3

OHCH3

HOCH3



119864(2)= minus119902119894

(119865119894119895)

120576119895minus 120576119894

(16)










(2) (kJmol)

1A 145 LP(2) O1





1B 117

LP(2) O1





LP(2) O2





1C 146

LP(2) O1





LP(2) O2





2A 133LP(2) O


2LPlowast(6) Fe 873

LP(2) O2





2B 143

LP(2) O1





LP(1) O2





2C 151

LP(2) O1





LP(1) O2





3A 166 LP(2) O1




3B 117

LP(2) O2





LP(1) O1





3C 120

LP(2) O2




2LPlowast(5) Fe 953

LP(1) O1




4LPlowast(2) Fe 793











Parameter O1-H1

O1-Fe O

2-Fe X

1-Fe X

2-Fe X

3-Fe X

4-Fe



1B120588(119903) 0353 0637 0354 0056 0057 0058 0058nabla2120588(119903) minus2123 0541 0061 0436 0454 0440 0446

minus119866(119903)V(119903) 0097 1071 0506 1061 1069 1056 1060

1C120588(119903) 0327 0048 0075 0054 0062 0049 0058nabla2120588(119903) minus1576 0213 0464 0278 0313 0227 0297

minus119866(119903)V(119903) 0116 0093 0987 0949 0960 0922 0947

2A


nabla2120588(119903)



2B

120588(119903)0310 0052 0076 0060 0053 0053 00530388lowast

nabla2120588(119903)


minus119866(119903)V(119903) 0113 0951 0980 0972 0956 0956 09500004lowast

2C

120588(119903)0347 0044 0073 0047 0057 0048 00540355lowast

nabla2120588(119903)


minus119866(119903)V(119903) 0099 0918 0981 0925 0946 0926 09460099lowast



3B120588(119903) 0316 0050 0077 0060 0053 0054 0053nabla2120588(119903) minus1511 0239 0451 0328 0239 0286 0284

minus119866(119903)V(119903) 0117 0943 0983 0972 0950 0958 0957





1-Fe bond of 1A



1-Fe bond




119894-Fe (119894 = 1 and 2) bonds



1-





3revealed the







4 Conclusion


2O or



1 L2 and L

3



2O or CH








all the O1-Fe and O





2and L

3 that of L

1instead increases







3and the C atom




Competing Interests


Acknowledgments


References
























































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of




1)]2+ 1A minus187321293208 minus187312426700

[Fe(L1)(OH

2)4]2+ 1B minus217923172776 minus217898173479


[Fe(L2)]2+ 2A minus194845209999 minus194833220631

[Fe(L2)(OH

2)4]2+ 2B minus225413720775 minus225418434320


[Fe(L3)]2+ 3A minus196522170297 minus196531620465

[Fe(L3)(OH

2)4]2+ 3B minus227113120555 minus227117906337



1(juglone) L

2(the derivative



2O and MeOH are











2has the highest




















1-Fe














O1-H O

1-Fe O

2-Fe X

1-Fe X

2-Fe X

3-Fe X

4-Fe



2B 09910976lowast 2145 1994 2088 2145 2140 2139

2C 09770969lowast 2221 2010 2196 2117 2186 2137








1-







1-H bond






any hydrogen bond










1-H bond is longer













2




1-H group is weaker






1-H





1A 608 575 1919 1917 6 minus23 1014 910 1041 10381B 1001 977 2132 2142 186 154 793 629 1710 17201C 233 211 1299 1309 251 222 898 679 897 904

L2

380359lowast

341323lowast 805 795 892 874 1377


319314lowast

315312lowast

2A 111798lowast



4141107lowast

4071104lowast

2B 271358lowast

250327lowast 1338 1351 251 218 868


9281016lowast

9371009lowast

2C 12401324lowast

12171301lowast 2255 2273 245 262 1904


908993lowast

910994lowast

L3 421 381 874 863 864 828 1366 1353 371 368




2







1 L2 and L










BDFEIPFEPAFE

L1 L2

0200400600800

10001200140016001800200022002400

Ther

mod

ynam

ic p

aram

eter

s (kJ

mol

)

L3






1-H group of all L










O

O

O

CN

Fe

O

O

OH

O

Fe

O

O

O

Fe

O

O

O

OH

Fe

OO

O

Fe

OO

O

Fe

OH

OO

OH

Fe

O

OO

O

Fe

OO

O

Fe

OH

OO

O

Fe

CN

028

032017

009

015

026

207

009008

008

199

018003

017 002

384

031010

029

016

020

011006 015022

010

003001

004

206

077

010

025

018009

016021

011003

093

006

001

004

003

004

004

001

407

022 0

02

006

011

025

004

002

008

004

001

001

430

007

005

006

004

001

002

003

010

025

005

004

004

004

390

013

020

012029

015

024

002006 001009

004

002

001

001

001064

009

428

007

005

006

001 011

027

003

005

005

005

005

003

005

423

008

025005

003008

002

004

009 008

004

004

004

004

004

OO

O

Fe

CN

004

004

004

003

427

010

006

008001

008

005

002

011

029

002

004

1A 2A 3A

1B 2B

2C 3A

OO

OH

Fe

O

390

0 10028

024

015

003

040

018

009

002

002014

005

044

001

002

002

002

3B

3C

2Alowast

2Blowast

3Blowast

OH2

OH2

OH2

OH2

OH2

OH2

OH2

OH2

OH2

OH2

OH2

OH2

OH2

OH2

OH2

OH2

HOCH3

HOCH3

HOCH3

HOCH3

HOCH3

OHCH3

OHCH3

OHCH3OHCH3

OHCH3OHCH3

HOCH3

OHCH3

HOCH3

OHCH3

HOCH3



119864(2)= minus119902119894

(119865119894119895)

120576119895minus 120576119894

(16)










(2) (kJmol)

1A 145 LP(2) O1





1B 117

LP(2) O1





LP(2) O2





1C 146

LP(2) O1





LP(2) O2





2A 133LP(2) O


2LPlowast(6) Fe 873

LP(2) O2





2B 143

LP(2) O1





LP(1) O2





2C 151

LP(2) O1





LP(1) O2





3A 166 LP(2) O1




3B 117

LP(2) O2





LP(1) O1





3C 120

LP(2) O2




2LPlowast(5) Fe 953

LP(1) O1




4LPlowast(2) Fe 793











Parameter O1-H1

O1-Fe O

2-Fe X

1-Fe X

2-Fe X

3-Fe X

4-Fe



1B120588(119903) 0353 0637 0354 0056 0057 0058 0058nabla2120588(119903) minus2123 0541 0061 0436 0454 0440 0446

minus119866(119903)V(119903) 0097 1071 0506 1061 1069 1056 1060

1C120588(119903) 0327 0048 0075 0054 0062 0049 0058nabla2120588(119903) minus1576 0213 0464 0278 0313 0227 0297

minus119866(119903)V(119903) 0116 0093 0987 0949 0960 0922 0947

2A


nabla2120588(119903)



2B

120588(119903)0310 0052 0076 0060 0053 0053 00530388lowast

nabla2120588(119903)


minus119866(119903)V(119903) 0113 0951 0980 0972 0956 0956 09500004lowast

2C

120588(119903)0347 0044 0073 0047 0057 0048 00540355lowast

nabla2120588(119903)


minus119866(119903)V(119903) 0099 0918 0981 0925 0946 0926 09460099lowast



3B120588(119903) 0316 0050 0077 0060 0053 0054 0053nabla2120588(119903) minus1511 0239 0451 0328 0239 0286 0284

minus119866(119903)V(119903) 0117 0943 0983 0972 0950 0958 0957





1-Fe bond of 1A



1-Fe bond




119894-Fe (119894 = 1 and 2) bonds



1-





3revealed the







4 Conclusion


2O or



1 L2 and L

3



2O or CH








all the O1-Fe and O





2and L

3 that of L

1instead increases







3and the C atom




Competing Interests


Acknowledgments


References
























































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of



O1-H O

1-Fe O

2-Fe X

1-Fe X

2-Fe X

3-Fe X

4-Fe



2B 09910976lowast 2145 1994 2088 2145 2140 2139

2C 09770969lowast 2221 2010 2196 2117 2186 2137








1-







1-H bond






any hydrogen bond










1-H bond is longer













2




1-H group is weaker






1-H





1A 608 575 1919 1917 6 minus23 1014 910 1041 10381B 1001 977 2132 2142 186 154 793 629 1710 17201C 233 211 1299 1309 251 222 898 679 897 904

L2

380359lowast

341323lowast 805 795 892 874 1377


319314lowast

315312lowast

2A 111798lowast



4141107lowast

4071104lowast

2B 271358lowast

250327lowast 1338 1351 251 218 868


9281016lowast

9371009lowast

2C 12401324lowast

12171301lowast 2255 2273 245 262 1904


908993lowast

910994lowast

L3 421 381 874 863 864 828 1366 1353 371 368




2







1 L2 and L










BDFEIPFEPAFE

L1 L2

0200400600800

10001200140016001800200022002400

Ther

mod

ynam

ic p

aram

eter

s (kJ

mol

)

L3






1-H group of all L










O

O

O

CN

Fe

O

O

OH

O

Fe

O

O

O

Fe

O

O

O

OH

Fe

OO

O

Fe

OO

O

Fe

OH

OO

OH

Fe

O

OO

O

Fe

OO

O

Fe

OH

OO

O

Fe

CN

028

032017

009

015

026

207

009008

008

199

018003

017 002

384

031010

029

016

020

011006 015022

010

003001

004

206

077

010

025

018009

016021

011003

093

006

001

004

003

004

004

001

407

022 0

02

006

011

025

004

002

008

004

001

001

430

007

005

006

004

001

002

003

010

025

005

004

004

004

390

013

020

012029

015

024

002006 001009

004

002

001

001

001064

009

428

007

005

006

001 011

027

003

005

005

005

005

003

005

423

008

025005

003008

002

004

009 008

004

004

004

004

004

OO

O

Fe

CN

004

004

004

003

427

010

006

008001

008

005

002

011

029

002

004

1A 2A 3A

1B 2B

2C 3A

OO

OH

Fe

O

390

0 10028

024

015

003

040

018

009

002

002014

005

044

001

002

002

002

3B

3C

2Alowast

2Blowast

3Blowast

OH2

OH2

OH2

OH2

OH2

OH2

OH2

OH2

OH2

OH2

OH2

OH2

OH2

OH2

OH2

OH2

HOCH3

HOCH3

HOCH3

HOCH3

HOCH3

OHCH3

OHCH3

OHCH3OHCH3

OHCH3OHCH3

HOCH3

OHCH3

HOCH3

OHCH3

HOCH3



119864(2)= minus119902119894

(119865119894119895)

120576119895minus 120576119894

(16)










(2) (kJmol)

1A 145 LP(2) O1





1B 117

LP(2) O1





LP(2) O2





1C 146

LP(2) O1





LP(2) O2





2A 133LP(2) O


2LPlowast(6) Fe 873

LP(2) O2





2B 143

LP(2) O1





LP(1) O2





2C 151

LP(2) O1





LP(1) O2





3A 166 LP(2) O1




3B 117

LP(2) O2





LP(1) O1





3C 120

LP(2) O2




2LPlowast(5) Fe 953

LP(1) O1




4LPlowast(2) Fe 793











Parameter O1-H1

O1-Fe O

2-Fe X

1-Fe X

2-Fe X

3-Fe X

4-Fe



1B120588(119903) 0353 0637 0354 0056 0057 0058 0058nabla2120588(119903) minus2123 0541 0061 0436 0454 0440 0446

minus119866(119903)V(119903) 0097 1071 0506 1061 1069 1056 1060

1C120588(119903) 0327 0048 0075 0054 0062 0049 0058nabla2120588(119903) minus1576 0213 0464 0278 0313 0227 0297

minus119866(119903)V(119903) 0116 0093 0987 0949 0960 0922 0947

2A


nabla2120588(119903)



2B

120588(119903)0310 0052 0076 0060 0053 0053 00530388lowast

nabla2120588(119903)


minus119866(119903)V(119903) 0113 0951 0980 0972 0956 0956 09500004lowast

2C

120588(119903)0347 0044 0073 0047 0057 0048 00540355lowast

nabla2120588(119903)


minus119866(119903)V(119903) 0099 0918 0981 0925 0946 0926 09460099lowast



3B120588(119903) 0316 0050 0077 0060 0053 0054 0053nabla2120588(119903) minus1511 0239 0451 0328 0239 0286 0284

minus119866(119903)V(119903) 0117 0943 0983 0972 0950 0958 0957





1-Fe bond of 1A



1-Fe bond




119894-Fe (119894 = 1 and 2) bonds



1-





3revealed the







4 Conclusion


2O or



1 L2 and L

3



2O or CH








all the O1-Fe and O





2and L

3 that of L

1instead increases







3and the C atom




Competing Interests


Acknowledgments


References
























































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of




1A 608 575 1919 1917 6 minus23 1014 910 1041 10381B 1001 977 2132 2142 186 154 793 629 1710 17201C 233 211 1299 1309 251 222 898 679 897 904

L2

380359lowast

341323lowast 805 795 892 874 1377


319314lowast

315312lowast

2A 111798lowast



4141107lowast

4071104lowast

2B 271358lowast

250327lowast 1338 1351 251 218 868


9281016lowast

9371009lowast

2C 12401324lowast

12171301lowast 2255 2273 245 262 1904


908993lowast

910994lowast

L3 421 381 874 863 864 828 1366 1353 371 368




2







1 L2 and L










BDFEIPFEPAFE

L1 L2

0200400600800

10001200140016001800200022002400

Ther

mod

ynam

ic p

aram

eter

s (kJ

mol

)

L3






1-H group of all L










O

O

O

CN

Fe

O

O

OH

O

Fe

O

O

O

Fe

O

O

O

OH

Fe

OO

O

Fe

OO

O

Fe

OH

OO

OH

Fe

O

OO

O

Fe

OO

O

Fe

OH

OO

O

Fe

CN

028

032017

009

015

026

207

009008

008

199

018003

017 002

384

031010

029

016

020

011006 015022

010

003001

004

206

077

010

025

018009

016021

011003

093

006

001

004

003

004

004

001

407

022 0

02

006

011

025

004

002

008

004

001

001

430

007

005

006

004

001

002

003

010

025

005

004

004

004

390

013

020

012029

015

024

002006 001009

004

002

001

001

001064

009

428

007

005

006

001 011

027

003

005

005

005

005

003

005

423

008

025005

003008

002

004

009 008

004

004

004

004

004

OO

O

Fe

CN

004

004

004

003

427

010

006

008001

008

005

002

011

029

002

004

1A 2A 3A

1B 2B

2C 3A

OO

OH

Fe

O

390

0 10028

024

015

003

040

018

009

002

002014

005

044

001

002

002

002

3B

3C

2Alowast

2Blowast

3Blowast

OH2

OH2

OH2

OH2

OH2

OH2

OH2

OH2

OH2

OH2

OH2

OH2

OH2

OH2

OH2

OH2

HOCH3

HOCH3

HOCH3

HOCH3

HOCH3

OHCH3

OHCH3

OHCH3OHCH3

OHCH3OHCH3

HOCH3

OHCH3

HOCH3

OHCH3

HOCH3



119864(2)= minus119902119894

(119865119894119895)

120576119895minus 120576119894

(16)










(2) (kJmol)

1A 145 LP(2) O1





1B 117

LP(2) O1





LP(2) O2





1C 146

LP(2) O1





LP(2) O2





2A 133LP(2) O


2LPlowast(6) Fe 873

LP(2) O2





2B 143

LP(2) O1





LP(1) O2





2C 151

LP(2) O1





LP(1) O2





3A 166 LP(2) O1




3B 117

LP(2) O2





LP(1) O1





3C 120

LP(2) O2




2LPlowast(5) Fe 953

LP(1) O1




4LPlowast(2) Fe 793











Parameter O1-H1

O1-Fe O

2-Fe X

1-Fe X

2-Fe X

3-Fe X

4-Fe



1B120588(119903) 0353 0637 0354 0056 0057 0058 0058nabla2120588(119903) minus2123 0541 0061 0436 0454 0440 0446

minus119866(119903)V(119903) 0097 1071 0506 1061 1069 1056 1060

1C120588(119903) 0327 0048 0075 0054 0062 0049 0058nabla2120588(119903) minus1576 0213 0464 0278 0313 0227 0297

minus119866(119903)V(119903) 0116 0093 0987 0949 0960 0922 0947

2A


nabla2120588(119903)



2B

120588(119903)0310 0052 0076 0060 0053 0053 00530388lowast

nabla2120588(119903)


minus119866(119903)V(119903) 0113 0951 0980 0972 0956 0956 09500004lowast

2C

120588(119903)0347 0044 0073 0047 0057 0048 00540355lowast

nabla2120588(119903)


minus119866(119903)V(119903) 0099 0918 0981 0925 0946 0926 09460099lowast



3B120588(119903) 0316 0050 0077 0060 0053 0054 0053nabla2120588(119903) minus1511 0239 0451 0328 0239 0286 0284

minus119866(119903)V(119903) 0117 0943 0983 0972 0950 0958 0957





1-Fe bond of 1A



1-Fe bond




119894-Fe (119894 = 1 and 2) bonds



1-





3revealed the







4 Conclusion


2O or



1 L2 and L

3



2O or CH








all the O1-Fe and O





2and L

3 that of L

1instead increases







3and the C atom




Competing Interests


Acknowledgments


References
























































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of



BDFEIPFEPAFE

L1 L2

0200400600800

10001200140016001800200022002400

Ther

mod

ynam

ic p

aram

eter

s (kJ

mol

)

L3






1-H group of all L










O

O

O

CN

Fe

O

O

OH

O

Fe

O

O

O

Fe

O

O

O

OH

Fe

OO

O

Fe

OO

O

Fe

OH

OO

OH

Fe

O

OO

O

Fe

OO

O

Fe

OH

OO

O

Fe

CN

028

032017

009

015

026

207

009008

008

199

018003

017 002

384

031010

029

016

020

011006 015022

010

003001

004

206

077

010

025

018009

016021

011003

093

006

001

004

003

004

004

001

407

022 0

02

006

011

025

004

002

008

004

001

001

430

007

005

006

004

001

002

003

010

025

005

004

004

004

390

013

020

012029

015

024

002006 001009

004

002

001

001

001064

009

428

007

005

006

001 011

027

003

005

005

005

005

003

005

423

008

025005

003008

002

004

009 008

004

004

004

004

004

OO

O

Fe

CN

004

004

004

003

427

010

006

008001

008

005

002

011

029

002

004

1A 2A 3A

1B 2B

2C 3A

OO

OH

Fe

O

390

0 10028

024

015

003

040

018

009

002

002014

005

044

001

002

002

002

3B

3C

2Alowast

2Blowast

3Blowast

OH2

OH2

OH2

OH2

OH2

OH2

OH2

OH2

OH2

OH2

OH2

OH2

OH2

OH2

OH2

OH2

HOCH3

HOCH3

HOCH3

HOCH3

HOCH3

OHCH3

OHCH3

OHCH3OHCH3

OHCH3OHCH3

HOCH3

OHCH3

HOCH3

OHCH3

HOCH3



119864(2)= minus119902119894

(119865119894119895)

120576119895minus 120576119894

(16)










(2) (kJmol)

1A 145 LP(2) O1





1B 117

LP(2) O1





LP(2) O2





1C 146

LP(2) O1





LP(2) O2





2A 133LP(2) O


2LPlowast(6) Fe 873

LP(2) O2





2B 143

LP(2) O1





LP(1) O2





2C 151

LP(2) O1





LP(1) O2





3A 166 LP(2) O1




3B 117

LP(2) O2





LP(1) O1





3C 120

LP(2) O2




2LPlowast(5) Fe 953

LP(1) O1




4LPlowast(2) Fe 793











Parameter O1-H1

O1-Fe O

2-Fe X

1-Fe X

2-Fe X

3-Fe X

4-Fe



1B120588(119903) 0353 0637 0354 0056 0057 0058 0058nabla2120588(119903) minus2123 0541 0061 0436 0454 0440 0446

minus119866(119903)V(119903) 0097 1071 0506 1061 1069 1056 1060

1C120588(119903) 0327 0048 0075 0054 0062 0049 0058nabla2120588(119903) minus1576 0213 0464 0278 0313 0227 0297

minus119866(119903)V(119903) 0116 0093 0987 0949 0960 0922 0947

2A


nabla2120588(119903)



2B

120588(119903)0310 0052 0076 0060 0053 0053 00530388lowast

nabla2120588(119903)


minus119866(119903)V(119903) 0113 0951 0980 0972 0956 0956 09500004lowast

2C

120588(119903)0347 0044 0073 0047 0057 0048 00540355lowast

nabla2120588(119903)


minus119866(119903)V(119903) 0099 0918 0981 0925 0946 0926 09460099lowast



3B120588(119903) 0316 0050 0077 0060 0053 0054 0053nabla2120588(119903) minus1511 0239 0451 0328 0239 0286 0284

minus119866(119903)V(119903) 0117 0943 0983 0972 0950 0958 0957





1-Fe bond of 1A



1-Fe bond




119894-Fe (119894 = 1 and 2) bonds



1-





3revealed the







4 Conclusion


2O or



1 L2 and L

3



2O or CH








all the O1-Fe and O





2and L

3 that of L

1instead increases







3and the C atom




Competing Interests


Acknowledgments


References
























































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of


O

O

O

CN

Fe

O

O

OH

O

Fe

O

O

O

Fe

O

O

O

OH

Fe

OO

O

Fe

OO

O

Fe

OH

OO

OH

Fe

O

OO

O

Fe

OO

O

Fe

OH

OO

O

Fe

CN

028

032017

009

015

026

207

009008

008

199

018003

017 002

384

031010

029

016

020

011006 015022

010

003001

004

206

077

010

025

018009

016021

011003

093

006

001

004

003

004

004

001

407

022 0

02

006

011

025

004

002

008

004

001

001

430

007

005

006

004

001

002

003

010

025

005

004

004

004

390

013

020

012029

015

024

002006 001009

004

002

001

001

001064

009

428

007

005

006

001 011

027

003

005

005

005

005

003

005

423

008

025005

003008

002

004

009 008

004

004

004

004

004

OO

O

Fe

CN

004

004

004

003

427

010

006

008001

008

005

002

011

029

002

004

1A 2A 3A

1B 2B

2C 3A

OO

OH

Fe

O

390

0 10028

024

015

003

040

018

009

002

002014

005

044

001

002

002

002

3B

3C

2Alowast

2Blowast

3Blowast

OH2

OH2

OH2

OH2

OH2

OH2

OH2

OH2

OH2

OH2

OH2

OH2

OH2

OH2

OH2

OH2

HOCH3

HOCH3

HOCH3

HOCH3

HOCH3

OHCH3

OHCH3

OHCH3OHCH3

OHCH3OHCH3

HOCH3

OHCH3

HOCH3

OHCH3

HOCH3



119864(2)= minus119902119894

(119865119894119895)

120576119895minus 120576119894

(16)










(2) (kJmol)

1A 145 LP(2) O1





1B 117

LP(2) O1





LP(2) O2





1C 146

LP(2) O1





LP(2) O2





2A 133LP(2) O


2LPlowast(6) Fe 873

LP(2) O2





2B 143

LP(2) O1





LP(1) O2





2C 151

LP(2) O1





LP(1) O2





3A 166 LP(2) O1




3B 117

LP(2) O2





LP(1) O1





3C 120

LP(2) O2




2LPlowast(5) Fe 953

LP(1) O1




4LPlowast(2) Fe 793











Parameter O1-H1

O1-Fe O

2-Fe X

1-Fe X

2-Fe X

3-Fe X

4-Fe



1B120588(119903) 0353 0637 0354 0056 0057 0058 0058nabla2120588(119903) minus2123 0541 0061 0436 0454 0440 0446

minus119866(119903)V(119903) 0097 1071 0506 1061 1069 1056 1060

1C120588(119903) 0327 0048 0075 0054 0062 0049 0058nabla2120588(119903) minus1576 0213 0464 0278 0313 0227 0297

minus119866(119903)V(119903) 0116 0093 0987 0949 0960 0922 0947

2A


nabla2120588(119903)



2B

120588(119903)0310 0052 0076 0060 0053 0053 00530388lowast

nabla2120588(119903)


minus119866(119903)V(119903) 0113 0951 0980 0972 0956 0956 09500004lowast

2C

120588(119903)0347 0044 0073 0047 0057 0048 00540355lowast

nabla2120588(119903)


minus119866(119903)V(119903) 0099 0918 0981 0925 0946 0926 09460099lowast



3B120588(119903) 0316 0050 0077 0060 0053 0054 0053nabla2120588(119903) minus1511 0239 0451 0328 0239 0286 0284

minus119866(119903)V(119903) 0117 0943 0983 0972 0950 0958 0957





1-Fe bond of 1A



1-Fe bond




119894-Fe (119894 = 1 and 2) bonds



1-





3revealed the







4 Conclusion


2O or



1 L2 and L

3



2O or CH








all the O1-Fe and O





2and L

3 that of L

1instead increases







3and the C atom




Competing Interests


Acknowledgments


References
























































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of




(2) (kJmol)

1A 145 LP(2) O1





1B 117

LP(2) O1





LP(2) O2





1C 146

LP(2) O1





LP(2) O2





2A 133LP(2) O


2LPlowast(6) Fe 873

LP(2) O2





2B 143

LP(2) O1





LP(1) O2





2C 151

LP(2) O1





LP(1) O2





3A 166 LP(2) O1




3B 117

LP(2) O2





LP(1) O1





3C 120

LP(2) O2




2LPlowast(5) Fe 953

LP(1) O1




4LPlowast(2) Fe 793











Parameter O1-H1

O1-Fe O

2-Fe X

1-Fe X

2-Fe X

3-Fe X

4-Fe



1B120588(119903) 0353 0637 0354 0056 0057 0058 0058nabla2120588(119903) minus2123 0541 0061 0436 0454 0440 0446

minus119866(119903)V(119903) 0097 1071 0506 1061 1069 1056 1060

1C120588(119903) 0327 0048 0075 0054 0062 0049 0058nabla2120588(119903) minus1576 0213 0464 0278 0313 0227 0297

minus119866(119903)V(119903) 0116 0093 0987 0949 0960 0922 0947

2A


nabla2120588(119903)



2B

120588(119903)0310 0052 0076 0060 0053 0053 00530388lowast

nabla2120588(119903)


minus119866(119903)V(119903) 0113 0951 0980 0972 0956 0956 09500004lowast

2C

120588(119903)0347 0044 0073 0047 0057 0048 00540355lowast

nabla2120588(119903)


minus119866(119903)V(119903) 0099 0918 0981 0925 0946 0926 09460099lowast



3B120588(119903) 0316 0050 0077 0060 0053 0054 0053nabla2120588(119903) minus1511 0239 0451 0328 0239 0286 0284

minus119866(119903)V(119903) 0117 0943 0983 0972 0950 0958 0957





1-Fe bond of 1A



1-Fe bond




119894-Fe (119894 = 1 and 2) bonds



1-





3revealed the







4 Conclusion


2O or



1 L2 and L

3



2O or CH








all the O1-Fe and O





2and L

3 that of L

1instead increases







3and the C atom




Competing Interests


Acknowledgments


References
























































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of



Parameter O1-H1

O1-Fe O

2-Fe X

1-Fe X

2-Fe X

3-Fe X

4-Fe



1B120588(119903) 0353 0637 0354 0056 0057 0058 0058nabla2120588(119903) minus2123 0541 0061 0436 0454 0440 0446

minus119866(119903)V(119903) 0097 1071 0506 1061 1069 1056 1060

1C120588(119903) 0327 0048 0075 0054 0062 0049 0058nabla2120588(119903) minus1576 0213 0464 0278 0313 0227 0297

minus119866(119903)V(119903) 0116 0093 0987 0949 0960 0922 0947

2A


nabla2120588(119903)



2B

120588(119903)0310 0052 0076 0060 0053 0053 00530388lowast

nabla2120588(119903)


minus119866(119903)V(119903) 0113 0951 0980 0972 0956 0956 09500004lowast

2C

120588(119903)0347 0044 0073 0047 0057 0048 00540355lowast

nabla2120588(119903)


minus119866(119903)V(119903) 0099 0918 0981 0925 0946 0926 09460099lowast



3B120588(119903) 0316 0050 0077 0060 0053 0054 0053nabla2120588(119903) minus1511 0239 0451 0328 0239 0286 0284

minus119866(119903)V(119903) 0117 0943 0983 0972 0950 0958 0957





1-Fe bond of 1A



1-Fe bond




119894-Fe (119894 = 1 and 2) bonds



1-





3revealed the







4 Conclusion


2O or



1 L2 and L

3



2O or CH








all the O1-Fe and O





2and L

3 that of L

1instead increases







3and the C atom




Competing Interests


Acknowledgments


References
























































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of







4 Conclusion


2O or



1 L2 and L

3



2O or CH








all the O1-Fe and O





2and L

3 that of L

1instead increases







3and the C atom




Competing Interests


Acknowledgments


References
























































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of




















































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of

















Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of










Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of

Documents

Research Article Structural and Antioxidant Properties of ...downloads.hindawi.com/journals/bca/2016/8636409.pdf · with the - +G(d,p) and - G(d) Pople-style basis sets on the atoms