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Production of Biodegradable Polymers using Group IV Complexes of Salicyl-benzotrizole and
benzoxazole Ligands
Sreenath Pappuru
Research Scholar
Department of Chemistry
Indian Institute of Technology Madras, India
International Conference and Exhibition on Biopolymers and Bioplastics 10th - 12th August 2015, San Francisco, USA
1
Contents
Introduction
Construction of group IV metal complexes containing Salicyl-benzotrizole and benzoxazole scaffold
Homo polymerization of rac-LA
Copolymerization of L-LA with -CL
DFT studies
Summary
Surgery
Degradable materials
Packaging
Medical
Bone replacement
Green sutures
Introduction
4
Ligand precursors used in this study
S. Pappuru, E. R. Chokkapu, D. Chakraborty, V. Ramkumar, Dalton Trans. 2013, 42, 16412–16427.
Synthetic routes for complexes 1−12
Catalyst Development
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Single Crystal X-ray StructuresSingle Crystal X-ray Structures
Single Crystal X-ray StructuresSingle Crystal X-ray Structures
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ONO
ON
O
TiO
OON
O
Cl
ON
O
Cl TiO
O
Pappuru, S.; Chakraborty, D.; Chand, D. K.; Unpublished results.
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ONO
Cl
ON
O
Cl HfO
OON
O
ON
O
ZrO
O
Pappuru, S.; Chakraborty, D.; Chand, D. K.; Unpublished results.
Single Crystal X-ray StructuresSingle Crystal X-ray Structures
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Ti
Cl
Cl
ON
O
Cl
Cl
ON
O
Ti
Cl
ClO N
O
Cl
Cl
ON
O
O
OO
Zr
Cl
Cl
ON
O
Cl
Cl
ON
O
Zr
Cl
ClO N
O
Cl
Cl
ON
O
O
OO
Pappuru, S.; Chakraborty, D.; Chand, D. K.; Unpublished results.
Single Crystal X-ray StructuresSingle Crystal X-ray Structures
Homo-Polymerization of rac-lactide
9Pappuru, S.; Chakraborty, D.; Chand, D. K.; Unpublished results.
1H NMR spectrum (500 MHz, CDCl3) of the poly(rac-LA) obtained from a reaction of rac–LA with 2 in 20:1 ratio at 140 oC.
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MALDI-TOF spectrum of the poly(rac-LA) obtained from a reaction between rac–LA and 4 in 20:1 ratio at 140 oC.
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5.145.165.185.205.225.24 ppm
5.150
5.159
5.171
5.206
5.220
5.145.165.185.205.22 ppm
5.145
5.153
5.164
5.200
5.214
5.155.20 ppm
5.152
5.161
5.172
5.209
5.221
5.155.205.25 ppm
5.146
5.156
5.166
5.202
5.215
5.155.205.25 ppm
5.145
5.153
5.165
5.201
5.214
5.125.145.165.185.205.225.245.26 ppm
5.147
5.157
5.168
5.204
5.218
Microstructural Analysis of PLAMicrostructural Analysis of PLA
Homonuclear decoupled 1H NMR (500 MHz, CDCl 3 ) spectrum of the methine region of PLA obtained using group IV complexes.
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sis sii
iis
iiiisi
sis sii iis
iiiisi
sis sii
iis
iii
isi
sis sii
iis
iii
isi
sis sii
iis
iii
isi
sis sii
iis
iii
isi
Cat 1 Cat 3
Cat 4 Cat 5 Cat 6
Cat 2
Thermal analysis
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DSC traces (heating rate: 10 °C/min, 2nd scan) of homopolymers of rac-LA with complexes 2-6 at 200 : 1 monomer initiator ratio
DSC traces (heating rate: 10 °C/min, 2nd scan) of homopolymers of rac-LA with complex 6 at various monomer initiator ratios.
co-polymerization of L-LA with -CL
14Pappuru, S.; Chakraborty, D.; Chand, D. K.; Unpublished results.
1H NMR spectra of co-polymers
1H NMR spectra (500 MHz, CDCl3) of the copolymer showing the - and α-methylene ranges in the copolymers produced by the reaction of L-LA and -CL using catalysts a) 6, b) 3, c) 2 and d) 1
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Cat 1
Cat 2
Cat 3
Cat 6
13C NMR spectra of co-polymers
Carbonyl range of 13C NMR spectra (125 MHz, CDCl3) of copolymers produced by the reaction of L-LA and -CL using catalysts a) 6, b) 3, c) 2 and d) 1
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Cat 1
Cat 2
Cat 3
Cat 6
13C NMR spectra (500 MHz, CDCl3) of Poly L-LA and PCL (a, d) and random poly(LA-co-CL) copolymers (b, c) prepared using 4 and 6 respectively, representing the linkages between LA and CL units along the copolymer chain
13C NMR spectra of co-polymers
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DSC traces (heating rate: 10 °C/min, 2 nd scan) of copolymers by complex 4 and 6 from Table.
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Tg values are lower than the physiological temperature of 37.4 oC, indicating that they can be used for the pharmaceutical and biomedical applicatons.
Zr
Cl
Cl
ON
O
Cl
Cl
ON
O
Zr
Cl
ClO N
O
Cl
Cl
ON
O
O
OO
6
ONO
Cl
ON
O
Cl HfO
O
4
Thermal analysis
Calculated free energy profiles (kcal mol-1) of the initiation step in the ROP of LA mediated by Ti (1) and Zr (2) complexes.
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DFT Calculations
The M06-2X functional was used.
Pappuru, S.; Chakraborty, D.; Chand, D. K.; Unpublished results.
Optimized structures of Zr complex (2) involved in the initiation step of the ROP of LA.
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DFT Calculations
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CatalystsLigands
Polymer Synthesis
Summary
O
O
O
O
O
O
O
O
+
rac-LA
O
O
O
O
L-LA
O
O
-CL
+
isotactic
randomHigh reactive
complex
Zr
Cl
Cl O
N
O
Cl
ClON
O
Zr
Cl
ClO
N
O
Cl
ClO N
O
O
O OZrZr
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