S1

Supporting Information for

A novel triple-mode fluorescent pH probe from monomer emission to aggregation-induced emission

Zhenghua Wang,a Jia-Hai Ye,a,* Jing Li,a Yang Bai,b Wenchao Zhang,a and Weijiang Heb,*

aSchool of Chemical Engineering, Nanjing University of Science and Technology, Nanjing, 210094, P. R. China, E-mail: yejiahai@njust.edu.cn

bState Key Laboratory of Coordination Chemistry, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing, 210093, P. R. China, E-mail: heweij69@nju.edu.cn

Table of Contents

1. General experimental section.......................................................................................S2

2. Synthesis section.....................................................................................................S3-S4

3. Photophysical properties detail.............................................................................S5-S14

4. 1H NMR, 13C NMR, mass pectra and FT-IR spectra..........................................S15-S17

5. Calculation of fluorescence quantum yields...............................................................S17

6. TEM images................................................................................................................S18

7. References…...............................................................................................................S18

Electronic Supplementary Material (ESI) for RSC Advances.This journal is © The Royal Society of Chemistry 2014

S2

1 General Experimental Section

1.1 General Methods.

All of the chemicals were purchased from the commercial source and used as analytic grade without further purification except especially noted. the stock solutions of metal ions were prepared form LiCl, NaCl, KCl, MgSO4, CaCl2, Ba(NO3)2, Al(NO3)2•9H2O, Pb(NO3)2, Cr2(SO4)3, MnCl2▪4H2O, FeCl3▪6H2O, Cd(NO3)2▪6H2O, Ni(NO3)2▪6H2O, CuCl2, AgNO3, Zn(OAc)2▪2H2O, CdCl2▪H2O and HgCl2 with doubly distilled water. NMR spectra were recorded at 25℃ on a Bruker AVANCE III 500 MHz ( 500 MHz and 125.72 MHz for 1H and 13C nuclei, respectively) with chemical shifts reported in ppm (in CDCl3, TMS as internal standard, and the multiplicities were expressed as follows: s = single, d = double, t = triplet, m = multiples). TLC analysis was performed on silica gel plates and column chromatography was conducted over silica gel (mesh 200–300). ESI-MS spectral data were recorded on a TSQ Quantum-HPLC/MS/MS (Thermo, USA). Fluorescence spectrums were determined on a Perkin Elmer LS 55. The pH values of sample solution were monitored by a PHS-3 system. Spectroscopic and colorimetric measurements were carried out in THF (HPLC) and deionized water. Solution samples were measured in 1.00 cm quartz cell. All emission spectra were recorded at 25℃ and under atmospheric pressure. UV-vis spectra were measured on a Shimadzu UV3600. FT-IR spectrum was performed on an ATR accessory with a Nicolet IS-10 FT-IR spectrometer, in the wave number range 500–4000 cm-1. Transmission electron microscope (TEM) images were recorded on a JEM-2100 instrument. Samples were prepared by dropping the solution onto a carboncoated copper grid.

1.2 General procedure for UV-vis and fluorescence studies

Stock solution of metal ions were prepared (1.0×10-2 M) in buffer solution pH = 6.86. A stock solution of probe 1 (1.0×10-5 M) was prepared in THF/H2O (2:8, v/v) immediately before the experiments. Stock solution of base and acid solution were obtained from NaOH and HCl and diluted into different concentrations. In experiments, a 3 mL solution of probe 1 was filled in a quartz optical cell of 1 cm optical path length and the base and acid were added, pH value were collected before fluorescence test. For fluorescence measurements, excitation was provided at 305 nm and emission was collected from 325 nm to 590 nm. The excitation and emission slits were ser to 3 and 3 nm, respectively.

S3

2 Synthesis Section

2.1 Synthesis of probe 1S1,S2

OH

CHO

O

CHO

Br+

N3

N3

NH2

H2N

NH

HN

O

O

b. NaBH4,THF/MeOH

4

2 3

1

K2CO3

Acetone

PPh3

MeOH

a. PhMe

Scheme S1: Synthesis of probe 1.

A mixture of p-Hydroxybenzaldehyde (1.22 g, 10 mmol), bromoethane (1.39 g, 12 mmol) and Potassium carbonate (4.14 g, 30 mmol) in acetone (50 ml) was refluxed for 24 h in a 100 ml flask. Afterwards filtered and the solvent was remove under reduced pressure. Residue was resolved with ethyl acetate and washed with brine, dried with anhydrous MgSO4, filtered, and concertrated. The residual compound was purified by chromatography on silica gel (EtOAc/PE = 6:1) to give compound 4 as colorless oily liquid (1.08 g, 73% yield). 1H NMR (500 MHz, CDCl3) δ (TMS ppm): 9.77 (s, 1H), 7.72 (d, J = 8.7 Hz, 2H), 6.88 (d, J = 8.7 Hz, 2H), 4.01 (d, J = 7.0 Hz, 2H), 1.34 (t, J = 7.0 Hz, 3H).

In a 100 ml three-necked flask, compound 2 (884 mg, 2 mmol) and PPh3 (1.572 g, 6 mmol) was dissolved in 40 ml methanol and then heated under 70℃ for 2 h. Then, the mixture was cooled down to the room temperature and the solvent was removed to get yellow oil. HCl was added and yellow solid was obtained. Filtered and the solid was washed with Et2O, water was added into filtrate and washed with Et2O. The water layer was combined and the aqueous ammonia was added into it. The solid was dissolved, extracted with dichloromethane. The organic layer was combined and dried over anhydrous MgSO4, filtered, and concentrated. The residual compound was purified by flash chromatography on silica gel (EtOAc/Et3N = 100:5) to yield 3 as a yellow solid (0.41 g, 52.6 % yield).

S4

A mixture of 3 (405 mg, 1 mmol, 1 equiv.) and 4 (300 mg, 2 mmol, 2 equiv.) in toluene (50 mL), in a flask equipped with a Dean-Stark trap, was refluxed for 24 h. Afterward, solvents were evaporated under reduced pressure, and the residual oil obtained was directly dissolved in ethanol/tetrahydrofuran (v:v = 1:1) 40 ml. Sodium borohydride (NaBH4; 0.15 g, 4 mmol, 4 equiv.) was added under ice bath, and the reaction mixture was stirred at 0 °C for 30 min and then refluxed for about 7 h. Afterward, water was added to quenching the reaction, extracted with dichloromethane. The organic layer was combined and washed with water, dried over anhydrous MgSO4, filtered, and concentrated. The residual compound was purified by flash chromatography on silica gel (EtOAc/PE=3:1) to give compound 1 as yellow solid (285 mg, 43.3% yield). 1H NMR (500 MHz, CDCl3) δ (TMS ppm): 7.20 (d, J = 8.5 Hz, 4H), 7.13–6.99 (m, 14H), 6.97 (d, J = 8.1 Hz, 4H), 6.84 (d, J = 8.5 Hz, 4H), 4.02 (q, J = 7.0 Hz, 4H), 3.68-3.69 (m, 8H), 1.41 (t, J = 7.0 Hz, 6H). 13C NMR (125 MHz, CDCl3) δ 158.04, 143.86, 142.47, 140.70, 132.16, 131.39, 131.37, 129.44, 127.66, 127.51, 126.39, 114.41, 63.46, 52.74, 52.52, 14.91. ESI-MS m/z: 659.28 [M+H+]

S5

3 Photophysical properties detail

350 400 450 5000

5

10

15

20

25

30

Fluo

resc

ence

Inte

nsity

Wavelength (nm)

THF 6:4 5:5 3:7 2:8 1:8.5 1:9

Fig. S1: Fluorescence spectra (λex = 305 nm) of probe 1 (10 µM) in a THF/H2O binary solvent mixture.

Fig. S2: Observed fluorescence changes of probe 1 (10 µM) under UV light (365 nm lamp) in a THF/H2O binary solvent mixture (water fraction increased from left to right)

S6

350 400 450 500 5500

20

40

60

80

100

fluor

esce

nce

inte

nsity

Wavelength (nm)

pH=1.99

pH=7.02

Fig. S3: Fluorescence responses to the probe 1 (10 µM) to different pH: 1.99, 2.01, 2.55, 2.98, 3.60, 4.`00, 4.77, 5.08, 5.62, 6.58 and 7.02 in THF/H2O (2:8, v/v)

2 3 4 5 6 7

30

40

50

60

70

80

90

100

fluor

esce

nce

inte

nsity

pH

slope= -11.20

Fig. S4: The fluorescence emission changes at 377 nm with the pH titration curve of probe 1 (10 µM) in THF/H2O (2:8, v/v), pH = 1.99~7.02

S7

350 400 450 500 5500

5

10

15

20

25

fluor

esce

nce

inte

nsity

Wavelength (nm)

pH=7.02

pH=8.50

Fig. S5: Fluorescence responses to the probe 1 (10 µM) to different pH: 7.02, 7.24, 7.59, 7.85, 8.03, 8.43 and 8.50

6.8 7.0 7.2 7.4 7.6 7.8 8.0 8.2 8.4 8.6

6

8

10

12

14

16

18

20

22

24 I377nm

I483nm

fluor

esce

nce

inte

nsity

pH

slope=-7.85

slope=7.81

Fig. S6: The fluorescence emission changes at 377 nm with the pH titration curve of probe 1 (10 µM), pH = 7.02~8.50

S8

7.2 7.4 7.6 7.8 8.0 8.2 8.4 8.6

0.4

0.6

0.8

1.0

1.2

1.4

1.6

1.8

I 483

nm/I 37

7 nm

pH

Fig. S7: Ration metric calibration curve I483 nm/I377 nm (intensity at 483 nm vs intensity at 377 nm) of probe 1 (10 µM) to different pH from 7.02 to 8.50 in THF/H2O (2:8, v/v).

350 400 450 500 5500

5

10

15

20

25

30

Fluo

resc

ence

Inte

nsity

Wavelength (nm)

pH=11.64

pH=8.50

Fig. S8: Fluorescence responses to the probe 1 (10 µM) to different pH: 8.50, 8.94, 9.57, 10.11, 10.51, 10.74, 11.13 and 11.64 in THF/H2O (2:8, v/v)

S9

8.0 8.5 9.0 9.5 10.0 10.5 11.0 11.5 12.018

20

22

24

26

28

30

Fluo

resc

ence

Inte

nsity

pH

Fig. S9: The fluorescence emission changes at 483 nm with the pH titration curve of probe 1 (10 µM), pH = 8.50~11.64

350 400 450 500 5500

20

40

60

80

100

fluor

esce

nce

inte

nsity

Wavelength (nm)

7.02 11.61 1.99 8.50

Fig. S10: Fluorescence intensity of probe 1 (10 µM) at different pH value in a solution of THF/H2O=(2:8, v/v) media

S10

350 400 450 500 5500

5

10

15

20

25

fluor

esce

nce

inte

nsity

Wavelength (nm)

Free Ag+ Al3+ Ba2+ Cd2+ Co+ Cr3+ Cu2+ Fe3+ Hg+ K+ Li+ Mg2+ Mn2+ Na+ Ni+ Pb2+ Zn2+

Fig. S11: Fluorescence response of probe 1 (10 µM) to various metal cations (4 equiv.) in THF/H2O (2:8, v/v) medium.

Free

Ag+ Al3+ Ba2+ Ca2+ Cd2+ Co2+ Cr3+ Cu2+ Fe3+

Hg+ K+ Li+ Mg2+ Mn2+ Na+ Ni+Pb2+ Zn2

+0.0

0.2

0.4

0.6

0.8

1.0

inte

nsity

ratio

Fig. S12: Ratios of fluorescence intensity at 377 nm of probe 1 (10 µM) in the presence of various metal cations (4 equiv.) in aqueous solution of THF/H2O (2:8, v/v)

S11

(a) Visible light (b) UV light (365 nm)

Fig. S13: Observed visual color and fluorescence change of probe 1 (10 µM) in a solution of THF/H2O (2:8, v/v) upon addition of various metal ions (4 equiv.), acid and base.

250 300 350 400 4500.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

abso

rban

ce

wavelength (nm)

7.15 6.33 5.45 4.81 4.37 3.96 3.60 3.44 2.97 2.35 2.08

Fig. S14: Absorbance spectra of probe 1 (10 µM) in a solution of THF/H2O (2:8, v/v) to different pH from 2.08 to 7.15.

S12

250 300 350 400 450

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

abso

rban

ce

wavelegth (nm)

7.17 7.44 8.04 8.22 8.69

Fig. S15: Absorbance spectra of probe 1 (10 µM) in a solution of THF/H2O (2:8, v/v) to different pH from 7.17 to 8.69.

250 300 350 400 450

0.10.20.30.40.50.60.70.80.91.01.11.21.31.41.51.6

abso

rban

ce

wavelength (nm)

8.69 8.99 9.35 9.94 10.32 10.89 11.17 11.43 11.84

Fig. S16: Absorbance spectra of probe 1 (10 µM) in a solution of THF/H2O (2:8, v/v) to different pH from 8.69 to 11.84.

S13

350 400 450 500 5500

5

10

15

20

25

30

7.17 8.38 9.47 10.96 6.41 4.23 2.62

Fluo

resc

ence

Inte

nsity

Wavelength (nm)

Fig. S17: Fluorescence intensity of probe 1 responses to different pH in a solution of THF (10 µM)

350 400 450 500 5500

50

100

150

200

pH=6.84

Fluo

resc

ence

Inte

nsity

Wavelength (nm)

pH=2.37

Fig. S18: Fluorescence intensity of probe 1 response under acidic condition (pH changed from 6.84 to 2.37) in a solution of water (10 µM)

S14

350 400 450 500 5500

20

40

60

80

100

120

140

160

180

200

Fluo

resc

ence

Inte

nsity

Wavelength (nm)

Fig. S19: Fluorescence intensity of probe 1 response with the addition of base (pH changed from 6.84 to 10.73) in a solution of water (10 µM)

Fig. S20: Change of 1H NMR spectra of probe 1 in d8-THF /D2O. (a) with the addition of 4 equiv. CF3COOH; (b) with the addition of 4 equiv. NaOH; (c) without any addition

S15

4 1H NMR, 13C NMR mass spectra and FT-IR spectra

-0.50.00.51.01.52.02.53.03.54.04.55.05.56.06.57.07.5f1 (ppm)

6.05

7.30

4.00

3.89

3.98

14.0

33.

79

0.07

1

1.39

21.

406

1.42

0

3.68

43.

692

3.99

64.

010

4.02

44.

038

6.83

56.

852

6.96

26.

978

7.00

97.

014

7.02

17.

028

7.04

37.

059

7.07

67.

081

7.08

97.

195

7.21

27.

260

Fig. S21: 1H NMR of compound 1 in CDCl3

-100102030405060708090100110120130140150160170180190200210f1 (ppm)

14.9

12

52.5

2252

.741

63.4

55

76.8

3977

.093

77.3

47

114.

406

126.

386

127.

509

127.

664

129.

440

131.

373

131.

386

132.

161

140.

695

142.

471

143.

857

158.

040

Fig. S22: 13C NMR of compound 1 in CDCl3

HN

NH

OO

HN

NH

OO

S16

20140509-WZH #20 RT: 0.25 AV: 1 NL: 7.04E7T: + c sid=-20.00 Q1MS [ 570.90-800.00]

580 600 620 640 660 680 700 720 740 760 780 800m/z

0

5

10

15

20

25

30

35

40

45

50

55

60

65

70

75

80

85

90

95

100

Rela

tive

Abu

ndan

ce

659.28

660.30

661.30

673.29657.29772.39711.32581.26 703.33687.29 730.32 747.33595.25 605.27 655.60 791.39621.24 631.23 759.33

Fig. S23: MS (ESI) spectrum of compound 1

0.01.02.03.04.05.06.07.08.09.010.011.0f1 (ppm)

3.13

2.09

2.03

2.00

0.98

-0.0

120.

065

1.42

81.

442

1.45

6

4.08

64.

100

4.11

44.

128

6.96

76.

984

7.26

0

7.80

77.

824

9.86

6

O

O

Fig. S24: 1H NMR of compound 4 in CDCl3

HN

NH

OO

m/z: 658.36

S17

4000 3600 3200 2800 2400 2000 1600 1200 800

40

60

80

920.

791301

.26

1172

.61

1113

.81

1044

.39

805.

2676

0.62

690.

66

1240

.95

1441

.77

1509

.18

1609

.3829

23.1

1

cm-1

T %

Fig. S25: FT-IR of compound 1

The FT-IR analysis was carried out, as displayed in Fig. S25. The compound 1 shows characteristic absorption at 2923 cm-1 corresponding to the asymmetric and symmetrical stretch vibration of N-H, at 1609 cm-1 assigned to the stretching vibration of C=C of TPE core, at 1509 and 1441 cm-1 due to the phenyl rings backbone (skeletal vibration), at 1240 cm-1 caused by the vibration of C-O, at 1113 and 1044 cm-1 belong to C-C backbone (skeletal vibration), at 805, 760 and 690 cm-1 related to Ar-H out-of-plane bending vibration.

5 Calculation of fluorescence quantum yields

The absolute quantum yields were measured, referring to the procedure in the literature.S3 They were calculated by using following equation:

Φu = (Φs·Fu·As·ηu2)/ (Fs·Au·ηs

2)

Where the subscripts s and u denote standard and test respectively, Φ is the fluorescence quantum yield, F is the integrated fluorescence intensity (area) spectra, A is the integrated absorbance area spectra, and η the refractive index of the solvent.

S18

6 TEM images

Fig. S26: TEM images of compound 1 with the addition of (a and c): acid; (b and d) base in THF/H2O mixture.

7 References

S1. J.-H. Ye, L. Duan, C. Yan, et al., Tetrahedron Letters, 2012, 53, 593.

S2. C. Anastasi, O. Hantz, E. De Clercq, et al., Journal of Medicinal Chemistry, 2004, 47, 1183.

S3. Albert M. B., Pure Appl. Chem., 2011, 83, 2213.