Title Page
ABSTRACT
Contents
PART 1. Styryl-based Dyes for DSSCs 26
1.1. Introduction 26
1.2. Experimental 29
1.2.1. Materials and analytical instruments 30
1.2.2. Synthesis of Dyes 30
1.2.3. Assembly and characterization of DSSCs 39
1.3. Results and discussion 40
1.3.1. Synthesis 40
1.3.2. Optical and electrochemical properties 43
1.3.3. Photovoltaic performances of the DSSCs 50
1.4. Conclusion 61
1.5. Reference 62
PART 2. Spontaneous Optical Response towards Cyanide Ion in Water by a Reactive Binding Site Probe 70
2.1. Introduction 70
2.2. Experimental 73
2.2.1. Materials and analytical instruments 73
2.2.2. Synthesis of R1 and R2 probes 74
2.3. Result and Discussion 82
2.3.1. Selectivity response of probes 83
2.3.2. Electronic Spectral Studies 87
2.3.3. Fluorescence spectral studies 90
2.3.4. ¹H NMR Spectral studies 96
2.3.5. Theoretical study 100
2.3.6. Application in real water sample 103
2.4. Conclusion 109
2.5. Reference 110
PART 3. Selective Detection of Cyanide Ion in 100% Water by Indolium Based Dual Reactive Binding Site Optical Sensor 117
3.1. Introduction 117
3.2. Experimental 119
3.2.1. Chemicals 119
3.2.2. Instruments 120
3.2.3. Synthesis of sensor R 121
3.2.4. Sample preparation for cyanide sensing 127
3.2.5. Protocol for practical application 127
3.3. Result and Discussion 128
3.3.1. Colorimetric response 128
3.3.2. UV-Vis Spectral Studies 131
3.3.3. Fluorescence spectral studies 135
3.3.4. ¹H NMR Spectral studies 139
3.3.5. Theoretical study 142
3.3.6. Real sample analysis 145
3.4. Conclusion 148
3.5. Reference 149
APPENDICES 23
Appx 1. ¹H NMR spectrum of 4-hydrazinylbenzoic acid 155
Appx 2. ¹³C NMR spectrum of 4-hydrazinylbenzoic acid 155
Appx 3. HRMS spectrum of 4-hydrazinylbenzoic acid 156
Appx 4. ¹H NMR spectrum of 2,3,3 -trimethyl-3 H-indole-5-carboxylic acid 156
Appx 5. ¹³C NMR spectrum of 2,3,3-triinethyl-3H-indole-5-carboxylic acid 157
Appx 6. HRMS spectrum of 2,3,3-trimethyl-3H-indole-5-carboxylic acid 157
Appx 7. ¹H NMR spectrum of 5-carboxy-1,2,3,3-tetramethyl-3H-indol-1-ium 158
Appx 8. ¹³C NMR spectrum of 5-carboxy-1,2,3,3-tetramethyl-3H-indol-1-ium 158
Appx 9. HRMS spectrum of 5-carboxy-1,2,3,3-tetramethyl-3H-indol-1-ium 159
Appx 10. ¹H NMR spectrum of 4-(N,N-diphenylamino)benzaldehyde 159
Appx 11. ¹³C NMR spectrum of 4-(N,N-diphenylamino)benzaldehyde 160
Appx 12. HRMS spectrum of 4-(N,N-diphenylammo)benzaldehyde 160
Appx 13. ¹H NMR spectrum of 4-(N,N-diphenylaniino)benzaldehyde 161
Appx 14. ¹³C NMR spectrum of 4-(N,N-diphenylamino)benzaldehyde 161
Appx 15. HRMS spectrum of 4-(N,N-diphenylamino)benzaldehyde 162
Appx 16. ¹HNMR spectrum of (E)-5-carboxy-2-(4-(N,N-diphenylamino)styryl)-1,3,3-trimethyl-3H-indol-1-ium 162
Appx 17. ¹³C NMR spectrum of (E)-5-carboxy-2-(4-(N,N-diphenylamino)styryl)-1,3,3-trimethyl-3H-indol-1-ium 163
Appx 18. HRMS spectrum of (E)-5-carboxy-2-(4-(N,N-diphenylamino)styryl)-1,3,3-trimethyl-3H-indol-1-ium 163
Appx 19. ¹H NMR spectrum of (E)-5-carboxy-2-(4-(N,N-diphenylamino)styryl)-1,3,3-trimethyl-3H-indol-1-ium 164
Appx 20. ¹³C NMR spectrum of (E)-5-carboxy-2-(4-(N,N-diphenylamiiio)styiyl)-1,3,3-trimethyl-3H-indol-1-ium 164
Appx 21. HRMS spectrum of (E)-5-carboxy-2-(4-(N,N-diphenylmnino)styryl)-1,3,3-trimethyl-3H-indol-1-ium 165
Appx 22. ¹H NMR spectrum of the product formed upon reaction of R1 with CN⁻ 165
Appx 23. ¹H NMR spectrum of the product formed upon reaction of R2 with CN- 166
Appx 24. HRMS spectrum of the product formed upon reaction of R1 with Cyanide ion 166
Appx 25. HRMS spectrum of the product formed upon reaction of R2 with Cyanide ion 167
Appx 26. ¹H NMR spectrum of (2,2'-(butane-1,4-diylbis(oxy))bis(4-diethylamino)benzaldehyde) 167
Appx 27. ¹³C NMR spectrum of 2,2'-(butane-1,4-diylbis(oxy))bis(4-diethylamino)benzaldehyde) 168
Appx 28. HRMS spectrum of 2,2'-(butane-1 ,4-diylbis(oxy))bis(4-diethylamino)benzaldehyde) 168
Appx 29. ¹H NMR spectrum of 2,2'-((1E,1'E)-((butane-1,4-diylbis(oxy))bis(4-(N,N-diethylamino)-2,1-phenylene))bis (ethene-2,1-diyl))bis(5-... 169
Appx 30. ¹³C NMR spectrum of 2,2'-((1E,1'E)-((butane-1,4-diylbis(oxy))bis(4-(N,N-diethylamino)-2,1-phenylene))bis (ethene-2,1-diyl))bis(5-... 169
Appx 31. HRMS spectrum of 2,2'-((1E,1'E)-((butane-1,4-diylbis(oxy))bis(4-(N,N-diethylamino)-2,1-phenylene))bis (ethene-2,1-diyl))bis(5-... 170
Abstract 171
Table 1.1. Optical parameters of sensitizers. 45
Table 1.2. Photovoltaic parameters of DSSCs. 54
Table 1.3. Electrochemcal parameters of DSSCs. 57
Table 2.1. Determination of CN⁻ in water samples of R1 106
Table 2.2. Determination of CN⁻ in water samples of R2 107
Table 3.1. Determination of CN⁻ in water samples. 147
Fig. 1.1. Double-branched symmetrical and unsymmetrical organic dyes design strategy and its chemical structures 38
Fig. 1.2. Absorption spectra of single branched (Dye A, Dye B), symmetric (Dye AA, Dye BB) and unsymmetric (Dye AB) dibranched dyes in solution. 44
Fig. 1.3. Absorption spectra of single branched (A, B), symmetric (AA, BB) and unsymmetric (AB) di-branched dyes on TiO₂ films. 48
Fig. 1.4. Cyclic voltammograms A, AA, B, BB and AB dyes 49
Fig. 1.5. J-V curves of DSSCs sensitized by Dye A, AA, B, BB, AB and (A + B) dyes 53
Fig. 1.6. IPCE spectra of DSSCs based on the dye sensitizers. 53
Fig. 1.7. Electrochemical impedance spectra of the dyes. 58
Fig. 1.8. Stepped light-induced transient measurements of photocurrent and volage (SLIM-PCV). 60
Fig. 2.1. Image of color change upon the addition of Cyanide ion to R1 72
Fig. 2.2. Color changes observed for R1 & R2 [1.25x10⁻⁴M] upon the addition of various anions under day light and UV lamp. 85
Fig. 2.3. Color changes observed by naked eye for R1 and R2 at different pH values, (A) before and (B) after adding one equivalent of cyanide ion 86
Fig. 2.4. UV-Vis absorption spectrum changes of R1 & R2 with cyanide ion VS other anions 88
Fig. 2.5. UV-Vis spectra of (A) R1 & (B) R2 [1x10⁻⁵ M] with incremental the addition of TBACN [0 - 1x10⁻⁵ M] in water (HEPES buffer pH 7.2). 89
Fig. 2.6. Fluorescence spectra of (A) R1 & (B) R2 [1.5x10⁻⁶ M] upon addition of TBACN [0-1.5 x 10⁻⁶ M] in water (HEPES buffer pH 7.2). 91
Fig. 2.7. Benesi-Hildebrand plot of R1 with Cyanide ion 92
Fig. 2.8. Benesi-Hildebrand plot of R2 with Cyanide ion 92
Fig. 2.9. Plot of fluorescence intensity of R1 versus concentration of cyanide 93
Fig. 2.10. Plot of fluorescence intensity of R2 versus concentration of cyanide 93
Fig. 2.11. Competitive experiment showing detection of CN⁻ by sensor R1 & R2 in the presence of different anions using fluorescence emission spectral technique. 95
Fig. 2.12. (A) Partial ¹H NMR spectrum of R1; (B) with the addition of TBACN in DMSO-D₆ 97
Fig. 2.13. (A) Partial ¹H NMR spectrum of R2; (B) with addition of TBACN in DMSO-D₆. 98
Fig. 2.14. Job's plot for the (A) R1 complex with cyanide (B) R2 complex with cyanide 99
Fig. 2.15. Optimized geometry diagram of the R1-cyanide complex 101
Fig. 2.16. Optimized geometry diagram of the R2-cyanide complex 101
Fig. 2.17. Frontier molecular orbitals and HOMO-LUMO energy level diagram of sensor R1 and its addition product. 102
Fig. 2.18. Frontier molecular orbitals and HOMO-LUMO energy level diagram of sensor R2 and its addition product. 103
Fig. 2.19. Color change of test strip R1 and R2 upon dipping in solution of cyanide ion in water. 104
Fig. 2.20. Plot of absorbance of R1 versus concentration of cyanide 108
Fig. 2.21. Plot of absorbance of R2 versus concentration of cyanide 108
Fig. 3.1. Image of color change upon the addition of various anions to R solution (in H₂O) 119
Fig. 3.2. Color changes observed on by naked eye of R [1.25x10⁻⁴ M] upon addition of various anions under day light 130
Fig. 3.3. Color changes observed for R at different pH values: (A) free R and (B) after the addition of 2eq. cyanide ion 130
Fig. 3.4. UV-Vis absorption changes of R with cyanide ion in presence of other anions 133
Fig. 3.5. UV-Vis spectra of R [1x10⁻⁵ M] with incremental addition of TBACN [0-2x10⁻⁵ M] in water (HEPES buffer pH 7.2). 133
Fig. 3.6. Scott plot of R with CN⁻ ion 134
Fig. 3.7. Plot of absorbance versus concentration of cyanide 134
Fig. 3.8. Job's plot for the probe R-CN⁻ complex 135
Fig. 3.9. Fluorescence spectra of R [1.5x10-6 M] upon addition of TBACN [0-3x 10-6 M] in water (HEPES buffer pH 7.2) (Inset: Linear plot of intensity with... 137
Fig. 3.10. Benesi-Hildebrand plot of R with CN⁻ ion 138
Fig. 3.11. Plot of fluorescence intensity versus concentration of cyanide 138
Fig. 3.12. Competitive experiment showing detection of CN⁻ by sensor R in the presence of other anions using fluorescence spectral technique. 139
Fig. 3.13. (A) ¹H NMR spectrum of R; (B) with addition of TBACN in DMSO-d₆ 141
Fig. 3.14. Mass spectrum of the product formed upon reaction of R with CN-. 142
Fig. 3.15. Frontier molecular orbitals and HOMO-LUMO energy level diagram of sensor R and its addition product. 144
Fig. 3.16. Optimized geometry diagram of the sensor-cyanide complex 144
Fig. 3.17. Color change of test strip upon dipping in solution of cyanide ion in water. 146
Scheme 1.1. Synthesis of single branched dyes (A, B) 41
Scheme 1.2. Synthesis of symmetrical and unsymmetrical double branched dyes (Dye AA, Dye BB, Dye AB) 42
Scheme 2.1. Synthesis route of R1 and R2 74
Scheme 3.1. Synthesis of R 121