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TITLE
STATEMENT
CERTIFICATE
ACKNOWLEDGEMENT
CONTENTS
PREFACE
CHAPTER 1. Introduction
1. 1.Theoretical principles of nonlinear optics
Table 1.1. Various NLO effects and possible applications
1.2. Organic materials for second harmonic generation
1.2.1. Early studies
1.3.Molecular engineering of NLO materials
Table 1.2. Structure and NLO efficiency of some organic molecules
Table 1.3. Thiophene-based donor-acceptor compounds
Table 1.4. Nonlinear optical coefficient of donor-acceptor subsht$edchromophorcs of tlic form D (CII=CEI), A
Table 1.6. Second-order l~yperpolarizabilitieso f some conjugatedchromophorcs
1.3.1. Effect of chirality on SHG
Tablc 1.7. SI-IG cfficicncics (rclativc to urea) of cyclobutancdioncderivatives
1.3.2. Role of hydrogen bonding for SHG materials
Table 1.8. SHG efficiency of nonchiral Cnitroaniline derivatives
1.3.3. Metallic complexes
Table 1.9. Powder SHG efficiencies of a series of salts of the type shown inChart 1.11
1.3.4. Polymeric systems
Poling steps
1.3.5. Supramolecular systems
1.3.6. Molecular recognition induced self-organization and NLO effects
1.3.7. Liquid crystals
1.4.Summary
1.5.References
CHAPTER 2. Synthesis and Studies of Photophysical and Second Harmonic Generation Properties of Some Butadiene Derivatives
2.1.Abstract
2.2.Introduction
2.3.Results and discussion
2.3.1. Synthesis of butadiene derivatives
Fig. 2.1. (a) 13c NMR spectrum of 6a in CDC13 and (b) in CDCI, containing trifluoroacetic acid.
2.3.2. Synthesis of bicyclic compounds
Fig. 2.2. Projection view drawing of the structure of 14a.The thermal ellipsoids are drawn at 50 O/o probability
Fig. 2.3. Projcction view drawing of the structure of 1%.The thermal ellipsoids arc drawn at 50 XI probability
2.3.3. Absorption and emission spectra
2.3.3.1. Solvent effects on fluorescence spectra
2.3.3.2. Effect of temperature on dual fluorescence
2.3.3.3. Substitution effects on dual fluorescence
2.3.3.4. Discussion on the mechanism of dual fluorescence
2.3.4. Second harmonic generation measurements
2.4.Experimental section
2.4.1. Measurement of second harmonic generation efficiency
2.4.2 Materials
General Procedure for the Synthesis of 5-Butylthio-2, 4-pentadienones (4a, band Sa, b)
2.5.References
CHAPTER 3. Studies of Substituent Effects on the NLO Properties of Some Donor-Acceptor Systems
3.1.Abstract
3.2.Introduction
3.3.Results and discussion
3.3.1. Synthesis
3.3.2. Absorption properties
3.3.3. Nonlinear optical studies
3.3.3.1. Determination of d33 values by the electric field poling method
3.3.3.2. Determination of (3 by hyper-Rayleigh scattering method
3.3.3.3. Theoretical calculations
3.3.3.4. Determination of SHG efficiency by Kurtz and Perry powder method
3.4.Experimental section
3.4.1. Second harmonic generation measurements
3.4.1.1. Electric field poling method
3.4.1.2. Hyper-Rayleigh scattering (HRS) measurements
3.4.1.3. Kurtz and Perry powder method
3.4.2 Materials
3.5.References
CHAPTER 4. Synthesis and Studies of Nonlinear Optical and Photoswitching Properties of Some Cholesterol-linked Azobenzene Derivatives
4.1.Abstract
4.2.Introduction
Fig. 4.1. The cholesteric liquid crystal: schematic representation ofthe helical structure
4.3.Results and discussion
4.3.1. Liquid crystalline properties
Fig. 4.2. Optical micrographs of 3a: (A) oily streak of cholesteric phaseand (B) fucal conic texture of smeetie phase.
Fig. 4.3. Optical micrographs of 3b: (A) c..h.. o.l+e.....s. t-e.. rT..i.ic. phase, a~d (B) focalconic texture of smectic phase,
Fig. 4.3. Optical micrographs of 3c: cholesteric phase.
Fig. 4.7. Optical micrographs of 3d: (A) oily streak of cholesteric pbaseand (B) focal conic texture of smectic phase.
Fig. 4.8. Optical micrograpl) f 5a: (A) oily streak of cholesteric phase on heating and (B) finger print texture of cholesteric phase on cooling.
Fig. 4.9dPptical micrographs of Sb: (A) I g streak of chotesteric phaseand (B) focal conic texture of smectic pbase.
4.3.2. Nonlinear optical studies
4.3.3. Photoinduced pitch change of liquid crystalline films
Fig. 4.15. Visual change of reflectance on irradiatian of a tbin film
Fig. 4.16. Change of cholateric pitch of eutectie mixture of 31,
4.4.Experimental section
4.4.1. Materials
General procedure for the synthesis of cholesteryl derivative of azobenzenes
Cholesteryl azophenyl carbonate (3a)
Cholesteryl4-nitroazophenyl carbonate (3b)
Cholesteryl4-N, N-dimethylaminoazophenyl carbonate (3c)
Cholcstcryl4-butylazophenylcarbonate (34
4.5.References
APPENDIX 1. X-ray Crystal Data of Compounds Listed in Chapter 2.Table A2.1. Summary of crystal data and intensity parameters for 14a (CZUHILIN~aOnd) 1% (CISHMN~OSZ)