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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)