Synthesis and characterisation of new amphiphilic molecules for non-linear optics

Abstract

New amphiphilic donor-n-acceptor chromophores have been prepared and characterised. The LB film forming and second order non-Linear optical properties of these amphiphiles have been Investigated. New electron acceptors have been prepared using the reagent 2-chlorobenzylthiocyanate. The scope of the reagent for the preparation of TCNQ derivatives has been Investigated. New DCNQI and N, 7, 7-tricyanoquinomethaneimines have been prepared and characterised. Attempts to prepare novel donor-n-acceptor compounds from these electron acceptors were unsuccessful. The synthesis, LB deposition and CT spectra of R-Q3CNQ (R = C(_6)H(_13) to C(_20)H(_41) and four substituted analogues have been studied. The second harmonic Intensity from Z-type films of C(_16)H(_33)-Q3CNQ was found to Increase quadratically with the number of LB layers. Zwitterionic amphiphiles with benzothiazolium and thiazolium donor groups (C(_16)H(_33)-BT3CNQ and C(_6)H(_13)-T3CNQ have been prepared and characterised. No SHG was observed from films of C(_4),H(_13)-T3CNQ. Films of C(_16)H(_33)-BT3CNQ are Y-type and optical SHG has been observed from odd numbers of layers. A variation In SH Intensity with the number of laser pulses has been observed. The synthesis, CT spectra and LB deposition of some new hemicyanine derivatives have been studied. The LB films have a Y-type structure and SHG was observed from films with odd numbers of layers. Novel push-pull chromophores with the 1,3-dithiole donor group have been prepared and characterised. The LB deposition, CT spectra and NLO properties have been studied.