New electron acceptor; cyclobutenediones for nonlinear optical materials

Abstract

Summary form only given. Technique for control of molecular orientation in a crystal was not yet discovered except only a few approaches such as ionic complexes and diacetylenes. If it is found, we can create new intelligent materials more easily for nonlinear optical, piezoelectric and pyroelectric devices etc. I report in this conference that a particular substituent containing a chiral amino acid derivative is the first electron acceptor capable of controlling molecular orientation in the crystal, and generating high second-order nonlinear optical effect. In order to produce an organic material with large second-order nonlinear optical effect, a high second-order molecular hyperpolarizablity (/spl beta/) and a non-centrosymmetric structure are required. For these objectives, new chiral electron acceptors based on cyclobutenedione structure have been studied. With cyclobutenedione particularly containing chiral 1-amino-2-propanol, highly polarizable chromophore parts are shown to be perfectly aligned on the same direction in the crystal (space group P1) and to produce high second harmonic generation (SHG). After investigations on relationships between molecular and crystal structures, we obtained so far 4 crystals with PI and 4 crystals with P2/sub 1/(molecular alignment with 90/spl deg). Spectroscopic analyses, /spl beta/ values and d-tensors of these cyclobutenediones will be discussed.