X-ray crystal structures, molecular mechanics and quantum chemical calculations, and calculations of the nonlinear optical polarizabilities in the series of monohalogen substituted derivatives of dicyanovinylbenzene

摘要

The molecular and crystal structure of a series of potential non-linear optical (NLO) compounds - o-, m- and p-halogen-substituted derivatives of dicyanovinylbenzene, has been studied. The molecular geometry was investigated with an X-ray diffraction analysis and discussed along with results of the molecular mechanics (MM3) and ab initio quantum calculations (MP2 and DFF). The influence of the crystal packing on the molecular planarity has been revealed. Calculations of the dipole moments and molecular hyperpolarizabilities for molecules in question were carried out in the finite field approach. In addition to a several acentric compounds of this series found before, in the present investigation one more acentric crystal of the p-I substituted dicyanovinylbenzene was found (space group Pna2(1), Z = 4). Second harmonic generation (SHG) of the laser light for this compound was confirmed by the Kurtz powder test. (C) 2002 Elsevier Science B.V. All rights reserved. [References: 32]