SMECTIC BIMETALLOMESOGENS IN BETA-ENAMINOKETONATE COPPER-COMPLEXES - THE STERIC EFFECT OF A METHYL SUBSTITUENT ON THE CORE GROUP AND THE CRYSTAL-STRUCTURE

A systematic study has been made of the liquid crystalline properties of two types of copper complexes derived from enamino-beta-ketonate an d iminopropyl-beta-ketonate Schiff bases that exhibit mesomorphism. Th ese complexes are structurally similar, and all have a bimetallic cent er as an expanded core group. The mesophase stability depends upon the steric bulk between the layer structures. The enamino-beta-ketonate c omplexes exhibit smectic A phases, however, the iminopropyl-beta-diket onates are not liquid crystalline. Examination of the structural featu res of these complexes revealed that the presence of a methyl group at tached to the core group was the cause for the lack of liquid crystall inity observed in the latter. The crystal and molecular structure of b is[3,5-dioctanoylphenyl 2-(3-hydroxypropyl)iminopropyl ketonato]copper (II) was determined by means of X-ray analysis. The Cu Cu intramolecul ar separation is 3.0375(5) Angstrom. The planar geometry is slightly d istorted toward square pyramidal by displacement of the copper by 0.01 8 Angstrom from the mean plane through atoms N(1), O(2), O(1A) and O(1 ).