NEW LATERALLY ALKOXY-BRANCHED METALLOMESOGENS WITH A LARGE NEMATIC RANGE

Three new homologous mesogenic series of -2-alkoxy-4'-(4-alkoxysalicyl aldimine)-azobenzenes containing four rings in the main core and a lat eral alkoxy branch on one of the inner rings have been synthesized. Th ese compounds possess a complexation site and were complexed with copp er. The ligands and the complexes are enantiotropic nematics with a la rge nematic range. Due to the lateral substitution, the melting points and clearing temperatures are in the same range for the ligands and t he complexes. Furthermore, the nematic range found in the complexes is larger than that found in the ligands if the number of carbons in the lateral chain is sufficient. With 12 carbons in the lateral chain, a 90 degrees C nematic range is obtained nearly independently of the num ber of carbons in the terminal alkoxy chain on the ''ester'' part of t he molecule. The lateral chain conformation is investigated through mo lecular modelling and its influence within the nematic range is discus sed.