Synthesis and characterization of reactive liquid crystalline Schiff bases, Rh(I) complexes, and their derived polymers

Two series of salicylaldimines have been synthesized that consist of model compounds with terminal methylenic chains and reactive compounds in which t he terminal chains have been modified with acrylate groups. The dicarbonylr hodium(I) complexes of these systems were prepared by reacting the ligands with the dimer [RhCl(cod)](2) and CO. Characterization of the metal-contain ing acrylates by H-1 NMR spectroscopy revealed that the Rh(I) can coordinat e to the terminal double bond to produce pentacoordinated complexes. Furthe rmore, investigation of the mesogenic properties of the complexes revealed that the bulkiness of the metallic center requires the presence of at least a three-ring aromatic core to avoid the suppression of liquid crystallinit y. The study was extended to include the side-chain polymers obtained from the acrylate-functionalized Schiff bases. Chelation of the preformed polyac rylate with low percentages of Rh(I) emerged as the best strategy to prepar e Rh(I)-containing polyacrylates. (C) 2000 John Wiley & Sons, Inc.