Synthesis and properties of metal-mesogenic nanostructures

Formation of metal-organic nanostructures in co-condensate films have been studied during low temperature codeposition of metal and organic component vapours using a new class of mesogenic ligands-long chain alkyl(alkoxy)cyan obiphenyls (CB): CnH2n+1-C6H5-C6H5-CN, where n = 5 (5 CB), 8 (8 CB), and Cn H2n+1O-C6H5-C6H5-CN, n = 8 (8 OCB). The existence of low temperature Ag-5CB complexes was shown by IR-UV-Visible and ESR techniques. By performing ab initio quantum chemistry calculations including partial geometry optimizati on and vibrational analysis for the sandwich-like cyanobenzene-silver compl exes, it is shown that the observed red shifts in the CN stretching region of the IR spectra of silver-cyanobiphenyl condensate films is a consequence of the formation of the pi-complexes. Thermal degradation of the complexes by annealing of the samples at 200-300 K led to the formation of nanosize (15-30 nm) silver particles incorporated in anisotropic CB-structure and th eir further aggregation in mesogenic matrices. (C) 1999 Elsevier Science S. A. All rights reserved.