Synthesis and properties of metal–mesogenic nanostructures

Abstract

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)cyanobiphenyls (CB): C n H 2 n+1 –C 6H 5–C 6H 5–CN, where n=5 (5 CB), 8 (8 CB), and C n H 2 n+1 O–C 6H 5–C 6H 5–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 optimization and vibrational analysis for the sandwich-like cyanobenzene–silver complexes, 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 π-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 their further aggregation in mesogenic matrices.