Preparation and characterization of organotransition metal Langmuir-Blodgett films

Abstract

A novel organotransition metal complex has been synthesized specifically for use with the Langmuir-Blodgett deposition technique. Characterization data for ruthenium (η 5-cyclopentadienyl)-(bistriphenylphosphine)-4-cyano-4″- n-pentyl- p- terphenyl hexafluorophosphate (RuCTP) are presented, confirming that monolayer and multilayer structures have been successfully prepared. Complexing of the ruthenium (η 5-cyclopentadienyl)-(bistriphenylphosphine) group to a liquid crystal molecule greatly enhances the electron withdrawing nature of the resulting molecule and, furthermore, induces multilayer formation. Optical second harmonic generation studies have enabled an estimate of the molecular hyperpolarizability to be made. The value of 40×10 -50 C 3 m 3 J -2 is significantly larger than those possessed by many inorganic materials. It has been shown that it is possible to incorporate an average of 1.7 molecules of 4-cyano-4″- n-pentyl- p- terphenyl per molecule of the ruthenium complex into the spaces between the terphenyl chains of the floating RuCTP molecules, resulting in an increased molecular packing density and a corresponding increase of 50% in the second harmonic signal strength.