Molecular organization of discotic mesogenic cis-dichlorobis(3,4,5-trialkoxyphenyllsonitrile)platinum(II) complexes on Langmuir and Langmuir-Blodgett films

Langmuir and Langmuir-Blodgett films of a new class of square planar metallomesogens, the cis-dichlorobis(3,4,5-trialkoxyphenylisonitrile)platinum (II) complexes (PtCn), have been prepared. The structure and the stability of the floating monolayers of these discotic complexes have been investigated by means of compression isotherms, surface potential measurements and Brewster angle microscopy (BAM). A certain influence of the peripheral substituents on the properties of the Langmuir films are observed. It is shown that the hexoxy derivative (PtC6), which shows mesogenic behavior at room temperature, has a more marked tendency to self-organization in ordered multilayers than the butoxy Complex (PtC4) which is not liquid crystalline at room temperature. The structural properties of films, transferred at different pressures, have been studied by AFM and UV-VIS, FT-IR transmission and reflection-absorption infrared spectroscopy (RAIRS). The transfer of the monolayers onto solid substrates leads to Langmuir-Blodgett films in which face-on orientation is found for the molecule cores. The organization of the aliphatic chains depends on the pressure at which the monolayers are transferred. (C) 2003 Elsevier B.V. All rights reserved.