LANGMUIR-BLODGETT-FILM FORMATION OF DISTEROIDAL-TCNQ

Disteroidal tetracyano-p-quinodimethane (TCNQ) with two ester groups (1) (2,2'-[2,5-bis(5alpha-cholestan-3-yl-oxycar-bonylethyl)-2,5-cyclohexadiene-1,4-diyliden]bis-propanedinitrile) was newly synthesized in order both to improve the monolayer stability on a water surface and to decline its TCNQ plane for interlayer electron transfer compared with the monosteroidal-TCNQ (3) (5beta-cholan-24-yl-TCNQ) reported previously (K. Naito, A. Miura and M. Azuma, Langmuir, 7 (1991) 627). Compound 1 yielded a stable and condensed monomolecular film on a pure water surface with a large occupied area, with a low surface viscosity and with a high collapse pressure, resulting in a good Y-type deposition property. Monosteroidal-TCNQ-propionic. acid (2) (2,2'-[2-carboxyethyl-5-(5alpha-cholestan-3-yl-oxycarbonylethyl)-2,5-cyclohexadiene-1,4-diyliden]bis-propanedinitrile) was also obtained. Compound 2 yielded a stable monomolecular film. However, its surface viscosity was high, resulting in a poorer deposition property. The molecular orientation of 1 in a Langmuir-Blodgett film was determined by X-ray diffraction and polarized UV-visible and Fourier transform IR spectroscopy.