Hybrid Langmuir and Langmuir-Blodgett films of a viologen derivative and TCNQ in a mixed valence state: preparation route and characterization

摘要

Hybrid Langmuir and Langmuir-Blodgett (LB) films containing two moieties of great chemical and electrochemical interest, namely a viologen derivative and tetracyanoquinodimethane (TCNQ) in a mixed valence state, were fabricated. To do so, positively ionized monolayers of 1,1'-dioctadecyl 4,4'-bipyridilium were prepared onto aqueous solutions of tetracyanoquinodimethane in a mixed valence state. Surface pressure vs. area (pi-A), surface potential vs. area (DeltaV-A), and Brewster angle microscope (BAM) images were recorded and interpreted in terms of molecular interactions as well as the incorporation of the hydrophobic anions into the monolayer. After a comprehensive study, a 10(-6) M TCNQ aqueous solution was chosen as the best one to build hybrid LB films. Thus, the floating films were transferred onto solid substrates that were characterized using several techniques including ultraviolet-visible (UV-vis), infrared (IR), scanning electron microscopy (SEM), and atomic force microscopy (AFM) proving the incorporation of the TCNQ onto the film. These films show a good optical conductivity as well as a high degree of order and layers with a constant architecture. (C) 2004 Elsevier B.V. All rights reserved.