Ordered Langmuir-Blodgett multilayers of copper phthalocyanine derivatives

Abstract

Copper(II) phthalocyanine derivatives with four alkoxycarbonyl chains as substituents were synthesized. Langmuir-Blodgett (LB) films of the two following compounds were deposited: Cu(II) [tetrakis(3,3-dimethyl-1-butoxycarbonyl)] phthalocyanine and Cu(II) [tetrakis( n-butoxycarbonyl)] phthalocyanine. Moreover, alternate LB films of the two compounds and LB films from a 1:1 mixture of them were prepared. Monolayers were spread onto the water surface from different solutions and were transferred onto quartz slides using the vertical lifting method. The deposition parameters and processes are described, and a UV-visible spectroscopic characterization of these compounds in different solvents and of the related LB films is presented. All isotherms and optical data are consistent with the molecules being stacked nearly edge-on to both the water surface and the substrate. Moreover, after deposition, the molecular faces exhibit a preferred orientation perpendicular to the dipping direction. Molecular order in the films was explored by polarized electronic absorption spectroscopy. Optical characterization of our LB films indicates the presence of some degree of molecular aggregation even in the multilayers. Finally, the results from a preliminary transmission electron microscopy study on the LB films are presented.