Preparation, characterization, and electrical properties of dual-emissive Langmuir-Blodgett films of some europium-substituted polyoxometalates and a platinum polyyne polymer

Abstract

A new series of organometallic/inorganic composite Langmuir-Blodgett (LB) films consisting of a rigid-rod polyplati- nyne polymer coordinated with 2,7-bis(buta-1,3-diynyl)-9,9-dihex- ylfluorene (denoted as PtP) as the p-conjugated organometallic molecule, an europium-substituted polyoxometalate (POM; POM ¼ Na9EuW10O36 ,K 13(Eu(SiW11O39)2 )a nd K 5(Eu(SiW11O39)(H2O)2)) as the inorganic component, and an amphiphilic behenic acid (BA) as the auxiliary film-forming agent were prepared. Structural and photophysical characterization of these LB films were achieved by p-A isotherms, absorption and photoluminescence spectra, atomic force microscopy imaging, scanning tunneling microscopy, and low-angle X-ray diffraction. Our experimental results indicate that stable, well-defined, and well-organized Langmuir and LB films are formed in pure water and POM sub- phases, and the presence of Eu-based POM in the subphase causes an area expansion. It is proposed that a lamellar layered structure exists for the PtP/BA/POM LB film in which the POM and PtP molecules can lay down with the interfacial planes. Lumi- nescence spectra of the prepared hybrid LB films show that near- white emission spectra can be obtained due to the dual-emissive nature of the mixed PtP/POM blends. These Pt-polyyne-based LB films displayed interesting electric conductivity behavior. Among them, PtP/BA/POM 13-layer films showed a good electrical response, with the tunneling current up to 6100 nA when the voltage was monitored between � 1a nd 7V.V C 2010 Wiley Peri- odicals, Inc. J Polym Sci Part A: Polym Chem 48: 879-888, 2010