Langmuir–Blodgett films of indandione-1,3 pyridinium betaine. I: Preparation, electronic structure, optical properties



The synthesis of a new polar amphiphilic derivative of indandione-1,3 pyridinium betaine (IPB) with different lengths of the aliphatic tail, containing 11 (C11IPB) and 17 (C17IPB) carbon atoms respectively, is described. The electronic structure (charge distribution, energy spectra, dipole moments in ground and excited states) of the IPB molecule has been calculated in the framework of the MO CNDO methods. Studies of compression π-A isotherms of these compounds show that C17IPB forms two stable phases of monolayer on the water surface, one in the 10–30 mN m−1 and the other in the 35–50 nM m−1 surface pressure region. The corresponding areas A0 per molecule are 37 and 33 Å2 respectively. Techniques for the preparation of Langmuir-Blodgett (LB) multilayers of C17IPB in the high-pressure region (π = 40 mN m−1) on glass, quartz or sapphire substrates are described. C17IPB forms LB multilayer films of Z-type configuration with oriented dipole moments. Ellipsometric data, luminescence spectra and results of preliminary studies of second-harmonic generation in these LB films are presented.