LANGMUIR-BLODGETT-FILMS OF ASYMMETRICALLY PHENYL-SUBSTITUTED LUTETIUM BISPHTHALOCYANINES - SPECTROSCOPY AND GAS-SENSING PROPERTIES

Langmuir-Blodgett (LB) films of two new asymmetrically substituted phenylbisphthalocyanines, tetra-3,4,5,6-phenyllutetium bisphthalocyanine (PcLuPc(4Ph)) and tetra-3,4,5,6-phenyl-tetra-3',4',5',6'-phenyllutetium bisphthalocyanine (Pc(4Ph)LuPc(4Ph)) have been prepared. The spectroscopic studies include UV-vis, FTIR, and surface-enhanced Raman scattering (SERS) techniques. Electrochromism in LB films, formed on ITO glass, was observed with an electrode potential ranging from -0.4 to +1.2 V in 0.1 M KClO4 aqueous solution. Similar color changes were observed after chemical oxidation-reduction and acid-base treatment. The presence of substituents and the lowering of the symmetry when compared to the parent compound LuPc(2), increases the number of IR-active modes particularly in the 600-780 cm(-1) region. The interaction of the LB films with NOx was followed using SERS on gold islands substrates.