Optical studies on composite Langmuir-Blodgett films containing ytterbium bis-phthalocyanine

Langmuir films of pure ytterbium bis-phthalocyanine (YbPc2) molecules and its mixtures with calix[4]resorcinarene (C[4]RA) molecules were studied by UVvis absorption spectra and surface pressure-area (Pi-A) isotherm measurements. Langmuir-Blodgett (LB) films of both pure YbPc2 and YbPc2-C[4]RA mixtures were produced and characterized with UV-vis spectra and surface plasmon resonance (SPR). In the case of LB films of pure YbPc2 molecules, values of 1.68 x 10(7) m(-1) and 1.76% were found for the absorption coefficient at spectral maxima and the reflectance loss. Mixed YbPc2-C[4]RA films give smaller values depending on the mixing ratio. SPR measurements, made in two media with different refractive indices, yielded accurate values of thickness of 2.06 +/- 0.06 nm and refractive index of 1.70 +/- 0.02 for LB films of pure YbPc2 molecules. Electrochromic effects, driven by electrochemical oxidation/reduction of the Yb central atom, were registered in LB films of pure YbPc2 molecules by both UV-vis absorption spectra and SPR measurements.