Porphyrin-TiO2 nanoparticle heterostructure assembly by Langmuir-Blodgett method

Surface pressure-area (pi-A) isotherm characteristics of 5.10,15-(4-hydroxy phenyl)-20-(4-hexadecyloxy- phenyl) porphyrin monolayers on both the water and TiO2 hydrosol subphases, the UV-vis absorption and fluorescence spectra of the monolayers deposited onto CaF2 substrates are investigated. pi-A is otherms find that the porphyrin ring extends to lie more flat on a TiO2 hyd rosol surface than on a water surface. The UV-vis absorption spectra of the deposited monolayers prove that the porphyrin TiO2 nanoparticle heterostru cture assembly is formed, in which the J-aggregated affect of porphyrin is weakened, comparing with that in the monolayer deposited from water subphas e. The fluorescence spectra show that the fluorescent emission quenching by the photoinduced electron transfer from the excited porphyrin molecule to TiO2 nanoparticle, occurs under excitation in the Soret band region of porp hyrin. (C) 1998 Elsevier Science Limited. All rights reserved.