Luminescent porphyrinosilica obtained by the sol–gel method

Hybrid materials consisting of a substituted porphyrinic macrocycle covalently bonded to a porous silica matrix have been prepared. The organic macrocycle 5,10,15,20-tetra-(p-hydroxy)phenylporphyrin, H2T(p-OH)PP, has been covalently bonded to silica gel porous networks, obtained by sol–gel reactions, by means of 3-isocyanatopropyl-triethoxysilane (IPTES), whose molecules act as bridges between the silica precursor tetraethoxysilane (TEOS) and the porphyrinic H2T(p-OH)PP macrocycles. Electronic absorption spectra show Soret and Q bands characteristic of trapped porphyrins inside the silica networks. Infrared spectroscopy monitoring has been employed to demonstrate the formation of covalent bonds between some substituents of the porphyrin molecules and the isocyanato group of IPTES.