Synthesis and properties of urea porphyrinosilica

The synthesis of a hybrid network consisting of alternating porphyrin as optical active agent and siloxane units (porphyrinosilica) can be achieved by sol–gel process. Due to several applications of these hybrids, we search for new methods to prepare them. A porphyrinosilica with a urea linker was synthesized through the reaction of NH2 groups present in the phenyl rings of mesotetrakis p-aminophenyl porphyrin (TAMPPH2) with 3-isocyanatopropyltriethoxysilane (IPTES) followed by condensation with tetraethoxysilane (TEOS). The polymerization reactions were carried out in ethanol or dimethylformamide using acidic or basic catalysis. The formation of urea bonds was confirmed by infrared spectroscopy. The absorption and luminescence spectra confirmed the presence of porphyrin in the network and were also established by thermal analysis. Nuclear magnetic resonance 29Si data for the porphyrinosilica addressed the degree of condensation and the extent of network formation.