Preparation of composite thin films of macrocyclic metal complex-solid axial ligand and their function

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Preparation of composite thin films of macrocyclic metal complex and solid axial ligand, i.e. metal oxide, was investigated in order to induce new functions which come from the chemical interaction between the components.Cobalt-tetraphenylporphyrin(CoTPP) was found to interact strongly with titania after evacuation at 473 K and to form anion radicals. Co-TPP did not interact with other metal oxides. CoTPP/titania exhibited large adsorption abilities for nitric oxide and carbon monoxide even at 373 K. This composite system was found to exhibit remarkable catalytic activity for the decomposition of nitric oxide at 373 K under the pressure of nitric oxide of above 20 Torr. In this reaction, nitrogen and nitrous oxide were produced at the molar ratio of 1/2, however no oxygen was detected in the gas phase, indicating that the produced oxygen was trapped on titania surface. The trapped oxygen was removed by the evacuation at 473 K. Total turn over number exceeded 3 based on the complex. Thi … More s system failed to show a high catalytic activity for decomposition of low concentration of nitric oxide, 500 ppm, at 373 K and to be decomposed oxidatively at 423 K.Cobalt tetrapropoxyphthalocyanine(CoTPPC) was synthesized because phthalocyanine compounds are expected to show much higher stability for oxidation reaction, however they are insoluble in organic solvents. CoTPPC was very soluble in conventional solvents such as benzene. CoTPPC /titania system was found to provide high catalytic activities for the decomposition of nitric oxide of low concentration(500 ppm) at 423 K. Nitrogen was produced selectively and no carbon dioxide was produced during the reaction. This system showed stability against the copresence of oxygen. Such a catlytic decomposition of nitric oxide at such a low reaction temperature is the first example for this reaction. In this system, the electron transfer from titania to the complex was confirmed by ESR measurements. Further investigation on increasing the catalytic activity and stability of this system is now on progress. Less