Supramolecular conformational effects in the electrocatalytic properties of electrostatic assembled films of meso(3-and 4-pyridyl) isomers of tetraruthenated porphyrins

Meso(3- and 4-pyridyl) porphyrins coordinated to four [Ru( bipy)(2) Cl](+) complexes, M(3-TRPyP) or M(4-TRPyP), where M=2H(+) and Zn2+, have been obtained and characterized by electrochemistry, spectroscopy and mass spectrometry. Layer-by-layer electrostatic assembled films with tetrasulfonated phthalocyaninatecuprate(II) anion, CuTSPc, displayed distinct electrocatalytic activity towards sulfite and nitrite oxidation. In general, the films derived from the M(4-TRPyP) isomers are more effective for the oxidation of nitrite, whereas those containing the M(3-TRPyP) isomers are more efficient for the oxidation of sulfite. The results demonstrated the influence of molecular geometry on the active sites of porphyrinic nanomaterials, enhancing the electron-transfer process in the M(3-TRPyP) derivative. This effect results from changes in the chemical environment around the active sites, induced by the contrasting molecular packing interactions with CuTSPc.