Characterization of an electropolymerized Pt(II) diamino phenyl porphyrin polymer suitable for oxygen sensing

The electropolymerization of di-phenyl-di-(4-aminophenyl)-porphyrin-Pt(II) and the application of this polymer to oxygen sensing using spectroscopic measurements is presented. The main advantage of this sensor is that the lumophore forms part of the sensing polymer. The absorption and luminescence spectra of the polymer retain the characteristic shape of the porphyrin monomer spectra indicating that the polymerization process does not perturb the porphyrin molecular orbitals. Images of the polymer surface obtained using atomic force microscopy suggest that a homogeneous polymer is formed and that the polymer structure grows in layers. The luminescence properties of this polymer are exploited for determining oxygen in the concentration range 0 to 0.2 atm (air). The weighted average luminescence lifetime of the polymer was found to vary from 63.7 mu s to 30.9 mu s in nitrogen and air environments respectively. The sensitivity of the polymer was determined from the Stern-Volmer plot which was linear over the concentration range studied giving a Stern-Volmer quenching constant (K-SV) of 5.05 +/- 0.14 atm(-1).