Fluorescence and phosphorescence of lutetium(III) and gadolinium(III) porphyrins for the intraratiometric oxygen sensing

Fluorescence and phosphorescence spectra, quantum yields of the emissions, and phosphorescence lifetimes of Lu(III) and Gd(III) porphyrins in solutions measured at 25°C and at –196°C are reported. The studied species were estimated in terms of a kind of a metal ion and a porphyrin ligand towards their application in luminescence-based oxygen sensing. The obtained results suggest a possibility of utilization of Ln(III) porphyrins in the intraratiometric luminescence intensity-based oxygen sensing. It concerns a simultaneous observation of a red-colored S₁→S₀ fluorescence (which is independent from both oxygen and temperature) and oxygen sensitive a near-infrared T₁→S₀ phosphorescence emitted by the same complex.