Excited states absorption spectra of porphyrins – Solvent effects

We propose a combination of different techniques to obtain the absorption cross-section spectra of triplet- and singlet-states in porphyrin-like molecules. Two extensions of the Z-scan technique are employed (pulse train Z-scan and white-light Z-scan) together with absorbance spectroscopy and laser flash photolysis. This approach allowed us to investigate features of excited-states absorption of meso-tetrakis (methylpyridiniumyl) porphyrin (TMPyP) that revealed the influence of solvents on the vibronic structuration of the transitions assigned to triplet-states, probably caused by hydrogen bonds established between the porphyrin and solvent molecules.