Photochemical properties of a Re(I) polymer containing dppz in its structure. An interplay between dark and bright states of dppz

Abstract

A new polymer, P4VP-Re(dppz), based on the poly-4-vinylpyridine structure containing Re(CO)3(dppz)+ pendants was synthesized. Multiple morphologies of P4VP-Re(dppz), such as vesicles, spherical nanoaggregates, large vesicle compounds, rings and pyramidal structures were observed by AFM and TEM in cast films of P4VP-Re(dppz) in solvents of different polarity and solvent/acid mixtures. Several conformations of a model monomer of P4VP-Re(dppz) were studied by TD-DFT to ascertain the effect of protonation over the molecular structure as well as over the absorption spectroscopy of P4VP-Re(dppz). P4VP-Re(dppz) excited states and their redox reactivity towards the sacrificial reductant TEOA were studied by flash photolysis experiments either in DMF and in DMF/HClO4. Those experiments were compared to the ones derived from thermal reactions of P4VP-Re(dppz) with solvated electrons in pulse radiolysis experiments. All the photophysical and photochemical properties studied were rationalized in terms of an interplay between 3IL(ππ*), 3MLCT(phz) and the 3MLCT(phen) states.