Ruthenium and Osmium Complexes of Phosphine-Porphyrin Derivatives as Potential Bimetallic Theranostics: Photophysical Studies

Abstract

A series of (η 6 - p -cymene)ruthenium(II)- and osmium(II) complexes of porphyrin-phosphane derivatives have been synthesized as potential bimetallic theranostic candidates. The photophysical and electrochemical properties were investigated, and these species desirably exhibit no or almost no photoinduced intramolecular atom, energy, and electron transfer between the dye and the metallic fragment. These favorable features are mostly associated with the presence of their long chain (i.e., ∼ 1 nm) separating the two functional units. Interestingly, a decrease in emission intensity and lifetimes (up to 35-fold) has been observed, which was ascribed to a small heavy atom effect. This effect is possible as a chain folding driven by an intramolecular H-bond (N–H···Cl–M).