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

A series of (η6-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).