Probing second-sphere hydrogen-bonding interactions in metal complexes with time-resolved photoacoustic

Depending on the Lewis acid-base properties of the ligand moiety and the surrounding molecules, some coordination metal complexes can interact with the solvent molecules through second-sphere donor-acceptor (SSDA) interactions. In aqueous media, hydrogen bonding governs the solute-solvent interactions. In this report, the enthalpy content, Delta H-MLCT, and the structural volume change, Delta V-MLCT, associated with the formation and decay of the metal-to-ligand charge-transfer triplet state ((MLCT)-M-3) of ruthenium (II) bipyridine cyano complexes were determined using time-resolved photoacoustics (TRP), in water, water pools of reverse micelles, and in the presence of polyammonium macrocycle [32]ane-[N8H8](8+), for the formation of supercomplexes. The results are explained as function of the structure and properties of the hydrogen-bonding interactions between the,metal complexes and the surrounding molecules.