Raw data for "Photophysical and structural characterization of a ruthenium complex-pyrene Coulombic dyad photocatalyst"

Abstract

Coulombic dyads have recently emerged as a novel class of photocatalysts that exploit noncovalent ion-pair interactions to combine the favorable photophysical properties of metal complexes and organic chromophores in solution. A key mechanistic step in these systems is a Dexter-type energy transfer between the ionic components. This study thoroughly investigates the (photo)physical properties and geometry of the first reported Coulombic dyad, composed of dicationic tris(1,10-phenanthroline)ruthenium(II) (Ruphen) and 1,3,6,8-pyrenetetrasulfonate (PTS). This serves as a textbook-like system with mixed dynamic and static quenching behavior, which was investigated by various emission-based time-resolved and steady-state spectroscopic methods, highlighting their differences and the importance of accurate models to determine the association constant. Temperature-dependent measurements revealed a decrease in dynamic and static quenching efficiency at elevated temperatures and provided thermodynamic parameters characterizing ion-pair formation. The time constant for intra-ion-pair energy transfer from the triplet metal complex to the organic chromophore was determined to be ~87 ps using femtosecond transient absorption spectroscopy. Structural insights were obtained from single-crystal X-ray crystallography and molecular dynamics simulations. The simulations revealed a high persistence of the ion-pair in the ground-state and a dynamic yet geometrically well-defined association. A structural similarity was found between solution and solid-state arrangements, indicating π-interactions besides Coulombic interactions between the ions. These interactions enable sufficient orbital overlap rationalizing the observed efficient Dexter energy transfer, which is as fast as in many covalently linked systems. These in-depth investigations provide a comprehensive picture of structure-property relationships in Coulombic dyads, offering valuable insights for their future design and applications.