Two-Dimensional Supramolecular Architecture of a Dinuclear Platinum(II) Complex Exhibiting Dual Emission in Aqueous Solution.
Two-dimensional (2D) supramolecular architectures have attracted considerable attention owing to their unique structural anisotropy and collective electronic and optical properties. In this study, a terpyridine-based dinuclear platinum(II) complex (Pt2-L) incorporating chiral R-aminoethyl moieties was synthesized as a building block for supramolecular polymerization. The self-assembly behavior of Pt2-L was systematically investigated as a function of H2O content in DMSO, revealing the formation of well-defined supramolecular architectures. Very interestingly, the self-assembled Pt2-L exhibits two strong emission bands at approximately 420 nm and in the 570-650 nm region, which are attributed to aggregation-indued emission (AIE) and metal-metal-to-ligand charge transfer (MMLCT) transitions arising from Pt···Pt interactions, respectively. Time-dependent morphological studies showed that the thermodynamically stable 2D structures were generated through spherical aggregates as kinetic intermediates. Notably, the helicity of the thermodynamic 2D supramolecular architectures was opposite to that of the intermediate structures. Thermodynamic analysis using a van't Hoff plot revealed a Gibbs free energy change of -31.9 kJ mol-1 for the supramolecular polymerization process. Furthermore, FT-IR, photoluminescence, and WAXS analyses suggest that intermolecular hydrogen bonding, π-π stacking, and Pt···Pt metallophilic interactions cooperatively act as key driving forces for the formation of the supramolecular architecture.