Self-Assembly of Polynuclear Coordination Cage and Organic Dyes Adsorption Behavior in Water

The metal–metal bonding interaction-driven self-assembly of polynuclear metal coordination clusters, with their diverse dynamic molecular structures and excellent photophysical properties, has become a hot topic in cluster chemistry. Aurophilicity, as a directional noncovalent bonding force, plays a very important role in the controllable self-assembly of gold(I) supramolecular aggregates. In this work, a dodecanuclear gold(I) supramolecular capsule is formed using a class of tris(thiourea) ligands with multiple sulfur coordination sites and diphosphine gold(I) complex dppmAu2Cl2 through Au–Cl/Au-P coordination substitution and aurophilicity interaction. Within the dimeric cluster structure, the planar dinuclear coordination units [(P^P)Au2(S^S)] located on the upper rim of the bowl-shaped hexanuclear cluster compound could self-assemble into a dynamic cluster-based cage through strong intermolecular metal–metal bonding interactions. Inside its internal cavity, a disordered hexafluorophosphate is completely encapsulated through multiple C–H···F hydrogen bonding interactions, which, as a dynamic polynuclear cluster containing aurophilic units, exhibits good photophysical properties while selectively adsorbing organic dyes. In water, the crystalline cationic cluster achieves a selective adsorption efficiency for anionic dyes MO and AR at 75.5 mg/g. Adsorption kinetic studies show that the cluster compound efficiently adsorbs anionic dye molecules through electrostatic interactions.