Ligand-Induced Intramolecular Cuprophilic and Argentophilic Interactions in Bimetallic Cu(I) and Ag(I) Phosphine Complexes and the Assessment of Their Antityrosinase and Antibacterial Effects

Abstract

Binuclear silver(I) and copper(I) complexes, 1 and 5, with bridging diphenylphosphine ligands were prepared. In 1, the silver(I) center is located inside a trigonal plane composed of three phosphorus donors from three separate and bridging dppm ligands. The fourth coordination site is filled with neighboring silver(I) ions. The short Ag···Ag distance, as a result of small bite angles from bridging dppm ligands, was determined to be 2.9463(4) Å. In 5, the Cu···Cu distance is 2.915(6) Å, significantly shorter than that observed in comparable structures. Intramolecular hydrogen bonding interactions in these complexes, such as C–H···F, C–H···O, and O–H···F interactions and π···π interactions, played a significant role in the crystal packing and stability of these molecules in the solid state. Derivatization of 1 and 5 using selected sulfur donor dialkyldithiophosphates gave six novel heteroleptic binuclear complexes. Single crystal X-ray diffraction studies of five of these complexes revealed interesting structural features, including strong metallophilic interactions in 1 and 5 and multiple intramolecular and intermolecular hydrogen bonding interactions. The antibacterial activities of complexes 1, 2, 3, 7, and 8 were also screened against gram-positive (Staphylococcus aureus PTCC 1112) and gram-negative (Escherichia coli PTCC 1330) bacteria. Antityrosinase and hemolytic effects of the selected compounds were also determined. Time-dependent density functional theory (TD-DFT), interaction region indicator (IRI), and fuzzy atom bond order (FBO) analyses of the selected complexes provided insights into the electronic and structural characteristics of the metal complexes.