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

Binuclear silver(I) and copper(I) complexes, <b>1</b> and <b>5</b>, with bridging diphenylphosphine ligands were prepared. In <b>1</b>, 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 <b>5</b>, 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 <b>1</b> and <b>5</b> 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 <b>1</b> and <b>5</b> and multiple intramolecular and intermolecular hydrogen bonding interactions. The antibacterial activities of complexes <b>1</b>, <b>2</b>, <b>3</b>, <b>7</b>, and <b>8</b> were also screened against gram-positive (<i>Staphylococcus aureus</i> PTCC 1112) and gram-negative (<i>Escherichia coli</i> 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.