Novel silver(I)– and gold(I)–N-heterocyclic carbene complexes. Synthesis, characterization and evaluation of biological activity against tumor cells

Abstract Two novel neutral N-heterocyclic carbene (NHC) complexes of silver ( 1 ) and gold ( 2 ), derived from 1,1′-(1,2-ethylene)-3,3′-dimethyldiimidazolium dibromide ( L 1 ), were synthesized, characterized (experimentally and computationally) and evaluated for biological activity in terms of binding to calf thymus (CT) DNA and inhibition of tumor cell lines. Spectroscopic absorption and viscosity measurements suggested the interaction with DNA to be noncovalent, probably π–π stacking or electrostatic. Additionally, electrophoresis and melting point studies and competitive studies showed a moderate interaction with CT DNA, principally complex 2 . The compounds exhibited lipophilic properties in the order: 2  >  1  >  L 1 . Compounds 1 and 2 exerted growth inhibitory and cytotoxic activity against tumor cell lines in the lower micromolar range.