When Chirality Makes the Difference: The Case of Novel Enantiopure N-Heterocyclic Carbene-Gold and -Silver Complexes

N-heterocyclic carbene (NHC)-gold and -silver complexes have attracted the interest of the scientific community because of their multiple applications and their versatility in being chemically modified in order to improve their biological properties. However, most of these complexes contain one or more chiral centers, and have been obtained and studied as racemic mixture. In particular, concerning the interesting biological and medicinal properties, many questions about how the chirality may influence these properties still remain unanswered. Aiming at a better understanding, herein a series of enantiopure NHC-gold and -silver complexes was synthesized, characterized and biologically evaluated in different in vitro systems. The individuated complexes exerted different properties based on the complexed metal and the specific configuration, with the (R)-gold-NHC complexes being the most active, particularly as anti-inflammatory molecules. Docking simulations indicated a different binding mode for each enantiomer. Moreover, anticancer and antibacterial activities were also evaluated for the considered enantiomers. Overall, the reported data may contribute to a better understanding of the different biological properties exerted by the enantiopure gold and silver complexes.