Nanofiber Composites Containing BIAN N-heterocyclic Gold Carbene Complexes and Cytotoxicity in Human Cancer Cells

A carbene is a divalent carbon atom linked to two other groups by covalent bonds, and possesses two unshared valence electrons. These electrons can be paired in the same orbital as anti-parallel spins (singlet) represented as σ2 or pπ2 in different orbitals, or as parallel spins (triplet) represented as σ1 pπ1. (Droge and Glorius, 2010). N-Heterocyclic carbenes (NHCs) are singlet carbenes in which the E substituents are nitrogen atoms; these carbenes are neutral 2-electron donors, with an ability to bond to both hard and soft metals, making them versatile ligands (Weskamp et al., 1999; Herrmann, 2002). NHCs are easy to synthesize and functionalize since they form a stronger bond to metals and therefore form more stable metal complexes. The reactivity of a carbene is influenced by the nature of the substituents attached to the carbene carbon atom (Bourissou et al., 2000). The N-heterocyclic carbene (NHC) metal complexes possess diverse biological activities and a few of them have been reported as potential chemotherapeutic agents (Hindi et al., 2009; Teyssot et al., 2009; Gautier and