title: Origin of the unusual ultraviolet absorption of Arsenicin A.
abstract: This paper presents a combined experimental and theoretical study of the electronic spectrum of the natural adamantane-type polyarsenical Arsenicin A. Experiments reveal that this molecule strongly absorbs UV light in the absence of an obvious chromophore. The observed absorbance is supported by the time-dependent density functional (TD-DFT) calculations with B3LYP, M06-L, and M06-2X functionals combined with the 6-311+G(3df,2pd) basis set, as well as by symmetry-adapted cluster/configuration interaction (SAC-CI) theory. The theoretical investigations reveal that the absorption is facilitated by through-space and through-bond interactions, between the lone pairs on the arsenic and oxygen atoms and the σ-bonding framework of the molecule, that destabilize occupied and stabilize unoccupied molecular orbitals.
authors: Research School of Chemistry, Australian National University, Canberra, ACT, Australia.
authors: Sundaram
authors: S
authors: Arulmozhiraja
authors: Michelle L
authors: ML
authors: Coote
authors: Di
authors: D
authors: Lu
authors: Geoffrey
authors: G
authors: Salem
authors: S Bruce
authors: SB
authors: Wild
mesh_terms: D001152:Arsenicals / Q000737:chemistry*; D011789:Quantum Theory; D013056:Spectrophotometry, Ultraviolet; D014466:Ultraviolet Rays
chemical_list: D001152:Arsenicals; C517594:arsenicin A