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The stereocontrol of E→ Zisomerization on a (1E,3E)-diene, instead of a simple alkene, can be more challenging due to the increased number of isomerization possibilities. Herein, we report visible light-mediated regioselective (1E,3E→ 1E,3Z) isomerization of (1E,3E)-diene. The reaction conditions are mild and easy to apply and can be applied to a wide range of substances, with an excellent yield and selectivity (90:10). It is evident from the crystal structures that the cause of regioselectivity for the isomerization of 1,3-diene may not be limited to 1,3-allylic strains; CH−π interaction may also play a vital role. Computational studies suggest that this regioselective photoisomerization is a thermodynamically feasible process and requires the accumulation of spin density on the modified double bond for the transformation to occur.

trans-2-Chlorovinyldichloroarsine (lewisite, L agent, Lew-I) acts as a blistering agents. British anti-lewisite (BAL, 2,3-dimercaptopropanol) has long been used as an L-agent antidote. The main reaction channels for the detoxification proceed via breaking of As–Cl bonds and formation of As–S bonds, producing stable, nontoxic ring product [(2-methyl-1,3,2-dithiarsolan-4-yl)methanol]. M06-2X/GENECP calculations have been carried out to establish the enhanced rate of detoxification mechanism in the presence of NH3and H2O catalysts in both gas and solvent phases, which has been modeled by use of the polarized continuum model (PCM). In addition, natural bond orbital (NBO) and atoms in molecules (AIM) analysis have been performed to characterize the intermolecular hydrogen bonding in the transition states. Transition-state theory (TST) calculation establishes that the rates of NH3-catalyzed (2.88 × 10–11s–1) and H2O-catalyzed (2.42 × 10–11s–1) reactions are reasonably faster than the uncatalyzed detoxification (5.44 × 10–13s–1). The results obtained by these techniques give new insight into the mechanism of the detoxification process, identification and thermodynamic characterization of the relevant stationary species, the proposal of alternative paths on modeled potential energy surfaces for uncatalyzed reaction, and the rationalization of the mechanistic role played by catalysts and solvents.