Structural Dynamics of C2F4I2 in Cyclohexane Studied via Time-Resolved X-ray Liquidography

The halogen elimination of 1,2-diiodoethane (C2H4I2) and 1,2-diiodotetrafluoroethane (C2F4I2) serves as a model reaction for investigating the influence of fluorination on reaction dynamics and solute–solvent interactions in solution-phase reactions. While the kinetics and reaction pathways of the halogen elimination reaction of C2H4I2 were reported to vary substantially depending on the solvent, the solvent effects on the photodissociation of C2F4I2 remain to be explored, as its reaction dynamics have only been studied in methanol. Here, to investigate the solvent dependence, we conducted a time-resolved X-ray liquidography (TRXL) experiment on C2F4I2 in cyclohexane. The data revealed that (ⅰ) the solvent dependence of the photoreaction of C2F4I2 is not as strong as that observed for C2H4I2, and (ⅱ) the nongeminate recombination leading to the formation of I2 is slower in cyclohexane than in methanol. We also show that the molecular structures of the relevant species determined from the structural analysis of TRXL data provide an excellent benchmark for DFT calculations, especially for investigating the relevance of exchange-correlation functionals used for the structural optimization of haloalkanes. This study demonstrates that TRXL is a powerful technique to study solvent dependence in the solution phase.

Bis(phenylsulfonyl)methane mediated synthesis of olefins via a halogen elimination and double bond migration

An effective dehydrochlorination of bis(phenylsulfonyl)alkane to prepare alkene building blocks is developed.

Probing Chemical Catalysts – How Can Advanced Crystallography Help?

Crystallography can directly provide ultimate three-dimensional structural information in a way that other science difficult to approach. We will discuss how we have used photocrystallography studies and anomalous scattering analysis to probe chemical catalysts: 1) Photochemical HCl splitting provides an opportunity to store solar energy as a chemical fuel, and is mechanistically simpler than water splitting chemistry. Families of binuclear transition metal complexes have been developed for photochemical HX-splitting but the bottle-neck to development of second generation catalysts is the challenge of halogen elimination chemistry. Current photocrystallography experiments have allowed direct observation of metastable intermediates in the photochemical manifolds of both Rh2 and Pt2 complexes, which has led to the design on new families of halide-bridged Rh2 catalysts for HX splitting. 2) Metal atom substitution within homotrinuclear clusters of Co, Mn, and Fe can have dramatic effects in the local electronic structure, which results in the changes in observed reactivity, substrate binding affinities, and catalytic function. Anomalous scattering measurements are critical for the unambiguous assignment of the trinuclear core composition, which has allowed us to investigate changes in both ensemble electronic structures and reactivity profiles.

Stability of Self-Assembled Organic-Inorganic Layered Perovskite

ABSTRACTPhoto-stability of (C6H5C2H4NH3)2PbX4 (X; Br and I) films was studied and the degradation processes were discussed. The prepared films were not stable against the UV-light irradiation. The PhE-PbX4 films were readily oxidized by the UV-light irradiation in air. In vacuum, the PhE-PbI4 films changed to β-phenethylamine intercalated PbI2 due to the elimination of halogen species. On the contrary, no degradation was observed for the PhE-PbBr4 films. These results suggested that the photo-irradiation induced photochemical reaction was one of the possible reasons for the degradation. To suppress the oxidation and halogen elimination induced by the photochemical reaction, PMMA-coated PhE-PbX4 films were also fabricated and their photo-stability was examined.