Observation of intermediates by online mass spectrometry to demonstrate the multiple mechanisms of dye-sensitized photocatalysis.

Online mass spectrometry was applied to reveal multiple mechanisms of visible-light irradiated dye-sensitized photocatalysis for o-phenylenediamine oxidation. The reactants, products and short-lived intermediates were recorded and dynamically tracked. Dimer and unexpected trimer intermediates were observed to deduce the stepwise aerobic photooxidation mechanism with multiple routes, which was supported by theoretical calculations.

Visualizations of Mercury Methylation and Dynamic Transformations by In Vivo Imaging.

Visualization of Hg(II) and MeHg in their native contexts is significant for examining mercury poisoning, while it is challenging because of indistinguishable fluorescent (FL) signals during FL imaging. Herein, visualizations of mercury methylation and dynamic transformations of Hg(II) and MeHg are achieved in living biological systems. Well distinguishable FL responses (blue emission for Hg(II), yellow emission for MeHg) are obtained by a double-response FL probe (DPAHB) without any interference. As demonstrated by experimental and computational studies, the distinguishable signals are attributed to selective binding with DPAHB and different inhibition of excited-state proton transfer. Through control tests for live-dead markers, mercury methylation is demonstrated to be employed in living biological systems. Therefore, the methylation and dynamic transformations of both ions are monitored in zebrafish by imaging, and these results are confirmed by traditional high-performance liquid chromatography-based methods. The methylation of Hg(II) to MeHg, dynamic transformations and final accumulations of both species in zebrafish tissues are visualized successfully. This method is also convenient for fast evaluation of detoxification reagents. This is the first visualization of in vivo mercury methylation and dynamic transformation of both species and is effective for studying pathological processes in their native contexts.

Insight into the Bonding Mechanism and the Bonding Covalency in Noble Gas-Noble Metal Halides: An NBO/NRT Investigation.

The bonding between noble gas and noble metal halide like hydrogen bonding (H-bonding) motivates us to investigate the bonding mechanism and the bonding covalency in NgMX (Ng = He, Ne, Ar, Kr, Xe, Rn; M = Cu, Ag, Au; X = F, Cl, Br, I) complexes using natural bond orbital (NBO) and natural resonance theory (NRT) methods. In this study, we introduce the new resonance bonding model in H-bonding into NgMX bonding. We provide strong evidence for resonance bonding involving two important resonance structures: Ng: M-X ↔ Ng+-M :X- in each of NgMX complexes, originating in the nNg → σ*MX hyperconjugative interaction. The covalency of the bonding could be understood by the localized nature of Ng-M bonds in these two resonance structures, and the degree of Ng-M covalency can be quantitatively described by calculated NRT bond orders bNgM. Furthermore, we find that the bond order satisfies conservation of bond order, bNgM + bMX = 1, for all of the studied complexes. On the basis of the conservation of bond order and some statistical correlations, we also reveal that the Ng-M bond (except He-Ag and Ne-Ag bonds) can be tuned by changing the auxiliary ligand X. Overall, the present studies provide new insight into the bonding mechanism and the covalency of the bonding in noble gas-noble metal halides, and develop one resonance bonding model.