A Green and Wide-Scope Approach for Chiroptical Sensing of Organic Molecules through Biomimetic Recognition in Water.

Optical chirality sensing has attracted a lot of interest due to its potential in high-throughput screening in chirality analysis. A molecular sensor is required to convert the chirality of analytes into optical signals. Although many molecular sensors have been reported, sensors with wide substrate scope remain to be developed. Herein, we report that the amide naphthotube-based chirality sensors have an unprecedented wide scope for chiroptical sensing of organic molecules. The substrates include, but are not limited to common organic products in asymmetric catalysis, chiral molecules with inert groups or remote functional groups from their chiral centers, natural products and their derivatives, and chiral drugs. The effective chirality sensing is based on biomimetic recognition in water and on effective chirality transfer through guest-induced formation of a chiral conformation of the sensors. Furthermore, the sensors can be used in real-time monitoring on reaction kinetics in water and in determining absolute configurations and ee values of the products in asymmetric catalysis.

Bis-Naphthalene Cleft with Aggregation-Induced Emission Properties through Lone-Pair⋠⋠⋠π Interactions.

A rigid molecular cleft shows unique aggregation-induced emission (AIE) by restricting the motion of aldehyde through intermolecular lone pair⋅⋅⋅π interactions, which are tuned by side chains. This AIE luminogen was demonstrated to work as a fluorescent sensor for aniline and an optical chirality sensor for chiral amine.

Theoretical Studies on Palladium-Mediated Enantioselective C-H Iodination.

DFT calculations have been carried out to investigate the reaction mechanism for Pd(II)-mediated enantioselective C-H iodination. Iodination of the aryl ortho C-H bond of benzylamines catalyzed by Pd(II) diacetate complexes in the presence of the L-MPAA ligand experiences three main steps: first, C-H bond activation; second, oxidative addition of iodine on Pd(II) and reductive elimination of iodobenzene; third, catalyst regeneration through ligand exchange. The C-H bond activation is found to be the rate-determining step of the overall iodination due to higher activation energy. The reaction barrier for the formation of iodinated (R)-benzylamine is lower than that of (S)-benzylamine, which confirms the R enantioselectivity in iodination at room temperature. The retainment of the coordination of one acetic acid on Pd(II) and the chelating MPAA ligand during the catalyzed reaction are suggested to give space economy to facilitate the C-H bond activation. The NHTf functional group on the substrate is found to be very important for ortho C-H iodination at ambient condition. Our calculated results are consistent with the experimental observations.

A mechanism study on the hydrogen evolution reaction catalyzed by molybdenum disulfide complexes.

Density functional theory (DFT) calculations show that H2 evolution is attributed to active sulfur hydrides derived from MoS2 complexes via two- or three-electron reduction from the synthesized [(PY5Me2)MoS2]2+. Water acts as a bridge for H2 evolution from the intermolecular H+/H- coupling between sulfur hydride complexes and hydrated protons.

Oxatub[5,6]arene: synthesis, conformational analysis, and the recognition of C60 and C70.

Large oxatub[n]arenes (n = 5, 6) have been synthesized and characterized. Their conformational complexity was analyzed and host-guest chemistry was studied. In particular, the rather flexible oxatub[6]arene is able to accommodate C60 and C70 with moderate binding affinities. Computational results suggest that there are different binding affinities to C60 or C70 for each conformer of oxatub[6]arene. This endows oxatub[6]arene with conformational adaptability according to the needs of its guests.

Dynamic characteristics of the novel strobilurin fungicide SYP-3343 in aerobic soils.

SYP-3343, (E)-2-(2-((3-(4-chlorophenyl)-1-methyl-1H-pyrazole-5-yloxy)methyl)phenyl)-3-methoxyacrylate, is a newly developed strobilurin fungicide. However, the environmental behavior and fate of SYP-3343 in soil have not been well-documented. In this study, ¹4C-labeled SYP-3343 was employed to investigate the dynamic characteristics in three typical soils under aerobic conditions. Radioactivity analysis after high-performance liquid chromatography (HPLC) showed that SYP-3343 degraded rapidly in the coastal soil with a half-life of 43.8 days. After incubation of 100 days, its extractable residues were greater than 76.0% and bound residues were less than 12.4%, indicating that SYP-3343 was not easy to accumulate in soils. The mineralization to ¹4CO2 reached 5.4% for acidic soil, 2.8% for neutral soil, and 1.7% for alkaline soil, suggesting that it was difficult to cleave the pyrazole ring completely. In addition, dynamic characteristics of SYP-3343 in sterile and non-sterile loamy soil showed that soil microbes affected SYP-3343 residue in soil and could accelerate the process of degradation and mineralization.