Metal-Free Enantioselective 1,4-Addition of Diarylphosphine Oxides to α,ß-Unsaturated Carboxylic Esters.

The catalytic asymmetric conjugate addition of phosphorus nucleophiles to unsaturated compounds, catalyzed by metallic or nonmetallic catalysts, has been extensively developed. However, the enantioselective transformations involving α,ß-unsaturated carboxylic esters for constructing chiral c-p bonds have been rarely reported, particularly in metal-free processes. In this study, we present a novel metal-free methodology for enantioselective 1,4-addition of diarylphosphine oxides to α,ß-unsaturated carboxylic esters using classical chiral oxazaborolidine catalysts. Remarkably high yields and enantioselectivities were obtained for most of the products. Furthermore, these valuable chiral phosphorus esters serve as crucial intermediates that can be transformed into various derivatives including amides, acids, and alcohols in a single step.

The mediating effects of coping styles on the relationship between trait mindfulness and romantic relationship satisfaction.

The purpose of the current study was to explore the influence of coping styles and trait mindfulness on the satisfaction of romantic relationships (RRS) among college students. Of the 305 participants, 258 (males: 115, 44.6%) had previously been in, or were presently in a romantic relationship. All participants completed the MAAS, CSQ, and questions about RRS. There was a significant meditating role of mature coping styles in the relationship between trait mindfulness and RRS (indirect effect [95% CI] = 0.021 [0.001, 0.052]). However, the mediating effect of immature coping styles was not significant (indirect effect [95% CI] = 0.038 [-0.020, 0.097]). Mature coping style plays an important mediating role in the relationship between mindfulness and relationship satisfaction.

Synergistic biodegradation of poly(ethylene terephthalate) using Microbacterium oleivorans and Thermobifida fusca cutinase.

Poly(ethylene terephthalate) (PET) is a major source of plastic pollution. Biodegradation technologies are of paramount interest in reducing or recycling PET waste. In particular, a synergistic microbe-enzyme treatment may prove to be a promising approach. In this study, a synergistic system composed of Microbacterium oleivorans JWG-G2 and Thermobifida fusca cutinase (referred to as TfC) was employed to degrade bis(hydroxyethyl) terephthalate (BHET) oligomers and a high crystalline PET film. A novel degradation product that was obtained by M. oleivorans JWG-G2 treatment alone was identified as ethylene glycol terephthalate (EGT). With the addition of TfC as a second biocatalyst, the highest synergy degrees for BHET oligomers and PET film degradation were 2.79 and 2.26, respectively. The largest amounts of terephthalic acid (TPA) and mono(2-hydroxyethyl) terephthalate (MHET) (47 nM and 330 nM, respectively) were detected after combined treatment of PET film with M. oleivorans JWG-G2 at 5 × 103 µL/cm2 and TfC at 120 µg/cm2, and the degree of PET film surface destruction was more significant than those produced by each treatment alone. The presence of extracellular PET hydrolases in M. oleivorans JWG-G2, including three carboxylesterases, an esterase and a lipase, was predicted by whole genome sequencing analysis, and a predicted PET degradation pathway was proposed for the synergistic microbe-enzyme treatment. The results indicated that synergistic microbe-enzyme treatment may serve as a potentially promising tool for the future development of effective PET degradation. KEY POINTS: • An ecofriendly synergistic microbe-enzyme PET degradation system operating at room temperature was first introduced for degrading PET. • A novel product (EGT) was first identified during PET degradation. • Potential PET hydrolases in M. oleivorans JWG-G2 were predicted by whole genome sequencing analysis.

Scalable dextran-polypyrrole nano-assemblies with photothermal/photoacoustic dual capabilities and enhanced biocompatibility.

Polypyrroles have shown great potential in photoacoustic imaging and photothermal therapy owing to its excellent photothermal conversion capabilities. However, the synthesis of polypyrrole-based nano-assemblies which have colloidal stability in biological buffers requires a number of steps, including the polymerization of pyrrole monomers, self-assembly of polypyrrole-based copolymers, and even an additional step to increase the biocompatibility of the nano-assemblies. Herein, a "polymerization/assembly" two-in-one synthesis is proposed for the first time to achieve the one-step synthesis of a new family of polypyrrole-based nano-assemblies, dextran-polypyrrole nano-assemblies (Dex-PPy NAs), under ambient conditions and in aqueous media. In addition, the approach employs tetravalent cerium ions as initiators which can initiate the polymerization of pyrrole monomers through the initiation of free radicals from dextran molecular chains. The resultant Dex-PPy NAs have a photothermal conversion efficiency reaching as high as 41 % and an excellent photostability. More importantly, the NAs with controllable nanoscale dimensions display no signs of cytotoxicity in both in vitro and in vivo studies owing to their biocompatible dextran "shell". An in vivo study further confirmed that the Dex-PPy NAs have excellent real-time photoacoustic imaging and photothermal therapy capabilities for malignant tumors. Therefore, this study represents an important step towards the scalable synthesis of polypyrrole-based nano-assemblies with photothermal/photoacoustic dual capabilities and enhanced biocompatibility.

A near-infrared xanthene-based fluorescent probe for selective detection of hydrazine and its application in living cells.

Developing fluorescent probes for selective determination of the toxic and carcinogenic hydrazine are pretty significant. Herein, a rhodamine dye coupled to naphthalene was selected as a near-infrared fluorophore and acetyl group as a trigger unit for hydrazine sensing with a Stokes shifts of 62 nm. The probe showed about 77-fold NIR fluorescence enhancement in the presence of hydrazine. In addition, the detection limit was as low as 3.4 ppb, and the fluorescence intensity at 654 nm showed a satisfactory linearity with the concentration range of hydrazine from 0 to 120 µM. More importantly, the practical utility of probe has been successfully proved through the fluorescence bioimaging of hydrazine in living cells with low cytotoxicity and quantitative N2H4 detection in environmental water samples.

A colorimetric and turn-on NIR fluorescent probe based on xanthene system for sensitive detection of thiophenol and its application in bioimaging.

Developing fluorescent probes for specific detection of extremely toxic thiophenols is pretty significant in the field of environment, chemistry and biology. We report herein a turn-on red fluorescent xanthene-based probe (RD-Probe) for detecting thiophenol with high selectivity over other analytes including aliphatic thiols. The probe could play the part of a "naked-eye"colorimetric indicator toward thiophenol. Moreover, the relative fluorescence intensity at 653 nm displayed good linearity with the concentration of thiophenol ranging from 0 to 6 µM, and the limit of detection for thiophenol could be as low as 15 nM. Furthermore, the practicability of RD-Probe has been successfully proved through the quantitative thiophenol detection in real water samples and fluorescence bioimaging of thiophenol in HeLa cells.

Copper-catalyzed ipso-selenation of aromatic carboxylic acids.

The copper-catalyzed decarboxylative selenation of aromatic carboxylic acids with diselenide is reported. This transformation tolerated a diverse set of functional groups on the substrates, including pentafluorobenzoic acid and heteroaromatic acids, delivering diaryl and methyl aryl selenides in good to excellent yields. Mechanistic studies indicated that the copper catalyst is essential in the activation of the Se-Se bond and the decarboxylation of aromatic acids. The utility of the products has been demonstrated in the facile synthesis of 10H-phenoselenazine and 11-methyldibenzo-(b,f)-1,4-selenazepine.