Ming Chen

A synergistic Cu/Fe-catalyzed aerobic oxyphosphorylation of alkynes or alkynyl carboxylic acids with H-phosphonate is disclosed. The useful β-ketophosphonate products were obtained in good yields under oxygen atmosphere in a novel way. This reaction exhibits a wide substrate scope, and the mechanistic experiments indicate that a radical mechanism forms both C-P and C═O bonds simultaneously. This mechanism contrasts existing aerobic difunctionalization of alkynes.

Abstract The design of high‐performance compounded flame retardants based on multielement can be of great significance for reducing the flammability of polymer materials. In this article, a new type of N‐P‐Cu containing supermolecular assembly network (MPCSN) flame retardant was prepared and subsequently added into thermoplastic polyurethane elastomer (TPU)/silicon microencapsulated ammonium polyphosphate (SiAPP) composites. The obtained results indicated that a series of TPU/SiAPP/MPCSN composites exhibited strong adhesions with the TPU matrix. Additionally, the thermal and flame retardant performances of TPU composites were markedly improved after the introduction of different proportions of SiAPP to MPCSN. For example, the peak of heat release rate, the total heat release, the peak of smoke production rate, the total smoke release of the TPU composite containing 7.5 wt% SiAPP and 2.5 wt% MPCSN (TPU/SiAPP3/MPCSN1) remarkably decreased by 68.7%, 52.9%, 52.4%, and 49.4%, respectively, besides the highest LOI value (27.5 vol%) and UL‐94 V‐0 rating, compared with those of pure TPU. The improved flame retardance of the TPU/SiAPP3/MPCSN1 composite was due to the explanations: On one hand, a compact intumescent char effectively protected the TPU matrix from heat and oxygen and retarded the gaseous products permeation into the combustion zone; on the other hand, evolved phosphorus‐containing free radicals captured the H• and HO• generated from the TPU material. The synergistic effect of SiAPP and MPCSN resulted in strong flame suppression, accompanied by 10.8% and 37.8% reductions in FIGRA and Av‐EHC, respectively. This article offers a facile approach to fabricate highly effective flame‐retardant TPU composites.

Lasso peptides are attracting increasing attention due to their broad range of biological activities. The knot topology of lasso peptides, which contains an isopeptide bond-bridged macrocycle threaded by its C-terminal tail, has been proven to be an important structural feature for their bioactivities. The preparation of lasso peptides has been achieved by biosynthetic methods; nevertheless, a chemical synthesis of lasso peptides has not been described so far. Herein, a cryptand-imidazolium complex is designed as a multi-linker support and applied in the chemical synthesis of the lasso peptide BI-32169. Furthermore, the chiral switching of the support and the introduction of d-amino acids enable the synthesis of the d-enantiomer of BI-32169, which shows not only a strong glucagon receptor antagonist activity, but also a much higher enzymatic stability compared to the l-lasso peptide.

ABSTRACT The ultraviolet (UV)‐C ageing behavior of silicone rubber (SiR) incorporated with titanium dioxide nanoparticles (nano‐TiO 2 ) was studied under UV‐C radiation. The SiR incorporated with nano‐TiO 2 displayed excellent physical properties when exposed to UV‐C radiation. With the increase of the ageing time, the SiR with nano‐TiO 2 showed no significant change in crosslinking density and Shore A hardness. Moreover, compared with the SiR without nano‐TiO 2 , the SiR incorporated with nano‐TiO 2 also exhibited high retention ratio in tensile properties, especially elongation at break. It was found that nano‐TiO 2 was a good ultraviolet light stabilizer during the UV ageing process of SiR and the optimum content of nano‐TiO 2 was 2 phr. The results of Fourier transform infrared spectroscopy and X‐ray photoelectron spectroscopy showed the appearance of OH and CO and the decrease of the intensity of SiC 2 O 2 in SiR samples during the process of UV‐C ageing. Based on these results, a possible UV ageing mechanism of SiR could be proposed. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135 , 46099.