Metal-organic-framework-derived copper-based catalyst for multicomponent C-S coupling reaction

Copper-based metal-organic frameworks(Cu-MOFs)are a promising multiphase catalyst for catalyzing C-S coupling reactions by virtue of their diverse structures and functions.However,the unpleasant odor and instability of the organosulfur,as well as the mass-transfer resistance that exists in multiphase catalysis,have often limited the catalytic application of Cu-MOFs in C-S coupling reactions.In this paper,a Cu-MOFs catalyst modified by cetyltrimethylammonium bromide(CTAB)was designed to enhance mass transfer by increasing the adsorption of organic substrates using the long alkanes of CTAB.Concurrently,elemental sulfur was used to replace organosulfur to achieve a highly efficient and atom-economical multicomponent C-S coupling reaction.

Efficient homogenous catalysis of CO_(2) to generate cyclic carbonates by heterogenous and recyclable polypyrazoles

The cycloaddition between CO_(2)and epoxides to produce cyclic carbonate is an attractive and efficiency pathway for the utilization of CO_(2)as C1 source.The development of catalyst to mediate cycloaddition between CO_(2)and epoxides at low temperature and pressure is still a challenge.Herein,a series of polypyrazoles with glass transition temperature(T_(g))in the range of 42.3-52.5℃ were synthesized and served as catalyst to mediate the cycloaddition of CO_(2)and epoxides by the assistant of tetrabutylammonium bromide.The catalytic behaviors of polypyrazole on the model cycloaddition of CO_(2)to epichlorohydrin,including the reaction parameters optimization and versatility were investigated in detail,and excellent yield(99.9%)and selectivity(99%)were obtained under the optimized reaction conditions of70℃ and 1.0 MPa for 6.0 h.Noteworthily,the polypyrazole acts as homogeneous catalyst during reaction(higher than T_(g)).And under room temperature,polypyrazoles can be easily separated and recovered,which is a promising feature of a heterogeneous catalyst.Furthermore,the reaction mechanism was proposed.The DFT calculation suggested that the formation of hydrogen bond between pyrazole and epoxide greatly reduced the energy barrier,which play an important role in promoting CO_(2)cycloaddition.

一种同时具备显著增强的双折射和二次谐波效应的类BBO三聚硫氰酸盐

在新兴的自旋轨道角动量光子技术领域,对兼具强二次谐波和大双折射的非线性光学晶体有很大的需求.基于此,本文采用具有大π共轭效应的[HC_(3)N_(3)S_(3)]_(2)−和碱金属阳离子K+相结合,成功合成了一例新型类β-BaB_(2)O_(4)(BBO)手性三聚硫氰酸盐K_(4)(HC_(3)N_(3)S_(3))_(2)·H_(2)O(1).与具有最优排列的π共轭[B3O6]3−环的BBO相比,1中[HC_(3)N_(3)S_(3)]_(2)−环的排列并不理想,但倍频响应和双折射显著增强(1.8×BBO;Δn=0.402@550 nm,~3.3×BBO).第一性原理计算分析表明,π共轭[HC_(3)N_(3)S_(3)]_(2)−环是产生优异光学性能的根本原因.这项工作证明了π共轭[HC_(3)N_(3)S_(3)]_(2)−是优秀的双功能“材料基因”,在新兴光子技术的光学集成器件研究中值得更多的关注.

Surface activity and cleaning performance of rosin-based quaternary ammonium salt type asymmetric Gemini surfactants

Rosin,a renewable and abundant resource,has been extensively processed and chemically modified to endow it with special properties,especially in the surfactant industry.In this study,four rosin-based quaternary ammonium asymmetric gemini surfactants(RGS-2-n)with different alkyl chain lengths(n=12,14,16,18)were synthesized using a simple two-step method based on dehydroabietylamine as the raw material.The feasibility of these surfactants for cleaning purposes was comprehensively evaluated,suggesting that the surfactants own high surface activity and good cleaning performance.Furthermore,by successfully introducing the amine group of dehydroabietylamine into the hydrophilic group of the surfactants,we avoided its potential harm to the environment and water pollution.Density functional theory proves rosin-based gemini surfactants with asymmetric structure can further improve cleaning efficiency.Overall,our findings suggests that RGS-2-n surfactants are promising and sustainable candidates for cleaning electric plates,and provide new opportunities for rosin application in the electric industry.

A mussel-inspired supramolecular hydrogel with robust tissue anchor for rapid hemostasis of arterial and visceral bleedings

In recent years,the developed hemostatic technologies are still difficult to be applied to the hemostasis of massive arterial and visceral hemorrhage,owing to their weak hemostatic function,inferior wet tissue adhesion,and low mechanical properties.Herein,a mussel-inspired supramolecular interaction-cross-linked hydrogel with robust mechanical property(308.47±29.20 kPa)and excellent hemostatic efficiency(96.5%±2.1%)was constructed as a hemostatic sealant.Typically,we combined chitosan(CS)with silk fibroin(SF)by cross-linking them through tannic acid(TA)to maintain the structural stability of the hydrogel,especially for wet tissue adhesion ability(shear adhesive strength=29.66±0.36 kPa).Compared with other materials reported previously,the obtained CS/TA/SF hydrogel yielded a lower amount of blood loss and shorter time to hemostasis in various arterial and visceral bleeding models,which could be ascribed to the synergistic effect of wound closure under wet state as well as intrinsic hemostatic activity of CS.As a superior hemostatic sealant,the unique hydrogel proposed in this work can be exploited to offer significant advantages in the acute wound and massive hemorrhage with the restrictive access of therapeutic moieties.

One-step synthesis of cyclic polypyrazole and the self-assembly vesicles driven by hydrogen bond

The synthesis of cyclic polymer is an important topic in polymer chemistry. Herein, we report a one-step method to prepare cyclic polypyrazoles. Monomers with two functional groups, diazo and alkyne, were synthesized and polymerized via 1,3-diploar cycloaddition in bulk under heating without any catalyst.Polypyrazoles with molecular weights in the range of 3800-4400 g/mol and yields in the range of 78.8-98.7% were successfully synthesized. No chain end group was detected by LC-QTOF-MS and FTIR, which proves the cyclic structure of polypyrazoles. What is noteworthy is that the cyclic polypyrazoles can selfassemble into vesicles during the reprecipitation process, which was proved by the results of SEM and TEM. The reason for that is the formation of intermolecular hydrogen bond between NH and ester groups.