A new microporous metal-organic framework compound featuring chiral (salen)Mn struts is highly effective as an asymmetric catalyst for olefin epoxidation, yielding enantiomeric excesses that rival those of the free molecular analogue. Framework confinement of the manganese salen entity enhances catalyst stability, imparts substrate size selectivity, and permits catalyst separation and reuse.

The approach using pyrrolidine enamine as substrate has been studied for this synthesis, and an important catalyst structural feature has been developed. After survey of pyrrolidine-based Brønsted acid catalyst, tetrazole catalyst (3f) was found to be optimal in synthesis of aminooxy carbonyl compounds in high yields, with complete enantioselectivity not only for aldehydes but also for ketones.

The regiodivergent palladium-catalyzed C-H arylation of pyrazolo[1,5-a]pyrimidine has been achieved, wherein the switch in regioselectivity between positions C3 and C7 is under complete catalyst control. A phosphine-containing palladium catalyst promotes the direct arylation at the most acidic position (C7), whereas a phosphine-free catalyst targets the most electron-rich position (C3).

The upper rim cone tetraguanidinocalix[4]arene 1 is a highly effective catalyst of ATP hydrolysis. The catalytically most active species is the triprotonated form of the catalyst. The three protonated guanidinium groups provide the electrostatic driving force for substrate binding and activation, while the neutral guanidine most likely acts as a nucleophilic catalyst.

Synthesis and utilization of a simple copper on iron catalyst in the coupling of aryl halides with thiols through disulfide intermediate is reported. The iron support of copper catalyst ensures reductive media for the coupling, allows easy removal of the metals by outer magnetic field and enables the recycling of the catalyst.

This work describes a highly active and stable acid activated carbon fibre and amorphous MoS(x) composite hydrogen evolution catalyst. The increased electrochemical-surface area is demonstrated to cause increased catalyst electrodeposition and activity. These composite electrodes also show an improved stability towards the mechanical degradation of the MoS(x) catalyst.

in this research, (carboxy-3-oxopropylamino)-3-propylsilylcellulose (copapsc) as an organocatalyst, has been synthesized by grafting of succinic anhydride on the nh2-modified cellulose (cellulose functionalized with 3- aminopropyltriethoxysilane). the –co2h group-functionalized cellulose (copapsc) is used as a catalyst for the synthesis of coumarin derivatives from the reaction of phenolic subs...

The role of the crystal morphology and dissolution kinetics of Grubbs’ catalyst on self-healing capability is examined. Self-healing polymers require complete coverage of the crack plane with polymerized healing agent for optimal recovery of mechanical integrity. Lack of catalyst leads to incomplete coverage, partial polymerization, and poor mechanical recovery. Catalyst availability is determi...

The theoretical characterization of the self-organizing molecular structures emerging from ensembles of distinct interacting chemicals turns to be very important in revealing those dynamics that led to the transition from the non-living to the living matter as well as in the design of artificial protocells [12, 13, 14]. In this work we aim at studying the role of a semi-permeable membrane, i.e....

The MIT Lincoln Laboratory IDS evaluation methodology is a practical solution in terms of evaluating the performance of Intrusion Detection Systems, which has contributed tremendously to the research progress in that field. The DARPA IDS evaluation dataset has been criticized and considered by many as a very outdated dataset, unable to accommodate the latest trend in attacks. Then naturally the...