Multifunctional Templating Strategy for Fabrication of Fe,N-Codoped Hierarchical Porous Carbon Nanosheets

Due to the unique physical and chemical merits including excellent electrical conductivity,superior chemical stability,and tunable carbon framework,two-dimensional(2 D)porous carbon nanosheets have drawn increasing research interest and demonstrated promising potentials in various applications.However,regulating the nanostructure of 2 D porous carbon nanosheets by facile and efficient strategies remains a great challenge.Herein,we develop a new strategy to construct Fe,N-codoped hierarchical porous carbon nanosheets(Fe-N-HPCNS)by using 2 D Fe-Zn layered double hydroxides(Fe-Zn-LDH)as multifunctional templates.Fe-Zn-LDH could functionalize not only as 2 D structure directing agents but also as ternary hierarchical porogens for micro-,meso-and macropores and in situ Fe dopants.This multifunctional templating strategy toward 2 D porous carbon nanosheets can improve the utilization of templates and shows great advantages against conventional procedures that additional porogens and/or dopants are often needed.     

A Practical and Robust Zwitterionic Cooperative Lewis Acid/Acetate/Benzimidazolium Catalyst for Direct 1,4-Additions

A catalyst type is disclosed allowing for exceptional efficiency in direct 1,4-additions. The catalyst is a zwitterionic entity, in which acetate binds to Cu^II, which is formally negatively charged and serving as counterion for benzimidazolium. All 3 functionalities are involved in the catalytic activation. For maleimides productivity was increased by a factor >300 compared to literature (TONs up to 6700). High stereoselectivity and productivity was attained for a broad range of other Michael acceptors as well. The polyfunctional catalyst is accessible in only 4 steps from N-Ph-benzimidazole with an overall yield of 96 % and robust during catalysis. This allowed to reuse the same catalyst multiple times with nearly constant efficiency. Mechanistic studies, in particular by DFT, give a detailed picture how the catalyst operates. The benzimidazolium unit stabilizes the coordinated enolate nucleophile and prevents that acetate/acetic acid dissociate from the catalyst.