Cation-controlled catalysis with crown ether-containing transition metal complexes

Abstract

This Feature Article reviews the structural motifs and catalytic applications of crown ether-containing catalysts and details the development of “pincer-crown ether” ligands for applications in controlled catalysis.

Performance and selectivity of lower-rim substituted calix[4]arene as a stationary phase for capillary gas chromatography

“…This interesting nding suggests the stronger molecular interactions of the aromatics with the C4A-C10 stationary phase. The stronger retention for the aromatics can be ascribed to the unique aromatic skeleton of the calix [4]arene stationary phase with the 3D cavity, which may favor enhancing their p-p interactions to a large extent. And for aromatics, the p-p interactions between the calix [4]arene stationary phase and analytes may dominate.…”

“…Macrocyclic compounds (crown ethers, cyclodextrins, calixarenes and cucurbiturils) have unique conguration characteristics, such as different cavity size, conformation, and functionality, allow the formation of host-guest interactions between hosts and numerous guests, and result in widely varying applications in supramolecular chemistry, coordination chemistry, and separation science. [1][2][3][4][5] In chromatographic separation, macrocyclic compounds have been reported as adsorption materials for sample preparation and as stationary phases for liquid chromatography (LC), gas chromatography (GC) and capillary electrochromatography (CEC). [6][7][8][9][10] Calixarenes, the third generation of host supramolecules following crown ethers and cyclodextrins, were obtained by the oligomerization of para-substituted phenol and formaldehyde.…”

“…Zhang et al has developed the mixed mode stationary phase based on calixacrown graed polysiloxanes, which has been successfully used for the separation of aromatic isomers in GC. 30 Yu et al reported the mixture of calix [4]arene and OV-1701 as stationary phase in the gas chromatograph, successfully separated alcohols, halohydrocarbons and aromatic compounds and found that tert-butyl on the upper rim of calix [4]arene played a signicant role in the recognition process of solute molecules. 31 Delahousse et al used calix [6]arene derivative as stationary phase through the sol-gel method for GC separation of PCBs and PAHs.…”

“…31 Delahousse et al used calix [6]arene derivative as stationary phase through the sol-gel method for GC separation of PCBs and PAHs. 28 As illustrated in Scheme 1, we presents the investigation of utilizing the p-tert-butyl(tetradecyloxy)calix [4]arene (C4A-C10) stationary phase for GC separations. Compared with mixedmode stationary phases, C4A-C10 stationary phase can reect retention behaviors and interaction mechanisms of calixarene-type stationary phases more directly.…”

Pillar[5]arene Based [1]rotaxane Systems With Redox-Responsive Host-Guest Property: Design, Synthesis and the Key Role of Chain Length

“…Pillar[ n ]arenes (Ogoshi et al, 2008; Cragg and Sharma, 2012; Xue et al, 2012; Si et al, 2015; Wang et al, 2015, 2016; Sun et al, 2018; Xiao and Wang, 2018; Xiao et al, 2019a,b), which are the newest host compounds in supramolecular chemistry after crown ethers (Liu et al, 2017; Yoo et al, 2019), cyclodextrins (Fu et al, 2019), calix[ n ]arenes (Dalgarno et al, 2007), and cucurbiturils (Murray et al, 2017), have attracted extensive investigations due to their pillar-like topology, rigid structures, electron-rich cavities, and rich host-guest properties (Song and Yang, 2015; Li et al, 2019; Wang et al, 2019). Up to now, pillar[ n ]arene-based pseudo[1]rotaxanes with ammonium units, urea groups, pyridinium salt or biotin units as the axles have been investigated a lot (Strutt et al, 2012; Ni et al, 2014; Wu et al, 2015), but the further formation of [1]rotaxanes is difficult due to the lack of reactivity with stoppers.…”