2412-10-4Relevant academic research and scientific papers
Cucurbit[7]uril host-guest complexes and [2]pseudorotaxanes with N-methylpiperidinium, N-methylpyrrolidinium, and N-methylmorpholinium cations in aqueous solution
Gamal-Eldin, Mona A.,MacArtney, Donal H.
, p. 1234 - 1241 (2013)
The formations of host-guest complexes between cucurbit[7]uril and a series of N-substituted N-methylpiperidinium, N-methylpyrrolidinium, and N-methylmorpholinium cations in aqueous solution have been investigated using 1H NMR spectroscopy and electrospray ionization mass spectrometry. Dications comprising the N-methylheterocyclic head groups, bridged by a decamethylene chain, form sequential 1:1 ([2]pseudorotaxanes) and 2:1 host-guest complexes with cucurbit[7]uril. The cucurbituril initially resides over the decamethylene chain, however with further additions of the host molecule a translocation of the hosts to the cationic N-heterocyclic head groups occurs. The order of the magnitude of the cucurbituril host-guest stability constants, determined by competitive 1H NMR binding experiments, follows the trend in the hydrophobicity of the quaternary ammonium cations.
Insight into the Alkaline Stability of N-Heterocyclic Ammonium Groups for Anion-Exchange Polyelectrolytes
Chen, Nanjun,Fan, Jiantao,Hu, Chuan,Jin, Yiqi,Lee, Young Moo,Li, Hui,Liu, Haijun,Wu, Bo,Xu, Shaoyi
supporting information, p. 19272 - 19280 (2021/07/25)
The alkaline stability of N-heterocyclic ammonium (NHA) groups is a critical topic in anion-exchange membranes (AEMs) and AEM fuel cells (AEMFCs). Here, we report a systematic study on the alkaline stability of 24 representative NHA groups at different hydration numbers (λ) at 80 °C. The results elucidate that γ-substituted NHAs containing electron-donating groups display superior alkaline stability, while electron-withdrawing substituents are detrimental to durable NHAs. Density-functional-theory calculations and experimental results suggest that nucleophilic substitution is the dominant degradation pathway in NHAs, while Hofmann elimination is the primary degradation pathway for NHA-based AEMs. Different degradation pathways determine the alkaline stability of NHAs or NHA-based AEMs. AEMFC durability (from 1 A cm?2 to 3 A cm?2) suggests that NHA-based AEMs are mainly subjected to Hofmann elimination under 1 A cm?2 current density for 1000 h, providing insights into the relationship between current density, λ value, and durability of NHA-based AEMs.
An unusual Michael addition-dealkylation or elimination via the reaction of tertiary or secondary amines with a (Z)-iodoacrylate
Maw, Graham,Thirsk, Carl,Whiting, Andrew
, p. 8387 - 8390 (2007/10/03)
A series of (E)-ammonium or amino acrylates have been prepared via the Michael addition of methyl (Z)-iodoacrylate and several secondary and tertiary alkylamines. Tertiary amines undergo concomitant addition-dealkylation, almost quantitatively producing (
