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
N-杂环铵 (NHA) 基团的碱性稳定性是阴离子交换膜 (AEM) 和 AEM 燃料电池 (AEMFC) 的关键课题。在这里,我们报告了对 24 个代表性 NHA 基团在不同水合数(λ) 在 80 °C。结果表明,含有给电子基团的 γ 取代 NHA 显示出优异的碱性稳定性,而吸电子取代基对耐久的 NHA 有害。密度泛函理论计算和实验结果表明,亲核取代是 NHA 的主要降解途径,而霍夫曼消除是基于 NHA 的 AEM 的主要降解途径。不同的降解途径决定了 NHA 或基于 NHA 的 AEM 的碱性稳定性。AEMFC 耐久性(从 1 A cm -2到 3 A cm -2)表明基于 NHA 的 AEM 主要在 1 A cm -2电流密度下进行 1000 小时的霍夫曼消除,从而深入了解电流密度与λ之间的关系 基于 NHA 的 AEM 的价值和耐久性。
Carbonylation of quaternary ammonium salts to tertiary amides using NaCo(CO)4 catalyst
作者:Yizhu Lei、Rui Zhang、Qing Wu、Hui Mei、Bo Xiao、Guangxing Li
DOI:10.1016/j.molcata.2013.10.014
日期:2014.1
the catalytic carbonylation of quaternary ammoniumsalts under anhydrous condition. Quaternary ammoniumsalts, a kind of versatile reagents that were widely used in organometallic chemistry, can be carbonylated to tertiaryamides by an in situ prepared NaCo(CO)4 catalyst. It was found that the counterions (Cl−, Br−, I−, OTf−) in the quaternary ammoniumsalts played a significant role in the reaction
Palladium-catalyzed carbonylation of quaternary ammonium halides to tertiary amides
作者:Yizhu Lei、Rui Zhang、Linjuan Wu、Qing Wu、Hui Mei、Guangxing Li
DOI:10.1002/aoc.3126
日期:2014.4
anhydrous conditions was investigated using palladium catalyst. The carbonylation of tetramethylammonium iodide was chosen as a model reaction and studied systematically. Ligand‐free PdCl2 showed efficient catalytic performance for this transformation. A palladium catalyst loading as low as 0.05 mol% was sufficient for high yield (96.9%) of N,N‐dimethylacetamide, corresponding to a turnover frequency
Cucurbit[7]uril host–guest complexes and [2]pseudorotaxanes with N-methylpiperidinium, N-methylpyrrolidinium, and N-methylmorpholinium cations in aqueous solution
作者:Mona A. Gamal-Eldin、Donal H. Macartney
DOI:10.1039/c2ob27282b
日期:——
1 : 1 ([2]pseudorotaxanes) and 2 : 1 host–guestcomplexes 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–gueststability constants, determined by competitive 1H NMR binding experiments
使用1 H NMR光谱和电喷雾电离质谱法研究了葫芦[7]尿素与一系列N-取代的N-甲基哌啶鎓,N-甲基吡咯烷鎓和N-甲基吗啉鎓阳离子之间的主-客体络合物的形成。由十甲基链桥接的包含N-甲基杂环首基的阳离子与葫芦丝[7]尿嘧啶形成顺序的1:1([2]假轮烷)和2:1主体-客体复合物。葫芦素起初位于十甲基链上,但是随着主体分子的进一步添加,主体易位至阳离子N-发生杂环首基。通过竞争性1 H NMR结合实验确定的葫芦素主体-客体稳定性常数的大小顺序遵循季铵阳离子疏水性的趋势。
Multi-functional hybrid perovskites with triple-channel switches and optical properties
作者:Meng-Meng Lun、Fo-Ling Zhou、Da-Wei Fu、Qiong Ye
DOI:10.1039/d2tc01063a
日期:——
excitation. The phasetransitiontemperatures of 2 and 3 achieve a very high value: ca. 380 K. Meanwhile, good nonlinear optical properties (SHG) and optimized PL properties were obtained. Thus, multi-functional hybrid perovskites simultaneously with triple-channel switches and optical properties were successfully fabricated. This work might provide a new impetus for designing new organic hybrid perovskites
具有高转变温度的多功能开关材料可以在较宽的温度范围内工作,特别适用于汽车、航空航天和发电行业等极端热条件下的实际应用。卤素取代策略是一种有效的分子修饰方法,可以将卤素原子引入阳离子中,增加阳离子运动的能垒,从而获得高转变温度的化合物。在此,通过卤化原型的有机阳离子 ( N , N -dimethylmorpholinium)PbBr 3 (compound 1 ),我们报道了两种三通道电介质/SHG/PL 开关材料 ( N -ClCH 2 -N-甲基吗啉鎓)PbBr 3和( N - BrCH 2 -N-甲基吗啉鎓)PbBr 3 ( 2和3 )。这些化合物采用由共面八面体[PbBr 6 ] -链和有机阳离子构成的一维钙钛矿结构,在紫外光激发下可发出橙红色光。2和3的相变温度达到了非常高的值:约。380 K. 同时,获得了良好的非线性光学特性 (SHG) 和优化的 PL 特性。因此,成功地制造