Department of Chemistry, Simon Fraser University, 8888 University Dr., Burnaby, BC, V5A 1S6, Canada.
Angew Chem Int Ed Engl. 2016 Apr 4;55(15):4818-21. doi: 10.1002/anie.201511184. Epub 2016 Mar 7.
Four benzimidazolium hydroxide compounds, in which the C2-position is attached to a phenyl group possessing hydrogen, bromine, methyl groups, or phenyl groups at the ortho positions, are prepared and investigated for stability in a quantitative alkaline stability test. The differences between the stability of the various protecting groups in caustic solutions are rationalized on the basis of their crystal structures and DFT calculations. The highest stability was observed for the m-terphenyl-protected benzimidazolium, showing a half-life in 3 M NaOD/CD3OD/D2O at 80 °C of 3240 h. A high-molecular-weight polymer analogue of this model compound is prepared that exhibits excellent mechanical properties, high ionic conductivity and ion-exchange capacity, as well as remarkable hydroxide stability in alkaline solutions: only 5% degradation after 168 h in 2 M KOH at 80 °C. This is the most stable hydroxide-conducting benzimidazolium polymer to date.
四种苯并咪唑鎓氢氧化物化合物被制备出来，其中 C2 位连接有一个苯基，该苯基带有氢、溴、甲基或邻位苯基。在定量碱性稳定性测试中研究了它们的稳定性。基于晶体结构和 DFT 计算，对各种保护基在苛性溶液中的稳定性差异进行了合理化解释。间三联苯保护的苯并咪唑鎓的稳定性最高，在 80°C 的 3M NaOD/CD3OD/D2O 中的半衰期为 3240 h。还制备了这种模型化合物的高分子量聚合物类似物，该类似物表现出优异的机械性能、高离子电导率和离子交换容量，以及在碱性溶液中出色的氢氧化物稳定性：在 80°C 的 2M KOH 中 168 h 后仅降解 5%。这是迄今为止最稳定的氢氧化物导电苯并咪唑鎓聚合物。
