作者:Zoran Glasovac、Luka Barešić、Ivana Antol、Davor Margetić
DOI:10.1002/cplu.201800247
日期:2018.9
colorless to yellow. Measured pKa (BH+ ) in acetonitrile ranges from 12-16, which is comparable to the pyridinium cations. The proton transfer equilibria were also tested in acetonitrile/water mixture where all but the most acidic derivatives showed pKa (BH+ ) of 4-6 units which corresponds to apparent association constants of 104 -106 dm3 mol-1 . UV/Vis spectra of neutral and protonated forms were modelled
制备了一系列苯甲酰基胍盐,并研究了由阴离子的存在引起的UV / Vis光谱变化。所有化合物均与碱性阴离子(如磷酸二氢根和乙腈中的乙酸根)一起去质子化。通过使N1-苯甲酰基-N3-(对硝基苯基)氯化胍去质子化获得最明显的光谱变化,其显示肉眼可见的颜色从无色变为黄色。乙腈中测得的pKa(BH +)为12-16,与吡啶鎓阳离子相当。还在乙腈/水混合物中测试了质子传递平衡,除最酸性衍生物外,所有其他衍生物均显示pKa(BH +)为4-6个单位,这对应于104 -106 dm3 mol-1的表观缔合常数。使用CAM-B3LYP和PBE0功能,通过TD-DFT方法对中性和质子化形式的UV / Vis光谱进行建模,并与CC2结果进行比较。在CAM-B3LYP的情况下,定义了远程交换校正量的参数ω被改变以达到与实验光谱的最佳一致性。对于中性苯甲酰基胍,优化的ω参数为0.10 a0 -1,对于中性硝基苯甲酰基和质子化体系,优化的ω参数为0