摘要
用光度法测得三种桥链冠醚卟啉和二种卟啉胆固醇酯的质子化常数，并用HMO法进行了量子化学计算，讨论了取代基的电子效应及空间效应对常数的影响．
The overall protonation constants of three bridged crowned porphyrins and two cholesterol-porphyrins were determined by spectrometric methods and the quantum chemistry computation with HMO were made by 486 type microcomputer. The influence of electron effect and steric hindrance of substituting group on overall protonation constants was discussed.Experimental data and theoretical discussion showed that simple portonated cation (PH ) has been formed before the formation of double protonated cation (PH ), but simple protonated cation (PH ) is unstable. Degree of porphyrins protonation depend on electron and steric effect. Protonation constants are increased by the donor groups through conjugate effect,while steric hindrance of substituting group reduces the constants decrease.
出处
《物理化学学报》
SCIE
CAS
CSCD
北大核心
1996年第4期325-328,共4页
Acta Physico-Chimica Sinica
关键词
卟啉
质子化常数
共轭效应
HMO法
卟啉胆固醇酯
Porphyrin, Apparent protonation constants, Conjugate effect, Steric hindrance, UV-VIS spectra
