乌头碱类生物碱电喷雾串联质谱行为及碎片离子稳定性的量子化学计算

乌头碱类生物碱电喷雾串联质谱数据对于分析该类化合物的生物活性及毒性提供了实验依据,结合量子化学计算分析乌头类生物碱电喷雾串联质谱碎片稳定性及其断裂规律,可以深入研究乌头碱类的构效关系.用abinitioHF/6-31G*方法优化六种乌头类生物碱结构,在此基础上计算相关活性部位母体与取代基之间的结合能,用以比较、判断化学键的稳定性.用此计算结果较好地解释了C8乙酰基、C14苯甲酰基和N-乙基/甲基等3种取代基失去的先后顺序,以及R3为OH.的吸电子效应对周围原子的影响;研究了缩环丢失中性CO分子的过程,从理论上预测了连在不同位置的4种甲氧基的失去规律.这表明电喷雾串联质谱中乌头碱类化合物经多次碰撞所产生的统计结果与量子化学计算结果符合得较好.

ESI-MSn Behavior and Quantum Chemistry Calculation of Stability of Fragment Ions of Diester-diterpenoid Alkaloids(DDA)

Quantum chemistry calculations were carried out to theoretically analyze the stability of fragments and the rules of elimination of substituents in electrospray ionization tandem mass spectra(ESI-MSn) for DDA.Geometries of the six DDA were optimized at ab initio HF/6-31G* level.The calculations provided the binding energies of the corresponding active bonds and the comparison of the data gave the criterion about the stability of chemical bonds.The order of eliminations of carboxyl,benzyl,ethyl or methyl as well as the influence on eliminations of.OH at C3 on the atoms around also studied.The process of elimination of CO and the rules of elimination of four methoxy groups on different carbon atoms were predicted theoretically.The results of Quantum chemistry calculation were in pretty agreement with the experimental data of ESI-MSn.