【作者】 孙巨龙；

【导师】 韩克利； 杨世和；

【作者基本信息】 中国科学院研究生院（大连化学物理研究所） ， 物理化学， 2004， 博士

【摘要】 金属离子-分子络合物的光诱导反应在许多生物、化学以及物理过程中扮演着重要角色。本论文采用激光溅射和超音速膨胀技术,产生了两种离子-分子络合物Mg⁺（OCNC₂H₅）_n 和Mg⁺-cytosine,并在反射式飞行时间质谱仪中研究了它们的光解行为。在230–440 nm 光谱范围测量了镁离子-异氰酸乙酯分子络合物Mg⁺（OCNC₂H₅）_n（n = 1-3）的光解行为光谱。对于二元络合物Mg⁺-OCNC₂H₅的光解,既观测到非反应的汽化产物Mg+,也观测到两个弱的反应产物Mg⁺OCN 和C₂H₅⁺ ;对于多配位体络合物Mg⁺（OCNC₂H₅）_2-3 的光解,仅观测到非反应的蒸发产物。利用密度泛函理论的B3LYP/6-31+G**方法,对络合物Mg⁺（OCNC₂H₅）_n（n = 1-3）的光解进行了理论研究。对于Mg⁺（OCNC₂H₅）₍1-2,实验测量的光解行为光谱与理论计算的吸收谱符合得很好。在Mg～+与C₂H₅NCO 分子络合化过程中,提出一种新的轨道杂化机制,对络合物Mg⁺-OCNC₂H₅ 构型中出现的接近直线的Mg⁺-O-C-N-C 骨架结构给予了合理解释。在Mg⁺（3 2^P←3 2^S）原子跃迁的两侧,研究了金属镁离子-碱基分子络合物Mg⁺-cytosine 的光诱导反应。在Mg⁺原子跃迁的红端和蓝端分别观测到5 个和6 个解离通道。利用密度泛函理论的B3LYP/6-311+G^**方法,研究了胞嘧啶分子的互变异构化现象。利用密度泛函理论的B3LYP/6-31+G**方法,优化了4 种Mg⁺-cytosine 母体络合物的基态构型,计算了各个解离通道的反应能。根据理论计算结果,对实验观测的解离通道给予了合理解释。更多还原

【Abstract】 Photo-induced reactions in metal ion-molecular complexes play animportant role in a wide range of biological, chemical, and physical processes.Ion-molecule complexes of Mg⁺（OCNC₂H₅）_n and Mg⁺-cytosine wereproduced in a laser-ablation supersonic expansion source, followed byphotodissociation investigation in the reflection time-of-flight mass spectrometer（RTOFMS）.Photodissociation action spectra of Mg+（OCNC₂H₅）_1-3 were recorded in thespectral range of 230-440 nm. Except for minor reactive products Mg+OCN andC2H5 at short wavelengths from the photo-reaction of the singly solvatedcomplex Mg⁺（OCNC₂H₅）, only evaporation products were observed from thephotodissociation of Mg⁺（OCNC₂H₅）_n （n=1-3）. Theoretical study was performedon the photodissociation of Mg⁺（OCNC₂H₅）_1-3 at B3LYP/6-31+G^** level. Thecalculated absorption spectra of Mg⁺（OCNC₂H₅）_1-2 agree well with observedphotodissociation action spectra. An sp hybridization mechanism was proposedfor the complexation of Mg+ and C2H5NCO, which rationalizing the nearly linearbackbone of Mg⁺-O-C-N-C in the complex of Mg⁺（OCNC₂H₅）.Photo-induced reactions in the magnesium cation-base molecule complex ofMg+-cytosine have been studied on both sides of the Mg⁺ （3 2^P ←3 2^S） atomictransition （～280 nm）. The evaporation product, Mg⁺, as well as other four and fivereactive products were observed in the long and short wavelength regions,respectively. The tautomerism of neutral cytosine in gas phase was investigated byB3LYP/6-311+G** method. The ground-state geometries of the complexescomposed of magnesium cation and the low-lying tautomers of cytosine werefully optimized at the B3LYP/6-31+G** level. The bond dissociation energies（BDEs） of the complexes for the channels we observed were calculated at thesame theoretical level. Based on the calculations, the dissociation pathways of thecomplexes of Mg+-cytosine were given a reasonable interpretation.更多还原