【作者】 张士国；

【导师】 杨频；

【作者基本信息】 山西大学 ， 无机化学， 2005， 博士

【摘要】 研究核酸碱基与无机小分子之间的作用,有助于探索核酸生物学功能的微观机制和阐明无机小分子的生理学意义。本文首次应用量子化学的从头算方法、密度泛函理论方法,系统地研究了核酸碱基与BH₃、BF₃、BCl₃、CO、NO之间的作用。对所形成的复合物的几何构型、能量与稳定性、分子振动性质、分子间的相互作用等进行了研究。 对胸腺嘧啶-BH₃复合物分别用B3LYP/6-31G（d）和MP2/6-31G（d）进行计算预测了该复合物的构型及结合能,得到了5种构型,B与O直接相连的构型比较稳定,所有构型中均存在电荷授受,各构型的结合能与电荷转移量有良好的相关性,复合物的形成,使其红外光谱均有不同程度的红移,红移幅度与复合物的稳定性相关。 对鸟嘌呤-BH₃体系的计算发现了该体系的7个能量极小的复合物。由吡啶型N或羰基O或氨基N与B原子结合形成的复合物体系相对稳定。按照分子中的原子理论的分析,在多数复合物中双氢键形成。振动分析表明复合物中BH₃的伸缩振动频率均出现红移,且红移幅度与复合物的结合能有相关性,复合物中所有的形成双氢键的N-H键的伸缩频率亦出现红移。 对腺嘌呤-BH₃形成的复合物体系优化计算,找到了6个稳定的构型,其中由腺嘌呤的吡啶型N₁,N₃和N₇提供孤对电子与B的空p轨道作用的3个构型比较稳定,而且这三个位点的N原子与B的结合力十分接近,振动分析结果表明BH₃,NH₂和N₉-H的伸缩发生红移而C-H的伸缩和NH₂的面内弯曲发生蓝移,自然键轨道分析的结果表明复合物中均存在电荷由腺嘌呤到BH₃的转移,转移量与复合物的稳定性相关。 对胞嘧啶-BH₃复合物分别进行理论计算以预测该复合物的构型及稳定化能,得到了5种稳定构型,B与N和O直接相连的构型比较稳定,各构型的稳定化能随电荷转移量增加而增大。 对尿嘧啶-BH₃复合物的理论计算得到了5种稳定构型,对各构型进行了振动频率分析和自然键轨道分析,各构型都存在不同程度的电荷转移,转移方式和转移量与结合方式有关。 对鸟嘌呤-BX₃（X=F,Cl）复合物体系在B3LYP/6-311+G^*水平上进行了DFT计算,每一系列各得到4个稳定的构型,所有的稳定构型均由吡啶型N或羰基O或氨基N与B以σ-p作用结合而成。鸟嘌呤-BF₃中最稳定的是B与N₃作用形成的构型,而鸟更多还原

【Abstract】 The studies about the interaction between nucleic acid bases and small inorganic molecules are helpful to investigate the micro-mechanism of the biological function of nucleic acids and to explain the physiology process of small inorganic molecules. This thesis presents a systematical investigation to complexes formed between various nucleic acid bases and BH3,BF3,BC13,CO,NO et. al. using the ab initio methods, density functional theory (DFT) calculations.Geometries and combination energies are predicated at B3LYP/6-31G(d) and MP2/6-31G(d) level for thymine-BH3 complexes and 5 geometries have been obtained. The charge transference exists in all the conformers and the combination energies have a good line relationship with their charge transference. The calculated results showed that when the complex formed their IR spectrum moved to the red side and the frequency shifts are relative to the stabilities of the complexes.Seven configurations with no imaginary frequencies have been obtained for the guanine-BH3 systems. The results indicate that four of the seven configuration are relatively stable ones in which the pyridine-type nitrogen atoms or carbonyl oxygen or nitrogen of amino group offers its lone pair electron to the empty p orbital of born atom. According to the AIM analysis, dihydrogen bonds have been formed in most of them. The frequencies analysis showed that all the stretching vibrations of BH3 undergo red shifts in complexes, and the shifts are relatively to the combining energies of complexes.Geometries and binding energies are predicted for adenine-BH3 complexes and 6 optimized configurations have been obtained. The results indicate that the three configurations in which the pyridine-type nitrogen atoms offer their lone pair electrons to the empty p orbital of born atom are the most stable ones and the 3 pyridine-type nitrogen atoms have the similar abilities to combine with B atom. The vibration analysis showed that the stretching frequencies of BH3, NH2 and N9-H suffered red shifts while that of the bending of NH2 and the stretching of C-H bond showed blue shifts. The charge transferences from adenine to BH3 existed in the complexes according to the results of NBO analysis.Geometries and combination energies are predicated at B3LYP/6-31G and MP2/6-31Glevel for cytosine-BH3 complexes and 5 geometries have been obtained. The outcome indicates that the configurations with the boron atom combines with N or O directly are relative stable ones. The stabilities of the remainders that formed with n-p interaction are weaker. The stabilities of all configurations are relative to their charge transference.Five configurations have been obtained in the calculations for uracil-BH3 complexes. The vibrational analysis and natural bond orbital analysis are carried out for the obtained configurations. The phenomena of charge transference exist in all the conformers. The style and amount of charge transference are varied with the configurations.Geometries and binding energies are predicted at B3LYP/6-311+G* level for the guanine-BX3 (X=F,C1) systems and four conformers with no imaginary frequencies have been obtained for both guanine-BF3 and guanine-BC^ respectively. The formation for all the configurations are based on the o-p action that pyridine-type N or carbonyl O offers its lone electron pair to the empty p orbital of B. In the most stable configuration of guanine-BF3, BF3 connected to N3 of guanine. While in the most stable configuration of BCI3 complexes, BCI3 connected to O10 of guanine. Guanine-BF3 complexes are more stable than guanine-BCb ones. Besides a-p actions, hydrogen bonds between guanine and BX3 were formed according to the AIM analysis.Geometries and binding energies are predicted for the adenine-BX3 (X=F,C1) systems and four configurations have been obtained for both adenine-BF3 and adenine-BCb respectively. The most stable conformer is BF3 or BCI3 connected to N3 of adenine and with the stabilization energy of 94.39 or 86.19 kJ/mol at B3LYP/6-311+G* level. Three of four configurations are relatively stable as they are formed with the fact that pyridine-type N offer lone electron pair to the empty orbital of B for both BF3 and BC13 complexes. Just as guanine-BX3 systems, adenine-BF3 complexes are more stable than adenine-BCl3 ones and the concomitances of charge transference from adenine to BX3 were occurred.For the cytosine-BX3(X=F,Cl) systems, geometries and binding energies were using the B3LYP method of DFT and MP2 method of ab initio with 6-311+G* or 6-311++G* bases sets. Three configurations were found for each system. In the most stable conformer of cytosine-BF3 or cytosine-BCl3, boron atom of BX3(X=F,C1) connected to carbonyl oxygen Og of cytosine with a stabilization energy of-78.71 and -69.62 kJ/mol respectively. The analyses for the combining interaction between BX3 and cytosine with the更多还原