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用密度泛函理论,在BL3YP/6-311++G**基组水平上研究5-氟尿嘧啶…NO复合物体系,用更大基组(6-311+G(2df,p)和aug-cc-pVDZ)进行单点能的计算,发现5个能量极小的复合物。同时,使用自然键轨道(NBO)法和分子中的原子(AIM)法对5-氟尿嘧啶和NO分子间的作用本质进行了分析。结果显示,5-氟尿嘧啶和NO的结合方式是NO的N、O原子与5-氟尿嘧啶的N-H键形成氢键,或O原子与5-氟尿嘧啶分子间通过弱π键结合在一起。最稳定复合物的结合能为-7.86 kJ/mol。N原子与5-氟尿嘧啶的结合更有优势,N结合的复合物中,NO键长缩短,伸缩振动频率蓝移,而O结合的复合物中,NO键长伸长,伸缩振动频率发生红移。
The density functional theory (DFT) was used to study the 5-fluorouracil NO complex system at BL3YP / 6-311 ++ G ** basal group level, using the larger base set (6-311 + G (2df, p) cc-pVDZ) for single-point energy calculations and found five extremely energy-poor complexes. At the same time, the nature of the interaction between 5-Fluorouracil and NO molecules was analyzed using the natural bond orbital (NBO) method and the atomic (AIM) method in the molecule. The results showed that the combination of 5-Fluorouracil and NO was NO of N and O atoms formed hydrogen bond with N-H bond of 5-fluorouracil or O atom and 5-Fluorouracil molecule were linked by weak π bond. The binding energy of the most stable complex is -7.86 kJ / mol. The combination of N atom and 5-fluorouracil is more advantageous. In the N-bound complex, the NO bond length is shortened and the stretching vibration frequency is blue shifted. In the O-bound complex, the NO bond length is elongated and the stretching vibration frequency is red shifted .