胸腺嘧啶…NO复合物结构与性质的理论研究

A Theoretical Study on Structure and Properties of the Complexes between Thymine and NO

用密度泛函理论在B3LYP/6-311+G(d,p)基组水平上对胸腺嘧啶…NO复合物体系进行了理论计算,发现了4个能量极小的复合物。其结合方式是NO的N或O原子与胸腺嘧啶的N-H键形成氢键,最稳定的复合物的结合能为-9.65 kJ/mol。NO的N原子与胸腺嘧啶的结合具有更强的优势,N结合的复合物中NO的键长缩短,而O结合的复合物中NO键长伸长。同时,对复合物的振动分析发现,在胸腺嘧啶中所有的与NO结合的N-H键的伸缩频率下降,而所有氨基的面内弯曲振动频率是增加的。

The calculations about the interaction between thymine and nitrogen monoxide were made and four isomers with minimum energies were found out. Both N and O can combine with N - H bonds of cytosine and then hydrogen bonds between them were formed. The nitrogen atom of NO had a privilege to bind with thymine, which made nitrogen combined complexes had larger population in experiment. The length of NO bond diminished in N combined complexes and it lengthened in O combined complexes. Still, the frequencies of NO in the former suffered blue shifts but did red shifts in the latter.