嘌呤结构和性质的密度泛函理论研究

嘌呤(purine)是一种重要的生物分子.用密度泛函理论(DFT)B3LYP方法,在6-311G**基组水平下,计算嘌呤的分子全优化几何构型、电子结构、自然键轨道(NBO)、IR光谱和热力学等性质.根据计算可知,嘌呤分子呈平面结构,整个分子构成大的共轭体系,具有一定的芳香性;嘌呤环上4个N原子有强的亲核活性,H13原子有强的亲电活性;求得并归属IR谱频率和强度以及200-1200K的热力学性质S0m,H0m和C0p,m,对深入研究嘌呤的反应和性质有帮助.

Density functional theory studies on the structure and properties of purine

The molecular geometry,electronic structures,natural bond orbital(NBO),IR spectra and thermodynamic properties of purine have been obtained by using density function theory(DFT) method at the B3LYP/6-311G** level.According to the results,all atoms of purine are coplanar and the molecule is constituted of a π conjugate system except H.Four nitrogen atoms of purine ring have the nucleophilic activity,at the same time,the thirteen hydrogen atom of purine ring has the electrophilic activity.The IR spectra are obtained and assigned by means of normal-mode analyses.Thermodynamic properties(S0m,H0m and C0p,m) at 200~1200K are provided using statistical thermodynamics method.These thermodynamic properties are helpful to the further study on the reaction and properties for purine.