新型鸟嘌呤类似物y-鸟嘌呤及其异构体电子光谱性质的理论研究  

Theoretical study on the photophysical properties of the newly designed guanine analog y-guanine and its tautomers

作　　者：张来斌[1] 任廷琦[1,2] 

机构地区：[1]曲阜师范大学物理工程学院,曲阜273165 [2]山东科技大学电子通信与物理学院,青岛266590

出　　处：《物理学报》2015年第7期290-297,共8页Acta Physica Sinica

基　　金：山东省自然科学基金(批准号:ZR2011BQ026);曲阜师范大学科研启动基金(批准号:BSQD20100107)资助的课题~~

摘　　要：荧光核酸碱基类似物的设计合成是众多研究领域的热点课题.本文利用密度泛函理论(DFT)和含时密度泛函理论(TDDFT)考察了新型鸟嘌呤类似物y-鸟嘌呤(y G-t1)及其五个异构体(y G-t2到y G-t6)的结构性质、电子性质和光谱性质,同时考察了甲醇溶剂和碱基配对对其光谱性质的影响.研究表明,气相中y-鸟嘌呤的标准结构并不是最稳定的结构,其具有三个能量相近的异构体,y-鸟嘌呤最有可能以这三种形式存在.光谱性质研究表明y-鸟嘌呤的最大吸收波长比天然鸟嘌呤大得多,人们可以对其进行选择性激发.y-鸟嘌呤的标准结构与其异构体显示出不同的光谱特性,因此可以利用其电子光谱指纹对它们进行区分.研究发现甲醇溶剂将使y-鸟嘌呤标准结构的最大吸收波长和荧光发生蓝移,而使其他异构体相应值发生红移;与胞嘧啶配对将使y G-t1,y G-t2,y G-t5和y G-t6的最大吸收波长和荧光波长发生蓝移,表明y-鸟嘌呤的电子光谱性质受环境影响较大.Recently, newly created unnatural fluorescent nucleobase analogs have gained increasing attention. In the present work, a comprehensive theoretical study on the structural, electronic, and excited-state properties of y-guanine（y G-t1）and its five possible tautomers（y G-t2, y G-t3, y G-t4, y G-t5 and y G-t6） is performed. Tautomerization analysis reveals that the canonical form of y G is not the most stable tautomer in the gas phase since it has three tautomers with the same stabilities. The spectroscopic properties are investigated： It is found that these tautomers have different absorption spectra, and so we can distinguish them by their spectroscopic signatures. In addition, effects of methanol solution and hydrogen bonding with cytosine on the absorption and emission spectra are examined. The methanol solution is found to red-shift both the absorption and emission maxima of the studied bases except for y G-t1, for which the absorption and emission maxima are blue-shifts after solvation. On the other hand, hydrogen bonding with cytosine is found to blue-shifted both the absorption and emission maxima of y G-t1, y G-t2, y G-t5, and y G-t6. Theoretical predictions here are helpful for the investigation of the tautomerism of y G and the optical properties of y DNA.

关 键 词：y-鸟嘌呤 电子光谱 密度泛函理论 溶剂效应 

分 类 号：O629[理学—有机化学]