计算机与应用化学
計算機與應用化學
계산궤여응용화학
COMPUTERS AND APPLIED CHEMISTRY
2013年
5期
553-556
,共4页
2-硫代黄嘌呤%酸解离常数%密度泛函%IEFPCM模型%CPCM模型
2-硫代黃嘌呤%痠解離常數%密度汎函%IEFPCM模型%CPCM模型
2-류대황표령%산해리상수%밀도범함%IEFPCM모형%CPCM모형
2-thioxanthine%dissociation constant%density functional theory%IEFPCM model%CPCM model
采用密度泛函B3LYP方法在6-311+G**级别上对2-硫代黄嘌呤气相和水相中较稳定的两个构型2TX(1,3,7)和2TX(1,3,9)及可能的8种离子构型进行了几何构型全优化和频率分析，水相优化选用IEFPCM模型，单点能计算采用CPCM溶剂模型并选取UAKS空穴方法。为了获得较精确的能量，在MP2/6-311+G**级别下各物种分别在两相中进行了单点能计算。根据所计算的溶剂化吉布斯自由能进一步得到了水相4种相对稳定的离子异构体的pKa值，理论计算结果与实验值基本一致，从而揭示了水溶剂中2-硫代黄嘌呤的电离活性部位和离子构型的存在形式。
採用密度汎函B3LYP方法在6-311+G**級彆上對2-硫代黃嘌呤氣相和水相中較穩定的兩箇構型2TX(1,3,7)和2TX(1,3,9)及可能的8種離子構型進行瞭幾何構型全優化和頻率分析，水相優化選用IEFPCM模型，單點能計算採用CPCM溶劑模型併選取UAKS空穴方法。為瞭穫得較精確的能量，在MP2/6-311+G**級彆下各物種分彆在兩相中進行瞭單點能計算。根據所計算的溶劑化吉佈斯自由能進一步得到瞭水相4種相對穩定的離子異構體的pKa值，理論計算結果與實驗值基本一緻，從而揭示瞭水溶劑中2-硫代黃嘌呤的電離活性部位和離子構型的存在形式。
채용밀도범함B3LYP방법재6-311+G**급별상대2-류대황표령기상화수상중교은정적량개구형2TX(1,3,7)화2TX(1,3,9)급가능적8충리자구형진행료궤하구형전우화화빈솔분석，수상우화선용IEFPCM모형，단점능계산채용CPCM용제모형병선취UAKS공혈방법。위료획득교정학적능량，재MP2/6-311+G**급별하각물충분별재량상중진행료단점능계산。근거소계산적용제화길포사자유능진일보득도료수상4충상대은정적리자이구체적pKa치，이론계산결과여실험치기본일치，종이게시료수용제중2-류대황표령적전리활성부위화리자구형적존재형식。
The geometrical structures of 2-thioxanthine two stable tautomers 2TX(1,3,7) and 2TX(1,3,9) as well as eight possible ionic forms were fully optimized in the gaseous and aqueous phases using Density Functional Theory B3LYP method at 6-311+G**level. The IEFPCM model was employed for the geometry structure optimization in the aqueous phase. Single point energy calculations were carried out at MP2/6-311+G**level combined with CPCM model for getting more accurate energies. The pKa values of five stable ionic tautomers were obtained in the base of the solvation Gibbs free energy. The calculated results are in good agreement with that in the experiments, exploring the activity side and existing form of ionic tautomers for 2-thioxanthine in the aqueous phase.
