Emel'yanenko Vladimir N, Zaitsau Dzmitry H, Shoifet Evgeni, Meurer Florian, Verevkin Sergey P, Schick Christoph, Held Christoph
Department of Physical Chemistry and Department, Science and Technology of Life, Light and Matter, University of Rostock , Dr-Lorenz-Weg 1, D-18059, Rostock, Germany.
Department of Physical Chemistry, Kazan Federal University , Kremlevskaya str. 18, 420008 Kazan, Russia.
J Phys Chem A. 2015 Sep 17;119(37):9680-91. doi: 10.1021/acs.jpca.5b04753. Epub 2015 Sep 2.
The thermochemical properties available in the literature for adenine and cytosine are in disarray. A new condensed phase standard (p° = 0.1 MPa) molar enthalpy of formation at T = 298.15 K was measured by using combustion calorimetry. New molar enthalpies of sublimation were derived from the temperature dependence of vapor pressure measured by transpiration and by the quarz-crystal microbalance technique. The heat capacities of crystalline adenine and cytosine were measured by temperature-modulated DSC. Thermodynamic data on adenine and cytosine available in the literature were collected, evaluated, and combined with our experimental results. Thus, the evaluated collection of data together with the new experimental results reported here has helped to resolve contradictions in the available enthalpies of formation. A set of reliable thermochemical data is recommended for adenine and cytosine for further thermochemical calculations. Quantum-chemical calculations of the gas phase molar enthalpies of formation of adenine and cytosine have been performed by using the G4 method and results were in excellent agreement with the recommended experimental data. The standard molar entropies of formation and the standard molar Gibbs functions of formation in crystal and gas state have been calculated. Experimental vapor-pressure data measured in this work were used to estimate pure-component PC-SAFT parameters. This allowed modeling solubility of adenine and cytosine in water over the temperature interval 278-310 K.
文献中腺嘌呤和胞嘧啶的热化学性质杂乱无章。通过燃烧量热法测量了在T = 298.15 K时新的凝聚相标准（p° = 0.1 MPa）摩尔生成焓。新的升华摩尔焓是根据通过蒸腾法和石英晶体微量天平技术测量的蒸气压对温度的依赖性推导出来的。通过温度调制DSC测量了结晶腺嘌呤和胞嘧啶的热容。收集、评估了文献中关于腺嘌呤和胞嘧啶的热力学数据，并将其与我们的实验结果相结合。因此，这里报告的评估数据集合以及新的实验结果有助于解决现有生成焓中的矛盾。推荐了一组可靠的腺嘌呤和胞嘧啶热化学数据用于进一步的热化学计算。使用G4方法对腺嘌呤和胞嘧啶的气相摩尔生成焓进行了量子化学计算，结果与推荐的实验数据非常吻合。计算了晶体和气体状态下的标准摩尔生成熵和标准摩尔吉布斯生成函数。利用本工作中测量的实验蒸气压数据估算了纯组分PC-SAFT参数。这使得能够对278 - 310 K温度区间内腺嘌呤和胞嘧啶在水中的溶解度进行建模。
