Structures For "A Theoretical Investigation On The Aminolysis Of Pyromellitic And 1,4,5,8- Naphthalenetetracarboxylic Dianhydrides"

Aniline aminolysis reaction of pyromellitic (PMDA) and 1,4,5,8-naphthalenetetracarboxylic (NTDA) dianhydrides is investigated by means of density functional theory (BP86-D3(BJ)/def2-TZVP). The concerted mechanism is shown to be more favorable for both substrates, in comparison to the stepwise one, with the aminolysis of PMDA presenting lower activation energy than the reaction of NTDA. This result is shown to be related to the lower ring tension in NTDA. Solvation also shows significant influence on the kinetics and thermodynamics of these reactions, as determined by two different methods, implicit with the universal solvation model SMD, and explicit with alchemical FEP molecular dynamics simulations. The comparison between SMD and FEP enables us to explore possible inaccuracies on the SMD model, and examine the suitability of the FEP approach as a physics-based method for the calculation of the solvent contribution in different reactions.本研究采用密度泛函理论（BP86-D3(BJ)/def2-TZVP）方法，对均苯四甲酸二酐（pyromellitic dianhydride, PMDA）与1,4,5,8-萘四甲酸二酐（1,4,5,8-naphthalenetetracarboxylic dianhydride, NTDA）的苯胺氨解反应进行了系统的理论探究。结果表明，相较于分步式反应机理，协同式反应机理对两种底物均更具优势；其中均苯四甲酸二酐的氨解反应活化能低于1,4,5,8-萘四甲酸二酐的对应反应，该结果与1,4,5,8-萘四甲酸二酐更低的环张力密切相关。溶剂化效应对上述反应的动力学与热力学过程均具有显著影响，本研究通过两种不同方法开展分析：一是采用通用溶剂化模型SMD的隐式溶剂化方法，二是采用化学突变型自由能微扰（alchemical free energy perturbation, FEP）的显式溶剂化分子动力学模拟。通过对比SMD与FEP的计算结果，本研究可探究SMD模型可能存在的精度不足问题，并验证FEP方法作为基于物理原理的溶剂贡献计算手段在不同反应中的适用性。