Salt and co-crystal formation from the reaction of fumaric acid with different N-heterocyclic compounds: Experimental and DFT study

In this work, four fumaric acid adducts with different nitrogenous bases were synthesized and characterized with FT-IR, ¹H NMR, ¹³C NMR and UV-Vis. spectroscopies. The solid-state structures of the compounds were determined by X-ray diffraction analysis. In addition, quantum chemical calculations employing density functional theory (DFT/B3LYP) method with the 6 − 311++G(d,p) basis set were performed to study the structural and spectroscopic properties of the compounds, and the results were compared with the experimental findings. X-ray analysis suggests that the crystal structures is stabilized by O–H···O, N–H···O, O–H···N and C–H···O type hydrogen bonds and also π···π stacking interactions. The harmony between the experimental and theoretical structural and spectroscopic data is acceptable in general.

本研究合成了四种与不同含氮碱基结合的富马酸加合物，并通过傅里叶变换红外光谱（FT-IR）、氢核磁共振波谱（¹H NMR）、碳核磁共振波谱（¹³C NMR）以及紫外-可见分光光度法（UV-Vis）对其进行了表征。采用X射线衍射分析确定了该系列化合物的固态晶体结构。此外，本研究采用基于6−311++G(d,p)基组的密度泛函理论（DFT/B3LYP）方法开展量子化学计算，以探究该类化合物的结构与波谱学性质，并将理论计算结果与实验观测数据进行对比。X射线衍射分析结果表明，该类晶体结构主要通过O–H···O、N–H···O、O–H···N以及C–H···O型氢键和π···π堆积相互作用得以稳定。总体而言，实验与理论得到的结构及波谱学数据之间具有较好的一致性。