School of Chemistry and Chemical Engineering, Chongqing University, Daxuecheng South Road 55, 401331 Chongqing, China.
J Phys Chem A. 2022 Jul 21;126(28):4608-4616. doi: 10.1021/acs.jpca.2c03770. Epub 2022 Jul 7.
The binary molecular complexes formed between the aromatic heterocycles furan and thiophene with formic acid were investigated using pulsed-jet Fourier transform microwave spectroscopy and quantum chemical computations. For both of the complexes, rotational spectra of the lowest energy isomer were detected and assigned. Rotational spectroscopic results and density functional theory calculations support that the preferred conformation of the furan-formic acid complex is characterized by a relatively strong O-H···O and a weak C-H···O hydrogen bonds while the O-H···π and C-H···O hydrogen bonds stabilize the thiophene-formic acid complex. Natural bond orbital analysis further proves the experimental observation, suggesting that the strength of the O-H···O(furan) interaction is about two times stronger than that of O-H···π(thiophene). The symmetry adapted perturbation theory analysis reveals that electrostatic interaction is dominant in stabilizing the two complexes and that dispersion becomes significant in the thiophene-formic acid complex compared to furan-formic acid.
采用脉冲喷射傅里叶变换微波光谱学和量子化学计算研究了呋喃和噻吩与甲酸之间形成的二元分子配合物。对于这两种配合物，都检测并分配了最低能量异构体的旋转光谱。旋转光谱结果和密度泛函理论计算支持呋喃-甲酸配合物的首选构象特征是相对较强的 O-H···O 和较弱的 C-H···O 氢键，而 O-H···π 和 C-H···O 氢键稳定噻吩-甲酸配合物。自然键轨道分析进一步证实了实验观察结果，表明 O-H···O（呋喃）相互作用的强度大约是 O-H···π（噻吩）的两倍。对称自适应微扰理论分析表明，静电相互作用是稳定这两个配合物的主要因素，与呋喃-甲酸相比，色散在噻吩-甲酸配合物中变得显著。
