Ghalla H, Govindarajan M, Flakus H T, Issaoui N, Yaghmour S J, Oujia B
University of Monastir, Quantum Physics Laboratory, Faculty of Science, Monastir 5079, Tunisia.
Department of Physics, BGCW College, Puducherry, India.
Spectrochim Acta A Mol Biomol Spectrosc. 2015 Feb 5;136 Pt B:579-93. doi: 10.1016/j.saa.2014.09.071. Epub 2014 Sep 30.
In this work, molecular geometries and fundamental vibrational frequencies of 2-furanacetic acid (2FAA) and its hydrogen bonded dimer were investigated using DFT/B3LYP method with 6-311++G(d,p) as basis set. The FT-infrared and FT-Raman spectra of the 2FAA compound were recorded in the region 4000-400 cm(-1). The theoretical wavenumbers were scaled and compared with experimental FT-IR and FT-Raman spectra. Complete vibrational assignments and analysis of the fundamental modes of monomer and dimer structures were performed on the basis of the potential energy distribution (PED) calculations. A study on the electronic properties, such as excitation energies, oscillator strength, wavelengths, HOMO and LUMO energies, are performed by time-dependent DFT (TD-DFT) approach. Molecular stability arising from hyperconjugative interactions and charge delocalization has been analyzed using Natural Bond Orbital (NBO) analysis. Topological parameters such an electron density and its Laplacian at bond critical points (BCP) of O-H and O⋯H contact bonds were analyzed in details with the help of the atoms in molecules (AIM) approach in order to study the intermolecular hydrogen bonding. The nonlinear optical properties of the title molecule have been investigated. Moreover, molecular electrostatic potential (MEP) surface was plotted for predicting sites and relative reactivities towards electrophilic and nucleophilic attack. The nonlinear optical properties were reported and compared with that of the urea. The thermodynamic properties like heat capacity, entropy, and enthalpy have been calculated for the molecule at different temperatures.
在本工作中，采用密度泛函理论（DFT）/B3LYP方法，以6-311++G(d,p)为基组，研究了2-呋喃乙酸（2FAA）及其氢键二聚体的分子几何结构和基本振动频率。在4000 - 400 cm⁻¹区域记录了2FAA化合物的傅里叶变换红外（FT-IR）光谱和傅里叶变换拉曼（FT-Raman）光谱。对理论波数进行了标度，并与实验FT-IR和FT-Raman光谱进行了比较。基于势能分布（PED）计算，对单体和二聚体结构的基本振动模式进行了完整的振动归属和分析。通过含时密度泛函理论（TD-DFT）方法对激发能、振子强度、波长、最高占据分子轨道（HOMO）和最低未占据分子轨道（LUMO）能量等电子性质进行了研究。利用自然键轨道（NBO）分析研究了超共轭相互作用和电荷离域产生的分子稳定性。借助分子中的原子（AIM）方法，详细分析了O-H和O⋯H接触键在键临界点（BCP）处的拓扑参数，如电子密度及其拉普拉斯算子，以研究分子间氢键。研究了标题分子的非线性光学性质。此外，绘制了分子静电势（MEP）表面，以预测亲电和亲核攻击的位点及相对反应活性。报道了非线性光学性质，并与尿素的进行了比较。计算了该分子在不同温度下的热容量、熵和焓等热力学性质。
