Xavier S, Periandy S
Department of Physics, St. Joseph College of Arts and Science, Cuddalore, Tamil Nadu, India; Bharathiyar University, Coimbatore, Tamil Nadu, India.
Department of Physics, Tagore Arts College, Puducherry, India.
Spectrochim Acta A Mol Biomol Spectrosc. 2015;149:216-30. doi: 10.1016/j.saa.2015.04.055. Epub 2015 Apr 25.
In this paper, the spectral analysis of 1-phenyl-2-nitropropene is carried out using the FTIR, FT Raman, FT NMR and UV-Vis spectra of the compound with the help of quantum mechanical computations using ab-initio and density functional theories. The FT-IR (4000-400 cm(-1)) and FT-Raman (4000-100 cm(-1)) spectra were recorded in solid phase, the (1)H and (13)C NMR spectra were recorded in CDCl3 solution phase and the UV-Vis (200-800 nm) spectrum was recorded in ethanol solution phase. The different conformers of the compound and their minimum energies are studied using B3LYP functional with 6-311+G(d,p) basis set and two stable conformers with lowest energy were identified and the same was used for further computations. The computed wavenumbers from different methods are scaled so as to agree with the experimental values and the scaling factors are reported. All the modes of vibrations are assigned and the structure the molecule is analyzed in terms of parameters like bond length, bond angle and dihedral angle predicted by both B3LYP and B3PW91 methods with 6-311+G(d,p) and 6-311++G(d,p) basis sets. The values of dipole moment (μ), polarizability (α) and hyperpolarizability (β) of the molecule are reported, using which the non-linear property of the molecule is discussed. The HOMO-LUMO mappings are reported which reveals the different charge transfer possibilities within the molecule. The isotropic chemical shifts predicted for (1)H and (13)C atoms using gauge invariant atomic orbital (GIAO) theory show good agreement with experimental shifts. NBO analysis is carried out to picture the charge transfer between the localized bonds and lone pairs. The local reactivity of the molecule has been studied using the Fukui function. The thermodynamic properties (heat capacity, entropy and enthalpy) at different temperatures are also calculated.
本文借助从头算和密度泛函理论的量子力学计算，利用1-苯基-2-硝基丙烯的傅里叶变换红外光谱（FTIR）、傅里叶变换拉曼光谱（FT Raman）、傅里叶变换核磁共振光谱（FT NMR）和紫外可见光谱（UV-Vis）对该化合物进行了光谱分析。FT-IR（4000 - 400 cm⁻¹）和FT-拉曼光谱（4000 - 100 cm⁻¹）在固相下记录，¹H和¹³C NMR光谱在CDCl₃溶液相中记录，UV-Vis光谱（200 - 800 nm）在乙醇溶液相中记录。使用B3LYP泛函和6 - 311 + G(d,p)基组研究了该化合物的不同构象及其最低能量，确定了两个能量最低的稳定构象，并将其用于进一步计算。对不同方法计算得到的波数进行缩放，使其与实验值相符，并报告了缩放因子。对所有振动模式进行了归属，并根据B3LYP和B3PW91方法分别采用6 - 311 + G(d,p)和6 - 311++G(d,p)基组预测的键长、键角和二面角等参数对分子结构进行了分析。报告了分子的偶极矩（μ）、极化率（α）和超极化率（β）的值，并据此讨论了分子的非线性性质。报告了HOMO-LUMO映射，揭示了分子内不同的电荷转移可能性。使用规范不变原子轨道（GIAO）理论预测的¹H和¹³C原子的各向同性化学位移与实验位移显示出良好的一致性。进行了自然键轨道（NBO）分析以描绘定域键和孤对之间的电荷转移。使用福井函数研究了分子的局部反应活性。还计算了不同温度下的热力学性质（热容、熵和焓）。
