Kanagathara N, Marchewka M K, Drozd M, Gunasekaran S, Rajakumar P R, Anbalagan G
Department of Physics, Vel Tech University, Chennai 62, India.
Institute of Low Temperature and Structure Research, Polish Academy of Sciences, 50-950 Wrocław, 2, P.O. Box 937, Poland.
Spectrochim Acta A Mol Biomol Spectrosc. 2015 Jun 15;145:394-409. doi: 10.1016/j.saa.2015.03.002. Epub 2015 Mar 10.
Single crystals of melaminium benzoate dihydrate (MBDH) have been grown from aqueous solution by the slow solvent evaporation method at room temperature. Crystalline nature of the grown crystal has been confirmed by X-ray powder diffraction studies. The optimized geometry, frequency and intensity of the vibrational bands of MBDH were obtained by the Hartree-Fock and density functional theory using B3LYP/cam-B3LYP with 6-311++G(d,p) basis set. The harmonic vibrational frequencies were calculated and the scaled values have been compared with the experimental FT-IR and FT-Raman spectral values. The obtained vibrational wavenumbers and optimized geometric parameters are found to be in good agreement with the experimental data. UV-Visible spectrum was recorded in the region 200-400 nm and the electronic properties, HOMO-LUMO energies and other related electronic parameters are calculated. The isotropic chemical shifts computed by (1)H and (13)C NMR analysis also show good agreement with experimental observation. Natural bond orbital (NBO) analysis has been performed on MBDH compound to analyze the stability of the molecule arising from hyperconjugative interactions and charge delocalization. Molecular electrostatic potential surface (MEP) has also been performed by DFT/cam-B3LYP method with 6-311++G(d,p) basis set. Differential scanning calorimetric measurements performed on the powder sample indicate the phase transition point approximately at 368 and 358K for heating and cooling, respectively.
通过室温下缓慢溶剂蒸发法从水溶液中生长出了二水合苯甲酸三聚氰胺（MBDH）单晶。通过X射线粉末衍射研究证实了生长晶体的晶体性质。使用B3LYP/cam - B3LYP方法并结合6 - 311++G(d,p)基组，通过哈特里 - 福克和密度泛函理论获得了MBDH的优化几何结构、振动带的频率和强度。计算了谐波振动频率，并将缩放值与实验FT - IR和FT - Raman光谱值进行了比较。发现获得的振动波数和优化的几何参数与实验数据吻合良好。在200 - 400nm区域记录了紫外 - 可见光谱，并计算了电子性质、HOMO - LUMO能量和其他相关电子参数。通过(1)H和(13)C NMR分析计算得到的各向同性化学位移也与实验观察结果吻合良好。对MBDH化合物进行了自然键轨道（NBO）分析，以分析由超共轭相互作用和电荷离域引起的分子稳定性。还通过DFT/cam - B3LYP方法结合6 - 311++G(d,p)基组进行了分子静电势表面（MEP）分析。对粉末样品进行的差示扫描量热测量表明，加热和冷却时的相变点分别约为368K和358K。
