Middya Asif Iqubal, Chakraborty Abhijit
Department of Physics, The University of Burdwan, Golapbag Campus, Burdwan, 713104, West Bengal, India.
J Mol Model. 2025 Jul 12;31(8):207. doi: 10.1007/s00894-025-06432-6.
The oxygen, sulfur, and selenium derivatives of tetralin termed as isochroman (IC), isothiochroman (ITC), and isoselenochroman (ISC) showed interesting conformational patterns. In particular, ITC and IC have immense pharmacological significance. The twisted conformer is the global minimum in IC, where the bent is a transition state (TS) and remains 1100 ± 100 cm higher. The bent form in ITC and ISC possesses the lowest energy. But, the twisted conformer lies higher by about 80 ± 20 cm in ITC and 700 ± 50 cm in ISC. The potential energy surfaces (PES) locate all the conformations and TSs. Molecular electrostatic potentials indicate the sites of electrophilic interactions, and the small energy difference between the minima in ITC predicts an interesting interplay of intermolecular interactions in suitable environments. The validity of the maximum hardness principle and minimum electrophilicity principles is checked. Frontier molecular orbitals show the change in electron densities on excitation, which are mostly π → π in nature. Hyperconjugative interactions involving different σ and lone pair orbitals explain the change in conformational patterns in these molecules. We suggest some experiments to corroborate our findings.
Computations are performed with different functionals (B3LYP, M06-2X, and ωB97X-D) in DFT as well as ab initio methods (MP2 and CCSD) with 6-311G + + (2d, 3p) and augmented cc-pVDZ as basis sets. Gaussian 09 is used for the above computations. PED analyses were performed by Veda 4 software. For viewing and plotting purposes, Gaussview 5.0 and Origin 8.5 are used.
萘满的氧、硫和硒衍生物，即异苯并二氢吡喃（IC）、异硫代苯并二氢吡喃（ITC）和异硒代苯并二氢吡喃（ISC）呈现出有趣的构象模式。特别是，ITC和IC具有巨大的药理意义。扭曲构象是IC中的全局最低能量构象，其中弯曲构象是过渡态（TS），能量比扭曲构象高1100±100 cm⁻¹。ITC和ISC中的弯曲构象具有最低能量。但是，扭曲构象在ITC中比最低能量构象高约80±20 cm⁻¹，在ISC中高约700±50 cm⁻¹。势能面（PES）确定了所有构象和过渡态。分子静电势表明亲电相互作用的位点，ITC中最低能量构象之间的小能量差预示着在合适环境中分子间相互作用的有趣相互作用。检验了最大硬度原理和最小亲电性原理的有效性。前线分子轨道显示了激发时电子密度的变化，其本质上大多是π→π*跃迁。涉及不同σ轨道和孤对轨道的超共轭相互作用解释了这些分子中构象模式的变化。我们提出了一些实验来证实我们的发现。
使用密度泛函理论（DFT）中的不同泛函（B3LYP、M06 - 2X和ωB97X - D）以及从头算方法（MP2和CCSD）进行计算，基组为6 - 311G++(2d, 3p)和aug - cc - pVDZ。使用Gaussian 09进行上述计算。通过Veda 4软件进行势能分布（PED）分析。为了查看和绘图，使用Gaussview 5.0和Origin 8.5。
