Vibrational, NMR spectrum and orbital analysis of 3,3',5,5'-tetrabromobisphenol A: a combined experimental and computational study.
Vibrational, NMR spectrum and orbital analysis of 3,3',5,5'-tetrabromobisphenol A: a combined experimental and computational study.
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DOI：
10.1016/j.saa.2012.12.004
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发表时间：
2013-03
期刊：
影响因子：
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通讯作者：
Shanshan Qiu;Jin Wei;Feng Pan;Jingping Liu;A. Zhang
中科院分区：
文献类型：
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作者：
Shanshan Qiu;Jin Wei;Feng Pan;Jingping Liu;A. Zhang
本文对3，3 ′，5，5 ′-四溴双酚A（TBBPA）的结构、振动、NMR和HOMO-LUMO分析进行了实验和理论研究。记录了TBBPA的FT-IR（400- 4000 cm-1）和FT-Raman（100- 4000 cm-1）光谱。用密度泛函理论（DFT）方法在6- 31 G（d）基组下计算了分子的几何构型和振动频率。优化后的几何性质、标度振动波数、红外光谱强度、拉曼活性与实验数据吻合较好。红外和拉曼光谱的指定振动模式进行了比较与相应的多溴联苯醚（PBDEs）的性质。比较分析表明，C-Br振动的红移可能是由于O原子与苯之间的p-π共轭作用使电子密度进一步均衡化所致。自然成键轨道（NBO）分析表明，分子间超共轭作用主要是由σ（O-H），σ*（C-C），π（C-C），π*（C-C）键轨道之间的轨道重叠形成的。与LP（2）O向π*（C-C）转化产生的较高的E（2）值（33.65-34.82kcal/mol）相比，LP（3）Br和π*（C-C）转化产生的较高的E（2）值（8.23-9.73kcal/mol）有助于在转化过程中C-Br断裂优先于C-O断裂。在6- 31 G（d）水平上的计算结果与实验数据符合良好（r2=0.999）。相关轨道的等值面分析表明，所有的主激发都具有π-π ~* 特征，并且都集中在苯环上。
In the present work, the experimental and theoretical studies on the structure, vibrations, NMR and HOMO–LUMO analysis of 3,3′,5,5′-tetrabromobisphenol A (TBBPA) are presented. The FT-IR (400–4000cm−1) and FT-Raman (100–4000cm−1) spectra of TBBPA were recorded. The molecular geometry, vibrational frequencies were calculated by using density functional theory (DFT) method with the 6-31G(d) basis set. The optimized geometric properties, scaled vibrational wavenumbers, IR intensities, Raman activities show good agreement with the experimental data. The assigned vibrational modes of the IR and Raman spectra were compared with the corresponding properties of the polybrominated diphenyl ethers (PBDEs). Comparative analysis indicated that the red shift of C–Br vibration could probably be ascribed to the further electronic density equalization due to the p–π conjugation between O atom and the benzene. The natural bonding orbital (NBO) analysis demonstrated that the intermolecular hyperconjugative interactions are mainly formed by the orbital overlap between σ (O–H), σ*(C–C), π (C–C), π*(C–C) bond orbitals. Compared to the higher E(2)value (33.65–34.82kcal/mol) originated from LP(2)O to π*(C–C), the one (E(2): 8.23–9.73kcal/mol) from LP(3)Br and π*(C–C) contributes to the preferential tendency of C–Br breakage to the C–O breakage in the transformation. The calculated NMR results obtained on the 6-31G(d) level proves good agreement with the experimental data (r2=0.999). Analysis of isosurface of the related orbital shows that all the main excitation exhibit π–π*character localized on the benzene rings.