Synthesis, spectroscopic and TD-DFT quantum mechanical study of azo-azomethine dyes. A laser induced trans-cis-trans photoisomerization cycle
Synthesis, spectroscopic and TD-DFT quantum mechanical study of azo-azomethine dyes. A laser induced trans-cis-trans photoisomerization cycle
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DOI：
10.1016/j.saa.2017.11.016
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发表时间：
2018-03-05
影响因子：
4.4
通讯作者：
Yancheva, Denitsa
中科院分区：
文献类型：
--
作者：
Georgiev, Anton;Kostadinov, Anton;Yancheva, Denitsa
本文介绍了三种偶氮甲亚胺染料的合成、光谱表征和量子力学计算。通过对二甲氨基苯甲醛与三种不同的对氨基苯偶氮染料的缩合反应合成了染料。采用密度泛函理论（DFT/B3 LYP）和6-311 ++G（d，p）基组，在真空下对反式（E）和顺式（Z）异构体的优化几何构型、电子密度和振动频率进行了量子化学计算.计算得到的热力学参数为电子总能量E（RB 3LYP）、焓H-298（电子和热耗散之和），自由吉布斯能G（298）计算了反式（E）和顺式（Z）异构体的电子和热自由吉布斯能之和（电子和热自由吉布斯能之和）和偶极矩μ，以估计Δ E-transs（->）（cis）、Δ mu（反式->顺式）、Δ H-反式->顺式、Δ G（反式->顺式）和Δ S-反式->顺式值。在分子几何优化后，用TD-DFT计算得到了它们的电子光谱，并与气相沉积纳米薄膜的光谱进行了关联。进行NBO分析以了解分子内电荷转移和共振稳定化的能量。用紫外-可见光谱法研究了溶剂化变色现象在五种不同极性有机溶剂中的表现。在DMF中，用波长λ = 355 nm（主要是E -> Z）和λ = 491 nm（主要是Z -> E）的泵浦激光，在300 nm - 800 nm光谱范围内，以相同的浓度和照射次数进行了动态光异构化实验，以研究染料-CH=N-和-N=N-发色团的光动力学trans-cis-trans性质。(C)2017爱思唯尔B. V.保留所有权利。
This paper describes the synthesis, spectroscopic characterization and quantum mechanical calculations of three azo-azomethine dyes. The dyes were synthesized via condensation reaction between 4-(dimethylamino)benzaldehyde and three different 4-aminobenzene azo dyes. Quantum chemical calculations on the optimized molecular geometry and electron densities of the trans (E) and cis (Z) isomers and their vibrational frequencies have been computed by using DFT/B3LYP density-functional theory with 6-311 ++G(d,p) basis set in vacuo. The thermodynamic parameters such as total electronic energy E (RB3LYP), enthalpy H-298 (sum of electronic and thermal enthalpies), free Gibbs energy G(298) (sum of electronic and thermal free Gibbs energies) and dipole moment mu were computed for trans (E) and cis (Z) isomers in order to estimate the Delta E-trans (->) (cis), Delta mu(trans -> cis), Delta H-trans -> cis, Delta G(trans -> cis) and Delta S-trans -> cis values. After molecular geometry optimization the electronic spectra have been obtained by TD-DFT calculations at same basis set and correlated with the spectra of vapour deposited nanosized films of the dyes. The NBO analysis was performed in order to understand the intramolecular charge transfer and energy of resonance stabilization. Solvatochromism was investigated by UV-VIS spectroscopy in five different organic solvents with increasing polarity. The dynamic photoisomerization experiments have been performed in DMF by pump lasers lambda = 355 nm (mostly E -> Z) and lambda = 491 nm (mostly Z -> E) in spectral region 300 nm - 800 nm at equal concentrations and times of illumination in order to investigate the photodynamical trans-cis-trans properties of the -CH=N- and -N=N- chromophore groups of the dyes. (C) 2017 Elsevier B.V. All rights reserved.