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偶氮苯铼配合物的光致顺反异构化机理的理论研究
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摘要
本文我们采用了密度泛函理论(DFT)研究了金属铼配合物对偶氮苯光致异构化过程的影响,并分析了Re(CO)_3-AB在S_0和T_1态的顺反异构化机理。计算结果表明该金属二亚氨与偶氮苯的结合会明显的降低偶氮苯顺反异构过程的能垒,使反应更容易进行。研究发现在基态(S_0),该反应遵循的是绕角NNC和CNN反转的rotation-assisted inversion机理;在第一激发三重态(T_1)遵循的是绕CNNC二面角旋转的rotation机理。同时我们采用了含时密度泛函理论(TD-DFT),研究了低激发态(T_1,S_1,T_2,S_2)的势能剖面。通过分析我们给出了两条rotation路径:(a)从cis构型被激发到S_2态,经过S_0/S_1的圆锥交叉点(CI)到达S_0的trans结构;(b)从S_1态弛豫到T_1态,在S_0-T_1-S_0区域经系间窜越到达产物。
In this paper, we performed density-functional theory(DFT) to probe effects of the isomerization of azo portion caused by excitation of the MLCT bands and the thermal cis → trans isomerization of Re(CO)_3-AB, a diimine ligand with an azo group substituent.On the potential energy surface of the ground state(S_0) from cis to trans, we detected two planar inversion transition states TS-inv-1 and TS-inv-2 following rotation-assisted inversion mechanism.In the T_1 state, only the rotation pathway exists.Specifically, we investigated the photoisomerization pathway, the potential energy profiles of the vertical excitation for the excited states(T_1, S_1, T_2 and S_2) were calculated, analyzed two possible rotation isomerization routs through the inversion and rotation pathway.
引文
[1]A.Hasheminasab,L.Wang,M.Dawadi,J.Bass,R.Herrick,J.Rack and C.Ziegler,Dalton Trans.,2015,44,15400-15403.
    [2]A.Cembran,F.Bernardi,M.Garavelli,L.Gagliardi and G.Orlandi,J.Am.Chem.Soc.,2004,126,3234-3243.

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