Theoretical study of the isomerization mechanism of azobenzene and disubstituted azobenzene derivatives
Theoretical study of the isomerization mechanism of azobenzene and disubstituted azobenzene derivatives
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DOI：
10.1021/jp057413c
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发表时间：
2006-07-06
影响因子：
2.9
通讯作者：
Roitberg, Adrian E.
中科院分区：
文献类型：
--
作者：
Crecca, Christina R.;Roitberg, Adrian E.
采用从头算方法研究了一系列偶氮苯异构化反应中取代基的影响。从三维势能面的地面和电子激发态的能量障碍。在基态（S-0）下，发现翻转途径是首选的。结果表明，给电子取代基增加了反转路径沿着的异构化能垒，吸电子取代基降低了反转路径上的异构化能垒，第一激发态（S-1）的反转路径表现为反式-顺式能垒，S-0和S-1之间没有曲线交叉.与此相反，一个圆锥形的交叉点被发现之间的地面和第一激发态沿着的旋转路径为每个偶氮苯的研究。在该途径中没有发现障碍，因此我们假设在n -> pi*（S-1）pi*（S-2）pi* 和pi -> pi* 激发后。
A series of azobenzenes was studied using ab initio methods to determine the substituent effects on the isomerization pathways. Energy barriers were determined from three-dimensional potential energy surfaces of the ground and electronically excited states. In the ground state (S-0), the inversion pathway was found to be preferred. Our results show that electron donating substituents increase the isomerization barrier along the inversion pathway, whereas electron withdrawing substituents decrease it. The inversion pathway of the first excited state (S-1) showed trans -> cis barriers with no curve crossing between S-0 and S-1. In contrast, a conical intersection was found between the ground and first excited states along the rotation pathway for each of the azobenzenes studied. No barriers were found in this pathway, and we therefore postulate that after n -> pi* (S-1 pi* (S-2 pi* and pi -> pi* excitations.