Photoisomerization of azobenzenes isolated in cryogenic matrices.
Photoisomerization of azobenzenes isolated in cryogenic matrices.
复制标题
低温基质中分离的偶氮苯的光致异构化。
DOI：
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发表时间：
2016
期刊：
影响因子：
--
通讯作者：
I. Reva
中科院分区：
文献类型：
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作者：
L. Duarte;L. Khriachtchev;R. Fausto;I. Reva
在氩气和氙气中分离了2，2 ′-二羟基偶氮苯（DAB）、2，2 ′-偶氮甲苯（AT）和偶氮苯（AB），用红外光谱和理论计算表征了它们的分子结构和光化学转化。所有这些化合物都可以采用围绕中心CNNC部分的E和Z异构体形式，其可以通过DAB和AT的几种构象和互变异构体修饰来富集。首次鉴定出大量的DAB和AT异构体。对于DAB，在沉积后发现具有两个分子内通过OHN氢键形成的六元准环的E偶氮烯醇异构体。用紫外光照射产生了不同的E偶氮烯醇形式与两个分子内H-键合的五元准环。光转化被证明是可逆的，并且可以通过在不同波长下的照射来相互转换形式。这两种形式之间的异构化构成了偶氮苯型分子中E → E异构化的直接实验观察。进一步的照射产生带有OH和NH基团的形式。对于AT，两个E异构体与CH 3基团形成五元和五/六元准环与偶氮基团中观察到的沉积矩阵。用UV光照射AT产生Z形式，其可以在不同的照射波长下转换回E形式。在氙基质中沉积E-AB，观察到E → Z和Z → E光转化（与先前在氩基质中仅发生Z → E转化的报道相反）。AB光异构化在升高的温度下变得更加明显，从而表明负责阻碍AB光异构化的基质效应基本上是由于空间限制。这些化合物观察到的不同的光异构化通道进行了讨论，在一个小振幅踏板运动。
2,2'-Dihydroxyazobenzene (DAB), 2,2'-azotoluene (AT) and azobenzene (AB) were isolated in argon and xenon matrices and their molecular structures and photochemical transformations were characterized by infrared spectroscopy and theoretical calculations. All these compounds can adopt the E and Z isomeric forms around the central CNNC moiety, which can be enriched by several conformational and tautomeric modifications for DAB and AT. A number of DAB and AT isomeric forms were identified for the first time. For DAB, the E azo-enol isomer with two intramolecular six-membered quasi-rings formed via OHN hydrogen bonds was found after deposition. Irradiation with UV light generated a different E azo-enol form with two intramolecular H-bonded five-membered quasi-rings. Phototransformation was shown to be reversible and the forms could be interconverted by irradiation at different wavelengths. The isomerization between these two forms constitutes a direct experimental observation of an E → E isomerization in azobenzene-type molecules. Further irradiation generated a form(s) bearing both OH and NH groups. For AT, two E isomers with the CH3 groups forming five-membered and five/six-membered quasi-rings with the azo group were observed in the as-deposited matrices. Irradiation of AT with UV light generated a Z form that can be converted back to the E form at different irradiation wavelengths. E-AB was deposited in a xenon matrix and both E → Z and Z → E phototransformations were observed (contrary to what was previously reported in an argon matrix where only the Z → E conversion occurred). AB photoisomerization becomes more pronounced at elevated temperatures, thus indicating that the matrix effects responsible for hindering the AB photoisomerization are essentially due to steric restrictions. The different photoisomerization channels observed for these compounds are discussed in terms of a small-amplitude pedal motion.
影响因子：
21.8
作者：
Tochitsky I;Banghart MR;Mourot A;Yao JZ;Gaub B;Kramer RH;Trauner D
通讯作者：
Trauner D
影响因子：
3.3
作者：
Boeckmann, Marcus;Marx, Dominik;Doltsinis, Nikos L.
通讯作者：
Doltsinis, Nikos L.