Synthesis of azo-conjugated metal ladithiolenes and their photo- and proton-responsive isomerization reactions
Synthesis of azo-conjugated metal ladithiolenes and their photo- and proton-responsive isomerization reactions
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DOI：
10.1021/ja028080p
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发表时间：
2003-03-12
影响因子：
15
通讯作者：
Nishihara, H
中科院分区：
文献类型：
--
作者：
Nihei, M;Kurihara, M;Nishihara, H
开发了一种通用的偶氮共轭金属硫烯的合成方法，并合成了各种中心金属和取代基的新配合物。用X-射线单晶衍射法测定了以二苯基膦乙烷为配体的Ni(II)、Pd(II)和Pt(II)偶氮共轭金属硫烯的分子结构。虽然可逆式反式-顺式光异构化反应的能量远低于偶氮苯的可逆式光致异构化反应的能量，但其热稳定性远高于具有类似低能反式-顺式光异构化反应的有机偶氮苯衍生物。偶氮基发生了新的质子响应，光异构化和质子化的结合导致了一种新的质子催化的顺反异构化，其速度与金属硫烯部分的氧化还原电位有关。包括其他偶氮共轭金属硫烯的研究表明，质子化是偶氮共轭金属硫烯的共同特征，但反式到顺式的光异构化强烈依赖于反式的电子结构或顺式的空间效应。
A versatile synthetic method of azo-conjugated metalladithiolenes was developed, and new complexes with various central metals and substituent groups were synthesized. Molecular structures of the azo-conjugated metalladithiolenes of Ni(II), Pd(II), and Pt(II) with diphenylphosphinoethane as a coligand were determined by X-ray crystallography. While the energy of the reversible trans-to-cis photo isomerization is considerably lower than that of azobenzene, the thermal stability of the cis form is much higher than that of the organic azobenzene derivatives showing similar low-energy trans-to-cis photo isomerization. A novel proton response of the azo group occurs, and the combination of photoisomerization and protonation leads to a novel proton-catalyzed cis-to-trans isomerization, the rate of which correlates with the redox potential of the metalladithiolene moiety. The study including other azo-conjugated metalladithiolenes has indicated that the protonation is a common feature for the azo-conjugated metalladithiolenes, but trans-to-cis photoisomerization is strongly dependent on the electronic structure of the trans form or a steric effect in the cis form.