Wang Jiang, Shi Lin-Xi, Wang Jin-Yun, Chen Jin-Xiang, Liu Sheng-Hua, Chen Zhong-Ning
State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian 350002, China.
Key Laboratory of Pesticide & Chemical Biology, College of Chemistry, Central China Normal University, Wuhan 430079, China.
Dalton Trans. 2017 Feb 14;46(6):2023-2029. doi: 10.1039/c6dt04421b.
4,5-Bis(2-methyl-5-phenylthiophen-3-yl)-1,3-dithiol-2-one (L1o) was elaborately designed to afford dithienyl-dithiolene as a new photochromic ligand. We describe herein the preparation and characterization of unprecedented photochromic dithienyl-dithiolene complexes with cis-orientation of dithienylethene (DTE) stabilized by metal chelation instead of conventional cyclopentene. The treatment of L1o with sodium methoxide in methanol afforded a disodium salt of dithiolate dianion, which reacts with M(dppe)Cl (dppe = 1,2-bis(diphenylphosphino)ethane, M = Ni, Pd) to give neutral compounds M(dppe)(dithiolate) as established by X-ray crystallography. The reaction of L1o with NiCl in the presence of sodium methoxide allows the isolation of an anionic nickel(ii) bis(dithienyl-dithiolene) complex with photochemical inertness. In contrast, the corresponding reaction with ZnCl afforded a dianionic zinc(ii) complex chelated by two dianionic dithienyl-dithiolenes, which displays stepwise photocyclization upon irradiation with UV light at 312 nm as demonstrated experimentally and theoretically. Only when dithienyl-dithiolene behaves as a dicationic ligand instead of neutral or monoanionic species, it is possible to achieve reversible photochromism in the corresponding metal complexes.
4,5-双(2-甲基-5-苯基噻吩-3-基)-1,3-二硫醇-2-酮(L1o)经过精心设计，以提供二噻吩基二硫纶作为一种新型光致变色配体。我们在此描述了前所未有的光致变色二噻吩基二硫纶配合物的制备和表征，该配合物中二噻吩乙烯(DTE)的顺式取向通过金属螯合而非传统的环戊烯得以稳定。在甲醇中用甲醇钠处理L1o得到二硫醇盐二价阴离子的二钠盐，该盐与M(dppe)Cl(dppe = 1,2-双(二苯基膦基)乙烷，M = Ni、Pd)反应，通过X射线晶体学确定得到中性化合物M(dppe)(二硫醇盐)。在甲醇钠存在下，L1o与NiCl反应可分离出具有光化学惰性的阴离子镍(ii)双(二噻吩基二硫纶)配合物。相比之下，与ZnCl的相应反应得到一种由两个二价阴离子二噻吩基二硫纶螯合的二价阴离子锌(ii)配合物，实验和理论证明该配合物在312 nm紫外光照射下会发生逐步光环化。只有当二噻吩基二硫纶作为二价阳离子配体而非中性或单阴离子物种时，才有可能在相应的金属配合物中实现可逆光致变色。
