- Thermally Induced trans-to-cis Isomerization and Its Photoinduced Reversal Monitored using Absorption and Luminescence: Cooperative Effect of Metal Coordination and Steric Substituent
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For ethene derivatives with large groups the cis-isomer is often quite unstable and unavailable. Herein, we report an exception of two stable coordination complexes, (cis-L)ZnCl2, starting from trans-1,2-bis(1-R-benzo[d]imidazol-2-yl)ethene (R=H, L1; R=CH3, L2) ligands under solvothermal condition (T ≥140 °C). Using the intensity of the absorption and luminescence spectra as probes we proposed its progressive cis-to-trans reversal upon irradiation with UV light, which was confirmed by powder X-ray diffraction (PXRD). Similar results observed in the series of (cis-L2)MIICl2 [M=Fe (4), Co (5), Ni (6)] demonstrate the universal strategy. The results of PXRD, NMR spectroscopy, ESI-MS and DFT calculations support the above conclusion. NMR spectroscopy indicates that irradiation of 1 converts an optimized 71 % of the cis-isomer to trans, whereas the free trans-L1 ligand transforms to only 15 % cis-isomer under similar conditions.
- Zhang, Jun-Quan,Zhang, De-Shan,Chen, Qiu-Jie,Xu, Hai-Bing,Kurmoo, Mohamedally,Zeng, Ming-Hua
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p. 5177 - 5185
(2019/03/17)
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- Two new Zinc(II) and Cadmium(II) complexes of a semi-rigid bis(2-benzimidazole): Synthesis and characterization
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Two new complexes Zn(TBimE)Cl2 1 and Cd(TBimE)(I)2 2 based on a semi-rigid ligand TBimE (TBimE = (E)-1,2-bis(2-benzimidazolyl)ethane) have been synthesized and their structures have been determined by X-ray single crystal diffractometry. X-ray diffraction analyses reveal that the “trans” TBimE is converted into “cis” conformation in the structures of the complexes, so that the TBimE can be used as a bidentate ligand to chelate the Zinc(II) and Cadmium(II) ions. Both 1 and 2 exhibit distorted tetrahedral geometries and the central metal atoms are coordinated by two N atoms from TBimE and two anions. The UV–Vis and emission spectra show that both the absorption and the emission of the complexes are assigned to the intraligand transitions and intraligand fluorescence, respectively.
- Zhang, Dong,Liu, Shu-Wei,Duan, Xiao-Qun,He, Yu-Lin,Deng, Yue-Yi
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p. 1457 - 1461
(2017/11/15)
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- A Simple Synthesis of 2,2'-Bisbenzimidazolylethylen And Its Analogues
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o-Aminomaleanilic acid (IIa) has been conveniently prepared and employed as a novel synthon for one-step synthesis of 2,2'-bisbenzimidazolylethylene (IIIa) in polyphosphoric acid medium.Analogous compounds (IIIb-f)have also been synthesized from o-hydroxy- and o-mercaptomaleanilic acids (IIb and IIc) following a similar procedure.
- Dash, Bhabagrahi,Dora, Essilidi K.,Panda, Chandra S.
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p. 697 - 698
(2007/10/02)
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