Structure and photochromism of Zn(II) thiocyanato complexes of 1-alkyl-2-{(o-thioalkyl)phenylazo}imidazole
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- 作者：Shefali Saha (Halder)a ; Chandana Sena ; Suman Roya ; Debashis Mallicka ; 1 ; Elena Ló ; pez-Torresb ; Chittaranjan Sinhaa ; c_r_sinha@yahoo.com" class="auth_mail" title="E-mail the corresponding author
- 关键词：Zn(II)-thioalkylphenyl-azoimidazole ; 1D chain structure ; Photochromism ; Activation energy ; Rotor mass and volume
- 刊名：Polyhedron
- 出版年：2015
- 出版时间：5 September 2015
- 年：2015
- 卷：97
- 期：Complete
- 页码：240-247
- 全文大小：2255 K
文摘
Zinc(II)-thiocyanato complexes of 1-alkyl-2-{(o-thioalkyl)phenylazo}imidazole), [Zn(SRaaiNR/)(SCN)(渭-SCN)2]n, are spectroscopically characterized. The single crystal X-ray structure of [Zn(SMeaaiNEt)(渭-SCN)(SCN)2]n shows 渭-SCN 1D chain followed by hydrogen bonded 3D supramolecular structure. The UV light irradiation in MeCN solution of the complexes shows E-to-Z (E and Z refer to trans and cis-configuration about 
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N, respectively) isomerisation of the coordinated azoimidazole. The rate of isomerisation follows: [Zn(SEtaaiNEt)(SCN)(渭-SCN)2] < [Zn(SMeaaiNEt)(SCN)(渭-SCN)2] ∼ [Zn(SEtaaiNMe)(SCN)(渭-SCN)2] < [Zn(SMeaaiNMe)(SCN)(渭-SCN)2]. Quantum yields (蠒E→Z) and the activation energy (Ea) of the photoisomerisation of the complexes are less than that of free ligand data. This is explained on considering the increase in effective rotor volume of the complexes (complex/rotor volume (cm3)/E-to-Z isomerisation rate (s−1): [Zn(SMeaaiNMe)(SCN)2]/218.515/2.827; [Zn(SMeaaiNEt)(SCN)2]/267.206/2.227; [Zn(SEtaaiNMe)(SCN)]/263.399/2.309; [Zn(SEtaaiNEt)(SCN)]/275.447/1.801) and hence the lowering of rate of photoisomerisation.
Ndash" data-inlimg="/entities/dbnd" src="/sd/grey_pxl.gif" class="glyphImg imgLazyJSB">, respectively) isomerisation of the coordinated azoimidazole. The rate of isomerisation follows: [Zn(SEtaaiNEt)(SCN)(渭-SCN)2] < [Zn(SMeaaiNEt)(SCN)(渭-SCN)2] ∼ [Zn(SEtaaiNMe)(SCN)(渭-SCN)2] < [Zn(SMeaaiNMe)(SCN)(渭-SCN)2]. Quantum yields (蠒E→Z) and the activation energy (Ea) of the photoisomerisation of the complexes are less than that of free ligand data. This is explained on considering the increase in effective rotor volume of the complexes (complex/rotor volume (cm3)/E-to-Z isomerisation rate (s−1): [Zn(SMeaaiNMe)(SCN)2]/218.515/2.827; [Zn(SMeaaiNEt)(SCN)2]/267.206/2.227; [Zn(SEtaaiNMe)(SCN)]/263.399/2.309; [Zn(SEtaaiNEt)(SCN)]/275.447/1.801) and hence the lowering of rate of photoisomerisation.