Dinuclear Zinc(II) Complexes of Tetraiminodiphenol Macrocycles and Their Interactions with Carboxylate Anions and Amino Acids. Photoluminescence, Equilibria, and Structure
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- 作者：Bula Dutta ; Pradip Bag ; Ulrich Flö ; rke ; and Kamalaksha Nag
- 刊名：Inorganic Chemistry
- 出版年：2005
- 出版时间：January 10, 2005
- 年：2005
- 卷：44
- 期：1
- 页码：147 - 157
- 全文大小：241K
- 年卷期：v.44,no.1(January 10, 2005)
- ISSN：1520-510X
文摘
The reaction equilibria [H4L]2+ + Zn(OAc)2 
[Zn(H2L)]2+ + 2HOAc (K1) and [Zn(H2L)]2+ + Zn(OAc)2 [Zn2L]2+ +2HOAc (K2), involving zinc acetate and the perchlorate salts of the tetraiminodiphenol macrocycles [H4L1-3](ClO4)2,the lateral (CH2)n chains of which vary between n = 2 and n = 4, have been studied by spectrophotometric andspectrofluorimetric titrations in acetonitrile. The photoluminescence behavior of the complexes [Zn2L1](ClO4)2,[Zn2L2(H2O)2](ClO4)2, [Zn2L2(
-O2CR)](ClO4) (R = CH3, C6H5, p-CH3C6H4, p-OCH3C6H4, p-ClC6H4, p-NO2C6H4),and [Zn2L3(-OAc)](ClO4) have been investigated. The X-ray crystal structures of the complexes [Zn2L2(H2O)2](ClO4)2, [Zn2L3(-OAc)](ClO4), and [Zn2L2(-OBz)(OBz)(H3O)](ClO4) have been determined. The complex [Zn2L2(-OBz)(OBz)(H3O)](ClO4) in which the coordinated water molecule is present as the hydronium ion (H3O+) ondeprotonation gives rise to the neutral dibenzoate-bridged compound [Zn2L2(-OBz)2]·H2O. The equilibrium constants(K) for the reaction [Zn2L2(H2O)2]2+ + A- [Zn2L2A]+ + 2H2O (K), where A- = acetate, benzoate, or the carboxylatemoiety of the amino acids glycine, L-alanine, L-histidine, L-valine, and L-proline, have been determinedspectrofluorimetrically in aqueous solution (pH 6-7) at room temperature. The binding constants (K) evaluated forthese systems vary in the range (1-8) × 105.
[Zn(H2L)]2+ + 2HOAc (K1) and [Zn(H2L)]2+ + Zn(OAc)2 [Zn2L]2+ +2HOAc (K2), involving zinc acetate and the perchlorate salts of the tetraiminodiphenol macrocycles [H4L1-3](ClO4)2,the lateral (CH2)n chains of which vary between n = 2 and n = 4, have been studied by spectrophotometric andspectrofluorimetric titrations in acetonitrile. The photoluminescence behavior of the complexes [Zn2L1](ClO4)2,[Zn2L2(H2O)2](ClO4)2, [Zn2L2(-O2CR)](ClO4) (R = CH3, C6H5, p-CH3C6H4, p-OCH3C6H4, p-ClC6H4, p-NO2C6H4),and [Zn2L3(-OAc)](ClO4) have been investigated. The X-ray crystal structures of the complexes [Zn2L2(H2O)2](ClO4)2, [Zn2L3(-OAc)](ClO4), and [Zn2L2(-OBz)(OBz)(H3O)](ClO4) have been determined. The complex [Zn2L2(-OBz)(OBz)(H3O)](ClO4) in which the coordinated water molecule is present as the hydronium ion (H3O+) ondeprotonation gives rise to the neutral dibenzoate-bridged compound [Zn2L2(-OBz)2]·H2O. The equilibrium constants(K) for the reaction [Zn2L2(H2O)2]2+ + A- [Zn2L2A]+ + 2H2O (K), where A- = acetate, benzoate, or the carboxylatemoiety of the amino acids glycine, L-alanine, L-histidine, L-valine, and L-proline, have been determinedspectrofluorimetrically in aqueous solution (pH 6-7) at room temperature. The binding constants (K) evaluated forthese systems vary in the range (1-8) × 105.