A promiscuous dicopper(II) system promoting the hydrolysis of bis(2,4‐dinitrophenyl)phosphate: Gaining mechanistic insight by means of structural and spectroscopic DFT studies

Catechol oxidases (COs) are plant enzymes that belong to the oxidoreductases class. They contain a dinuclear copper center in their active site. In this article, we have investigated the dicopper(II) model complex [Cu₂(μ‐OH)(C₂₁H₃₃ON₆)]²⁺ (Complex‐A) under a computational perspective, using the DFT method, since this approach has been very useful in the treatment of bimetallic copper systems. The structural and spectroscopic study of Complex‐A as well as the structural analysis of the BDNPP/Complex‐A (Complex‐B) adduct have been carried out. The calculated parameters for Complex‐A are in good accordance with the experimental X‐ray data. Some remarkable points can be observed from the calculated UV–vis relative excitations. The Complex‐B computed structure verifies its identity as a key intermediate species in the BDNPP hydrolysis mechanism. The Cu^II···Cu^II calculated distance in Complex‐B (3.026 Å) is shorter than the calculated for Complex‐A (3.080 Å); one copper atom is bonded to the oxygen of phosphate [Cu (2)···O64–P] at 2.511 Å. These arguments clearly suggest a monodentate interaction and lead to a new mechanism involving terminal substrate coordination and subsequent intramolecular nucleophilic attack by a bridging hydroxide. Such a hypothesis is completely new in terms of homobimetallic copper systems, and may have important implications regarding the chemistry of several biological dinuclear catalytic sites. © 2009 Wiley Periodicals, Inc. Int J Quantum Chem, 2010     

Mechanism of cleaving DNA through hydrolysis of a novel complex of Mg containing dien ligand

A series of elements necessary for life bodies, such as Mg, Cu, Mn, Fe, Co, Zn etc, arechosen as ceflter ions of complexes, because most of them act as active centers ofenZymes and auxiliary factors. We select dien as ligand because nitrogen, especiallymuti-nitrogen coordination is general in natural enzymes and simulated systems,furthermore dien has structural flexibility.The complexes of Mg containing dien and the activity of cleaving DNAA series of metals, such as Mg, Mn, Fe, Co, Ni, …     

Eu(Ⅲ)与Hbbimp的配合物的合成、表征及与活化磷酸二酯键模型物BDNPP的水解动力学研究

合成了Eu(Ⅲ)配合物[Eu2(bbimp)(CH3COO)(CH3CH2O)2(CH3CH2OH)](ClO4)2(A),产物经IR谱、UV谱、1HNMR谱、摩尔电导、元素分析对其结构进行了基本鉴定。用紫外光谱法研究了磷酸二酯键模型物双 (2,4 二硝基苯基)磷酸盐BDNPP与配合物A在pH7.26,25和37℃时,[BDNPP]=[A]=2.5×10-5mol·L-1时的动力学性质,得到BDNPP的二级水解速率常数为k25℃=3.027×103(mol·L-1)-1·min-1,k37℃=6.060×103(mol·L-1)-1·min-1,半衰期t1 2分别为12.9和6.6min,使BDNPP的水解速率大大提高。