A Unique Discrete Tetranuclear Cu鈥测€揅u(N-N)2Cu鈥揅u鈥?Copper(II) Complex, Built from a 渭3-1,2,4-Triazolato-渭-carboxylato Ligand, as an Effective DNA Cleavage Agent

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• 作者：Javier Hern谩ndez-Gil ; Sacramento Ferrer ; Alfonso Casti帽eiras ; Francesc Lloret
• 刊名：Inorganic Chemistry
• 出版年：2012
• 出版时间：September 17, 2012
• 年：2012
• 卷：51
• 期：18
• 页码：9809-9819
• 全文大小：462K
• 年卷期：v.51,no.18(September 17, 2012)
• ISSN：1520-510X

文摘

The title compound, characterized by means of an X-ray structure analysis, represents an easy example of a noncatena 鈥? + 2 + 1鈥?tetranuclear copper(II) 渭₃-triazolate compound. [Cu₄(atc)₂(dien)₄(ClO₄)₂](ClO₄)₂路2H₂O (1), where H₂atc = 5-amino-l,2,4-triazole-3-carboxylic acid and dien = diethylenetriamine = 1,4,7-triazaheptane, contains two copper atoms linked by a double diazinic bridge, each of which is further connected to a third and fourth copper atom (Cu鈥? through the triply bridging triazolato ring and the bidentate carboxylato group of the atc^{2鈥?/sup> ligands. The copper鈥揷opper distances within the tetranuclear unit are Cu鈥揅u = 4.059 脜, Cu鈥揅u鈥?= 5.686 and 6.370 脜, and Cu鈥测€揅u鈥?= 11.373 脜. The compound self-assembles into a tridimensional hydrogen-bonded network to generate a MOF. 1 exhibits antiferromagnetic behavior with g = 2.10(1), J = 鈭?4.1(2) cm鈥? and j = 鈭?.50(3) cm鈥?, where J is the coupling constant of the central Cu鈥揅u pair and j the coupling constant of the two Cu鈥揅u鈥?(Cu_central鈥揅u_pheripheral) pairs, as defined by H = 鈭?i>JS₂S_2a 鈥?j (S₁S₂ + S_2aS_1a). Complex 1 has been tested as nuclease mimic. It shows good binding propensity to calf thymus DNA, with a binding constant value of 6.20 脳 106 M鈥? (K_app) and 螖T_m = 18.3 掳C. Moreover, the compound displays efficient oxidative cleavage of pUC18 DNA, even at low concentration, in the presence of a mild reducing agent (ascorbate), with a rate constant for the conversion of supercoiled to nicked DNA (k_obs) of 0.126 min鈥?. The good reactivity of 1 toward DNA is explained from the electrostatic interactions of the cationic species produced in solution.}