title: Two novel ternary dicopper(II) μ-guanazole complexes with aromatic amines strongly activated by quantum dots for DNA cleavage.
abstract: Two novel (μ-guanazole)-bridged binuclear copper(II) complexes with 1,10-phenanthroline (phen) or 2,2'-bipyridine (bipy), [Cu2(μ-N2,N4-Hdatrz)(phen)2(H2O)(NO3)4] (1) and [Cu2(μ-N1,N2-datrz)2(μ-OH2)(bipy)2](ClO4)2 (2) (Hdatrz = 3,5-diamino-1,2,4-triazole = guanazole), have been prepared and characterized by X-ray diffraction, spectroscopy, and susceptibility measurements. Compounds 1 and 2 differ in the aromatic amine, which acts as a coligand, and in the Cu···Cu'-bridging system. Compound 1, which contains two mono-bridged copper ions, represents the first example of a discrete Cu-(NCN-trz)-Cu' complex. Compound 2, with two triply bridged copper ions, is one of the few compounds featuring a Cu-[(NN-trz)2 + (O-aquo)]-Cu' unit. Both compounds display antiferromagnetic coupling but of different magnitude: J (μ2,4-triazole) = -52 cm(-1) for 1 and J (μ1,2-triazolate) = -115 cm(-1) for 2. The DNA binding and cleavage properties of the two compounds have been investigated. Fluorescence, viscosimetry, and thermal denaturation studies reveal that both complexes have high affinity for DNA (1 > 2) and that only 1 acts as an intercalator. In the presence of a reducing agent like 3-mercaptopropionic acid, 1 produces significant oxidative DNA cleavage, whereas 2 is inactive. However, in the presence of very small quantities of micelles filled with core-shell CdSe-ZnS quantum dots (15 nM), 1 and 2 are considerably more active and become highly efficient nucleases as a result of the different possible mechanisms for promoting cooperative catalysis (metal-metal, metal-hydrogen bonding, metal-intercalation, and metal-nanoparticle). Electrophoresis DNA-cleavage inhibition experiments, X-ray photoelectron spectroscopy studies, and fluorescence ethidium bromide displacement assays reveal that in these novel nucleases the QDs act as redox-active protein-like nanoparticle structures that bind to the DNA and deliver electrons to the copper(II) centers for the generation of Cu(I) and reactive oxygen species.
authors: Departament de Química Inorgànica, Universitat de València , Vicent Andrés Estellés s/n, 46100 Burjassot, Valencia, Spain.
authors: Javier
authors: J
authors: Hernández-Gil
authors: Sacramento
authors: S
authors: Ferrer
authors: Alfonso
authors: A
authors: Castiñeiras
authors: Malva
authors: M
authors: Liu-González
authors: Francesc
authors: F
authors: Lloret
authors: Angela
authors: A
authors: Ribes
authors: Lucija
authors: L
authors: Coga
authors: Anja
authors: A
authors: Bernecker
authors: Juan C
authors: JC
authors: Mareque-Rivas
mesh_terms: D000588:Amines / Q000737:chemistry*; D019187:Cadmium Compounds / Q000737:chemistry; D003300:Copper / Q000737:chemistry*; D018360:Crystallography, X-Ray; D004247:DNA / Q000737:chemistry / Q000187:drug effects*; D053837:DNA Cleavage; D006144:Guanazole / Q000737:chemistry*; D008958:Models, Molecular; D015394:Molecular Structure; D009942:Organometallic Compounds / Q000138:chemical synthesis / Q000737:chemistry / Q000494:pharmacology*; D045663:Quantum Dots; D018036:Selenium Compounds / Q000737:chemistry; D013440:Sulfides / Q000737:chemistry; D017967:Zinc Compounds / Q000737:chemistry
chemical_list: D000588:Amines; D019187:Cadmium Compounds; D009942:Organometallic Compounds; D018036:Selenium Compounds; D013440:Sulfides; D017967:Zinc Compounds; D003300:Copper; D004247:DNA; C058667:cadmium selenide; D006144:Guanazole; C031238:zinc sulfide