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The interaction mechanism between a scarcely soluble copper­(II) complex of Cu­(II)-6-hydroxychromone-3-carbaldehyde-(3′-hydroxy)­benzoylhydrazone (CuCHz) in aqueous solution and its DMβCD complex was studied in the presence of ctDNA through spectroscopy and thermodynamic methods. The thermodynamic results indicate that the binding process of the CuCHz–DMβCD inclusion complex is a spontaneous process and the inclusion is enthalpy-driven. The binding constants of CuCHz and CuCHz–DMβCD with ctDNA are 2.69 × 103 and 14.7 × 103 L mol–1, respectively. The stoichiometry of the complex is 1:1, and the determined thermodynamic indicates that the process of binding is spontaneous and entropy-driven. A competitive binding titration with ethidium bromide revealed that CuCHz efficiently displaces EB from the EB–DNA system. In addition to the thermal denaturation experiments and docking studies, we can confirm that the mode of binding of this complex to ctDNA is intercalation mode. The presence of DMβCD enhances the aqueous solubility of CuCHz; nevertheless, the cyclodextrin did not affect the interaction of CuCHz with ctDNA because the inclusion complex breaks down when it binds with ctDNA.

Artículo de publicación ISIThe present work describes a study of complexation efficiency and selectivity of calix[4]arenes bearing benzoimidazolyl, benzothiazolyl, and benzoxazolyl heterocycles (5–7) towards several selected metal ions using fluorescence and UV–Vis spectroscopy. The binding ability of calixarene derivatives 5–7 toward selected divalent metal ions such as Ca, Cd, Pb, Ni, Mg, Mn, Co, Fe and Zn has been investigated by fluorescence spectroscopic techniques. Fluorescent chemosensor ability of three calixarene derivatives was highly selective for Pb (II) in contrast with other divalent metal studied. The highest association constant corresponds to benzoxazolyl calixarene derivative 7, with a Ka of (1.37 ± 0.06) 9 104 mol-1 L and detection limit for lead of 1.14 ± 0.05 mg L-1 in methanol being acceptable for the recognition of this metal at micromolar concentrations.FONDECYT (Grant 1100906 and 1050795

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