Synthesis, crystal structure elucidation, DNA-binding and micellization behavior of copper(II) carboxylate complexes
Muhammad Iqbal, Najeeb Ullah, Muhammad Abdul Haleem, Saqib Ali, Muhammad Nawaz Tahir, Mahboob-ur-Rehman
Abstract
Three new oxygen bridged binuclear and mononuclear copper(II) complexes having general formulae [L2Cu(2,2′-bipyridine)2CuL2] (A), [L′2Cu(2,2′-bipyridine)H2O] (B), [L″2Cu(2,2′-bipyridine)2CuL″2] (C) where L = ortho-nitrophenyl acetate, L′ = para-methoxyphenyl acetate and L″ = para-bromophenyl acetate have been prepared and characterized spectroscopically as well as structurally. The geometry around each Cu(II) ion was found square pyramidal in all the complexes. FT-IR data of the complexes were in agreement with that of the single crystal XRD. Electronic absorption spectra indicated broad absorption bands with λmax = 671, 715 and 700 nm typical of Cu2+ with 2B1g as ground state in A-C, respectively. Crystalline nature of the complexes was ascertained from its powder XRD spectra which showed several peaks in 2θ range 5–30. Electrochemistry yielded two redox pairs conforming to irreversible Cu(III)/Cu(II) and Cu(II)/Cu(I) processes typical of complexes with Cu2+ redox centers. Complex-surfactant interactions were studied via conductometry and absorption spectrophotometry. DNA binding abilities of complexes A-C were studied via absorption spectrophotometry, cyclic voltammetry, spectrofluorometry and viscosity measurement. The former three techniques yielded excellent intrinsic binding constant values for complexes. The excellent DNA-binding potency heralds the biological importance of the synthesized complexes.