Synthesis, crystal structure elucidation, DNA-binding and micellization behavior of copper(II) carboxylate complexes

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 lambda max = 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 2 theta 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.

Automated summary

Three new copper(II) complexes with oxygen bridges, [L2Cu(2,2 '-bipyridine)2CuL2] (A), [L ' 2Cu(2,2 '-bipyridine)H2O] (B), [L '' 2Cu(2,2 '-bipyridine)2CuL '' 2] (C), have been synthesized and characterized. The complexes exhibit square pyramidal geometry around each Cu(II) ion. Spectroscopic and crystallographic analysis confirm the structure and crystalline nature of the complexes. The complexes show strong DNA binding abilities, demonstrating their potential biological importance.