Experimental and molecular modeling studies on the DNA-binding of diazacyclam-based acrocyclic copper complex

Abstract The interaction of a new macrocyclic copper complex, [CuL(NO 3 ) 2 ] in which L is 1,3,6,10,12,15-hexaaza tricyclo[13.3.1.1 6,10 ] eicosane was investigated in vitro under simulated physiological conditions by multi-spectroscopic techniques and molecular modeling study. The fluorescence spectroscopy and UV absorption spectroscopy indicated the complex interacted with ct-DNA in a groove binding mode while the binding constant of UV–vis and the number of binding sites were 1.0 ± 0.2 × 10 4  L mol − 1 and 1.01, respectively. The fluorometric studies showed that the reaction between the complex with ct-DNA is exothermic (ΔH  = 14.85 kJ mol − 1 ; ΔS = 109.54 J mol − 1  K − 1 ). Circular dichroism spectroscopy (CD) was employed to measure the conformational change of DNA in the presence of [CuL(NO 3 ) 2 ] complex. Furthermore, the complex induces detectable changes in the viscosity of DNA. The molecular modeling results illustrated that the complex strongly binds to groove of DNA. Experimental and molecular modeling results showed that Cu(II) complex bound to DNA by a groove binding mode.