Insights into the interactions between DNA and an infinite clamp-like copper (II) complex

A Cu(II) complex [Cu 2 (phen) 2 (NAB) 2 (HO)] n (phen = 1, 10-phenanthroline and NABH = p -N, N-(2-hydroxyethyl)amino benzoic acid) was synthesized, and its structure was confirmed by X-ray diffraction. The structure of the complex appeared to be clamp-like, in which Cu(II) atoms adopt distorted square pyramidal geometry. Each Cu(II) is coordinated by two nitrogen atoms in phen ligand and two carboxyl oxygen atoms from each of the two NABH ligands. The clamp-like coordination units are bridged by adjacent hydroxyethyl groups into infinite 1D chain, which are further linked by extensive O···H hydrogen bonds and π–π interactions to form 3D networks. The titled complex displayed weak double-stranded DNA interaction activity. Spectroscopic and theoretical simulation results indicated that the complex attached onto DNA surface through hydrogen bonding with base pairs. Graphic abstract A novel benzoic acid derivative with two extremity hydroxyethyl groups was designed and used as auxiliary ligand to synthesize mixed coordinating clamp-like Cu(II)-phenanthroline complex. Hydrogen bonding played crucial role in bridging the clamps into infinite 1D chain and also the DNA complex interaction mode.