Solvothermal synthesis, crystal structure and DNA binding studies of a 3D supramolecular complex {[Cu(phen)CN][Cu(phen)][Cu(CN)2]} n assembled by double curvy chains

A new cyano-bridged copper (I) complex {[Cu(phen)CN][Cu(phen)][Cu(CN)2]}(n) ( 1) (phen = 1,10-phenanthroline) was synthesized under the solvothermal conditions, and characterized by elemental analysis, FI-IR spectra and single-crystal X-ray diffraction. The structure analysis reveals that complex 1 contains two [Cu( phen) CN] [Cu(phen)] [Cu(CN)(2)] subunits, being, respectively, constructed into two chains with different cyano backbones. The resulting chains offer a double curvy chain by Cu center dot center dot center dot Cu weak interactions and pi-pi stacking interactions. It is exciting that the double curvy chains adopt anti-parallel array and result in a novel 3D architecture through pi-pi stacking interactions. According to the supramolecular self-assembly of complex 1, four types of stacking mode of phenanthroline moieties are given and discussed. Absorption and fluorescence titration studies of complex 1 with calf thymus DNA are suggestive of the intercalation binding mode with a intrinsic binding constant of 7.52 x 10(3) M-1 and a linear Stern-Volmer quenching constant of 1.02 x 10(5) M-1.