Protonated Adenine and Cytosine Ribbons Stabilized by Dipicolinato Metal Frameworks

摘要

Stabilization of protonated adenine (ade) and cytosine (cyt) ribbons through hydrogen bonding interactions in a series of bis-dipicolinato metal(II) (metal = manganese, copper, zinc at +2 oxidation state) complexes are studied. Protonated assemblies of adenine as infinite chains in [1H, 9H-ade][3H, 7H-ade][MnL_2]·3H_2O and [1H, 9H-ade][3H, 7H-ade][CuL_2]·3H_2O (L = dipicolinato anion) are structurally characterized. The one-dimensional (1D) zigzag ribbons are comprised of alternate nonequivalent [1H, 9H-ade] and [3H, 7H-ade] adeninium cations. Protonated cytosinium cation aggregates with neutral cytosine to form pairs, and such pairs form tetrameric units with a length of 33.45 ? in the lattice of the seven coordinated manganese(II) complex [1H, 3H-cyt]_2[MnL_2(H_2O)]·2cyt·6H_2O. The discrete cations of cytosine stabilized by electrostatic, hydrogen bond, and stacking interactions within the inorganic layers build the closely packed organic?inorganic hybrid materials in the crystal lattice of the complexes [1H, 3H-cyt]_2[CuL_2]·5H_2O and [1H, 3H-cyt]_2[ZnL2]·5H_2O.