Impact of Isomeric Dicarboxylate Ligands on the Formation of One-Dimensional Coordination Polymers and Metallocycles: A Novel cis→trans Isomerization.

A series of Co(II), Ni(II) and Cu(II) coordination polymers and dinuclear metallocycles containing 4-aminopyridine (4-ampy) and benzenedicarboxylate ligands, {[M(4-ampy)(1,4-BDC)]·HO·CHCHOH} (M = Ni, ; Co, , 1,4-HBDC = benzene-1,4-dicarboxylic acid), {[Ni(4-ampy)(1,3-BDC)]·HO·CHCHOH} (1,3-HBDC = benzene-1,3-dicarboxylic acid), , [M(4-ampy)(1,2-BDC)] (M = Ni, ; Co, , 1,2-HBDC = benzene-1,2-dicarboxylic acid), [Co(4-ampy)(1,3-BDC)] , {[Cu(4-ampy)(1,4-BDC)] CHCHOH}, , and {[Cu(4-ampy)(1,4-BDC)]·HO}, ·HO, are reported, which were hydrothermally prepared and structurally characterized by using single crystal X-ray diffraction. Complexes and are isomorphous 1D zigzag chains, while displays a concave-convex chain and and are dinuclear metallocycles that differ in the boding modes of the 1,2-BDC ligands, forming a 3D and a 2D supramolecular structures with the and topologies, respectively. Complex exhibit a 1D helical chain and complexes and ·HO are 1D linear and zigzag chains, in which the Cu-1,4-BDC units adopt the and configurations, respectively. A novel irreversible structural transformation due to → isomerization of the Cu-1,4-BDC units was observed in ⋅HO and upon water adsorption of the desolvated product of ·HO.