Structural Variations Influenced by Ligand Conformation and Counteranions in Copper(II) Complexes with Flexible Bis-Triazole Ligand

Using a flexible bis-triazole ligand 1,4-bis(triazol-1-ylmethyl)benzene (L), four new copper(II) compounds {[Cu(trans-L)(cis-L)(2)(H2O)(2)](CF3SO3)(2)center dot 4H(2)O}(n) (1), {[Cu(cis-L)(2)(H2O)(2)](CF3SO3)(2)center dot 2H(2)O}(n) (2), {[Cu(trans-L)(2)]Cl-2}(n) (3), and {[Cu(trans-L)(cis-L)](BF4)(2)). (4) have been isolated. Conformations of L in 1-4 can be tuned as a result of changing the anion or metal/ligand ratio in the reaction system, which ultimately form a series of novel framework structures varying from 1D to 3D with different supramolecular architectures. 1 is a 1D single-chain structure, in which trinuclear water clusters link adjacent triflate anions to form ID supramolecular helix. 2 is composed of right-helical Cu(II) bis-triazole chains, which are interlinked via copper(II) ions as hingers forming a novel 2D layered structure. Eight-member supramolecular cycles constructed by coordinated water molecules and free triflate anions are found to be embedded into the 2D planes of 2. 3 contains 2D planar nanogrid networks stacked in an AB stacking fashion. Triple Cl...H-C hydrogen bonds reside between these 2D layers. 4 is a 3D MOF with large 1D rhombic channels with dimensionalities of 10.102 x 14.067 angstrom(2) accommodating BF4- anions, which also represents the first case of metal bis-triazole compound with CdSO4 topology. For 1-4, FT-IR and elemental analysis has been carried out, and the conformational variation of L also has been briefly discussed.