Hydrothermal syntheses and characterization of a series of luminescent Cd(II) frameworks with pyridine-based and benzene-based bis-triazole ligands

Using the pyridine-based and benzene-based bis-triazole ligands 2,6-di-(1,2,4-triazole-4-yl)pyridine (L-1) and 1,4-di-(1,2,4-triazole-4-yl)benzene (L-2), a series of luminescent Cd(II) coordination polymers, namely, [Cd(mu(2)-L-1)(2)I-2](n) (1), {[Cd-3(mu(3)-L-1)(6)](BF4)(5)(PF6)center dot 18H(2)O}(n) (2), [Cd(mu(2)-L-2)I-2](n) (3), [Cd(mu(2)-L-2)(mu(1,3)-NCS)(2)](n) (4), {[Cd(mu(2)-L-2)(L-2)(H2O)(3)]SiF6 center dot 3H(2)O}(n) (5), {[Cd(mu(2)-L-2)(L-2)(H2O)(3)]SiF6 center dot CH3OH center dot 2.5H(2)O}(n) (6), {[Cd(mu(2)-L-2)(3)](BF4)(2)}(n) (7) and {[Cd(mu(2)-L-2)(3)](ClO4)(2)}(n) (8), have been isolated. 1 represents a novel 2D framework containing 1D infinite right-and left-handed helical chains. 2 is a 3D coordination framework based on trinuclear Cd(II) clusters containing triangular channels, in which eighteen free water molecules, five free BF4- and one free PF6- anions are located. For 3, the L-2 ligands can bridge Cd-II centers forming a 1D chain, while for 4 the L-2 and mu(1,3)-NCS2 co-ligands can further bridge CdII centers forming a 2D corrugated layer. 5 and 6 represent a novel coordination framework containing 1D rhombic nano-porous channels, in which free SiF62- anions and free solvent molecules are located. 7 and 8 also represent a novel coordination framework containing another kind of trianglular nano-porous channel, in which free BF4- or ClO4- anions are located. Solid-state fluorescent spectra of 1-8 have been determined indicating strong fluorescent emission bands. The result also reveals that L-1 and L-2 can adopt versatile coordination modes and have great potential in the construction of these highly-dimensional luminescent coordination frameworks.