Anion-directed assembly of two fluorescent Cd(II) coordination polymers with a versatile multidentate N-donor building block 3-(2-pyridyl)-4,5-bis(4-pyridyl)-1,2,4-triazole

Assembly of Cd(II) nitrate with a novel tripyridyltriazole building block 3-(2-pyridyl)-4,5-bis(4-pyridyl)-1,2,4-triazole (L1) and pseudohalide anion dicyanamide (dca) or azide (N3) yields two coordination polymers {[Cd(L1)2(dca)2](H2O)2}n (1) and {[Cd2(L1)(μ1,1-N3)2(μ1,3-N3)(N3)](H2O)1.5}n (2). Single crystal X-ray diffraction analysis indicates that the Cd(II) centers in 1 are bridged by the bidentate L1 ligands to form 1D arrays, which are further extended to a 3D network via hydrogen bonding and aromatic stacking. Significantly, the L1 ligands in 2 display the unusual pentadentate coordination and the azide anions take different μ1,1-, μ1,3-, and unidentate binding modes, interlinking the Cd(II) ions to afford a complicated 3D open framework with the inclusion of lattice water guests. Both complexes exhibit strong solid state fluorescent emissions at room temperature.

Graphical AbstractThis work presents two fluorescent Cd(II) coordination polymers based on a novel tripyridyltriazole tecton and different pseudohalide anions (dicyanamide vs. azide), which exhibit distinct 1D double-chain motif and 3D channel-like coordination framework.Figure optionsDownload as PowerPoint slide