LAUSR

Abstract We report the synthesis and characterization of five transition metal coordination polymers (CPs) based on M(II) (M: Co, Ni and Cu), 2-(hydroxymethyl)-1 H -benzo[ d ]imidazole-5-carboxylic acid (H 2 L ) ligand. They are formulated as {[Co 2 (H L ) 2 (H 2 O) 3 (SO 4 )]·H 2 O} n ( 1 ), {[Co 2 (H L ) 2 (H 2 O) 2 ]·SiF 6 } n ( 2 ), {[Ni 2 (H L ) 2 (H 2 O) 3 (SO 4 )]·2H 2 O} n ( 3 ), {[Ni 2 (H L ) 2 (H 2 O) 4 ]·H 2 O·SiF 6 } n ( 4 ), {[Cu 2 (H L ) 2 (H 2 O) 2 ]·SiF 6 } n ( 5 ). The complexes 1–5 structure were characterized by single-crystal X-ray diffraction, elemental analyses, infrared spectroscopy (IR), powder X-ray diffraction (PXRD), and thermogravimetric analyses (TGA). Complexes 1–5 are two-dimensional (2D) network type coordination polymers that 1–3 , 5 crystallize in monoclinic system within the centrosymmetric space group P 2(1) /c , and 4 in triclinic system P -1 space group, they show the same coordination modes (κ 1 -κ 1 )-(κ 1 )-(κ 1 )- μ 3 in coordination polymers. Complexes 1 and 3 expand to three-dimensional framework by means of hydrogen bond interactions, and can be rationalized to be three-connected {6 3 } topological network, while 2 , 4 , 5 exhibit the topological network with a four-connected {4 4 ·6 2 } topological sql network. The luminescent properties (for complexes 1 , 2 ) and UV diffuse reflectance (for complexes 1–5 ) in the solid state at room temperature were also investigated and discussed. Complexes 1–5 act as effective heterogeneous catalysts, under mild conditions, for the homocoupling reaction of 4-substituted aryl iodides bearing electron-donating groups (-CH 3 , -OCH 3 ).