Four thiophene-pyridyl-amide-based ZnII/CdII coordination polymers: Assembly, structures, photocatalytic properties and fluorescent recognition for Fe3+

By tuning metal ions and combining with different dicarboxylates , four new semi-rigid thiophene-bis-pyridyl-bis-amide-based coordination polymers , namely, [Zn(3-bptpa)(1,3-BDC)]·DMA·2H 2 O ( 1 ), [Zn(3-bptpa)(5-MIP)] ( 2 ), [Cd(3-bptpa)(1,3-BDC)]·2H 2 O ( 3 ) and [Cd(3-bptpa)(5-MIP)]·4H 2 O ( 4 ) (3-bptpa= N,N′ -bis(pyridine-3-yl)thiophene-2,5-dicarboxamide, 1,3-H 2 BDC=1,3-benzenedicarboxylic acid, 5-H 2 MIP=5-methylisophthalic acid, DMA= N,N -dimethylacetamide), were solvothermally/hydrothermally synthesized and structurally characterized by single-crystal X-ray diffraction analyses, IR spectra , UV–vis diffuse-reflectance spectra (DRS), powder X-ray diffraction (PXRD) and thermal gravimetric analyses (TG). The structural analysis reveals that Zn-complexes 1 and 2 are similar 2D networks. While Cd-complexes 3 and 4 exhibit similar 2-fold interpenetrating 3D α -Po frameworks with the (4 12 ·6 3 ) topology. The photocatalytic properties for the degradation of methylene blue (MB) under ultraviolet light irradiation of the title complexes have been investigated in detail. Furthermore, the luminescent sensing behaviors for metal cations of 1–4 have been studied, the results indicate that 3 is an excellent fluorescent probe , with high sensitivity, selectivity , and simple regeneration, for environmentally relevant Fe 3+ ions.