Two multifunctional luminescent cobalt metal-organic frameworks for selectively and sensitively sensing of Cu2+, MnO4- and picric acid in water

Developing novel metal-organic frameworks (MOFs) and exploring their luminescent applications gains continuous concern. Herein, based on tetraphenylpyrazine fluorophore, two cobalt metal-organic frameworks (MOFs), denoted as {Co(HCOO)(Tipp)·H 2 O} n (1) and {Co(Tipp) 0.5 A} n (2) (Tipp ​= ​2, 3, 5, 6-tetrakis[4-[(1 H -imidazole-1-yl)-methyl]phenyl]pyrazine, H 2 A ​= ​4, 4'-oxybisbenzoic acid), have been prepared under hydrothermal condition. Structural analysis indicates that 1 has a (4, 6)-connected 3D seh network with the point symbol of {3∙4 2 ∙5 2 ∙6}{3 2 ∙4 2 ∙5 2 ∙6 4 ∙7 4 ∙8}. 2 shows a (2, 4)-connected 2D framework with a new Schläfli symbol of {4 2 ∙8 2 ∙10 2 }{4 2 ∙8 3 ∙10} 2 {4} 2 . Significantly, 1 and 2 can be employed as multifunctional sensors for selective and sensitive detection of Cu 2+ , MnO 4 - and picric acid in aqueous solution by fluorescence quenching. The limits of detection (LODs) for Cu 2+ , MnO 4 - and picric acid were down to 10 -7 ​M and quenching constant (K sv ) values reach the level of 10 5 ​M -1 . Moreover, the two sensors show good recyclability and can respond to analytes in a wide pH range. • Two cobalt metal-organic frameworks have been prepared with 3D and 2D networks, respectively. • The MOFs can be utilized as multifunctional sensors for Cu 2+ , MnO 4 - and TNP in water. • The sensors exhibit high selectivity, high sensitivity and recyclable use ability.