Three metal organic frameworks based on mixed ligands: synthesis, crystal structures and luminescent sensing of nitro explosives

Three new metal organic frameworks [Zn(bipa)(suc)] n ( 1 ), [Ni(bipa)(suc)(H 2 O) 2 ] n ( 2 ) and [Co(bipa) 1.5 (oip)(H 2 O)] n ( 3 ) (bipa = 2,5-bis(1-imidazole)pyrazine), H 2 suc = succinic acid, H 2 oip = 5-hydroxy isophthalic acid) have been synthesized by solvothermal method. They were then characterized by single crystal X-ray diffraction, elemental analysis, infrared spectrum and thermogravimetric analysis. Structural analyses showed that MOFs 1 and 3 exhibited a 3D supramolecular network, while MOF 2 presented a 2D layered structure and was further assembled to a 3D architecture via intermolecular O–H···O hydrogen bond. Moreover, the luminescence sensing of MOF 1 toward nitro explosives was investigated, owing to its excellent chemical stability and luminescence properties. MOF 1 showed remarkable fluorescence quenching toward TNP with a high K sv value of 6.48 × 10 4 M −1 and a low limit of detection of 1.4 × 10 −5 M. Also, the luminescent sensing mechanism of MOF 1 was investigated.