Selective fluorescent sensing and photocatalytic properties of three MOFs based on naphthalene-1,4-dicarboxylic acid and 2,4,5-tri(4-pyridyl)-imidazole

The solvothermal reactions of M II (M = Mn, Zn, Cd) ions with naphthalene-1,4-dicarboxylic acid (H 2 L ) and 2,4,5-tri(4-pyridyl)-imidazole (Htpim) gave rise to three MOFs, [Mn( L ) 0.5 ( L ) 0.5 (Htpim) 2 ] n ( 1 ), [Zn 4 ( L ) 4 (Htpim) 2 ] n ( 2 ) and [Cd 4 ( L ) 4 (Htpim) 2 (DMF) 2 ] n ( 3 ). Single-crystal X-ray diffraction analyses indicate that compounds 1-3 display diverse topologies. 1 possesses a 2D 4 4 network constructed by linking Mn centers, compound 2 exhibits a 3D (3,4,6)-connected {4·6 2 } 2 {4 2 ·6 4 } 2 {4 2 ·6 8 ·8 2 ·10 3 } net interlinked by [Zn 2 L 4 ] units, while compound 3 presents a 3D (3,7)-connected {4 2 ·5}{4 6 ·5 5 ·6 8 ·7 2 } framework assembled by dinuclear Cd nodes. 1 and 3 display high sensitivity in the detection of nitrobenzene (NB) as fluorescent sensors and Ca 2+ or Co 2+ ions as luminescent probes. Moreover, 3 exhibits a relatively good photocatalytic activity towards the degradation of rhodamine B (RhB) in aqueous solution under UV irradiation. Three MOFs display high sensitivity in the detection of NB and Ca 2+ or Co 2+ ions as luminescent probes. Moreover, 3 exhibits a relatively good photocatalytic degradation activity of rhodamine B.