A pH-Stable Tb III -Based Metal-Organic Framework as a Turn-On and Blue-Shift Fluorescence Sensor toward Benzaldehyde and Salicylaldehyde in Aqueous Solution.

A new polydentate tetracarboxylic acid with a benzothiadiazole unit (4',4'''-(benzo[ c ][1,2,5]thiadiazole-4,7-diyl)bis([1,1'-biphenyl]-3,5-dicarboxylic acid), H 4 BTDBA) has been used to prepare a pH-stable three-dimensional Tb III -based metal-organic framework (MOF) with the formula {[(CH 3 ) 2 NH 2 ] 0.7 [Tb 2 (BTDBA) 1.5 (lac) 0.7 (H 2 O) 2 ]·solvents} n (Hlac = lactic acid, JXUST-19 ). JXUST-19 exhibits a new (4,4,12)-connected topology based on tetranuclear [Tb 4 ] clusters. JXUST-19 can remain stable when soaked in water for at least 1 week and in aqueous solutions with various pH values (2-12) for 24 h. Fluorescence study indicates JXUST-19 can be employed as a rare turn-on and blue-shift MOF sensor toward benzaldehyde (BZ) and salicylaldehyde (SA). To date, JXUST-19 represents the first Tb III -based turn-on MOF sensor toward salicylaldehyde in aqueous solution, and the fluorescence enhancement and naked-eye detection of BZ have been rarely reported. In addition, JXUST-19 based fluorescent test papers, light-emitting diode lamp beads, and portable composite films were developed to realize naked-eye detection of BZ and SA, which has great potential in practical applications.