Thiadiazole-functionalized metal-organic frameworks multifunction-architectonics for dual-target sensing of ethylamine and gossypol

Fluorescent metal–organic frameworks (MOFs) have been widely developed as sensor matrix for single-target detection. Multi-target sensing with MOFs can be more efficient and cost-effective but relevant studies is still in its infancy. Here we report the construction of novel fluorescent Eu-MOF with electron-deficient, thiadiazole-functionalized ligand, 4,4′-(benzo[c][1,2,5]thiadiazole-4,7-diyl)dibenzoic acid (H2-TTPDC) as organic linkers, and Eu3+ ions as metal nodes for dual-target detection. Thanks to the conjugated structure and thiadiazole active group of the ligand, and the large pore structure of the MOF, sensitive detection of both ethylamine and gossypol was achieved with a detection limit of 1.30 μM and 4.32 μM, respectively. Strong hydrogen bonds between ethylamine and TTPDC result in the extended π-conjugation and thus give rise to the fluorescence “turn-on” detection of ethylamine with the Eu-MOF. Electron transfer caused by host–guest conjugation and strengthened π-π packing effect synergistically realize the “turn-off” sensing of gossypol. The precise emission change enabled by the intramolecular rotation structure of TTPDC facilitate the validation of the interaction between the MOF and the targets, and Eu-MOF displays preeminent anti-interference ability for sensing targets in complicated environments. The obvious emission changes achieved visible detection by naked eye under UV light.