Thiadiazole-functionalized Pb(ii)-MOF for “turn-on” fluorescence selective sensing of Al3+

Abstract

Multifunctional metal–organic frameworks (MOFs) for fluorescence sensing have received considerable attention. In this work, a novel thiadiazole-functionalized Pb(II) based MOF, [Pb(BTDB)(DMF)]_n (H₂BTDB = 4,4′-(benzo[c][1,2,5]thiadiazole-4,7-diyl)dibenzoic acid, DMF = N,N-dimethylformamide), has been constructed via a solvothermal method, which presents a two-dimensional layer structure. This Pb(II)-MOF exhibits chemical stability in some organic solvents for a long time, and the thiadiazole groups on the ligands endow this Pb(II)-MOF with outstanding fluorescence properties. Moreover, Pb(II)-MOF can selectively detect Al³⁺ through fluorescence enhancement and blue shift, with a detection limit of 11 μM, and this material as a fluorescent sensor to identify Al³⁺ demonstrates excellent anti-interference ability, sensitivity and recyclability. The mechanism of sensing is further explored using XPS and FTIR spectroscopy and the results reveal that the “turn-on” and blue-shift fluorescence phenomena are attributed to the intermolecular interaction between nitrogen atoms in the thiadiazole groups and Al³⁺.