Specific fluorescence sensing of hydrogen sulphide by an azide functionalized Zr(IV) MOF with DUT-52 topology

Abstract

In this work, we synthesized an azide functional group containing Zr(IV) based metal-organic framework (MOF) with DUT-52 (DUT = Dresden University of Technology) topology via solvothermal process. Acetic acid was used as a modulator to increase the crystallinity. The synthesized compound ( 1 ) was activated by exchanging occluded molecules with methanol and heating at 80 °C for 5 h. Both 1 and activated compound ( 1′ ) were characterized by X-ray powder diffraction (XRPD), Fourier transform infrared (FT-IR) and thermogravimetric analysis (TGA). Both 1 and 1′ are thermally stable up to 320 °C and chemically stable in solvents like methanol, 1 (M) HCl and water. The Brunauer-Emmett-Teller (BET) surface area of 1′ was found to be 505 m 2 g −1 . The data from fluorescence experiments suggested that 1′ exhibits sensitive and selective detection of H 2 S in aqueous medium. The limit of detection (LOD) value was found to 0.50 μM. This value lies in the lowest range of H 2 S detection by known MOFs. Moreover, the possible mechanism behind the enhancement of fluorescence intensity after addition of Na 2 S in 1′ was also examined. • A new azide functionalized Zr(IV)-based MOF ( 1 ) was synthesized. • The desolvated compound exhibited high selectivity and sensitivity towards H 2 S. • A remarkable increase (33 folds) in fluorescence intensity was observed. • The probe showed very fast response (within 2 min) for H 2 S detection in water. •Conversion of azide group to amine moiety is responsible for turn-on sensing.