A functionalized UiO-66 metal-organic framework acting as a fluorescent based selective sensor of hydrazine in aqueous medium

Herein, we successfully synthesized a 4-nitrobenzenesulfonyl (-O-SO2-Ph-NO2) functionalized Zr-UiO-66 MOF (1) material using 2-(((4-nitrophenyl)sulfonyl)oxy)terephthalic acid (H2BDC-O-SO2-Ph-NO2) linker and ZrCl4 metal salt under solvothermal reaction conditions. The MOF material displayed high thermal stability up to 370 °C under air atmosphere and considerable chemical stability in H2O, 1(M) HCl, acetic acid and aq. NaOH solution (pH 8 to 10). It also showed a large BET surface area of 1000 m2g-1 with a pore volume of 0.57 cm3g-1. The thermally activated MOF (1′) suspension displayed good selectivity towards the sensing of hydrazine (NH2NH2) in water. Together with rapid response time (4 min), 1′ displayed lowest ever limit of detection (52 ± 4 nM) of NH2NH2 among all the reported MOF based sensing probes of NH2NH2. Sensing of NH2NH2 in environmental water samples and MOF coated paper strips made it an extraordinary sensor of NH2NH2. The most interesting aspect of this robust probe is that it is the first MOF based sensor, which can sense NH2NH2 in the vapor phase. The response time for the vapor phase sensing was 8 min. The removal of electron withdrawing 4-nitrobenzenesulfonyl group by the nucleophilic attack of NH2NH2 is the reason behind the turn-on sensing which was proved by 1H NMR spectroscopy and mass spectrometric analysis.