A functionalized UiO-66 MOF acting as a luminescent chemosensor for selective and sensitive turn-on detection of superoxide and acetylacetone

Abstract

A luminescent ZrIV based UiO-66 metal-organic framework (MOF) with sulphonamide functionality was successfully synthesized using solvothermal method and characterized using various instrumental tools. This newly synthesized Zr-MOF (UiO-66-NH–SO2–Ph-NO2, 1; UiO = University of Oslo) with 2-((4-nitrophenyl)sulfonamido)terephthalic acid (BDC–NH–SO2-Ph-NO2) ligand displayed high thermal stability up to 330 °C under N2 atmosphere and chemical stability in H2O, 1 (M) HCl, glacial acetic acid and NaOH solution (pH 8 to 10). The MOF showed a large BET surface area of 1073 m2 g−1. The thermally activated MOF (1′) showed highly selective and sensitive fluorescent switch-on properties for superoxide (O2•-) in MeOH and acetylacetone (ACAC) in DMF medium even in presence of its competitors. The detection limit (98 nM) of O2•- using this probe is much lower than the known MOF based chemo-sensor for O2•-. The uniqueness of this MOF (1′) is its ability to detect ACAC up to the limit of 1.23 ppm, which is similar as the previously published MOF chemo-sensors for ACAC. The mechanisms of both the sensing processes were investigated in detail.