Dual-Function Metal–Organic Framework as Efficient Turn-Off Sensor for Water and Unusual Turn-On Sensor for Ag⁺

Abstract

Fluorescent sensors have been extensively employed in efficient energy utilization and environment protection. In this work, an amino-decorated metal−organic framework [Cd(3-NH 2 -pba) 2 ] 4 •8DMF (3-NH 2 -Hpba = 3-amino-4-(pyridin-4-yl)benzoic acid) was synthesized as a dual-function fluorescent sensor through the distinctive interaction of amino moieties with analytes. This compound exhibits highly sensitive turn-off sensing of trace water in ethanol with a detection limit to 0.09%, much below the required values for hydrated ethyl alcohol fuel internationally. Meanwhile, it can also be developed as an unusual turn-on sensor for the probe of Ag + in aqueous solution with the detection limit to 0.44 μM, lower than the maximum concentration of Ag + in drinking water according to the standard of the U.S. Environmental Protection Agency. It is the first example of MOF-based fluorescent sensor for simultaneously detecting trace water and Ag + .

Amine- and Imine-Functionalized Mn-Based MOF as an Unusual Turn-On and Turn-Off Sensor for d10 Heavy Metal Ions and an Efficient Adsorbent to Capture Iodine

“…Generally, MOF-based “turn-off” sensors are reported to trace metal ion pollutants. , However, reports on fluorescence “turn-on” sensors are rare. , To detect specific metal ions, including Al 3+ , Fe 3+ , Mg 2+ , Co 2+ , Cu 2+ , and Zn 2+ , a wide range of fluorescent MOFs has been explored in this aspect, , although sensitive and selective detection of heavy metal ions has been scarce. For instance, Guo et al synthesized a Cd-MOF able to detect Ag + ions, while Das and co-workers reported a Zn-MOF for Cd 2+ sensing . Zhang et al developed NH 2 -MIL-53 aluminum-based MOF to detect Hg 2+ with a limit of detection (LOD) of 0.15 μM .…”

Robust Al3+ MOF with Selective As(V) Sorption and Efficient Luminescence Sensing Properties toward Cr(VI)

“…Similar quenching results were obtained for the fluorescence titrations in different organic solvents such as THF and CH 3 CN (Figure S50) with detection limits of 0.196 and 0.245% v/v, respectively (Table S10). The strong fluorescence quenching of Al-MOF-1 even with a trace amount of water is attributed to the effect of O–H oscillators of the absorbed water molecules via a static quenching mechanism as presented above.…”

A Cu2I2-Based Coordination Framework as the Selective Sensor for Ag+ and the Effective Adsorbent for I2

“…Moreover, an obvious shift in I 3d electron binding energy could be measured for Ag + @ 1 (619.0 and 630.5 eV) compared with the original solid (618.8 and 630.3 eV) (Figure b), which indicated the occurrence of combination processes between guest Ag + and iodide species from [Cu 2 I 2 ] moieties in 1 . Therefore, we can speculate that the Ag–I interaction could exert a large influence on the efficiency of energy transfer in 1 , thus resulting in a luminescence quenching behavior. , …”