Sensitive and selective detection of chromium (VI) based on two-dimensional luminescence metal organic framework nanosheets via the mechanism integrating chemical oxidation-reduction and inner filter effect

Cationic Metal–Organic Framework-Based Mixed-Matrix Membranes for Fast Sensing and Removal of Cr2O72− Within Water

“…The LOD value of the Eu-mtb powder toward Cr 2 O 7 2– was calculated to be 0.207 mM, inconsistent with what has been reported in the literature ( Liu et al, 2017 ), which is probably due to the different evaluation formulae of the LOD. It is noteworthy that the LOD value of the Eu-mtb MMM (70 wt%) is significantly lower than that of Eu-mtb and other reported fluorescence powder-form MOFs for Cr 2 O 7 2– ( Figure 6C ) ( Hao and Yan, 2016 ; Lin et al, 2017 ; Jin et al, 2018 ; Xiao et al, 2018 ; Abdollahi and Morsali, 2019 ; Liu et al, 2019 ; Mi et al, 2019 ; Wiwasuku et al, 2019 ; Guo et al, 2020 ; Qiu et al, 2021 ), indicating that the Eu-mtb MMM (70 wt%) is a promising luminescent platform for sensing Cr 2 O 7 2– in aqueous solution with excellent sensitivity. It is speculated that the dramatically enhanced sensitivity of the Eu-mtb MMM (70 wt%) might be attributed to the enrichment of Cr 2 O 7 2– from the aqueous solutions inside MMMs and the uniform distribution of Eu-mtb particles without aggregation in MMMs, making it possible for the sufficient interactions between Cr 2 O 7 2– and the Eu-mtb framework.…”

“…In brief, 1 mg finely ground Eu-mtb powders were dispersed into aqueous solutions of Cr 2 O 7 2-(2 ml) with various concentrations, which were then treated by ultrasonication to form a homogenous suspension before fluorescence measurement. As shown in Supplementary Figure S16 6C) (Hao and Yan, 2016;Lin et al, 2017;Jin et al, 2018;Xiao et al, 2018;Abdollahi and Morsali, 2019;Liu et al, 2019;Mi et al, 2019;Wiwasuku et al, 2019;Guo et al, 2020;Qiu et al, 2021) In order to explore the possible mechanism of the fluorescence quenching from the Eu-mtb MMM (70 wt%) induced by Cr 2 O 7 2− , UV-vis spectra of aqueous solutions of various anions and cations were investigated. As shown in Figure 7, it is notable that the excitation peak of Eu-mtb is partially overlapped by the strong absorption of Cr 2 O 7 2− , resulting in the inner filter effect (IFE) (Mi et al, 2019;Guo et al, 2020).…”

Choline Oxidase-Integrated Copper Metal–Organic Frameworks as Cascade Nanozymes for One-Step Colorimetric Choline Detection

“…Since scientists discovered the first kind of inorganic nanometer material Fe 3 O 4 with catalytic activity, thorough research began to be carried out for other nanometer materials. − Some of them show similar catalytic activities to natural enzymes, and the catalytic reactions conform to the basic kinetic principles and mechanisms of enzymes, which are called nanozymes. Compared to natural enzymes, they exhibit similar catalytic activity, simple preparation, and stable properties, − thus show promising applications in many fields.…”

A novel ratiometric fluorescent and colorimetric sensor based on a 1,8-naphthalimide derivative for nanomolar Cu2+ sensing: smartphone and food applications

“…In particular, chemical sensors utilizing fluorescent organic dyes have attracted increasing attention in recent years due to their advantages of simplicity of synthesis, cost-effective analysis, selectivity and the sensitive recognition of metal ions. 1–12 Among the fluorescence sensors, ratiometric sensors with different emission behaviors have superior importance due to their advantages such as improved sensitivity towards trace amounts of metal ions in biological or environmental systems. They are also sensitive to low quantum ( Φ ) yields and usually show broad fluorescence bands.…”