Electrochemical Sensing of Perfluorooctanoic Acid via a Rationally Designed Fluorine-Functionalized Cu-MOF and In-Depth Analysis of Sensing Mechanism.

Perfluorooctanoic acid (PFOA), a prominent member of the per- and polyfluoroalkyl substance (PFAS) family, has emerged as a new perpetual pollutant posing significant environmental and health risks, necessitating developing highly selective materials for its sensitive detection in water. In this work, we developed an electroactive fluorine-functionalized Cu-MOF (F-Cu-NHBDC) through postmodification of the copper-2-amino-terephthalic acid (Cu-NHBDC) MOF with 2,3,5,6-tetrafluoroterephthalaldehyde (TFTA). Experimental and computational results suggested that F-F interactions between the decorated tetrafluorobenzaldehyde groups and PFOA, as well as among the PFOA molecules themselves, would induce self-aggregation of PFOA molecules on the surfaces or in the pores of F-Cu-NHBDC.

Fluorine-fluorine interaction-driven colorimetric sensor for PFOA-sensitive detection using F-functionalized Ce-UiO-66-NH MOF with oxidase-like activity.

A novel colorimetric sensor was designed for sensitive perfluorooctanoic acid (PFOA) detection based on a fluorine-functionalized Ce-metal-organic framework (F-Ce-UiO-66-NH) with oxidase-like activity, using 3,3',5,5'-tetramethylbenzidine (TMB) as the chromogenic substrate. This F-Ce-UiO-66-NH was synthesized through ligand exchange and post-modification with pentafluorobenzaldehyde (PFBA) on the basis of Ce-terephthalic acid (Ce-UiO-66), incorporating pentafluorophenyl groups that enhance the material's affinity for PFOA, leading to a more sensitive absorbance change in the presence of PFOA. Experimental and computational assays revealed that oxidase-like activity of F-Ce-UiO-66-NH primarily arises from hydroxyl radicals (•OH) generated through the conversion of superoxide radicals (•O).

Direct Comparative Studies Revealing the Contribution of TADF Activity of Organic Emitters Towards Efficient Electrochemiluminescence.

Electrochemiluminescence (ECL) featuring thermally activated delayed fluorescence (TADF) properties has attracted considerable interest, showcasing their potential for 100 % exciton harvesting, which marks a significant advancement in the realm of organic ECL. However, the challenge of elucidating the precise contribution of TADF to the enhanced ECL efficiency arises due to the lack of comparative studies of organic compounds with or without efficient TADF properties. In this study, we present four carbazole-benzonitrile molecules possessing similar chemical structures and comparable exchange energy (ΔE).

Dissecting amide-I vibrations in histidine dipeptide.

The amide-I vibrational characteristics and conformational preferences of the model compound - histidine dipeptide (Ac-His-NHCH, HISD) in gas phase and solution have been revealed with the help of ab initio calculations and wavefunction analyses. The Gibbs free energy surfaces (FESs) of solvated HISD were smoothed by solvent effect to exhibit different structural populations concerning various external environments. It was shown that the most stable conformations of HISD in CHCl and gas phase are C7eq, while those in DMSO and water are β and PPII, respectively.