Tetramodal saccharin (SAC) sensing with a novel Ba-MOF: Leveraging SAC-induced PET effect and enhanced photocatalytic oxidase-mimicking activity.

A tetramodal sensing method for the sensitive and selective detection of saccharin (SAC) was developed using a novel Ba-MOF. The fluorescent Ba-MOF was prepared via a solvothermal reaction between Ba2+ and 5,5'-(anthracene-9,10-diyl)diisophthalic acid (H4ADIP), and its single-crystal structure was unambiguously determined. Upon addition of SAC, the fluorescence of Ba-MOF was remarkably quenched, while its oxidase-like catalytic activity was significantly enhanced. This dual-response behavior enabled the establishment of a tetramodal sensing platform integrating fluorescence, colorimetric, photothermal and electrochemical detection. The sensor exhibited wide linear ranges, a low detection limit (58.50 nM), high selectivity and stability. Real sample analysis of Sprite, Coca-Cola and whipped cream using the standard addition method yielded recoveries of 93.40%-106.55% and RSD of 0.67%-4.87%. Mechanistic studies revealed that coordination of SAC to the Ba center reduced the band gap, enhancing oxidase-like activity, while photoinduced electron transfer (PET) from H4ADIP to SAC quenched the fluorescence.