Site-Memory-Triggered Reversible Acronym Encryption in a Nitrogen-Rich Pore-Partitioned MOF for Ultrasensitive Monitoring of Roxarsone and Dichloran over Multiple Platform

Abstract

Stimuli-responsive emission color modulation in fluorescent metal–organic frameworks (MOFs) promises luminescence-ink-based security application, while task-specific functionality-engineered pores can aid fast-responsive, discriminative, and ultralow detection of harmful organo-aromatics in the aqueous phase. Considering practical applicability, a self-calibrated fluoro-switch between encrypted and decrypted states is best suited for antiforgery measures, whereas image-based monitoring of organo-toxins by repetitive and handy methods over multiple platforms endorses in-field sensory potential. Herein, we constructed a mixed-ligand based chemically stable and bilayered-pillar MOF from –NH2-hooked pyridyl linker and tricarboxylate ligand that embraces negatively charged [Cd3(μ2-OH)­(COO)6] node and shows pore-space-partitioning by nitrogen-rich flanked organic struts. Owing to the presence of a self-calibrating triazolylamine moiety-grafted auxiliary linker, this anionic MOF delineates reversible and multicyclic fluoro-swapping between protonated-encrypted and deprotonated-decrypted domains in the alternative presence of acid and base. Such pH-triggered, site-specific luminescence variation is utilized to construct highly regenerative anticounterfeiting labels for vivid acronym encryption. The intense fluorescence signature of the material is further harnessed in extremely selective and quick responsive sensing of harmful feed additive roxarsone (ROX) and dichloran (DCNA) pesticide in highly recyclable fashion with significant quenching and nanomolar limits of detection (ROX: 52 ppb; DCNA: 26.8 ppb). Notably, the ultrasensitive fluoro-detection of both these organo-toxins is successfully demonstrated via a handy paper-strip method as well as on the vegetable surface for real-time monitoring. Comprehensive density functional theory studies validate the electron transfer mechanism through redistribution of molecular orbital energy levels by each of the targeted analytes in this electron-rich framework besides evidencing MOF-analyte supramolecular interactions.

Nitrogen-Rich Covalent Organic Polymer for Metal-Free Tandem Catalysis and Postmetalation-Actuated High-Performance Water Oxidation

“…It is worth mentioning that relatively low surface area and smaller pore size are the results of disordered skeleton structure, attributed to channel blockage by the outgrown linkage arms during polymerization, and/or blockage of the pores by triethylammonium chloride salt during COP synthesis . To gain further insight about the porosity of the material, CO 2 adsorption was conducted at 195 K (Figure i), − which revealed a maximum uptake of 43.18 cm 3 /g, and corresponds to the surface area of 110 m 2 /g.…”

Pendent carboxylic acid-fuelled high-performance uranium extraction in a hydrogen-bonded framework and prolifically improved water oxidation via post-metalation-actuated composite fabrication

“…14–18 These amazing structural features instigated researchers to check the applicability of MOFs in diverse areas such as fluorescence sensing, adsorption, heterogeneous catalysis, batteries, solar cells and so on. 19–27 Specifically, pore-functionalization in MOFs via immobilizing carboxylic sites can profoundly facilitate their detection and scavenging performances towards targeted analytes. However, they hardly remain as task-specific sites due to the extreme tendency of coordination with metal ions.…”

Dual Stimulus Responsive GO-Modified Tb-MOF toward a Smart Coating for Corrosion Detection

“…Nevertheless, upon pH recovery, reconstruction of the MOF occurs and reinstates the antenna effect. This reversible alternating process provides a theoretical foundation for utilizing Ln-MOF as a pH-responsive reversible switch. , It is noteworthy that the Tb represents the most extensively employed luminescent Ln species, and the green fluorescence is more easily recognized by the naked eye. The Tb compound has been repeatedly reported as a highly effective indicator for detecting Fe 3+ . − In addition to their distinctive photoluminescent properties, Ln-MOF materials also exhibit the advantages of exceptional porosity, a substantial specific surface area, and a high density of active sites commonly encountered in MOF materials .…”