We report a Ni-MOF (nickel metal–organic framework), Ni-SIP-BPY, synthesized by using two linkers 5-sulfoisophthalic acid (SIP) and 4,4′-bipyridine (BPY) simultaneously. It displays an orthorhombic crystal system with the Ama2 space group: a = 31.425 Å, b = 19.524 Å, c = 11.2074 Å, α = 90°, β = 90°, γ = 90°, and two different types of nickel­(II) centers. Interestingly, Ni-SIP-BPY exhibits excellent sensitivity (limit of detection, 87 ppb) and selectivity toward the 2,4,6-trinitrophenol (TNP)-like mutagenic environmental toxin in the pool of its other congeners via “turn-off” fluorescence response by the synergism of resonance energy transfer, photoinduced electron transfer, intermolecular charge transfer, π–π interactions, and competitive absorption processes. Experimental studies along with corroborated theoretical experimentation, vide density functional theory studies, shed light on determining the plausible mechanistic pathway in selective TNP detection, which is highly beneficial in the context of homeland security perspective. Along with the sensing of nitroaromatic explosives, the moderately low band gap and the p-type semiconducting behavior of Ni-SIP-BPY make it suitable as a photoanode material for visible-light-driven water splitting. Highly active surface functionalities and sufficient conduction band minima effectively reduce the water and result in a seven times higher photocurrent density under visible-light illumination.

Selective and sensitive moisture sensors have attracted immense attention due to their ability to monitor the humidity content in industrial solvents, food products, etc., for regulating industrial safety management. Herein, a hydroxy naphthaldehyde-based piezochromic luminogen, namely, 1-{[(2-hydroxyphenyl)­imino]­methyl}­naphthalen-2-ol (NAP-1), has been synthesized and its photophysical and molecular sensing properties have been investigated by means of various spectroscopic tools. Owing to the synergistic effect of both aggregation-induced emission (AIE) and excited-state intramolecular proton transfer (ESIPT) along with the restriction of CN isomerization, the probe shows bright yellowish-green-colored keto emission with high quantum yield after the interaction with a trace amount of water. This makes NAP-1 a potential sensor for monitoring water content in the industrial solvents with very low detection limits of 0.033, 0.032, 0.034, and 0.033% (v/v) from tetrahydrofuran (THF), acetone, dimethyl sulfoxide (DMSO), and methanol, respectively. The probe could be used in the food industry to detect trace moisture in the raw food samples. The reversible switching behavior of NAP-1 makes it suitable for designing an INHIBIT logic gate with an additional application in inkless writing. In addition, an Internet of Things-(IoT) based prototype device has been proposed for on-site monitoring of the moisture content by a smartphone via Bluetooth or Wi-Fi. The aggregated probe also has the ability to recognize Cu2+ from a purely aqueous medium via the chelation-enhanced quenching (CHEQ) mechanism, leading to ∼84% fluorescence quenching with a Stern–Volmer quenching constant of 1.46 × 104 M–1 and with an appreciably low detection threshold of 57.2 ppb, far below than recommended by the World Health Organization (WHO) and the United States Environmental Protection Agency (U.S. EPA). The spectroscopic and theoretical calculations (density functional theory (DFT), time-dependent DFT (TD-DFT), and natural bond orbital (NBO) analysis) further empower the understanding of the mechanistic course of the interaction of the host–guest recognition event.

Separation of C8 alkyl-aromatics (o-xylene, m-xylene, and p-xylene) remains one of the most challenging tasks to date due to their similar physical and chemical properties. Cd2+- and Zn2+-based luminescent metal–organic frameworks (MOFs) have been synthesized for the selective identification of m-xylene in a pool of other isomers by fluorometric methods. Inhibition of the photoinduced electron transfer process is the prime reason for fluorescence enhancement, owing to the comparable molecular orbital energies for m-xylene in comparison with o- and p-xylene. Density functional theory calculations signify that the extraordinary selectivity is mainly due to the high dipole moment of m-xylene that might enhance the ring current, leading to a strong π–π interaction with the MOF’s co-ligand. As a practical application, fluorometric sensing could be used for the estimation of m-xylene in different solvent media. Moreover, X-ray structural analysis reveals that the Zn2+-MOF can encapsulate m-xylene selectively within its framework among other constitutional isomers, which also emphasizes its capability for practical implementation.

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Selective sensing of biothiols holds immense importance due to the adverse roles of abnormal concentrations of biothiols in several diseases, henceforth demanding widespread research for developing sensory receptor towards selective...

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Continuous monitoring of a variety of biomolecules and bio-relevant ions is of tremendous importance to maintain the physiological balance and evaluation of metabolic parameters. Therefore, development of fast, selective, sensitive...