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Among the various essential trace elements for living organisms, the copper (Cu2+) ions are the most important. However, Cu2+ ions are vital for the human body and are associated with necessary physiological processes; insufficient or excessiveness has many hazardous effects on our bodies. In the present contribution, strategically, we have introduced a julolidine-coupled azine-based, 9,9'-((1E,1'E)-hydrazine-1,2-diylidene bis(methanylylidene)) bis(1,2,3,5,6,7-hexahydropyrido [3,2,1-ij] quinolin-8-ol) (HDBQ) reversible chromo-fluorogenic probe for specific detection of Cu2+ ions. Probe HDBQ exhibits observable orange colorimetric change from yellow, which is visible to the naked eye in daylight. The highly green fluorescence HDBQ becomes a non-fluorescent one with the incorporation of Cu2+ ions. Interestingly, the colorimetric change and non-fluorescent HDBQ-Cu2+ complex reverse to the original HDBQ in the presence of ethylenediamine tetraacetic acid (EDTA). The detection and quantification limit of HDBQ towards the detection of Cu2+ ions is found to be in the µM range, which is much lower than the limit (31.5 µM) recommended by WHO. We have also performed a colorimetric and fluorometric paper-based test strips-based experiment employing HDBQ for real-time on-site detection of Cu2+ ions. Using the reversibility characteristics of HDBQ for the consecutive addition of Cu2+ and EDTA, we have established the INHIBIT molecular logic gate. The present report brings a precise and sensitive probe for the detection of Cu2+ ions in real environmental and biological samples. [ABSTRACT FROM AUTHOR]

Organic luminescent materials having photoluminescence in their solid state have become emerging trends in chemistry, materials science, and biology due to their versatile potential applications. In the present contribution, we have introduced some methylenebis(4,1-phenylene) electron donor–acceptor-based fashionable solid-state fluorescent molecules, MBA, MBB, and MBH, having exciting photoluminescence characteristics in their solid and aggregate states. Interestingly, all probes exhibited a compelling aggregation-induced enhanced emission (AIEE) phenomenon in aqueous media. The mechanistic aspects of solid-state brightness and AIEE behavior are elucidated by diverse spectroscopic, microscopic, and X-ray crystallographic analyses. Employing their intriguing AIEE characteristics, the water-suspended low dimensional particles have been employed as a sensor, demonstrating rapid sensitivity and brilliant selectivity towards the nitro-explosive compound picric acid (PA). The estimated limits of detection (LOD) and quantification (LOQ) reach as low as the μM to nM range in the aqueous medium. The fluorescent paper strip-based test kit experiment has been demonstrated for instant detection of PA through visual examination in the solid state, rendering the protocol quick, cost-effective, and appropriate for on-spot solid-state recognition. [ABSTRACT FROM AUTHOR]

Selectively tracking and quantifying Al3+ ions is a significant concern to the scientific communities. In the present article, an imine‐linkage electron donor‐acceptor system, DSAN, (E)‐5‐(diethylamino)‐2‐(((2‐hydroxy‐4‐nitrophenyl)imino)methyl)phenol has been introduced which shows Al3+ ions endows red light fluorogenicity which could be utilized for sequential and detection of Al3+ ions and picric acid (PA) in both solid and liquid phases. Upon addition of Al3+ ions into the DSAN solution, an orange‐red fluorescence is noticed at 604 nm caused by the formation of Al3+ ions chelated DSAN complex having detection and quantification limit 0.2 μM and 0.62 μM respectively in dimethylformamide (DMF) medium. The complex formation is found to be a 1 : 1 stoichiometric ratio as evident from Job's plot analysis. Also, the binding affinity value is found to be 3.24×104 M−1 demonstrating a high affinity of DSAN towards Al3+ ions. This orange‐red fluorescence of Al3+ ions chelated DSAN complex solution is quenched due to the introduction of PA. A super handy paper‐strips‐based detection tool also been fabricated utilizing DSAN which could be employed to track trace amounts of Al3+ ions in the solid state. The mechanism involved in the detection of Al3+ ions is elucidated by density functional theoretical analysis. [ABSTRACT FROM AUTHOR]

Properly fusing various photophysical processes in a single chromo-fluorophore platform is crucial for developing a highly selective and sensitive chromo-fluorogenic probe to detect various target analytes. Moreover, deciphering the mechanistic approach for understanding the detection mechanism for any target analyte is paramount to facilitate the construction and development of new efficient probes for the selective detection and quantification of different target analytes. In this report, we introduce a phthalimide-based chromo-fluorogenic scaffold, DAID, fusing intramolecular charge transfer (ICT), photoinduced electron transfer (PET), and excited-state intermolecular proton transfer (ESIPT) processes in a single molecular platform. DAID showed turn-on and ratiometric chromo-fluorogenic behaviors toward trivalent transition metal ions Al3+, Fe3+, and Cr3+ in a 20% (v/v) water–DMSO mixture. A visual colorimetric change was detected in the DAID solution by incorporating trivalent transition metal ions. A remarkable turn-on green color emission enhancement was noticed in the DAID solution in the presence of these trivalent ions. The limit of detection and limit of quantification for these trivalent transition metal ions were in the nM range and were superior to those of other methods reported in the literature. Time-resolved fluorescence-lifetime-decay, 1H-NMR titration, and high-resolution mass spectrometric analysis were carried out to elucidate the detailed mechanistic aspects to understand the detection mechanism for the identification of the trivalent transition metal ions employing the DAID probe. The successful demonstration of DAID for practical applications is encouraging for its further application in a variety of fields, fusing and deciphering the various photophysical processes in a single chromo-fluorophore platform, which would enable researchers to develop new efficient probes to selectively detect various target analytes. [ABSTRACT FROM AUTHOR]