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A multi responsive fluorescent probe, N',2-bis(E-4-(diethylamino)-2-hydroxybenzylidene)hydrazine-1-carbothiohydrazideV(H2L) has been synthesized through one step condensation method. Probe, H2L shows 'turn-on' dual sensing properties towards Cd2+ and H2AsO4− at two distinct wavelength. The probe (H2L) is spectroscopically characterized and the chemo-sensing mechanism has been demonstrated through 1H NMR, absorption, steady state and time resolved emission study. The most promising advantage of the probe is its application in the one-pot detection of Cd2+ (λem = 462 nm) and H2AsO4−(λem = 492 nm) where intense emission appears at two different wavelengths and the observed limit of detection (LOD) of H2L towards Cd2+ and H2AsO4− are 2.67 × 10–8 M and 5.14 × 10–6 M respectively. Further the 'turn-on' emission property of H2L towards Cd2+ is applied to construct INHIBIT logic gate. [ABSTRACT FROM AUTHOR]

A simple antipyrine based fluorescent probe, 4-[(2-hydroxy-3-methoxy-benzylidene)-amino]-1,5-dimethyl-2-phenyl-1,2-dihydro-pyrazol-3-one (OVAP), has been successfully synthesized using a one-step condensation method. It exhibits dual sensing properties toward Al3+ and Zn2+ in the presence of other relevant metal ions and also displays novel aggregation induced emission enhancement (AIEE) characteristics in its aggregated/solid state. Aggregated OVAP microstructures with interesting morphologies have been synthesized using SDS as a morphology directing agent. Morphologies of the particles are characterized using optical microscopy. Photophysical properties of the as-synthesized OVAP hydrosol are studied using UV–Vis absorption, steady state and time resolved fluorescence spectroscopy. The 'turn on' luminescence property of OVAP is used for the selective detection of trace amounts of Al3+ and Zn2+ and a significant turn on fluorescence enhancement over ∼100-fold is triggered via chelation-enhanced fluorescence (CHEF) through complex formation. The 1 : 1 stoichiometry of each sensor metal ion complex is observed from Job's plot based on UV-Vis absorption titration. The LODs for Al3+ and Zn2+ are found to be 1.05 nM and 2.35 nM, respectively. Notably, the sensor, OVAP, is further demonstrated using a molecular INHIBIT logic gate. [ABSTRACT FROM AUTHOR]

Rhodamine and its derivatives have been widely used in designing fluorescent ‘turn on’ cation sensors, while very few rhodamine based fluorescent probes have been reported to date for the detection of anions in water. In this article, a new rhodamine based facile and convenient ‘turn on’ fluorescent chemosensor 2-(2-(1-hydroxynaphthyllideneamino)ethyl)-3′,6′-bis(diethylamino)spiro [isoindoline-1,9′-xanthen]-3-one (RAHN) has been developed by Schiff base condensation and characterized by standard techniques for selective detection of bisulfite anions in water. A faintly yellow colour solution of RAHN turns pink upon addition of bisulfite. Again RAHN is weakly emissive in solution but becomes strongly emissive on addition of bisulfite and the emission intensity increases gradually in the presence of increasing concentration of bisulfite. No other analytes can cause emission enhancement of RAHN, suggesting the selectivity of the probe towards bisulfite. The detection limit for bisulfite was found to be ∼0.4 μM. [ABSTRACT FROM AUTHOR]

An Anthracene based fluorescent probe, 1-(Anthracen-2-yliminomethyl)-napthalen-2-ol (AIN), was synthesized via simple one-pot reaction from inexpensive reagents. Intriguingly, it exhibited novel AIE characteristics in H 2 O-THF mixtures at high water content. Size and growth process of particles in different volume percentage of water and THF mixtures were investigated using TRPL, DLS, SEM and optical microscope. The fluorescent aggregates exhibited distinct Hg 2+ -selective “on-off” type fluorescence switching upon binding. Additionally, the fluorescence quenching showed a linear correlation in the Hg 2+ concentration range from 0.3 to 3.6 μM and the limit of detection was estimated as low as ∼3 ppb. The drastic decrease in emission intensity of AIN aggregates was observed in the presence of mercury ions via a complex interplay through the ground state complexation between AIN and Hg 2+ ions and external heavy atom induced perturbation by Hg 2+ ions to the excited states of the AIN. A large Stern–Volmer quenching constant was estimated to be 2.54 × 10 5  M −1 . The proposed analytical system with clear AIE characteristics demonstrates a potential outlook for the on-site visual detection of Hg 2+ in paper strips. Finally, the sensory probe was also applied to determine the concentration of Hg 2+ in real water samples to demonstrate its practical applications. [ABSTRACT FROM AUTHOR]

• A novel Phenolphthalein based probe has been synthesized. • It has been used to detect trace amount of Zn2+ and Al3+ ions in water. • Turn-on emission property of the probe is utilized to fabricate molecular INHIBIT logic gate. • It also displays the novel AIE phenomenon. A phenolphthalein based fluorescent probe, 3, 3-Bis-[4-hydroxy-3-(pyridine-2-yliminomethyl)-phenyl]-3H-isobenzofu ran-1-one (PHPA), has been synthesized. It exhibits high sensitivity and selectivity towards Zn2+ and Al3+over other relevant water soluble metal ions and also display novel aggregation-induced emission enhancement (AIEE) characteristics. Both complexes followed 2:1 metal to ligand stoichiometry calculated from Job's plot. A significant fluorescence enhancement with a turn-on ratio of ∼94-fold was triggered via chelation-enhanced fluorescence through sensor complex (Zn2+-PHPA) and∼245-fold increase for sensor complex Al3+-PHPA. In addition, the binding sites of both sensor complexes (PHPA-Zn2+ & PHPA-Al3+) have been confirmed through 1H NMR, 13C NMR, FT-IR and ESI-MS spectroscopy. The detection limits is found to be 8.5 × 10−8 M for complex PHPA-Zn2+ and 1.88 × 10−7 M for complex PHPA-Al3+, respectively. The reversible detection of Zn2+ and Al3+ complexes in methanol are also ascertained in the presence of Na 2 EDTA, enabling the construction of a molecular Logic gate. An advanced-level NOT-AND-OR logic gate has been constructed from a different chemical combinational input and emission output. Human serum albumin (HSA) binding studies were performed by various spectroscopic methods to expound possible bioactivity of PHPA. Interestingly; the AIEE properties of PHPA may advance its impact as studied in methanol-water mixtures with high water contents. To gain the knowledge into the AIEE mechanism of the PHPA, the size and growth process of particles in different volume percentage of water and methanol mixture were studied using time-resolved photoluminescence, dynamic light scattering, and optical microscopic image. The probe PHPA has also been used to detect intracellular Zn2+ ion in A549 cells. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] • A multianalyte selective fluorescent probe derived from rhodamine and phenolphthalein is synthesized. • It showed highly selective and sensitive response towards Cu2+, Fe3+ colorimetrically and Al3+, Cr3+ fluorimetrically. • Detection limits for Cu2+, Fe3+, Al3+ and Cr3+ are 1.21 µM, 1.75 µM, 2.27 µM, and 1.29 µM, respectively. • Test paper strips of the probe were prepared for rapid and selective detection for four analytes. • It is also used as a bio-imaging fluorescent probe against A549 cancer cell line. In this study, a novel rhodamine-phenolphthalein derivative (RBPF) was designed, synthesized, and characterized. RBPF exhibited the selective and sensitive colorimetric detection of Cu2+ and Fe3+ and fluorometric detection of Al3+ and Cr3+, thus functioning as a multiple-channel probe in MeOH-H 2 O (v/v = 9/1, 5 µM HEPES, pH 7.2) in the presence of other cations. A strong enhancement of the absorbance at around 555 nm was observed for the four mentioned cations. In contrast, in the presence of Al3+ and Cr3+, emissions were intensified within the red region of the spectra (583 and 586 nm, respectively). The RBPF sensor was found to bind to the metal ions at a 1:2 stoichiometric ratio. The proposed mechanism for the observed sensing behavior is the opening of the spirolactam ring of the rhodamine core in the presence of the four mentioned metal ions. The detection limits for Cu2+, Fe3+, Al3+, and Cr3+ were calculated to be 1.21 µM, 1.75 µM, 2.27 µM, and 1.29 µM, respectively. To test the practical use of the probe, TLC-based paper strips were fabricated. In addition, cell-imaging analysis of Al3+ and Cr3+ ions in the A549 cancer cell line produced promising concentration and time-dependent detection results. [ABSTRACT FROM AUTHOR]