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A designed aggregation-induced emission enhancement (AIEE) active fluorescence probe 2,3-Bis-[(2-hydroxy-napthalen-1-ylmethylene)-amino]-but-2-enedinitrile (L) was synthesized via one step condensation method. The probe shows swift sensitivity and selectivity toward Al3+over other relevant metal ions and also exhibits significant AIEE phenomena in methanol/water mixture. Significant enhancement of fluorescence intensity is triggered via chelation-enhanced fluorescence through complex (Al3+-L) formation. A 2:1 metal to ligand ratio is observed from Job's plot based on UV − Vis absorption titration and detection limit (LOD) is found as low as 31.14 nM. Moreover, 1H NMR titrations and fluorescence reversibility by adding Al3+ and EDTA sequentially had been performed to establish the binding site of sensor complex (Al3+-L). Time-resolved photoluminescence, dynamic light scattering, optical microscopy, and on-site visualization studies have been performed to understand the AIEE mechanism of L in different volume percentage of water and methanol mixture. An INHIBIT molecular logic gate has been constructed utilizing the fluorescence behavior of the probe, L in presence of Al3+ and strong chelating ligand EDTA. [ABSTRACT FROM AUTHOR]

Fluorescent chemosensor, 3-(Anthracen-2-yliminomethyl)-benzene-1,2-diol (ANB) has been synthesized by one-step condensation of 2-aminoanthracene and 2,3-dihydroxybenzaldehyde and characterized using 1H-NMR, FT-IR and Mass spectroscopic techniques. The probe ANB was found to be an efficient 'turn-on' fluorescence chemosensor for the selective detection of Al3+ ion over other metal ions in an aqueous solution. The chemosensor exhibits ~ 27-fold enhancement of emission intensity in presence of Al3+ ion. Fluorescence quantum values for ANB and (Al3+-ANB)-complex are 0.004 and 0.097, respectively. In addition, the binding constant and the limit of detection were found to be 1.22 × 104 M−1 and 0.391 µM, respectively. The chemosensor ANB binds to Al3+ ions in 2:1 stoichiometric ratio which was supported by Job's plot, 1H-NMR titration and florescence titration. Fluorescence reversibility of the sensor complex was well established by adding EDTA in the same condition and a molecular INHIBIT logic gate was fabricated using this reversible nature of the sensor complex. Additionally, the chemosensor ANB shows a novel aggregation-induced enhanced emission phenomenon, where the aggregate hydrosol of ANB shows enhance emission intensity. [ABSTRACT FROM AUTHOR]

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 Fluorescent chemosensor based on pyrene scaffold, 5-diethylamino-2-(pyren-1-yliminomethyl)-phenol (PDS) is synthesized using condensation method. It displays novel aggregation-induced emission (AIE) phenomena in its aggregated/solid state. The AIE characteristic of PDS is studied in CH3CN/H2O mixtures at different volume percentage of water and morphology of the aggregated particles are investigated by DLS and optical fluorescence microscopic study. The probe is aggregated into ordered one-dimensional (1-D) rod like microcrystals and exhibit high efficiency of solid-state emission with green colour. By taking advantage of its interesting AIE feature, the aggregated hydrosol has been utilized as 'off–on' type fluorescence switching chemosensor with superb selectivity and sensitivity towards Cu2+ions and the limit of detection (LOD) was calculated as low as 6.3 µM. A high Stern–Volmer quenching constant was estimated to be 2.88 × 105 M−1. The proposed chemosensor with AIE feature reveals a prospective view for the on-site visual recognition of Cu2+ ions in fluorescent paper strips and the synthesized probe is also exploited to find out the concentration of Cu2+ions in real water samples. [ABSTRACT FROM AUTHOR]

1-(Pyridin-2-yl-hydrazonomethyl)-naphthalen-2-ol (PNOH) is a naphthalene-based fluorescence dual chemo-sensor for Al3+ and Zn2+. The probe (PNOH) is spectroscopically characterised and the chemo-sensing mechanism has been demonstrated through 1H NMR, absorption and both steady state and time resolved fluorescence study. The 'turn-on' luminescence property of PNOH is used for the selective detection of trace amount of Al3+and Zn2+via chelation enhanced fluorescence (CHEF) through complex formation. The 1:1 stoichiometry of each sensor-metal complex is observed from Job's plot based on UV-Vis titration. Most promising advantage of the probe (PNOH) is its application in the one-pot detection of Al3+ (λem- 460 nm) and Zn2+ (λem- 510 nm) exciting at same wavelength (λex- 420 nm) while high intense emission appears at two different wavelengths. Limit of detection (LOD) of PNOH towards Al3+ & Zn2+ are found to be 60 nM & 365 nM respectively. Real water sample analysis has also been demonstrated by using the probe PNOH. [ABSTRACT FROM AUTHOR]

A 2,6-diformyl-p-cresol (DFC)-4-amino antipyrine (AP) based dual signaling fluorescent Schiff base ligand (DFCAP) is found to exhibit colorimetric and fluorescence turn on selective sensing towards metal ions, Zn2+ and Al3+. It also exhibits a significant aggregation induced emission (AIE) phenomenon by controlling the water–THF solvent ratio which provides robust green emissive fluorogenic aggregates with well-defined morphologies. Turn-on fluorescence enhancements as high as 195 fold and 168 fold in methanol for Al3+ and Zn2+ at 480 nm and 508 nm, respectively, were noticed. The binding constants and stoichiometry determined from the fluorescence titration data are K = 7.63 × 104 M−1 and 3.42 × 104 M−1 and 1 : 1 complexation for both Al3+ and Zn2+ respectively, supported by Job's method. DFCAP shows high sensitivity towards the detection of Zn2+ and Al3+ ions with very low detection limit values of ca. ∼21 nM and 30 nM respectively. Besides by applying its attractive AIE feature, the green emissive hydrosol functions as a good chemosensor with high sensitivity for a selected explosive TNP through ground state complexation with a LOD value of ca. ∼1.74 μM and especially a high Stern–Volmer quenching constant of ca. ∼4.14 × 105 M−1. For instant 'naked eye' response for the trace detection of TNP in the solution state, we fabricated a simple paper strip that could detect TNP on-site in a fast, inexpensive and simple way. [ABSTRACT FROM AUTHOR]