Pyrene Based Schiff Base for Cascade Fluorescent "On-Off" Detection of Aluminium(III) and Fluoride Ions and its Applications in Live Cells Imaging.

An easy-to-prepare pyrene-based Schiff base PNZ was synthesized by condensing equimolar amount of 1-pyrenebutyric hydrazide with 2-hydroxy-naphthaldehyde, and employed as a fluorescent chemosensor for in-situ cascade detection of aluminium (Al) and fluoride (F) ions. In DMSO:HO (1 : 1, v/v), the weakly emissive PNZ showed a significant fluorescence enhancement at 455 nm selectively upon the addition of Al due to the complexation-induced formation of a pyrene excimer. Schiff base PNZ and Al formed a complex in 2 : 1 binding ratio with the estimated binding constants of K=9826.

Aggregation-Induced Emission Active Benzidine-Pyridoxal Derived Scaffold for Detecting Fe and pH.

Present work introduces an aggregation-induced emission (AIE) active Schiff base 4,4'-((1E,1'E)-([1,1'-biphenyl]-4,4'-diylbis(azaneylylidene))bis(methaneylylidene))bis(5-(hydroxymethyl)-2-methylpyridin-3-ol) (BNPY). Schiff base BNPY was synthesized by reacting benzidine with pyridoxal. The non-fluorescent BNPY in freely soluble DMSO medium showed a significant fluorescence enhancement at 563 nm (λ = 400 nm) upon increasing the water fraction (fw) in DMSO above 60% due to the restriction of intramolecular rotation upon the aggregation of BNPY.

Improving Copper(II) Sensitivity by Combined use of AIEE Active and Inactive Schiff Bases.

An aggregation-induced emission enhancement (AIEE) active Schiff base PNN was synthesized by condensing benzidine with 2-hydroxynaphthaldehyde. The green-fluorescent PNN (λ = 510 nm) in DMF turned to yellow-fluorescent PNN (λ = 557 nm) upon increasing the fractions of HEPES buffer (10 mM, pH 7.4) above 40%.

'AIE + ESIPT' Active 2-hydroxy-naphthalene Hydrazone for the Fluorescence Turn-on Sensing of Al.

The aggregation-induced emission (AIE) behaviour of an easy-to-prepare Schiff base 2-hydroxy-naphthalene hydrazone (L) was explored in mixed DMSO/HEPES medium by selecting DMSO as a good solvent, whereas HEPES buffer (HO, 10 mM, pH 7.4) as a poor solvent. The weakly fluorescent L in pure DMSO showed a fluorescence enhancement at 532 nm upon increasing the fraction of HEPES above 70% because of the self-aggregation of L and excited state intramolecular proton transfer (ESIPT) process.