An aggregation-induced emission active vitamin B6 cofactor derivative: application in pH sensing and detection of latent fingerprints.

Aggregation-induced emission (AIE) properties of an easy-to-prepare and structurally planar Schiff base derivative of the vitamin B6 cofactor pyridoxal (L) were investigated in DMSO-H2O mixed solvents. Compound L showed weak fluorescence (λem = 425 nm) in pure DMSO, but increasing the fraction of water in DMSO resulted in a significant fluorescence enhancement at 575 nm due to the restriction of intramolecular rotation (RIR) of L upon aggregation. SEM analyses revealed the formation of hairy micelle-like or needle-shaped self-assemblies/aggregates of L. The DFT calculations were performed to examine the tendency of L to form self-aggregates, and the results indicate the formation of several intramolecular non-covalent interactions that energetically favored the self-aggregation of L. The pH sensing study revealed that the red-emission of aggregates of L between pH 5.9 and 9.0 turned into green emission at the basic pH with the estimated pKa values of 9.39 and 10.22. Further, the aggregates of L were applied for the visualization of latent fingerprints (LFPs) over a non-porous glass slide.

A multi-analyte selective dansyl derivative for the fluorescence detection of Cu(ii) and cysteine.

A new multi-analyte selective fluorescence chemosensor DA was synthesized by a simple one pot reaction between dansyl chloride and 2-aminobenzohydrazide in the presence of a base. In DMSO : H2O (1 : 1, v/v), the fluorescence of DA at 483 nm was blue shifted and enhanced at 474 nm along with a new shoulder peak appearing at 411 nm selectively in the presence of Cu2+ among the other tested metal ions due to the chelation enhanced fluorescence (CHEF) effect. Without any noticeable interference from potentially competitive metal ions, sensor DA can detect Cu2+ down to 9.79 × 10-7 M. Sensor DA gives satisfactory results for the quantification of Cu2+ in real water samples. Sequentially, the resultant in situ generated DA-Cu2+ complex is applied for the selective sensing of bioactive cysteine with a detection limit down to 1.76 × 10-6 M.