Synthesis and physicochemical characterization of Schiff bases used as optical sensor for metals detection in water

Highly fluorescent new Schiff base chemosensors for the selective detection of Cu(II) and their application in bioimaging technique

A new symmetrical and a new unsymmetrical Schiff bases are synthesized by condensing 1-(2,4-dihydroxyphenyl)ethanone with, Naphthalen-1-amine and Naphthalen-1,8-diamine under solvent free condition and characterized by IR, UV-visible, 1H NMR, 13C NMR and mass spectral studies. Cation recognizing potentiality of both the Schiff bases is explored-of the Schiff base 4-(1-(naphthalen-1-ylimino)ethyl)benzene-1,3-diol (NEBD) in aqueous methanolic medium and of Schiff base 4,4'-((naphthalene-1,8-diylbis(azanylylidene))bis(ethan-1-yl-1-ylidene))bis(benzene-1,3-diol) (NDBD) is scrutinized in aqueous ACN medium through dual modes namely absorption and emission methods. Both the Schiff base sensors are found to detect Cu(II) ion selectively. The detection occurs in an off-on mode (increase of emission intensity of the Schiff base in the presence of Cu(II) ion) and on-off mode (decrease of emission intensity of the Schiff base in the presence of Cu(II) ion) for the Schiff bases NEBD and NDBD respectively. For the Schiff base NEBD LOD for Cu(II) ion is 1.528 × 10-6 M and for NDBD it is 2.871 × 10-7 M. The sensing property is applied in bioimaging technique for the detection of human cancer cells HeLa. Both the Schiff bases are screened for their antimicrobial activities. Schiff base NEBD is found to be more potential than the standard drug amphotericin B towards Aspergillus niger. Regarding Schiff base NDBD, it is as potential as the standard drug towards all the organisms studied.

Mechanochemical Synthesis of Organic Dyes and Fluorophores

The syntheses of dyes and fluorophores have significant commercial importance. In recent years, mechanochemistry has emerged as a green and sustainable alternative for the synthesis of conventional dyes, new fluorophores, and also synthetic modification of known dyes for their use as chemosensors. The dyestuffs based on BODIPYs, rhodamine, fluorescein, perylenedimides, coumarins, benzothiazoles, etc. were synthesized or derivatized by grinding or milling. The synopsis aims to pay key attention to their synthesis and the applications as chemosensors will be briefly covered.