A New Schiff Base Based Fluorescent Sensor for Al(III) Based on 2-Hydroxyacetophenone and o-Phenylenediamine.

A simple Schiff base (L) based on 2-hydroxyacetophenone and o-phenylenediamine was prepared which acts as an effective fluorescent sensor for Al3+ with ca. 9.0 fold enhancement in fluorescence intensity and detection limit 10-4.3 M. L can quite clearly distinguish Al3+ over other metal ions Zn2+, Hg2+, Cd2+, Pb2+, Mn2+, Mg2+, Co2+, Ni2+, Cu2+, Ca2+, K+, Li+, Na+ and Fe3+. Cyclic voltammogram and square wave voltammogram of L shows a significant change on interaction with Al3+. Spectroscopic data and DFT calculations confirm 1:1 interaction between L and Al3+ which is reversible with respect to Na2EDTA.

Förster Resonance Energy Transfer-Mediated Globular Protein Sensing Using Polyelectrolyte Complex Nanoparticles.

Polyelectrolyte complex nanoparticles (PEC NPs) are synthesized using two oppositely charged polyelectrolytes, i.e., anionic poly(sodium 4-styrene sulfonate) (PSS) and cationic poly(diallyldimethylammoniumchloride), at molar mixing ratios (n -/n +) of ≈0.4, 0.67, 0.75, and 1.5 by applying consecutive centrifugation to modify the optical property of PSS. However, for n -/n + ≈ 0.75, PEC NPs exhibit a larger blue shift and a specific emission peak occurs at ≈278 nm for the 225 nm excitation. The mechanism of such modification of PSS emission after complex formation is proposed. This specific emission by PEC NPs nearly matches with the optical absorption wavelength of globular proteins. The emission intensity of PEC NPs is therefore quenched in the presence of globular proteins (bovine serum albumin, human serum albumin, lysozyme, and hemoglobin) through resonance energy transfer between the donor (PEC NPs) and acceptor (globular proteins). The spectral overlap integral and the variation of the separation distance from 1.8 to 2.5 nm between the donor and acceptor confirm the resonance energy transfer. Sensing of proteins by the PEC NPs is possible within the detection limit of 5 nM and therefore such PEC NPs can be used as an efficient and promising protein sensing material.

CuI incorporated cobalt ferrite nanoparticles as a magnetically separable catalyst for oxidative amidation reaction.

A Cu-incorporated magnetic nanocatalyst (CoFe2O4@SiO2-SH-CuI) has been developed by immobilizing CuI on the modified surface of CoFe2O4 magnetic nanoparticles. The surface of the silica coated cobalt ferrite magnetic core was first treated with 3-mercaptopropyl triethoxysilane to produce the thiol functionalized nanoparticle CoFe2O4@SiO2-SH. Further treatment of the nanoparticle with CuI produced the desired magnetic nanocatalyst. The versatility of the catalyst has been demonstrated for the synthesis of N-(pyridin-2-yl) benzamide via oxidative amidation of aryl aldehydes with 2-amino pyridine in the presence of an oxidant. The reaction was carried out in DMSO at 80 °C using TBHP (70% aqueous) in the presence of 20 wt% of the catalyst. Notably, the catalyst could be separated from the reaction mixture in the presence of an external magnetic field. During the study, a new compound N-(pyridin-2-yl)anthracene-2-carboxamide has been synthesized and its turn on fluorescence sensing properties towards various metal ions have been studied. Fluorescence experiments and theoretical studies indicated that the newly synthesized carboxamide molecule can be used for fluorescence sensing of the Hg2+ ion in aqueous solution.