Barnali Naskar

Syntheses, crystal structures, spectral studies, and DFT calculations of two new square planar Ni(II) complexes derived from pyridoxal-based Schiff base ligands

Two new complexes based on a Schiff base derived from pyridoxal N,N-dimethylethylenediamine (HL1) and N,N-diethylethylenediamine (HL2), [Ni(L1)SCN] (1) and [Ni(L2)SCN] (2), have been synthesized and structurally characterized by single-crystal X-ray diffraction along with other physical techniques, including elemental analyses, IR spectra, cyclic voltammetry, UV–vis, and luminescence studies. X-ray studies suggest that in both the complexes nickel lies in a slightly distorted square planar environment occupied by the tridentate ONN ligand and an isothiocyanate moiety. Density functional theory computations have been carried out to characterize the complexes. Two new square planar Ni(II) complexes, [Ni(L1)SCN] (1) and [Ni(L2)SCN] (2) are synthesized from pyridoxal-based Schiff base ligands and structurally characterized. DFT calculations are also done to establish their optimized electronic structures.

A highly selective “ON–OFF” probe for colorimetric and fluorometric sensing of Cu2+ in water

We present herein a diformyl phenol based probe, 3-({3-[2,3-dihydroxy-propylimino-methyl]-2-hydroxy-5-methyl-benzylidene}-amino)-propane-1,2-diol (H5dpm), as a colorimetric and fluorometric chemosensor for selective detection of Cu2+ in aqueous solution under physiological conditions. This simple system produces a colorimetric change enabling naked eye detection as well as on–off fluorescence response towards Cu2+ in an aqueous medium with a detection limit of 11.2 nM. To further demonstrate the utility of H5dpm, we next explored the application of H5dpm for imaging Cu2+ in Vero cells. The attractive imaging properties of the H5dpm probe will open up avenues for molecular imaging and biomedical applications.

A new fluorescence turn-on chemosensor for nanomolar detection of Al3+ constructed from a pyridine–pyrazole system

Herein, a new probe, 5-methyl-1-pyridin-2-yl-1H-pyrazole-3-carboxylic acid (1-pyridin-2-yl-ethylidene)-hydrazide (Hmppc), bearing a pyridine–pyrazole moiety, was synthesized, which offered potential for chemical sensing of Al3+. Investigations of the fluorescence behaviour of Hmppc in DMSO/H2O (2 : 8, v/v) solution under biologically relevant conditions in HEPES buffer (pH = 7.4) displayed a dramatic switch-on response to Al3+ as a result of chelation-induced enhanced fluorescence (CHEF). Detailed experimental studies reveal that Hmppc can detect Al3+ in solution with high sensitivity and selectivity, having a detection limit of 1.2 nM. Furthermore, to demonstrate the analytical potential of Hmppc, we validated our sensing system as a naked eye detector for Al3+. Interestingly, bioimaging studies on HepG2 cells demonstrated that Hmppc responded selectively towards Al3+, allowing real time detection of Al3+ in living cells.