Ajoy Kumar Pramanik

Coumarin based dual switching fluorescent ‘turn-on’ chemosensor for selective detection of Zn2+ and HSO4−: an experimental and theoretical study

A highly sensitive and selective coumarin based fluorescence ‘turn-on’ chemosensor (HL) for the efficient detection of Zn2+ and HSO4− over other ions has been developed. Theoretical study interprets the electronic structure and sensing properties of the developed HL.

A novel coumarin based molecular switch for dual sensing of Zn(II) and Cu(II)

An efficient coumarin based molecular switch for the dual sensing of two environmentally as well as biologically important cations Zn2+ and Cu2+ has been synthesized. The receptor H2L shows about 6 fold enhancement in fluorescence intensity upon the addition of Zn2+ and also exhibits quenching of emission intensity upon the addition of Cu2+ without interference of other metal ions present in solution. In the case of other metal ions no significant change in the emission intensity is observed. H2L presents a tunable system comprising of two INHIBIT logic gates with Zn2+ and Cu2+ or Zn2+ and EDTA as chemical inputs by monitoring the emission mode. An IMPLICATION logic gate is obtained with Cu2+ and EDTA as chemical inputs and emission as the output mode.

Benzimidazole based ratiometric and colourimetric chemosensor for Ni(II).

A highly sensitive and selective benzimidazole based colourimetric chemosensor (HL) for the efficient detection of Ni(2+) has been reported. The synthesized chemosensor HL is highly efficient in detecting Ni(2+) over other metal ions that commonly coexist with Ni(2+) in physiological and environmental samples. HL also shows distinct color change from orange yellow to blue visible under the naked eye due to specific binding with Ni(2+). This color change corresponds to a large red shift of the UV-Vis spectrum from 403 nm to 600 nm with a distinct isosbestic point at around 500 nm. The cation sensing property of the receptor HL has been examined by UV-Vis spectroscopy. Electronic structure of the HL-Ni(2+) complex and sensing mechanism has been interpreted by DFT and TDDFT calculations.

Cu(II) complexes of a new tetradentate N2SO donor: synthesis, structure, electrochemistry, and DFT computation

Cu(II) complexes having distorted square pyramidal geometry with N2SO donor azo–thioether ligand, [Cu(L)X] (X = Cl (1) and Br (2)), have been synthesized and characterized. The geometries of the complexes are confirmed by single crystal X-ray analysis. The complexes form supramolecular 1D chains by intermolecular H-bonding and π–π interaction between the pyridines. Spectral and electrochemical properties have been studied. Electronic structure and spectral properties are explained by DFT and TDDFT analysis.

Synthesis, crystal structure and spectral properties of 2-((1-Methyl-2-benzimidazolyl)azo)-p-cresol: An experimental and theoretical study

2-[(1-Methyl-2-benzimidazolyl)azo]-p-cresol (HL), containing phenolic-OH function and benzimidazole moiety has been synthesized and characterized. The chemical, electronic structure and photophysical properties have been studied by spectroscopic analysis abetted with DFT and TDDFT calculations. The change in electronic spectra of HL by titration with aq. NaOH is studied and well supported by TDDFT calculations. The structure is confirmed by single crystal X-ray study. In the unit cell, two HL molecules are H-bonded with H2O molecule and forms dimmeric structure. The molecule forms 2D-supramolecular structure by inter-molecular H-bonding and π-π interactions.