Sushil K. Dwivedi

Synthesis and application of a new class of D–π–A type charge transfer probe containing imidazole – naphthalene units for detection of F− and CO2

A new class of D–π–A type charge transfer probe, 3 and 4, containing imidazole – naphthalene moieties as donor and acceptor, respectively, has been synthesized via a Suzuki coupling reaction. Probe 3, upon interaction with different classes of anions, showed high selectivity toward fluoride with a detection sensitivity of 4 ppb (0.22 μM). The in situ generated imidazolyl ion (3 + F−) enables the detection of CO2 with the restoration of the original absorption and emission properties of 3. The mode of interaction has been confirmed by 1H NMR and DFT studies which suggested the deprotonation of the –NH fragment of the imidazolyl unit in the presence of F−.

Excited state proton transfer (ESIPT) based molecular probe to sense F− and CN− anions through a fluorescence “turn-on” response

A new chromogenic and fluorogenic hydrazone derivative of aminobenzthiazole and 2-hydroxy-1-naphthaldehyde was developed as a sensitive molecular probe, NTS, for the detection of fluoride (F−) and cyanide (CN−) anions. The photophysical and sensing behaviors of the probe, NTS, were investigated by absorption and fluorescence studies. Interestingly, in partial aqueous medium (DMSO/H2O 9 : 1, v/v), the probe shows a selective fluorescence “turn-on” response to both the anions. An excited state proton transfer mechanism (ESPT) has been followed theoretically and by means of spectroscopic studies. The immediate visualized color change of NTS with the respective anions on test paper strips and silica coated slides suggested the applicability of the probe to sense dual anions on solid surfaces and in solution as a chemosensor for fluoride and as a chemodosimeter for cyanide anions, respectively.

Design and Synthesis of Some Imidazolyl Derivatives: Photophysical Studies and Application in the Detection of Anions

A fluorescent probe based on dicyanovinylphenanthroimidazole (DCPPI) has been designed and synthesized and its potential application to recognize F and CN ions via different channels has been tested in different medium. DCPPI shows intramolecular charge transfer process and exhibit ratiometric response toward F and CN ions. The change in physicochemical properties of DCPPI in the presence of cyanide can be attributed to the formation of Michael type adduct, DCPPIA whereas both F and CN ions have shown affinities to interact with NH fragment of imidazolyl unit under the condition. The possible mode of interaction has been confirmed by absorption, emission, NMR and ESI-MS spectral data analysis.