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West Bengal, India

Sen B.,University of Burdwan | Mukherjee M.,University of Burdwan | Pal S.,University of Burdwan | Dhara K.,Sambhu Nath College | And 3 more authors.
RSC Advances | Year: 2014

A new highly sensitive and selective Hg(ii) probe, 2-(rhodamine-b- hydrazido)-N-(quinolin-8-yl)acetamide (L1) was developed and characterized. L1 specifically binds to Hg(ii) in the presence of a large excess of other competing ions with visually observable changes in both electronic and fluorescence spectral behaviour to make possible the naked eye detection of Hg(ii) at a very low level (up to 4.5 × 10-7 M) through a fluorescence resonance energy transfer (FRET) process in HEPES buffer (1 mM, pH 7.4; 2% EtOH) at 25 °C. The theoretical and experimental kinetic study also support the binding of Hg(ii) ion to induce the opening of the spirolactam ring in L1 for enabling the FRET process. Further studies reveal that the selective dissociation of the L-Hg complex in the presence of sulphide anions to restore the native structure of L1 is also useful in the detection of sulfide anions with a detection limit of a submicromolar range in the same medium of HEPES buffer (1 mM, pH 7.4; 2% EtOH) at 25 °C. L1 could be employed as a FRET based time dependent reversible chemosensor for imaging Hg(ii) in living cells and whole bodies, and also could be used as an imaging probe for the detection of sulfide anions in HeLa cells. This journal is © the Partner Organisations 2014. Source


Pal S.,University of Burdwan | Sen B.,University of Burdwan | Mukherjee M.,University of Burdwan | Dhara K.,Sambhu Nath College | And 3 more authors.
Analyst | Year: 2014

The effect of substituents on FRET in two newly designed rhodamine-based Hg2+ ion selective chemosensors (L1 and L2) has been explored by a systematic experimental and theoretical study. Comparison of these sensors in the analytical study and imaging of Hg2+ ions in living cells has also been included. © The Royal Society of Chemistry 2014. Source


Sen S.,University of Burdwan | Sarkar S.,University of Burdwan | Chattopadhyay B.,Indian Association for The Cultivation of Science | Moirangthem A.,University of Burdwan | And 3 more authors.
Analyst | Year: 2012

A newly designed probe, 6-thiophen-2-yl-5,6-dihydrobenzo[4,5]imidazo-[1,2- c] quinazoline (HL 1) behaves as a highly selective ratiometric fluorescent sensor for Fe 2+ at pH 4.0-5.0 and Fe 3+ at pH 6.5-8.0 in acetonitrile-HEPES buffer (1/4) (v/v) medium. A decrease in fluorescence at 412 nm and increase in fluorescence at 472 nm with an isoemissive point at 436 nm with the addition of Fe 2+ salt solution is due to the formation of mononuclear Fe 2+ complex [Fe II(HL)(ClO 4) 2(CH 3CN) 2] (1) in acetonitrile-HEPES buffer (100 mM, 1/4, v/v) at pH 4.5 and a decrease in fluorescence at 412 nm and increase in fluorescence at 482 nm with an isoemissive point at 445 nm during titration by Fe 3+ salt due to the formation of binary Fe 3+ complex, [Fe III(L) 2(ClO 4)(H 2O)] (2) with co-solvent at biological pH 7.4 have been established. Binding constants (K a) in the solution state were calculated to be 3.88 × 10 5 M -1 for Fe 2+ and 0.21 × 10 3 M -1/2 for Fe 3+ and ratiometric detection limits for Fe 2+ and Fe 3+ were found to be 2.0 μM and 3.5 μM, respectively. The probe is a "naked eye" chemosensor for two states of iron. Theoretical calculations were studied to establish the configurations of probe-iron complexes. The sensor is efficient for detecting Fe 3+in vitro by developing a good image of the biological organelles. © 2012 The Royal Society of Chemistry. Source


Dhara K.,Sambhu Nath College | Saha U.C.,University of Burdwan | Dan A.,Jadavpur University | Sarkar S.,University of Burdwan | And 2 more authors.
Chemical Communications | Year: 2010

{[Cu2(H2L)(OH)(H2O)]·(ClO 4)2(H2O)} (1) serves as a selective azide ion fluorescent sensor in aqueous medium. 1 binds with N3- to give [Cu6(HL)2(μ1,1-N3) 6] (2) which imposes rigidity and decreases the non-radiative decay of the excited state to give rise to fluorescent enhancement. 1 is highly selective over other various anions in aqueous medium. © 2010 The Royal Society of Chemistry. Source


Saha U.C.,University of Burdwan | Chattopadhyay B.,Indian Association for The Cultivation of Science | Dhara K.,Sambhu Nath College | Mandal S.K.,Kalyani University | And 5 more authors.
Inorganic Chemistry | Year: 2011

A new 2,6-bis(5,6-dihydrobenzo[4,5]imidazo[1,2-c]quinazolin-6-yl)-4- methylphenol (1) serves as a highly selective and sensitive fluorescent probe for Zn2+ in a HEPES buffer (50 mM, DMSO:water = 1:9 (v/v), pH = 7.2) at 25 °C. The increase in fluorescence in the presence of Zn2+ is accounted for by the formation of dinuclear Zn2+ complex [Zn 2(C35H25N6O)(OH)(NO 3)2(H2O)] (2), characterized by X-ray crystallography. The fluorescence quantum yield of the chemosensor 1 is only 0.019, and it increases more than 12-fold (0.237) in the presence of 2 equiv of the zinc ion. Interestingly, the introduction of other metal ions causes the fluorescence intensity to be either unchanged or weakened. By incubation of cultured living cells (A375 and HT-29) with the chemosensor 1, intracellular Zn2+ concentrations could be monitored through selective fluorescence chemosensing. © 2011 American Chemical Society. Source

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