Browsing by Author "Ramesh C. Gupta"

Now showing 1 - 15 of 15

A Chemodosimeter Exhibiting Fluorescence “Turn-On” Response to Detect Copper(II) Ions: Cell Imaging and Logic Function
(Wiley-Blackwell, 2019) Ramesh C. Gupta; Sushil K. Dwivedi; Syed S. Razi; Priya Singh; Biplob Koch; Arvind Misra
In the present work the photophysical properties of a chemodosimeter, 2-[4’-(N,N’-dimethylamino-biphenyl)-4-methylene]-iminophenol, 5 has been explored to recognize Cu 2+ ion selectively through naked eye sensitive fluorescence “turn-on” response. The observed fluorescence enhancement (∼58 fold) and rise in quantum yield (34%) with rapid response time is attributed to the hydrolysis of aldimine function in the presence of copper. The cell imaging studies showed that chemodosimeter, 5 is well-suited to detect Cu 2+ intracellularly. Additionally, the “Off–On” switching behavior of 5 has been utilized to mimic the function of a sequential logic circuit at molecular level. © 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
A coumarin-derived useful scaffold exhibiting Cu2+ induced fluorescence quenching and fluoride sensing (On-Off-On) via copper displacement approach
(Elsevier, 2015) Syed S. Razi; Priyanka Srivastava; Rashid Ali; Ramesh C. Gupta; Sushil K. Dwivedi; Arvind Misra
Some coumarin-thiazole based molecular scaffolds/probes have been designed and synthesized. The photophysical behavior of probes and their interaction with metal ions and anions have been examined through the absorption and fluorescence spectroscopy in different medium. Probe 6 showed good optical behavior in acetonitrile and upon interaction with different metal ions and anions displayed strong fluorescence quenching (∼87%; switch-Off) with Cu2+ while remained silent toward the tested anions, respectively. Moreover, 6-Cu2+ ensemble when tested toward different anions only fluoride (F-) enable copper displacement (as CuF2) and led to fluorescence enhancement (switched-On). Probe 6 has selectively detected Cu2+ in real water sample, and on cellulose paper strips. Additionally, the naked eye sensitive "On-Off-On" sensing behavior of 6 mimics the function of a sequential logic circuit at molecular level. The FTIR, NMR (1H and 13C), and ESI-MS spectroscopy supported the proposed mechanism of interaction. © 2014 Elsevier B.V. All rights reserved.
A new D-π-A type intramolecular charge transfer Dyad System to detect F-: Anion induced CO2 sensing
(Elsevier B.V., 2016) Syed S. Razi; Ramesh C. Gupta; Rashid Ali; Sushil K. Dwivedi; Priyanka Srivastava; Arvind Misra
A new D-π-A type intramolecular charge transfer (ICT) based fluorescence probe have been designed and synthesized by appending imidazole (donor, D) and benzothiazole (acceptor, A) moieties through a thiophene bridge. The molecular probe upon interaction with different class of anions showed fluorescence turn-on behavior to detect fluoride anion (F-) selectively, in acetonitrile. Job's plot analysis revealed a 1:1 binding stoichiometry between probe and F- with high binding constant and detection sensitivity (51 nM; 0.092 ppb). Moreover, upon interaction of 1 + F- with CO2 the original chromo and fluorogenic behavior of the probe was revived. The change in photophysical behavior and NMR spectroscopic studies suggested about the "On-Off-On" type of fluorescence sensing mechanism, involving deprotonation of -NH fragment of imidazolyl unit in the presence of F-. © 2016 Elsevier B.V. All rights reserved.
A sensitive TICT Probe exhibiting ratiometric fluorescence repose to detect hydrazine in solution and gas phase
(Elsevier B.V., 2020) Ramesh C. Gupta; Sushil K. Dwivedi; Rashid Ali; Syed S. Razi; Rudramani Tiwari; S. Krishnamoorthi; Arvind Misra
A twisted intramolecular charge transfer (TICT) based probe, dicyanovinyl-9-phenylanthracene (DPA) has been designed and synthesized for the detection of hydrazine (N2H4) with good limit of detection (LOD, 7.85 nM (0.25 ppb)). Upon interaction with hydrazine the terminal electron withdrawing dicyanovinyl function is changed to electron donating amino/hydrazone function. Consequently, the significant change in the photophysical property of the probe is attributed to a change in orientation of charge propagation. The probe with hydrazine shows ratiometric fluorescence “turn-on” response as well as naked-eye sensitive color change in the medium. The surface morphology studies (SEM and TEM) suggested about amorphousness and crystalline nature of the probe DPA and derivative DPA-HDz, respectively. The conducting behavior of the probe decreases upon interaction with hydrazine because of decrease in amorphousness of the matrix and increase in relatively more rigid crystalline structure. Additionally, the probe been utilized to detect hydrazine vapor in solution and on test paper strip with good naked-eye sensitive responses. © 2020 Elsevier B.V.
An efficient Hg2+ ensemble based on a triazole bridged anthracene and quinoline system for selective detection of cyanide through fluorescence turn-off–on response in solution and live cell
(Elsevier B.V., 2017) Ramesh C. Gupta; Syed S. Razi; Rashid Ali; Sushil K. Dwivedi; Priyanka Srivastava; Priya Singh; Biplob Koch; Hirdyesh Mishra; Arvind Misra
A simple triazole bridged molecular probe containing anthracene and quinoline moieties has been designed and synthesized as a fluorescent molecular probe (7). The photophysical behavior of the probe 7 has been examined and tested for the recognition of ions in partial aqueous medium and HeLa cell. The probe 7 has shown strong affinity for Hg2+ and has been utilized to develop a stable ensemble, 7·Hg2+. The ensemble, 7·Hg2+ upon interaction with different class of anions showed high affinity for cyanide with ∼16 fold fluorescence enhancement and high limit of detection, 1.25 μM. The live cell imaging studies showed that ensemble 7·Hg2+ is capable to detect CN− intracellularly. The analytical applicability of the probe for Hg2+ and CN− has been tested on the test paper strips. Additionally, the naked eye sensitive “On–Off–On” switching behavior of 7 has been utilized to mimic the function of a sequential logic circuit at molecular level. The 1H NMR titration, ESI-MS spectroscopy and DFT calculation confirms the binding behavior between 7 and Hg2+. © 2017 Elsevier B.V.
An efficient ICT based fluorescent turn-on dyad for selective detection of fluoride and carbon dioxide
(Royal Society of Chemistry, 2016) Rashid Ali; Syed S. Razi; Ramesh C. Gupta; Sushil K. Dwivedi; Arvind Misra
A new intramolecular charge transfer (ICT) based fluorescent turn-on ratiometric probe 2 (D-π-A type) has been designed and synthesized by bridging imidazole (donor, D) and benzothiazole (acceptor, A) moieties through a phenyl ring. The photophysical behavior of probe 2 in solvents of different polarities and at different pH values has been investigated. Upon interaction with different types of anions probe 2 showed selective high affinity for fluoride anions (F-) in aqueous DMSO (20%) solution. The ratiometric fluorescence turn-on behavior displayed by 2 with F- is attributed to changes in the ICT process. Job's plot analysis revealed a 1 : 1 binding stoichiometry for 2 + F- interactions with a high binding constant and detection sensitivity (30 ppb). Moreover, a solution of 2 + F- enabled the detection of CO2 (∼100 ppb; 2.29 μM) through enhanced emission. The mode of interaction has been confirmed by 1H NMR titration studies which suggested the deprotonation of the -NH fragment of an imidazolyl unit in the presence of F-. © The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2016.
An Efficient Molecular Scaffold Exhibiting Fluorescence “Turn–On” Response for Cyanide and HCN
(Wiley-Blackwell, 2018) Ramesh C. Gupta; Sushil K. Dwivedi; Rashid Ali; Arvind Misra
The present work describes design and synthesis of a biphenylaldimine derivative, probe 2 as an efficient molecular scaffold. The probe 2 showed good photophysical behavior and upon interaction with anions and gases showed high selectivity and sensitivity for CN- anion and HCN gas through a reaction based chemodosimeter approach with limit of detection 24 ppb and 7 ppm, respectively. The change in optical behavior of the probe is attributed to intramolecular charge transfer (ICT) mechanism. Probe 2 displayed enhanced emission, “turn-on” due to the formation of a new biphenyl oxazole derivative 4 in the medium along with change in color of the medium which was sensitive to the naked-eyes. The mechanism of interaction between probe and cyanide anion have been confirmed by the 1H NMR, 13C NMR and HRMS spectral data analysis. The molecular probe 2 has been successfully utilized to detect cyanide (CN-) and HCN gas in solution and on test paper strips. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Corrigendum to “A coumarin-derived useful scaffold exhibiting Cu2+ induced fluorescence quenching and fluoride sensing (On–Off–On) via copper displacement approach” [Sens. Actuators B: Chem. 209 (2015) 162–171](S0925400514014658)(10.1016/j.snb.2014.11.082)
(Elsevier B.V., 2021) Syed S. Razi; Priyanka Srivastava; Rashid Ali; Ramesh C. Gupta; Sushil K. Dwivedi; Arvind Misra
Objection: “As far as I see the N and S atoms in the thiazol cycle are indeed inter exchanged (if the Hantzsch thiazol synthesis is followed).You may contact the authors to confirm and prepare the corrigendum. The structure appears in multiple places in the paper, including the graphical abstract.” Corrections: The corrected version of Schemes and Table in entire manuscript should be as follows. The changes do not affect the conclusions drawn from Scheme 1. There is no influence of these changes on the overall conclusion of the manuscript. The authors would like to apologize for any inconvenience caused. Scheme 1 [Figure presented] Scheme 1: (i) Ethylacetoacetate/piperidine/ethanol/reflux (ii) Br2/chloroform/ethanol/rt (iii) ethanol/4a-d/rt (iv) Ethanol/salicylaldehyde/reflux. Table – 1: Properties of synthesized derivatives. [Table presented] Scheme 2 [Figure presented] Graphical abstract [Figure presented] © 2021
Dual Fluorophore Containing Efficient Photoinduced Electron Transfer Based Molecular Probe for Selective Detection of Cr3+ and PO4 3- Ions through Fluorescence " Turn-On-Off" Response in Partial Aqueous and Biological Medium: Live Cell Imaging and Logic Application
(American Chemical Society, 2018) Sushil K. Dwivedi; Ramesh C. Gupta; Priyanka Srivastava; Priya Singh; Biplob Koch; Biswajit Maiti; Arvind Misra
The present work describes a new photoinduced electron transfer (PET) based molecular probe in which naphthalimide (NPI) and anthracene (AN) chromophores are linked through a molecular bridge of piperazine and triazole units by the Click reaction. A typical meaningful structural variation has made the present probe highly selective for Cr3+ ion (limit of detection (LOD), 5.567 × 10-8 M) that displayed enhanced, "turn-On" emission (due to the PET-Off photophysical mechanism) and naked-eye sensitive bright green color fluorescence in the environment of interfering and competitive ions, in Tris-HCl buffer. The minimum energy structure obtained through theoretical calculations (density functional theory (DFT) and time-dependent (TD)-DFT) revealed a "tub" shape structure for probe 10. Upon complexation, the conformation of piperazine fragment changes from chair to boat in which the triazole and piperazine units create a cavity to tether Cr3+. Moreover, the probe showed excellent biocompatibility and cell permeability to sense Cr3+ sensitively in live cells and, thus, holds great promise for application in biological and environmental sciences. Additionally, the sensitive "Off-On-Off" sensing behavior of probe 10 providing two chemical inputs (Cr3+ and PO4 3-) helps to construct an INHIBIT logic gate. Also the probe has been utilized as printing material to decode secret information through the Cr3+ ion containing "marker ink" under UV light. © 2018 American Chemical Society.
Excited state proton transfer (ESIPT) based molecular probe to sense F- and CN- anions through a fluorescence "turn-on" response
(Royal Society of Chemistry, 2018) Rashid Ali; Ramesh C. Gupta; Sushil K. Dwivedi; Arvind Misra
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. © The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2018.
Influence of carbonization conditions on the gasification of acacia and eucalyptus wood chars by carbon dioxide
(1994) Mithilesh Kumar; Ramesh C. Gupta
Gasification rates of cubic shaped acacia and eucalyptus wood chars were measured thermogravimetrically in a carbon dioxide atmosphere at temperatures in the range 810-960 °C. The effects of wood species and carbonization conditions, such as temperature, heating rate and soaking time, were determined. Both reactivity and the activation energy for the gasification of wood chars were found to be strongly influenced by the carbonization conditions employed during their preparation and wood type. The reactivities of both the acacia and eucalyptus wood chars decreased with increasing preparation temperature; while the activation energy for their gasification increased. Slow carbonization (heating rate: 4 °C min-1) led to the production of wood chars having lower reactivities and higher activation energies than those of the wood chars prepared under rapid carbonization (heating rate: 30 °C min-1) at the same temperature. With increasing soaking time, at carbonization temperatures of 800 and 1000 °C, the reactivity of resulting wood chars was reduced. The results also show that the reactivities of acacia wood chars are higher than those of similarly prepared eucalyptus wood chars. © 1994.
Phenyl-end-capped-thiophene (P-T type) based ICT fluorescent probe (D-π-A) for detection of Hg2+ and Cu2+ ions: Live cell imaging and logic operation at molecular level
(Elsevier B.V., 2016) Syed S. Razi; Rashid Ali; Ramesh C. Gupta; Sushil K. Dwivedi; Gunjan Sharma; Biplob Koch; Arvind Misra
An intramolecular charge transfer (ICT) based fluorescence turn-on ratiometric probe BTIM (D-π-A type) has been designed and synthesized by bridging imidazole (donor, D) and benzothiazole (acceptor, A) moieties through a thiophene ring. The photophysical behavior of probe and its affinity toward metal ions has been investigated in HEPES buffer, protein medium and live cells. The probe upon interaction with different cations has shown high sensitivity and selectively for Hg2+ and Cu2+ ions through fluorescence "turn-On and turn-Off" response respectively along with naked-eye sensitive color changes. The significant change in photophysical behavior of the probe is attributable to restricted ICT upon complexation between probe and metal ions in a 1:1 stoichiometry. The mechanism of interaction has been established by 1H NMR, FT-IR, ESI-M Sand DFT calculation methods. The probe has shown excellent cell permeability and successfully detected Hg2+ and Cu2+ ions in Dalton's Lymphoma (DL) cells, in protein medium (BSA), in real water samples and on test paper strips. Moreover, the optical behavior of probe has been explored as a Coding-Decoding Fluorescent Blue Security Ink on silica gel surface and in construction of crossword puzzle with specific security code 'HCO'. © 2016 Elsevier B.V. All rights reserved.
Selective naked-eye detection of Hg2+ through an efficient turn-on photoinduced electron transfer fluorescent probe and its real applications
(American Chemical Society, 2014) Priyanka Srivastava; Syed S. Razi; Rashid Ali; Ramesh C. Gupta; Suresh S. Yadav; Gopeshwar Narayan; Arvind Misra
A simple molecular fluorescent probe 5 has been designed and synthesized by appending anthracene and benzhydryl moieties through a piperazine bridge. The probe upon interaction with different metal ions showed high selectivity and sensitivity (2 ppb) for Hg2+ through fluorescence "turn-on" response in HEPES buffer. The significant fluorescence enhancement (∼10-fold) is attributable to PET arrest due to complexation with nitrogen atoms of the piperazine unit and Hg2+ in 1:2 stoichiometry, in which a naked-eye sensitive fluorescent blue color of solution changed to a blue-green (switched-on). As a proof of concept, promising prospects for application in environmental and biological sciences 5 have been utilized to detect Hg 2+ sensitively in real samples, on cellulose paper strips, in protein medium (like BSA), and intracellularly in HeLa cells. Moreover, the optical behavior of 5 upon providing different chemical inputs has been utilized to construct individual logic gates and a reusable combinational logic circuit. The combinational circuit (switch ON mode; OR logic gate) is easily resettable to the original position (switch OFF mode; INHIBIT logic gate) by applying reset chemical inputs (OH- and PO43-) with great reproducibility. © 2014 American Chemical Society.
Smart PET based organic scaffold exhibiting bright “Turn–On” green fluorescence to detect Fe3+ ion: Live cell imaging and logic implication
(Elsevier B.V., 2018) Sushil K. Dwivedi; Ramesh C. Gupta; Rashid Ali; Syed S. Razi; Sumit K. Hira; Partha P. Manna; Arvind Misra
An efficient and simple photoinduced electron transfer (PET) based fluorescence turn–On probe 7 has been designed and synthesized by bridging naphthalimide and thiophene moieties through a piperazine unit. The photophysical behavior of probe and its affinity toward different metal ions have been investigated in partial aqueous medium, protein medium and live cells. The probe exhibited fluorescence “turn-On” response for Fe3+ ion with high sensitivity (limit of detection 0.373 μM) and selectively along with naked-eye sensitive visible green color in the medium. The significant change in photophysical behavior of the probe, upon a complexation between probe and Fe3+ is attributed to restriction in PET process. The probe 7 showed excellent biocompatibility and has been utilized in cellular imaging experiment to detect Fe3+ in MCF-7 live cells. Also, at molecular level probe 7 mimics the functions of a sequential logic circuit, corresponding to a memory device in which the two inputs (Fe3+ and AcO−) based sequential logic operations mimic the function of a memory element. © 2018 Elsevier B.V.
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
(Royal Society of Chemistry, 2017) Ramesh C. Gupta; Rashid Ali; Syed S. Razi; Priyanka Srivastava; Sushil K. Dwivedi; Arvind Misra
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-. © 2017 The Royal Society of Chemistry.