Browsing by Author "Sarita Gond"

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A colorimetric and ‘OFF-ON’ fluorometric chemosensor based on a rhodamine-pyrazole derivative for the detection of Al3+, Fe3+and Cr3+metal ions, and its intracellular application
(Royal Society of Chemistry, 2023) Sarita Gond; Pranjalee Yadav; Aayoosh Singh; Somenath Garai; Anusmita Shekher; Subash Chandra Gupta; Vinod P. Singh
The colorimetric and fluorescence responses of a new rhodamine-functionalized probe (E)-2-(((5-chloro-3-methyl-1-phenyl-1H-pyrazol-4-yl)methylene)amino)-3′,6′-bis(diethylamino)spiro[isoindoline-1,9′-xanthen]-3-one (RMP) are investigated. RMP has been thoroughly characterized using various spectroscopic tools and single crystal X-ray diffraction. Among different competing cations, it shows highly sensitive colorimetric and “OFF-ON” fluorescence responses towards Al3+, Fe3+and Cr3+metal ions. The spectral shifts are clearly noticeable in the visible region of the absorption spectrum and can be observed with the naked eye. Fluorescence quantum yield, stoichiometric ratio, binding constant and detection limit of RMP towards Al3+, Fe3+and Cr3+metal ions have been calculated. Furthermore, RMP-M3+ complexes are reversible and sensitive to EDTA, which effectively mimics a molecular logic gate. Al3+, Fe3+and Cr3+metal ions have been further applied in intracellular application in model human cells. © 2023 The Royal Society of Chemistry
A coumarin derived turn ‘off–on-off’ probe for selective sequential monitoring of Al3+ and Cu2+ ions with bio-imaging application
(Elsevier B.V., 2024) Sarita Gond; Avanish Kumar Singh; Pranjalee Yadav; Pradeep Kumar; S. Srikrishna; Vinod P. Singh
Herein, a coumarin-based chemosensor (E)-N'-(1-(2-oxo-2H-chromen-3-yl)ethylidene) thiophene-2-carbohydrazide (ACT) has been synthesized and thoroughly characterized by using various spectroscopic techniques. The molecular structure of the probe has been confirmed by single crystal X-ray diffraction technique. Hirshfeld surface analysis has also been carried out to investigate weaker interactions in the probe molecule. ACT shows a highly selective enhanced fluorometric response towards Al3+ in ethanol among different competing cations. Upon interaction with Al3+, a new complex ACT-Al3+ is formed which displays a strong yellow fluorescence due to chelation enhanced fluorescence process (CHEF). Furthermore, in situ ACT-Al3+ complex is exploited for sequential recognition of Cu2+ with fluorescence turn-off via paramagnetic quenching mechanism among different competing cations. This study presents an exceptionally low detection limits of ACT for Al3+ and Cu2+ ions (2.33 × 10−11 and 1.96 × 10−11 M, respectively). Furthermore, the binding constants of ACT for Al3+ and Cu2+ were found to be 7.97 × 104 and 9.79 × 104 M−1, respectively. The binding mechanism has been verified by 1H NMR titration and DFT calculations. Sensing behaviour of ACT towards Al3+ and Cu2+ have also been exploited in the development of paper strip kit and intracellular application in 3rd instar larvae of Drosophila. © 2024 Elsevier B.V.
A multifunctional basic pH indicator probe for distinguishable detection of Co2+, Cu2+ and Zn2+ with its utility in mitotracking and monitoring cytoplasmic viscosity in apoptotic cells
(Royal Society of Chemistry, 2022) Pranjalee Yadav; Sarita Gond; Anusmita Shekher; Subash Chandra Gupta; Udai P. Singh; Vinod P. Singh
Metal ions such as Co2+, Cu2+ and Zn2+ have extensive applications in biological and industrial realms, but the toxicity caused by these ions poses a serious threat to mankind. However, there is no report in the literature on the development of a chemosensor for distinguishable detection of these toxic ions. Addressing this challenge, a multifunctional probe as a basic pH indicator with both colorimetric and fluorescence turn-on responses has been reported. The probe selectively discriminates Co2+, Cu2+ and Zn2+ ions with brown, dark yellow and greenish yellow colors, respectively, in DMF : water (9 : 1 v/v, HEPES 10 mM). Additionally, a fluorescence turn-on response specific to Zn2+ has also been observed. The sensing mechanism has been explored using UV-Vis, fluorescence spectroscopy and 1H NMR titration and confirmed with computational results. The inhibition of C 00000000 00000000 00000000 00000000 11111111 00000000 11111111 00000000 00000000 00000000 N isomerization and excited state intramolecular proton transfer (ESIPT) along with chelation enhanced fluorescence emission (CHEF) result in fluorescence enhancement with Zn2+. Job's plot and HRMS spectra confirm a 1 : 1 (L : M) stoichiometry between the probe and metal ions. The probe is able to exhibit excellent viscochromism in DMF : glycerol medium. Live cell imaging on SiHa cells has been successfully performed for intra-cellular detection of Zn2+ at basic pH. Furthermore, the probe displays its utility in mitotracking and monitoring cytoplasmic viscosity changes in SiHa cells. It is efficiently used to recognize the apoptosis process by displaying an enhancement in fluorescence intensity from cancerous SiHa cells to apoptotic cells. © 2022 The Royal Society of Chemistry.
A novel 3-acetyl coumarin based AIE luminophore for colorimetric recognition of Cu2+ and F− ions
(Elsevier B.V., 2023) Sarita Gond; Pranjalee Yadav; Avanish Kumar Singh; Vinod P. Singh
A 3-acetyl coumarin appended probe 3-((Z)-1-((E)-((2-hydroxynaphthalen-1-yl) methylene) hydrazono)ethyl)-2H-chromen-2-one (CNH) has been successfully synthesized and characterized by different spectroscopic tools via IR, 1H & 13C NMR and HRMS. The probe displays solvent dependent colorimetric detection of Cu2+ and F− ions in THF and DMF media, respectively. CNH interacts with Cu2+ in 1:1 stoichiometry with limit of detection 1.4 × 10−6 M. The color change of probe with addition of Cu2+ ions is due to ligand to metal charge transfer (LMCT) as suggested by UV–Vis spectra and DFT studies. Furthermore, CNH interacts with F− in 1:1 stoichiometry with detection limit 1.32 × 10−6 M by proton transfer mechanism from O-H to F−, which enhances the electron density on CNH molecule as suggested by UV–Vis, NMR titration and DFT studies. In addition to intriguing colorimetric sensing applications, CNH displays remarkable aggregation induced emission (AIE) property in DMF/water binary mixture. The probe is almost non-fluorescent in solution but becomes strongly emissive in aggregate/solid state. The formation of aggregates at higher water content is confirmed by atomic force microscopy (AFM) and dynamic light scattering (DLS) studies in mixed water media. DLS measurements suggest the increase in average particle size from 100 nm to 299 nm upon increasing water fractions from (fw = 10%) to (fw = 90%). AFM studies also provide additional information about the aggregates at higher water fraction. In the range of 100–500 nm, the topography of surface shows that the aggregates are spherical in shape (fw = 90%). © 2022 Elsevier B.V.
A pyrene-thiophene based probe for aggregation induced emission enhancement (AIEE) and naked-eye detection of fluoride ions
(Elsevier B.V., 2019) Pranjalee Yadav; Sarita Gond; Ashish Kumar Singh; Vinod P. Singh
A pyrene based probe (E)-N’-(pyren-1-ylmethylene)thiophene-2-carbohydrazide (PTH), was synthesized and characterized by IR, NMR and HRMS spectroscopic tools. The probe exhibited aggregation induced emission enhancement (AIEE) in binary solvent mixture (ACN/water) on increasing water fraction and displayed bright yellow emission in solid state. Fluorescence spectroscopy, time resolved fluorescence and DLS analysis have been exploited to gain insight into the mechanism. These results indicated an enhancement in quantum yield and average lifetime with an increase in water content. In addition to intriguing AIEE property, PTH demonstrated excellent selectivity and sensitivity for F− over various other anions. A plausible mechanism for interaction of the probe with F− has been proposed on the basis of 1H NMR titration, absorption spectra and DFT study. The recognition process was found to be driven by the high electronegativity of F− leading hydrogen bonded adduct followed by deprotonation of PTH. Instant naked eye response along with commendable detection limit (2.02 × 10−7 M) and binding constant (6.18 × 104 M−1) increased the pertinency of the probe. © 2019 Elsevier B.V.
A reversible and selective chromogenic thiazole tagged chemosensor for Hg2+in aqueous medium: Crystal structure, theoretical investigations and real sample analysis
(Elsevier B.V., 2023) Gautam Kumar; Ananya Srivastava; Sarita Gond; Pranjalee Yadav; Aayoosh Singh; Vinod P. Singh
A novel thiazole tagged Schiff base chemosensor, (E)-N'-((2-aminothiazol-5-yl)methylene)-2-hydroxybenzohydrazide (ATH) has been synthesized in excellent yield by a simple one pot method and characterized by single crystal X-ray diffraction and spectroscopic techniques. The sensing ability of ATH was determined for detection of Hg2+ ions in the presence of different metal ions in aqueous medium. It behaves as an extremely selective and sensitive chromogenic sensor for naked-eye detection of Hg2+ ions with a colour change from colourless to yellow due to ligand to metal charge transfer. Remarkably, the binding constant (Ka) and limit of detection (LOD) for ATH[sbnd]Hg2+ complex were found as 1.75 × 104 M −1 and 8.85 × 10−7 M, respectively. The Job's plot indicated that the stoichiometric ratio of ATH to Hg2+ is 1:1. The binding mechanism was established based on FT-IR, 1H NMR titration, mass spectrometry and density functional theory studies. The chemosensor exhibited an excellent colorimetric property in 7.0–12.0 pH range. The chemosensor was found to be reversible and reusable in the presence of CN− ions with logic gate behaviour. Further, the chemosensor was utilized to sense Hg2+ ions in tap and Ganga river water samples. © 2023 Elsevier B.V.
Design and development of a highly efficient hydrazone based sensing material for selective detection of F− ions
(Elsevier B.V., 2023) Sarita Gond; Pranjalee Yadav; Vinod P. Singh
A 2,4-dinitrophenyl hydrazine appended sensing material has been synthesized and characterized by NMR, IR and HRMS spectral studies. The selective colorimetric sensing property of the chemosensor for F− has been thoroughly investigated with UV–Vis, NMR and DFT analysis. The limit of detection (LOD) and association constant has been found to be 1.37 μM and 3.09 × 107 M−1, respectively. High electronegativity of F− is responsible for hydrogen bonding induced deprotonation of chemosensor and subsequent color change from yellow to pink. Paper strip kit of the chemosensor has been applied successfully for sensing of F−. © 2023 Elsevier B.V.
Development of a reversible chromogenic sensor for Cu2+ in aqueous ethanol
(Elsevier B.V., 2021) Pranjalee Yadav; Sarita Gond; Aayoosh Singh; Vinod P. Singh
A naphthaldehyde appended sensor has been synthesized and characterized by spectroscopic techniques. The sensor has been efficiently utilized in selective chromogenic detection of Cu2+ in aqueous ethanol amongst various metal ions. Cu2+ interacts with the sensor in 1:2 (M:L) stoichiometry with binding constant of 1.1 × 103 M−1/2 and detection limit of 9.342 × 10−7 M. Ligand to metal charge transfer (LMCT) accounts for the selective color change from colorless to yellow with Cu2+ as suggested by UV–Vis and DFT studies. This sensor offers certain advantages over the existing chemosensors in terms of reversibility, reusability and solid state applications. © 2021 Elsevier B.V.
Development of an ‘OFF-ON-OFF’ colorimetric and fluorometric pH sensor for the study of physiological pH and its bioimaging application
(Elsevier B.V., 2022) Sarita Gond; Pranjalee Yadav; Brijesh Singh Chauhan; S. Srikrishna; Vinod P. Singh
2-hydroxyl-1-naphthaldehyde based probe 1,1′((1E,1′E)((4hydroxy1,3phenylene) bis(azanylylidene)bis(methanylylidene)bis(naphthalen-2-ol) (NAP) has been synthesized and thoroughly characterized by IR, 13C & 1H NMR, fluorescence, UV-Vis, and mass spectral studies. The detection of pH is a necessary feature of the intracellular atmosphere and probably affects all cellular systems. NAP acts as a highly sensitive pH sensor in ethanol/HEPES (7:3, v/v) medium. Upon increasing the pH of NAP solution from acidic-neutral-basic medium, a distinct color change occurs from colorless-yellow-brown followed by a subsequent bathochromic shift in UV-Vis spectra and fluorescence response from ‘OFF-ON-OFF’. Photo-induced electron transfer (PET) mechanism has been proposed for the fluorescence change on the basis of theoretical studies on protonated, neutral and deprotonated NAP. Bioimaging investigations display a pH dependent fluorescence behavior of NAP in gut tissue of drosophila 3rd instar larvae. Additionally, NAP paper strips have been successfully developed for solid state pH sensing based on colorimetric and fluorescence responses. © 2021 Elsevier B.V.