Browsing by Author "Richa Yadav"

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A dual optical probe with larger stokes shift for simultaneous detection of Cu2+ and Zn2+ ions and aggregation induced enhanced emission empowering selective detection of Cu2+ ions
(Elsevier B.V., 2021) Avinash Kumar Sonkar; Abhishek Rai; Kamini Tripathi; Richa Yadav; Manjari Shukla; Brijesh Singh Chauhan; S. Srikrishna; Lallan Mishra
A new aggregation induced enhanced emission (AIEE) active probe (1) has been synthesized via single step condensation reaction of 2-amino-3-benzyloxypyridine with 3-allylsalicylaldehyde in methanol. Probe 1 has been fully characterized by various spectroscopic techniques i.e. IR, NMR (1H and 13C), HRMS and X-ray crystallography. 1 displays a large stokes shift of 190 nm. It recognizes Cu2+ ions colorimetrically and fluorescence intensity enhances on the addition of Zn2+ ions. 1 form nanoaggregates in H2O:CH3OH (80:20, v/v) which detects Cu2+ ions selectively. 1 in the presence of Zn2+ ions and its nanoaggregates n1 show switch on behaviour of green fluorescence comparable to mitochondrial membrane potential indicator, Mitotracker-Red, in larval gut tissues of Drosophila melanogaster. © 2020 Elsevier B.V.
A stable and highly sensitive fluorescent probe for detection of hypochlorite ion in vitro and in living cells
(Chemical Society of Japan, 2019) Richa Yadav; Keiko Odera; Abhishek Rai; Akimi Noguchi; Ryoya Takahashi; Lallan Mishra
We designed and synthesized 2-[(2-amino-5-nitro-phenyl-amino)-methyl]-5-diethylamino-phenol (L1) as a stable and highly sensitive hypochlorite probe. L1 may be used in both colorimetric and fluorometric applications, as well as in paper-strip detection for selective hypochlorite ion sensing. In this study, we successfully applied L1 to the imaging of local hypochlorite generation in the endosomes, including phagosomes, of living cells. Thus, L1 is an appropriate probe for the detection and visualization of hypochlorite ions in vitro and in living cells. © 2019 The Chemical Society of Japan.
A viscochromic, mechanochromic, and unsymmetrical azine for selective detection of Al3+ and Cu2+ ions and its mitotracking studies
(Royal Society of Chemistry, 2019) Richa Yadav; Abhishek Rai; Avinash Kumar Sonkar; Vipin Rai; Subash Chandra Gupta; Lallan Mishra
A hydrazone obtained by the reaction of 2-hydroxynaphthaldehyde with hydrazine hydrate was allowed to react further with 4-diethylamino-2-hdroxybenzaldehyde to provide an unsymmetrical azine derivative (NDEA). The azine has been characterized using spectroscopic techniques and single crystal X-ray crystallography. It selectively detects Al3+ and Cu2+ ions in aqueous methanol (DMSO:H2O:MeOH = 0.1:1.9:8.0, v/v, HEPES buffer, pH 7.4) and exhibits naked eye visible color changes from greenish yellow to bright yellow and brown on the addition of Al3+ and Cu2+ ions, respectively, with concomitant changes in their absorption spectra. The corresponding solutions containing Al3+ and Cu2+ ions also display changes in their emission spectra via "TURN ON" and "TURN OFF" pathways with a detection limit of 1.65 × 10-7 M and 1.52 × 10-7 M, respectively. NDEA works as a reversible probe towards Al3+ ions and Cu2+ ions by the addition of F- ions and EDTA2- ions, respectively. The complexes of NDEA, separately with Al3+ and Cu2+ ions, have been optimized by DFT (density functional theory). It also exhibits viscochromic and mechanochromic properties. Most importantly, NDEA significantly detects these ions in rat C6 glioma cell lines and displays good cell permeability. It also co-localizes with the commercially available Mitotracker Red and exhibits a unique application as a live cell mitochondrial tracker. Practically, NDEA detects Al3+ and Cu2+ ions in real water samples and blood serum with a high accuracy. © The Royal Society of Chemistry and the Centre National de la Recherche Scientifique.
Pyridyl substituted 4-(1,3-Dioxo-1H,3H-benzo[de]isoquinolin-2-ylmethyl)-benzamides with aggregation enhanced emission and multi-stimuli-responsive properties
(Elsevier B.V., 2017) Ashish Kumar Srivastava; Alok Kumar Singh; Niraj Kumari; Richa Yadav; Antonino Gulino; Adolfo Speghini; Rajamani Nagarajan; Lallan Mishra
1,8-Naphthalimide connected to benzoic acid chloride via methylene group was condensed separately with 3-amino pyridine and 4-amino pyridine and provided compounds 4-(1,3-Dioxo-2,3-dihydro-1H-phenalen-2-ylmethyl)-N-pyridin-3-yl-benzamide 1 and 4-(1,3-Dioxo-2,3-dihydro-1H-phenalen-2-ylmethyl)-N-pyridin-4-yl-benzamide 2. The compounds are characterized by spectral (IR, UV–Visible, 1H and 13C NMR) measurements and supported by their X-ray crystallography. Their photoelectron spectroscopy, SEM and TEM measurements are also made. They are found luminescent in DMF solution as well as in the solid state and form nano-aggregates with enhanced emission (AEE) in aqueous-DMF solution. Their AEE behavior depends on the polarity of the solvents. On grinding, crystalline solids 1 and 2 turn to amorphous and the process is reversible on annealing as supported by their powder X-ray diffraction (PXRD) measurements. Both compounds show mechanochromic properties and display multi-stimuli response. Density Functional Theory calculations rationalize their optical data. © 2016 Elsevier B.V.
Remarkable Confinement Effect of Nanofiber in Carbon Nanotubes for Dehydrogenative Coupling of Alcohols with α-Diaminobenzene: A Route for the Synthesis of Benzimidazoles
(Wiley-VCH Verlag, 2018) Melad Shaikh; Richa Yadav; Pawan K. Tyagi; Lallan Mishra; Kalluri V. S. Ranganath
Magnetic nanofiber (MNF) confined in carbon nanotubes (CNTs) has been efficiently used in dehydrogenative coupling. A remarkable effect has been observed in the coupling of alcohols with diaminobenzene. This represents a new method to produce benzimidazoles in high yields under heterogeneous conditions without using expensive metals such as Pt, Ru, and Ir. This MNF was synthesized by reacting magnetite nanoparticles (MNPs) with various spacers such as di-, tri- and tetracarboxylic acids. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Synthesis, characterization, and supramolecular architectures of two distinct classes of probes for the visualization of endogenously generated hypochlorite ions in response to cellular activity
(Elsevier B.V., 2019) Richa Yadav; Keiko Odera; Abhishek Rai; Ryoya Takahashi; Lallan Mishra
Two distinct classes of compounds, (E)-2-(((3-amino-4-nitrophenyl) imino) methyl)-5-(diethylamino) phenol (SB) and 5-(diethylamino)-2-(5-nitro-1H-benzo[d]imidazol-2-yl) phenol (IM) were synthesized. SB, a bright red colored compound was crystallized in acetonitrile as a triclinic crystal system while IM, yellow colored compound crystallized as a monoclinic crystal system in dimethylformamide by vapor diffusion of diethylether. These compounds were characterized using spectroscopic techniques (IR, UV–visible, 1H, and 13C NMR), and X-ray crystallography. SB and IM displayed classical and non-classical H-bonding involving C-H…O and π…π interactions. These compounds detected hypochlorite ions in aqueous DMSO (1: 9, v/v, HEPES buffer, pH 7.4), and detection was visible via color changes by naked eye. We also performed UV–visible and fluorescence titrations, showing detection limits of 8.82 × 10−7 M for SB and 2.44 × 10−7 M for IM. The fluorometric responses from SB and IM were also studied against different ROS and anions. DFT calculations were performed to strengthen the proposed sensing mechanisms of both SB and IM. Hypochlorite, which is endogenously generated by myeloperoxidase in endosomes, was specifically visualized using SB and IM in lipopolysaccharide-treated RAW264.7 cells. These probes were also used to image the generation of hypochlorite by RAW264.7 cells during phagocytosis of non-fluorescent polystyrene beads. © 2019 Elsevier B.V.