Browsing by Author "Rashid Ali"

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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 polynuclear hetero atom containing molecular organic scaffold to detect Al3+ ion through a fluorescence turn-on response
(Royal Society of Chemistry, 2015) Rashid Ali; Syed S. Razi; Priyanka Srivastava; Mohammad Shahid; Arvind Misra
A simple polynuclear hetero atom (N and O) containing molecular organic scaffold/probe, 3 has been designed and synthesized and explored as a potential chemosensor to detect Al3+ (22 nM; ∼0.6 ppb) ion in a HEPES buffer. Upon interaction with different metal ions and anions the weak emission intensity (switched Off) of 3 (at 528 nm; λex = 376 nm) was enhanced significantly (switched On; ∼6.0 fold; Φ3+Al3+ = 0.07) only in the presence of Al3+ wherein, the color of the solution changed from a naked-eye sensitive fluorescent dark green to bright yellow-green. The observed chelation enhanced fluorescence (CHEF) is attributable to restricted ESIPT and C=N isomerization processes due to complexation between the potential coordination sites (N and O atoms; hard base) of 3 and Al3+ (hard acid) in a 1:1 stoichiometry, consequently. The mechanism of the interaction has been confirmed by the change in optical behaviors, 1H/13C NMR, FTIR, and ESI-MS spectroscopy data analysis. Moreover, chemosensor 3 has also been utilized to detect Al3+ in real water samples and on test paper strips. © The Royal Society of Chemistry 2015.
A selective quinoline-derived fluorescent chemodosimeter to detect cyanide in aqueous medium
(2014) Syed S. Razi; Rashid Ali; Priyanka Srivastava; Arvind Misra
A simple quinoline derived probe 3 has been described. Probe 3 having aldehyde function upon interaction with cyanide undergo nucleophilic addition reaction to form cyanohydrin derivative 4 in which fluorescence intensity enhances significantly, 'turn-on' by photoinduced electron transfer (PET) OFF-ON mechanism. The color of probe solution switched-on to fluorescent blue which is visible to the naked-eye. Job's plot analysis revealed a 1:1 stoichiometry for an interaction between 3 and cyanide along with detection limit 0.058 μM (1.5 ppb). The mode of interaction to detect cyanide in aqueous medium through a reaction based chemodosimeter approach has been confirmed by NMR, mass, FTIR, and DFT data analysis. © 2013 Elsevier Ltd. 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.
A simple blue fluorescent probe to detect Hg2+ in semiaqueous environment by intramolecular charge transfer mechanism
(2013) Priyanka Srivastava; Rashid Ali; Syed S. Razi; Mohammad Shahid; Satyakam Patnaik; Arvind Misra
An efficient intramolecular charge transfer fluorescent probe bridging benzhydryl moiety and dansyl fluorophore through piperazine unit has been synthesized and characterized. The photophysical behavior of synthesized probe has been analyzed in the presence of different cations in aqueous acetonitrile solution. The probe has shown sensitivity to detect Hg2+ ion selectively over other tested cations at 20 nM level. The probable mode of binding of Hg2+ through the nitrogen and oxygen atoms of piperazine and dansyl has been established by spectral data analysis. © 2013 Elsevier Ltd. All rights reserved.
A simple naphthalimide based PET probe for Fe3+ and selective detection of pyrophosphate through displacement approach: Cell imaging studies and logic interpretation
(Elsevier B.V., 2020) Sushil K. Dwivedi; Rashid Ali; Manjeet Singh; Tulika Gupta; Aditya K. Kar; Ved Prakash; Anbumani Sadasivam; Satyakam Patnaik; Arvind Misra
The present work describes design, synthesis and photophysical behavior of a new molecular fluorescent probe 5. The probe 5 upon interaction with different metal ions in phosphate buffer (THF:H2O; 1:99, v/v; pH 7.2) exhibited enhanced emission (turn–On) with Fe3+ (LOD = 1.05 × 10−9 M) selectively due to the formation of an ensemble, 5.Fe3+. On the other hand the interaction of ensemble 5.Fe3+ with different class of anionic species fluorescence quenching (turn–Off) was observed with pyrophosphate ions (PPi) (LOD = 4.2 × 10-7 M) selectively due to the formation of ferricpyrophosphate in the medium. The Off–On–Off emission behavior exhibited by the probe in the presence of Fe3+ and PPi is attributed to PET–Off–On mechanism, respectively. The live cell imaging and in vivo studies in zebra fish suggested about the potential biological application of probe to detect both the ions. The ensemble, 5.Fe3+ has also been tested to detect PPi in DNA polymerase chain reaction (PCR) product. Additionally, the probe upon providing Fe3+ and PPi ions as chemical inputs sequentially mimic “write-read-erase-read” functions through the formation of an INHIBIT gate. © 2020 Elsevier B.V.
A simple naphthalimide-based receptor for selective recognition of fluoride anion
(Arkat, 2012) Arvind Misra; Mohammad Shahid; Pratibha Dwivedi; Priyanka Srivastava; Rashid Ali; Syed S. Razi
Synthesis of a simple fluorescent naphthalimide based receptor 4-aminobenzyl-N-methyl-1,8-naphthalimide 3 was carried out as a selective fluoride ion sensor. In acetonitrile, interaction of 3 with different anions such as, AcO-, F-, Cl-, Br-, I -, and SCN- revealed significant fluorescence quenching only with the F- anion. In the presence of the fluoride anion, the color of the solution changed from a fluorescent green to violet and this was visible to the naked eye. The probable mode of sensing mechanism by photo-induced electron transfer (PET) reaction is attributed to deprotonation of acidic NH proton in the presence of fluoride which was confirmed by change in optical properties intramolecular charge transfer (ICT) and 1H NMR spectral data analysis. The Job's plot analysis displayed a 1:1 stoichiometry for interaction between 3 and F-. The extent of fluorescence quenching was estimated by Stern-Volmer plot. © ARKAT-USA, Inc.
A Survey on the Usage of Pattern Recognition and Image Analysis Methods for the Lifestyle Improvement on Low Vision and Visually Impaired People
(Pleiades journals, 2021) M. Anitha; V. D. Ambeth Kumar; S. Malathi; V. D. Ashok Kumar; M. Ramakrishnan; Abhishek Kumar; Rashid Ali
Abstract: According to World Health Organization in 2017 nearly 253 million people are visually impaired of whom 36 million are blind. Braille books involve the tactile format that helps the visually impaired people to gain knowledge but only a limited resource is available. Enormous papers and studies describe the method for obtaining machine readable document from textual image. In upcoming days character recognition might serve a key role to create a paperless environment that helps the visually impaired people to gain enormous amount of educational material. Handwritten script recognition is gaining vital importance in today’s electronically interconnected society. In the field of machine learning and pattern matching handwritten has gained lot of attention. This paper first summarizes the pros and cons of technologies developed for the visually impaired people in terms of education material obtained from text image and handwritten image. Along with that it presents a performance comparison of different methods. Finally, it describes the future research work in this domain. © 2021, Pleiades Publishing, Ltd.
A useful scaffold based on acenaphthene exhibiting Cu 2+ induced excimer fluorescence and sensing cyanide via Cu 2+ displacement approach
(2012) Mohammad Shahid; Syed S. Razi; Priyanka Srivastava; Rashid Ali; Biswajit Maiti; Arvind Misra
A new simple organic scaffold based on acenaphthene 4 was designed and synthesized. The chromogenic and fluorogenic properties of 4 toward different metal ions and anions were investigated in H 2O/MeCN (8:2, v/v) solution. The probe 4 in the presence of Cu 2+ exhibited strong static excimer emission at 507 nm along with a decrease in monomer emission at ∼400 nm ratiometrically, attributed to a complexation through aldimine and amide groups of 4. Additionally, 4 upon interaction with different anions illustrated significant fluorescence enhancement with cyanide. However, interaction of complex, 4-Cu 2+ with CN - revealed fluorescence quenching attributed to formation of stable [Cu(CN) x] 1-x species in the medium. A naked-eye sensitive fluorescent green color of solution was changed to blue. The mechanism of interaction between 4 and Cu 2+ and sensing of cyanide through Cu 2+ displacement approach was confirmed by the change in optical behaviors and 1H NMR and ESI-MS spectral data analysis. © 2012 Elsevier Ltd. All rights reserved.
An azo based colorimetric probe for the detection of cysteine and lysine amino acids and its real application in human blood plasma
(Royal Society of Chemistry, 2014) Syed S. Razi; Rashid Ali; Priyanka Srivastava; Mohammad Shahid; Arvind Misra
The present work describes the rational design and synthesis of a simple azo based colorimetric chemodosimeter to selectively detect Cys and Lys in the environment of competitive different class of amino acids in HEPES buffer under physiological conditions. The probes 3a and 3b containing aldehyde functionality upon interaction with Cys and Lys afforded stable thiazolidine and aldimine derivatives and displayed a sensitive ratiometric response in the absorption spectra due to a change in the intramolecular charge transfer (ICT) process. The whole recognition process for amino acids gives rise to a rapid significant colorimetric response with readily detectable naked-eye sensitive color changes in the real biological sample. The mechanism of interaction between the probes and amino acids has been confirmed by the optical behavior, FT-IR, NMR and ESI-MS data analysis. © 2014 the Partner Organisations.
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
An efficient multichannel probe to detect anions in different media and its real application in human blood plasma
(Royal Society of Chemistry, 2014) Syed S. Razi; Rashid Ali; Priyanka Srivastava; Mohammad Shahid; Arvind Misra
A simple coumarin derived chromo and fluorogenic chemosensor has been synthesized and tested to detect anions in different medium. The designed chemosensor has shown a high colorimetric response for F- and AcO- ions in acetonitrile in which the color of solution changed from a yellow-green to red and orange respectively whereas, in aqueous medium the probe showed high fluorogenic response and selectively reacted with cyanide through a Michael type nucleophilic addition reaction in which a nonfluorescent (switched-off) color of the solution, "turn-on" to became fluorescent blue (switched-on). The multichannel mode of interaction between the probe and anions has been confirmed by absorption, emission, FT-IR, NMR, ESI-MS spectral data analysis. Moreover, the probe has shown high sensitivity to detect cyanide in a real sample, human blood plasma as well as on paper strips. This journal is © the Partner Organisations 2014.
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
Detection of Zn2+ ion on a reusable fluorescent mesoporous silica beads in aqueous medium
(2013) Mohammad Shahid; Priyanka Srivastava; Syed S. Razi; Rashid Ali; Arvind Misra
An efficient sensor system was designed and built by immobilizing a fluorescent bischromophoric dyad through a sol-gel reaction on mesoporous silica beads of high surface area. The silica supported dyad, SSD containing anthracene and naphthalimide moieties have shown high sensitivity and selectivity to detect Zn2+ among the tested cations in aqueous medium. The Job's plot analysis showed a 1:1 stoichiometry for a complexation between SSD and Zn2+ in which the relative fluorescence intensity enhanced, ̃6 times due to restricted photoinduced electron transfer reaction and color of the beads were changed from a fluorescent yellow green to blue. The reversible mode of complexation was tested in the presence of EDTA. © Springer Science+Business Media B.V. 2012.
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.
Fluorescence quenching of molybdenum disulfide quantum dots for metal ion sensing
(Springer, 2020) Himanshu Mishra; Vijay K. Singh; Rashid Ali; K. Vikram; Jai Singh; Arvind Misra; Hirdyesh Mishra; Anchal Srivastava
Abstract: In the present work, we have used hydrothermally synthesized in situ functionalized MoS2-QDs for a sensitive (limit of detection ~ 2.06 µM) and selective detection of Fe3+ ions. A detailed study of fluorescence quenching behavior for MoS2-QDs in the presence of Fe3+ ions has been performed using the Stern–Volmer plot, modified Stern–Volmer plot, and time-resolved photoluminescence measurements. Absorption based titration spectra and time-resolved photoluminescence measurements confirmed the fluorescence quenching is static with three decay times originated from the three different fluorescing sites. Interestingly, it is found that emission spectra consist of three bands at positions ~ 450 nm (P1, ~ 2.76 eV), ~ 475 nm (P2, ~ 2.61 eV), and ~ 503 nm (P3, ~ 2.46 eV). These peaks show a systematic quenching with the increasing concentration of Fe3+ ions. Quenching constants corresponding to these emission bands are found of the order of ~ 103 M−1. Large values of bimolecular quenching constants (~ 1011 M−1 s−1) suggest a strong binding interaction between MoS2-QDs and Fe3+ ions. Furthermore, to understand the fluorescence quenching of MoS2-QDs in the presence of Fe3+ ions, a ground-state complex formation-based mechanism has been proposed and elucidated in detail. Graphic abstract: [Figure not available: see fulltext.]. © 2020, Springer-Verlag GmbH Austria, part of Springer Nature.
Highly sensitive cell imaging Off-On fluorescent probe for mitochondria and ATP
(Elsevier Ltd, 2015) Priyanka Srivastava; Syed S. Razi; Rashid Ali; Saurabh Srivastav; Satyakam Patnaik; Saripella Srikrishna; Arvind Misra
A smart Off-On molecular scaffold/fluorescent probe 1 has been designed and synthesized. The probe has shown considerable photostability, cell permeability, organelle specificity and selectivity for ATP. The multicolor live cell imaging experiments in HeLa cells showed high selectivity of probe 1 for mitochondria with fluorescence turn-on response. As a proof of concept and promising prospects for application in biological sciences probe 1 has been utilized to detect ATP sensitively in a partial aqueous medium and intracellularly in HeLa cells. The favorable interaction between triphosphate unit of ATP and piperazine N atoms of probe 1 is attributed to synergistic effects of H-bonding and electrostatic interactions that encouraged the CH-π and π→π stacking between anthracene and purine rings. Consequently, the observed enhanced turn-on emission and a naked-eye sensitive blue-green color in the medium is attributable to arrest in photoinduced electron transfer (PET) process. © 2015 Elsevier B.V.