Browsing by Author "Rimpi Bhandari"

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A PET based pH-responsive bridged organic scaffold exhibiting sensitivity for lysosome and Hg2+ ion through fluorescence Off–On–Off response
(Elsevier B.V., 2024) Rimpi Bhandari; Ravisen Rai; Mohammed Kaleem; Nikita Shraogi; Satyakam Patnaik; Arvind Misra
A 1,5–bis(1,4-piperazinyl–naphthalimide–N–ethylmorpholine) pyridine based flexible fluorescence probe 7 is designed, synthesized, and its photophysical behavior has been examined in different media. The photophysical behavior of probe 7 in phosphate (PBS) buffer (10 % DMSO) showed pH sensitivity and selectivity for Hg2+ ion in solution and live cell with a change in naked-eye sensitive visible color. In acidic medium (pH ≤ 6) probe 7 showed enhanced (∼21 fold) “turn–On” emission, while at pH ≥ 7.4 probe 7 remained in the “turn–Off” state. The observed fluorescence “turn–On” response is attributed to inhibition in photoinduced electron transfer (PET) process. Jobs plot analysis revealed a 1:2 stoichiometry for an interaction between probe 7 and Hg2+ ion with good limit of detect (LOD) 5.78 × 10−8 M (57 nM). The reversibility in complexation and the mode of interaction were confirmed by EDTA and through NMR and HRMS spectroscopic data. MTT assay and cell imaging studies showed biocompatibility of the probe 7 to detect lysosomes and Hg2+ ion in A549 cells. For analytical application paper strip test was performed to detect Hg2+ ion with naked-eye sensitive visible color change. © 2023 Elsevier B.V.
A sensitive molecular probe exhibiting significant change in their photophysical and morphological behavior upon interaction with Fe3+ ion
(Elsevier B.V., 2025) Rimpi Bhandari; Mohammed Kaleem; Ravisen Rai; Nikita Shraogi; Satyakam Patnaik; Arvind Misra
An efficient molecular probe 8 has been designed and synthesized. The photophysical, electrochemical and morphological behavior of the probe has been examined in the absence and presence of different ions. The probe 8 at 90 % water fraction in acetonitrile showed aggregation induced emission (AIE). Probe 8 upon interaction with ions binds with Fe3+ ion selectively in a 1:1 stoichiometry and showed fluorescence “turn-Off” response with good limit of detection (LOD = 92.2 nM). The particle size (DLS method) of probe upon increasing water fraction in acetonitrile showed a gradual increase while upon formation of a stable complex, 8 + Fe3+ particle size decreased along with change in morphology of the probe. SEM and TEM studies showed that in pure acetonitrile probe self-assemble into a sheet like structure of uneven surface. While in aggregated state (fw, 90 %) it changes to a uniform hollow rectangular rod shape structure. Further interaction of the probe with Fe3+ ions in aggregated state acquired a well-defined smooth sheet. Electrochemical (CV) studies suggested that the redox property of the probe incurred a marginal change in band gap upon complexation with Fe3+. The cell imaging studies were performed to detect Fe3+ in HeLa cells. The paper strip test and real water sample analysis showed the potential analytical application of probe to detect Fe3+ with a naked-eye sensitive visible color change. The formation of a complex, 8 + Fe3+ involving N and O atoms of the probe molecule was confirmed by 1HNMR and HRMS data. © 2024 Elsevier B.V.
A simple TICT/ICT based molecular probe exhibiting ratiometric fluorescence Turn-On response in selective detection of Cu2+
(Elsevier B.V., 2023) Ravisen Rai; Rimpi Bhandari; Mohammed Kaleem; Nilesh Rai; Vibhav Gautam; Arvind Misra
The work reported herein describes photophysical behavior of a new fluorescent probe APDA. The probe exhibited sensitivity for Cu2+ ion in 80% aqueous acetonitrile medium. Probe shows dual emission due to TICT and ICT states and upon interaction with different metal ions Cu2+ induces hydrolysis of imine bond to rejuvenate aldehyde derivative with ratiometric “turn–On” fluorescence response, through ICT state while emission due to TICT state get diminished. Similarly, the synthesized model compound ADA under similar experimental condition supported hydrolysis of imine bond in the presence of copper. Jobs plot analysis, based on emission titration data suggested a 1:1 binding stoichiometry between probe APDA and Cu2+ ion. The limit of detection (LOD) was found to be 4.4 × 10-8 M (44 nM). The probe has been applied on test paper strip to detect Cu2+ ion with naked-eye sensitive response. Also, the cell imaging studies revealed the potential applicability of probe to detect Cu2+ ion in live cells. The mechanism of sensing was confirmed by 1H, 13C NMR, FTIR and mass spectrometry data analysis. © 2023 Elsevier B.V.
An Anthracene-Imidazoanthraquinone Conjugate Exhibiting Ratiometric Fluorescence Turn – on Behavior with CN− and F− Anions
(John Wiley and Sons Inc, 2025) Ravisen Rai; Mohammed Kaleem; Rimpi Bhandari; Arvind Misra
A new conjugate, 2-(4-(anthracen-9-yl) phenyl)-[1,2-d]imidazole-1H-anthraquninone (AQI) has been designed and synthesized as a molecular probe 4. The photophysical and electrochemical behavior of the probe in the absence and presence of different class of ions were examined in acetonitrile solution. The probe 4 with F− and CN− anions showed ratiometric fluorescence “turn – On” response due to variation in ICT processes. Cyclic voltammetry of probe exhibited reversible redox behavior wherein the band gap (Eg =1240/λmax) of probe (ΔE =3.220 eV) decreased (~2.583 eV) after the interaction with F− and CN− anions. The probe interacted with both anions in a 1 : 1 stoichiometry with good binding constants (KF−=.05×106 M−1 and KCN− = 1.46×106 M−1) and limit of detection/quantification (LOD/LOQ) in nM range. pH studies showed that probe 4 has potential to detect the anions under physiological conditions (between pH 6–10). The probe upon interaction with both F− and CN− anions showed a naked-eye sensitive color change in solution and on test paper strips. The probable complexes, 4+F−/CN− upon interaction with trifluoroacetic (TFA) acid showed reversible behavior wherein the intensity of probe rejuvenated. The output emission signal of the probe upon providing F− and TFA as a chemical inputs mimic the function of a memory device with ‘‘write–read–erase–read’’ functions and has also been utilized to construct a molecular key-pad lock security device system. Also, the probe showed sensitivity to detect the F− in toothpaste. The mechanism of interaction has been confirmed by different spectroscopic data analysis. © 2025 Wiley-VCH GmbH.
An Efficient Fluorescent Probe Based on Triphenylimidazole End-Capped Diketopyrrolopyrrole for Selective Detection of CN− and TFA Through On–Off–On Response
(John Wiley and Sons Ltd, 2025) Arvind Kumar Misra; Rimpi Bhandari; Mohammed Kaleem; Ravisen Rai; Tripathi Shivam Saroj Kumar
A triphenyl-imidazole end-capped donor–acceptor type potential molecular probe 3 has been designed and synthesized. Probe 3 upon interaction with different classes of metal ions/anions and NPPs displayed high selectivity with CN− anion (LOD = 20.42 nM) through fluorescence “turn-Off” response and a naked-eye sensitive visible color change. Job's plot analysis revealed a 1:2 binding stoichiometry. The interaction of 3.CN− with trifluoroacetic acid (TFA) showed reversible behavior wherein the intensity of the probe rejuvenated, fluorescence “turn On-Off-On response,” along with a change in color of the medium. The change in rate constants and fluorescence lifetime of the probe suggested that the interaction of probe with CN− occurred in two steps: H-binding and deprotonation of –NH functions of imidazolyl units. The mode of binding of probe with CN− was confirmed by 1H NMR, FTIR, and HRMS data. The potential application of molecular probe has been examined to detect the CN−, TFA, and TFA vapor on test paper strips. The smartphone-based RGB analysis of paper strips also supported on-site colorimetric detection of CN−. Probe shows good recovery percentage of CN− in real water sample analysis. The output emission using chemical inputs CN− and TFA mimics the function of an IMP logic gate. © 2025 John Wiley & Sons Ltd.
An Imidazole-Naphthalimide-Based pH-Sensitive Molecular Probe for Selective Detection of Picric Acid and Cell Imaging
(American Chemical Society, 2024) Ravisen Rai; Rimpi Bhandari; Mohammed Kaleem; Nikita Shraogi; Satyakam Patnaik; Hirdyesh Mishra; Arvind Misra
A new naphthalimide core containing molecular probe has been designed and synthesized. The photophysical properties of the probe in solvents of different polarities showed solvatochromic behavior. Probe displayed a weak aggregation-induced emission in THF-water (fw; 80%-90%) with a blue shift. Studies under a wide pH range (HEPES buffer) displayed significant fluorescence quenching under acidic medium. Probe showed “Off-On” behavior under acid and alkaline conditions. Probe upon interaction with different classes of ions and nitroaromatic compounds (NACs) displayed remarkable fluorescence quenching (switched-Off) with picric acid (PA) selectively in aqueous-THF (9:1, v/v) solution. Similarly, upon interaction with different biomolecules and anions, a probable complex of probe with picric acid (5.PA) showed enhanced emission with uric acid (UA) selectively. Interestingly, the quenched emission of 5.PA was rejuvenated upon interaction with UA and the OH- ion. Job’s plot analysis revealed a 1:2 binding stoichiometry between probe and PA with a binding constant of 2.26 × 108 M-2 and a limit of detection (LOD) of 1.19 × 10-7 M (119 nM). Also, the 5.PA could able to detect UA with an LOD of 3.05 × 10-7 (305 nM). The optical behavior of the probe was utilized to detect the PA and UA on test paper strips through color changes that are visible with the naked eye. Additionally, the cell imaging studies showed affinity of the probe for lysosomes as well as the ability to detect PA sensitively. The “On-Off” switching behavior of the probe upon providing sequential chemical inputs of PA and OH- ion mimics the “write-read-erase-read” functions and IMPLICATION logic gate. © 2024 American Chemical Society
Boron-Salphen Conjugate based Molecular Probe Exhibiting Fluorescence On-Off-On Response in Detection of Cu2+ and ATP through Displacement Approach
(John Wiley and Sons Ltd, 2024) Rimpi Bhandari; Ravisen Rai; Mohammed Kaleem; Rajesh Pratap; Nikita Shraogi; Satyakam Patnaik; Subrato Bhattacharya; Arvind Misra
Synthesis and photophysical properties of a fluorescent probe HBD is described. Probe upon interaction with metal ions, anions and nucleoside pyrophosphates (NPPs) showed fluorescence quenching with Cu2+ due to chelation enhanced quenching effect (CHEQ). Moreover, interaction of ensemble HBD.Cu2+ with anions and NPPs showed fluorescence “turn-On” response with ATP selectively. “On-Off-On” responses observed with Cu2+ and ATP is attributed to an interplay between ESIPT and TICT processes. Cyclic voltammogram of probe exhibited quasi-reversible redox behaviour with three oxidation and two reduction potentials and the change in band gaps of probe suggested the interaction with Cu2+ and ATP. The 2 : 1 and 1 : 1 binding stoichiometry for an interaction between probe and Cu2+ (LOD, 62 nM) and ensemble, HBD.Cu2+ with ATP (LOD, 0.4 μM) respectively are realised by Job's plot and HRMS data. Cell imaging studies carried out to detect Cu2+ and ATP in HeLa cells. Also, the output emission observed with Cu2+ and ATP is utilized to construct an implication (IMP) logic gate. Test paper strips showed naked-eye visible color responses to detect Cu2+ and ATP. In real water samples probe successfully detected copper (0.03 μM) between 5–6.5 ppb level (ICP-MS method). © 2024 Wiley-VCH GmbH.
Photochemical and electrochemical behavior of a molecular probe: Fluorescence on-off-on response to detect multiple ions (Cu2+, ClO− and CN−) with different rate of reaction
(Elsevier Ltd, 2025) Mohammed Kaleem; Ravisen Rai; Rimpi Bhandari; Hirdyesh Mishra; Arvind Misra
A molecular probe 3 containing phenyl substituted imidazolyl unit and diaminomaleonitrile (DAMN) moiety has been synthesized and characterized. Photophysical and electrochemical behavior probe 3 were studied in partial aqueous medium (ACN/H2O, 9.5:0.5 v/v). Probe 3 upon interaction with different class of ions showed sensitivity for Cu2+, ClO− and CN− ions with different response time and reaction rates due to variation in intramolecular charge transfer (ICT) process. Both Cu2+ and ClO− ions displayed enhanced emission due to hydrolysis of imine bond to form compound 2 in the medium whereas, with CN− fluorescence quenching was observed due to the deprotonation of –OH/–NH2 functions. The kinetic and optical behavior of the probe suggested that interaction occurred in two steps with Cu2+ (complexation and hydrolysis; absk1,2,3(Cu2+) = 1.17, 0.74 and 0.06 s−1) and ClO− (hydrolysis and deprotonation; absk1,2(ClO−) = 3.0 and 0.60 s−1) ions while CN− (absk1,2(CN−) = 2.13 and 1.66 s−1) induces deprotonation in one step. The interaction of probe 3 with ClO− was relatively fast than with Cu2+/CN− ions. Job's plot analysis between probe 3 and ions revealed a 1:1 (Cu2+/ClO−) and 1:2 (CN−) ratio stoichiometry with good limit of detection (nM) and binding affinity (LOD, 17; KCu2+ = 3.23 × 106 M−1; LOD, 18.5; KClO− = 5.23 × 105 M−1 and LOD, 23.2; KCN− = 5.50 × 109 M−2) respectively. Probe 3 displayed a naked–eye sensitive fluorescence response to detect tested ions on test paper strips and good recovery percentage of ions in real water sample analysis. © 2024 Elsevier Ltd