Browsing by Author "Vinod P. Singh"

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5-[{(2-Hydroxynaphthalen-1-yl)methylene}amino]pyrmidine-2,4(1H,3H)-dione as Al3+ selective colorimetric and fluorescent chemosensor
(2013) Vinod P. Singh; Karishma Tiwari; Monika Mishra; Nitin Srivastava; Satyen Saha
The synthesis and characterization of 5-[{(2-hydroxynaphthalen-1-yl) methylene}amino]pyrmidine-2,4(1H,3H)-dione (AMN), a tridentate Schiff base fluorescent sensor for selective determination of Al3+ in acetonitrile as well as in aqueous solution have been described. The AMN was characterized by IR, NMR, UV-vis and ESI-mass spectral analyses. UV-vis, fluorescence and 1H NMR titrations were performed to study the binding mode of AMN with Al3+. The AMN shows an enhanced fluorescence in the presence of Al3+ and forms 1:1 complex with Al3+. Other cations Na+, K+, Ca2+, Cr3+, Mn2+, Fe3+, Co2+, Ni2+, Cu 2+, Zn2+ and Hg2+ show no appreciable change in fluorescence intensity. The lowest detection limit for Al3+ in acetonitrile and water was determined to be 3.2 × 10-7 M and 1 × 10-6 M, respectively. © 2013 Elsevier B.V.
5-Fluorouracil and 5-fluorouracil-histidine complexes with AlIII, CrIII and FeIII ions and their antitumour activity
(Elsevier Ltd, 1997) Krishan K. Narang; Vinod P. Singh; D. Bhattacharya
Complexes of the type [M(L-H)(OH)Cl], [Cr(L-H)(H2O)2(OH)Cl] and [M′(L-H)(L′-H)(H2O)Cl], where L = 5-fluorouracil; L′ = histidine (HISD); M = AlIII or FeIII and M′ = AlIII, CrIII or FeIII were synthesized and characterized. The complexes are insoluble in water and common organic solvents. 5-Fluorouracil is coordinated to the metal ion through the O atom of C(4)=O and the N atom of N(1) while histidine coordinates through the O atom of - COO- and the N atom of - NH2 groups. The μeff values, electronic spectral bands and ESR spectra suggest a polymeric 6-coordinate spin free octahedral stereochemistry for CrIII and FeIII complexes. The in vivo antitumour effect of 5-fluorouracil and its complexes was examined on C3H/He mice against P815 murine mastocytoma. As evident from their T/C values CrIII and FeIII complexes display significant and higher antitumour activity compared to 5-fluorouracil while the AlIII complexes show lower activity. The in vitro results of the complexes on the same cells indicate that CrIII and FeIII complexes show higher inhibition on 3H-thymidine and 3H-uridine incorporation in DNA and RNA replication, respectively. © 1997 Elsevier Science Ltd.
8(E)-4-[{2-(2,4-dinitrophenyl)hydrazono}benzene-1,3-diol] as a solvatochromic Schiff base and chromogenic signaling of water content by its deprotonated form in acetonitrile
(Royal Society of Chemistry, 2014) Karishma Tiwari; Monika Mishra; Vinod P. Singh
A simple, cost effective Schiff base (E)-4-[{2-(2,4-dinitrophenyl) hydrazono}benzene-1,3-diol] (DBH) is synthesized and characterized by various physico-chemical and spectroscopic tools along with single crystal X-ray crystallography. This is the first report which describes its solvatochromism in solution and the signaling behavior of deprotonated DBH for the determination of water content in acetonitrile through UV-visible absorption spectra. Addition of acetate ions in acetonitrile solution of DBH results in the formation of deprotonated DBH. The effect of water content on the formation of deprotonated DBH is utilized in signaling. The deprotonated DBH exhibits a pronounced chromogenic signaling behavior that can be detected by the naked eye in response to the changes in water content in acetonitrile. Prominent color changes are observed up to 2% water content in acetonitrile and limit of detection (LOD) of the deprotonated DBH for determination of the water content in acetonitrile is calculated as 0.012%. © 2014 the Partner Organisations.
A chromogenic diarylethene-based probe for the detection of Cu2+ in aqueous medium in Drosophila for early diagnosis of Alzheimer
(Elsevier Ltd, 2024) Gautam Kumar; Ananya Srivastava; Prabhat Kumar; S. Srikrishna; Vinod P. Singh
A diarylethene-based probe (Z)-N'-((2-amino-5-chlorophenyl)(phenyl)methylene)-2-hydroxy benzohydrazide (KBH) has been proficiently developed and its structure has been confirmed by single crystal X-ray diffraction technique. It displays a selective and sensitive colorimetric sensing of Cu2+ ions in aqueous medium with a naked eye colour change from colourless to yellow. It exhibits a significantly low limit of detection as 1.5 nM. A plausible binding mechanism has been proposed using Job's plot, FT-IR, 1H NMR titration, HRMS and DFT studies. The chemosensor is effectively reversible and reusable with EDTA. Test strip kit and real water sample analysis have been shown to establish its practical applicability. Further, the potential of KBH for the early diagnosis of Cu2+ ion-induced amyloid toxicity has been investigated in eye imaginal disc of Alzheimer's disease model of Drosophila 3rd instar larvae. The in-vivo interaction of KBH with Cu2+ in gut tissues of Drosophila larvae establishes its sensing capability in biological system. Interestingly, the in-vivo detection of Cu2+ has been done using bright field imaging which eliminates the necessity of a fluorescent label, hence making the method highly economical. © 2024
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 dihydrazone based fluorescent probe for selective determination of Al3+ ions
(Elsevier, 2014) Divya Pratap Singh; Vinod P. Singh
A highly selective fluorescent sensor N,N′-bis((2-hydroxynaphthalen- 1-yl)methylene) oxalohydrazide (H2ohn) for the determination of Al3+ ions was synthesized and characterized by different physico-chemical and spectroscopic techniques. The single crystal structure of H2ohn receptor has also been reported. The H2ohn shows an enhanced fluorescence in the presence of Al3+ ions in ethanol-water (2:3 v/v) solution. Other cations viz. Na+, K+, Mg 2+, Ca2+, Mn2+, Fe3+, Co 2+, Ni2+, Cu2+, Zn2+, Pb 2+, Cd2+ and Hg2+ show no appreciable change in fluorescence intensity. The binding mode of H2ohn receptor with Al3+ was studied by UV-visible, fluorescence and 1H NMR titrations. The receptor acts as a dibasic hexadentate ligand and interacts with two Al3+ ions with a high binding constant KB=2. 62×1011 M-2. The lowest detection limit for Al 3+ complex of H2ohn was determined to be 8.56×10-10 M. The structures of H2ohn and its Al(III) complex were also optimized by DFT calculations. © 2014 Elsevier B.V. All rights reserved.
A highly selective coumarin-based chemosensor for dual sensing of Cu2+ and Zn2+ ions with logic gate integration and live cell imaging
(Royal Society of Chemistry, 2024) Avanish Kumar Singh; Amit Kumar Singh; Shashi Kant Sharma; Vijay Kumar Sonkar; Vinod P. Singh
In this paper, a coumarin-based Schiff base chemosensor has been synthesized and developed to detect Cu2+ and Zn2+ ions in nanomolar concentrations. The probe selectively distinguishes Cu2+ and Zn2+ from among several metal ions in DMF : H2O (7 : 3, v/v, pH 7.4) HEPES buffer. The structure of the probe and its sensing behavior were investigated by FT-IR, UV-vis, fluorescence, HRMS, and NMR analyses, along with X-ray crystallography and computational studies. CIH detects Zn2+ and Cu2+ using different strategies: CHEF-induced fluorescence enhancement and paramagnetic fluorescence quenching, respectively. Job's plots show a 1 : 1 binding interaction between CIH and Cu2+ or Zn2+ ions. The binding constant values for Cu2+ (1.237 × 105 M−1) and Zn2+ (1.24 × 104 M−1) suggest a better ability for Cu2+ to interact with CIH than Zn2+. An extremely high sensitivity of the probe was highlighted by its very low detection limits (LOD) of 5.36 nM for Cu2+ and 3.49 nM for Zn2+. The regeneration of the probe with the addition of EDTA in its complexes allows the formation of molecular logic gates. CIH has been successfully employed in mitotracking and intracellular detection of Zn2+ and Cu2+ in SiHa cells. © 2024 The Royal Society of Chemistry.
A highly sensitive and selective fluorescent sensor for Al3+ ions based on thiophene-2-carboxylic acid hydrazide Schiff base
(Royal Society of Chemistry, 2013) Karishma Tiwari; Monika Mishra; Vinod P. Singh
An efficient fluorescent receptor (E)-N-[(2-hydroxy-naphthalen-1-yl) methylene]thiophene-2-carbohydrazide (THN) for Al3+ ions was synthesized and characterized by physicochemical and spectroscopic tools along with single crystal X-ray crystallography. This is the first report showing the crystal structure of THN and its sensing property for Al3+ ions. THN selectively and sensitively detects Al3+ ions without any interference among various cations, Na+, K+, Ca 2+, Cr3+, Mg2+, Mn2+, Fe 3+, Co2+, Ni2+, Cu2+, Zn 2+ and Hg2+ by a strong fluorescent change in ethanol-water medium (EtOH-H2O, 1:4 v/v). The THN interacts with Al3+ in a tridentate mode to form a [AlCl2(THN)(H 2O)]·H2O complex. The binding constant was determined to be 7.06 × 106 M-1 and the limit of detection (LOD) was calculated to be 1.35 × 10-9 M which is the second highest reported till date in the literature. The 1H NMR titration, ESI-MS and DFT studies have also been performed in support of the binding details of the THN-Al3+ complex. © The Royal Society of Chemistry 2013.
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 multifunctional coumarin-based probe for distinguishable detection of Cu2+ and Zn2+: its piezochromic, viscochromic and AIE behavior with real sample analysis and bio-imaging applications
(Royal Society of Chemistry, 2023) Aayoosh Singh; Pranjalee Yadav; Saumya Singh; Pradeep Kumar; S. Srikrishna; Vinod P. Singh
A multifunctional coumarin based organic luminophore, CTH, has been synthesized and its fluorescence properties are investigated. The probe displays the properties of aggregation-induced emission (AIE), viscochromism, piezochromism and distinguishable flourometric sensing of Cu2+ and Zn2+ ions. The molecular structure of the probe has been determined by FT-IR, UV-Vis, NMR, and HRMS spectral studies. Powder XRD, dynamic light scattering (DLS), scanning electron microscopy (SEM), differential scanning calorimetry (DSC) and density functional theory (DFT) calculations have been carried out to explore the photo-physical properties of the synthesized probe. CTH is non-emissive in ethanol, but upon adding water its emission intensity increases by 8-fold and fluorescence quantum yield increases from Φ = 1.19 × 10−3 (fw = 70%) to Φ= 8.50 × 10−3 (fw = 99%), indicating typical AIE behaviour. The probe demonstrates excellent viscochromism with increasing glycerol fraction in EtOH. Upon grinding, the probe exhibits piezochromic properties and shows an emissive color change from blue to bright green along with a bathochromic shift of 83 nm. In addition to the aforementioned properties, the probe selectively discriminates Cu2+ and Zn2+ from a pool of different metal ions in DMF : H2O (3 : 7, v/v, pH 7.4) HEPES buffer. CTH detects Cu2+ and Zn2+ ions via paramagnetic fluorescence quenching and CHEF induced fluorescence enhancement, respectively. Job's plots suggest 1 : 1 binding stoichiometry for both CTH-Cu2+ and CTH-Zn2+ complexes. Significant low detection limits (LODs) of 6.75 nM for Cu2+ and 2.97 nM for Zn2+ have been observed and molecular logic gates have also been constructed. The probe has been effectively utilized in the bio-imaging of Cu2+ and Zn2+ in the gut tissue of Drosophila and in the quantification of Cu2+ and Zn2+ in real water samples. © 2023 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 efficient probe for dual mode recognition of Al3+ and Cu2+ with logic gate behaviour: Crystal structure, theoretical and in-vivo bio-imaging investigations
(Elsevier B.V., 2022) Pranjalee Yadav; Rohit Kumar; S. Srikrishna; Anoop Kumar Pandey; Lokman H. Choudhury; Chandan Upadhyay; Vinod P. Singh
This work presents the synthesis, characterization, crystal structure and spectroscopic investigations of isophthalohydrazide based probe. Among various tested metal ions, the probe selectively detects Al3+ and Cu2+ in aqueous ethanol via fluorometric and colorimetric methods, respectively. It displays a fluorescence “turn-on” response with Al3+ and visual colour change from colourless to yellow with Cu2+. Sensing mechanism is explored with UV–Vis, fluorescence spectroscopy and 1H NMR titration, and confirmed with computational results. Suppression of C[dbnd]N isomerization and photo-induced electron transfer (PET) along with chelation enhanced fluorescence emission (CHEF) result in “turn-on” fluorescence with Al3+ while ligand to metal charge transfer (LMCT) accounts for visual colour change with Cu2+. Job's plot and HRMS confirm 1:2 (L:M) stoichiometry. The probe also exhibits efficient reversibility and reproducibility with EDTA which are successfully mimicked with combinatorial logic gate and truth table. Additionally, solid state applications and bio-imaging investigation on gut tissue of Drosophila 3rd instar larvae are performed. © 2021 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.
A water soluble, highly sensitive and selective fluorescent probe for Al3+ ions and its application in live cell imaging
(Elsevier B.V., 2017) Shraddha Rani Gupta; Priya Singh; Biplob Koch; Vinod P. Singh
An efficient, aminothiazole based, fluorescent probe (E)-2-(2-aminothiazol-5-yl)-N'-((2-hydroxynaphthalen-1-yl)methylene)acetohydrazide (NTH) for the detection of Al3+ ions was synthesized and characterized by different physico-chemical and spectroscopic tools. An attractive glowing blue color was observed in the presence of Al3+ with single channel emissions for NTH (λem 451 & λex 391 nm). NTH, selectively detected Al3+ ions among various other ions without any significant interference in Tris-HCl buffer solution (10 mM, pH ∼ 7.4). The >C[dbnd]N– isomerization was responsible for the turn ‘on’ fluorescence response after Al3+ binding. The stoichiometry of NTH with Al3+ was determined to be 1:1 by Job's plot. The binding constant and limit of detection (LOD) were observed as 3.65 × 109 M−1 and 1.09 × 10−9 M, respectively. The 1H NMR titration and DFT studies were also performed in support of binding details of NTH-Al3+ complex. MTT assay on live A549 cells suggested viability of the probe to A549 cells even at higher concentration (100 μM) with no serious cytotoxicity in cells. Live cell imaging study clearly indicated that the accumulation of Al3+ in the cytoplasm of cells could be detected by NTH. © 2017 Elsevier B.V.
Aluminium(III), chromium(III) and iron(III) complexes with 5-iodouracil and 5-iodouracil-histidine and their antitumour activity
(2009) Vinod P. Singh; Shweta Singh; K.K. Narang; D. Bhattacharya
Complexes of the type [Al(HL)(OH)Cl2], [M(HL)(OH)2 Cl] and [M′(HL)(L′)(OH)Cl], where HL = 5-iodouracil; HL′ = histidine; M = Cr(III), Fe(III) and M′ = Al(III), Cr(III), Fe(III), were synthesized and characterized. The complexes are polymeric showing high decomposition points and are insoluble in water and common organic solvents. The μeff values, electronic spectral bands and ESR spectra suggest a polymeric 6-coordinate spin-free octahedral stereochemistry for the Cr(III) and Fe(III) complexes. 5-Iodouracil acts as a monodentate ligand coordinating to the metal ion through the O atom of C(4) = O while histidine through the O atom of -COO- and the N atom of -NH2 group. In vivo antitumour effect of 5-iodouracil and its complexes was examined on C3H/He mice against P815 murine mastocytoma. As evident from their T/C values, Cr(III) and Fe(III) complexes display significant and higher antitumour activity compared to the 5-iodouracil ligand. The in vitro results of the complexes on the same cells indicate that Cr(III) and Fe(III) complexes show higher inhibition on 3 H-thymidine and 3H-uridine incorporation in DNA and RNA replication, respectively, at a dose of 5 μg/mL.
Construction of Spiropyrroloindolines by Dearomative [3+2]-Cycloaddition of Indoles with Oxindole-Embedded Azaoxyallyl Cations
(Georg Thieme Verlag, 2023) Bandana Singh; Tishyasoumya Bera; Vinod P. Singh; Priyasha Priyasha; Dinabandhu Das; Jaideep Saha
A dearomative [3+2]-cycloaddition reaction of oxindoleembedded azaoxyallyl cations with indoles at the C3 position has been developed. The use of this new class of azaoxyallyl cation species in the reaction permits access to more-elaborate hexahydropyrrolo[2,3-b]indole moieties that contain a spiro-oxindole ring. The transformation displays a broad substrate scope and good regio- and stereoselectivity for the cycloaddition step. Several observations suggested that this class of azaoxyallyl cations can display a different reactivity pattern from those of commonly employed azaoxyallyl cation systems. © 2022. Thieme. All rights reserved.
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.