BITS Faculty Publications
Permanent URI for this communityhttp://localhost:4000/handle/123456789/1867
Browse
32 results
Search Results
Item A water-soluble turn-on fluorescent probe for detection and plant bioimaging of AI3+ and AS3+ ions(Wiley, 2025-04) Khungar, BhartiAn imidazolium salt (E)-3-(hydroxy-4-(((2-hydroxyphenyl) imino) methyl) benzyl)-1-methyl-1 H-imidazol-3-ium chloride (HBIm) is synthesized and evaluated for its fluorescence behavior toward metal ions. The probe detected Al3+ and As3+ ions when excited at 326 nm in an aqueous medium. The nonfluorescent HBIm exhibited a “turn-on” fluorescence response upon being treated with Al3+ (λem = 510 nm) and As3+ (λem = 499 nm) ions due to the chelation-enhanced fluorescence effect. The detection limits for Al3+ and As3+ are low and are found to be 0.38 and 2.37 nM, respectively. Furthermore, the binding constants for these ions are significantly high, 1.59 × 105 M−1 for Al3+ and 3.54 × 104 M−1 for As3+. The binding mechanism between HBIm and Al3+ and As3+ ions is supported by various techniques, including ESI-MS, Job's plot, 1H NMR, X-ray photoelectron spectroscopy, SEM-EDS, and density functional theory studies. The reversibility experiments are conducted using EDTA ions to develop the corresponding logic gates. HBIm has the potential to detect Al3+ and As3+ ions in real samples, such as plant cells, tissues, and water samples.Item Recent advancement on peptide-based fluorescent/colorimetric sensors for metal ion detection(Wiley, 2025-10) Khungar, Bharti; Sakhuja, RajeevModernization and technology development lead to an increase in the contamination of toxic metal ions into the direct environment. Unlike the other pollutants, metal ions cannot be degraded by chemical or biological ways, and are hard to abolish. To check and regulate metal ion contamination, numerous advancements have been wittnessed to develop the materials that can sense particular metal ion selectively with synchronized variation in their optical behavior. In this realm, peptide serves as a toolbox with exceptional advantages over other chemical-based metal sensors owing to specific properties, such as biocompatibility, low toxicity, high selectivity, and environment friendly nature. In addition, short peptides affixed with fluorophores have been rationally designed to exhibit high specificity for metal ions by providing multiple coordination sites in their side chains with functionalities, including thiols, amines, carboxyls, and imidazoles, exhibiting promising applications in environmental monitoring, medical diagnostics, and biochemical research. Under this realm, fluorescence-based peptide sensors have been studied for rapid and on-site detection of metal ions, including Fe3+, Ni2+, Ag1+, Cu2+, Zn2+, Cd2+, Pb2+, Hg2+, As3+, and Al3+ following various photophysical pathways. This review showcases the recent advancements on the development of peptide-fabricated metal sensing agents and their mechanism of metal binding accompanied with photophysical changes.Item Two-pot synthesis of indolizinoindole derivatives via lewis acid-mediated intramolecular regioselective cyclization of 3-acylpyrroles(Wiley, 2025-02) Khungar, Bharti; Kumar, IndreshA two-pot method has been developed to access indolizino[8,7-b]indole derivatives through Lewis acid-mediated regioselective C5-cyclization of 3-acylpyrrole prepared from the feedstock materials. The overall reaction proceeds through amine-catalyzed direct aldol reaction/Paal-Knorr reaction/oxidation between succinaldehyde, aromatic aldehyde, and tryptamine in a sequential multicomponent fashion for N-alkyl pyrrole followed by dearomative cyclization. A series of substituted indolizino[8,7-b]indoles have been prepared with good yields and excellent regioselectivity.Item Pyridinium-based schiff-base fluorescent chemosensor for sequential detection of al3+ ions and tnp: applications in cell imaging and latent fingerprint visualization(Wiley, 2024-12) Jha, Prabhat Nath; Khungar, BhartiA fluorescent pyridinium-based chemosensor (E)-1-(2-(3-hydroxy-4-((pyridin-2-ylimino) methyl) phenoxy) ethyl) pyridin-1-ium bromide (BzPySB) was synthesized and characterized using various spectroscopic techniques. The chemosensing potential of BzPySB was explored using UV-vis and fluorescence spectroscopy in the aqueous medium. The turn-on fluorescence behavior was observed for BzPySB in the presence of Al3+, while other metal ions were non-responsive. The B−H and Job′s plot confirmed the 1 : 1 stoichiometric ratio of the BzPySB and Al3+. The in situ generated complex BzPySB-Al3+ offered selectivity toward TNP via fluorescence turn-off phenomena with high Ksv and LOD values. The “off-on-off” sensing mechanism was elucidated through 1H NMR, mass spectrometry, and DFT calculations. The probe also detected Al3+ in plant and MCF-7 cells, highlighting its potential in biological systems. Moreover, BzPySB exhibited solid-state luminescent properties credited to weak π-π interaction, leading to its successful application in the visualization of latent fingerprints.Item Two-pot sequential multicomponent metal-free synthesis of pyrrolo[2,3-d]pyridazin-7-ones and pyrrolo[2,3-d]pyrizidines(RSC, 2023) Khungar, Bharti; Kumar, IndreshMetal-free rapid access to pyrrole-2,3-dione has been developed under mild conditions from easily available materials, which was utilized to synthesize pyrrolo[2,3-d]pyridazin-7-one's and pyrrolo[2,3-d]pyrizidines. The overall two-pot process proceeds through (i) the first pot, metal-free direct Mannich reaction-oxidative aromatization of succinaldehyde with C-acyl imine in situ generated to pyrrole-2,3-dione, and (ii) the second pot, further condensation with various hydrazines to synthesize several pyrrolo-pyrizidinones and pyrrolo-pyrizidines in moderate to good yields.Item A Deep Learning Approach for Molecular Crystallinity Prediction(Springer, 2019-05) Khungar, BhartiWith the success of Convolutional Neural Networks (CNN) in computer vision domain, cheminformatics is slowly moving away from feature Engineering towards Network Engineering. New deep networks and approaches are being proposed to explore the chemical behavior and their properties. In this paper, we propose a deep learning approach using Convolutional Neural Network for predicting the crystallization propensity of an organic molecule. The work is inspired from Chemception and architecture is based on the Inception-Resnet v2 model. The proposed approach only requires a 2D molecular drawing to predict if the molecule has a good probability of forming crystals, without the need of any molecular descriptor, any advanced chemistry knowledge or any study of crystal growth mechanisms. We have evaluated our approach on the Cambridge Structural Database (CSD) and the ZINC datasets. Compared with the machine learning approach of generating molecular descriptors plus SVM classification, our proposed approach gives a better classification accuracy.Item Bis-Cinnamamide Derivatives as APE/Ref-1 Inhibitors for the Treatment of Human Melanoma(MDPI, 2022) Khungar, BhartiHuman malignant melanoma exhibits imbalances in redox status, leading to activation of many redox-sensitive signaling pathways. APE/Ref-1 is a multifunctional protein that serves as a redox chaperone that regulates many nuclear transcription factors and is an important mechanism in cancer cell survival of oxidative stress. Previous studies showed that APE/Ref-1 is a potential druggable target for melanoma therapy. In this study, we synthesized a novel APE/Ref-1 inhibitor, bis-cinnamoyl-1,12-dodecamethylenediamine (2). In a xenograft mouse model, compound 2 treatment (5 mg/kg) significantly inhibited tumor growth compared to the control group, with no significant systemic toxicity observed. We further synthesized compound 2 analogs to determine the structure-activity relationship based on their anti-melanoma activities. Among those, 4-hydroxyphenyl derivative (11) exhibited potent anti-melanoma activities and improved water solubility compared to its parental compound 2. The IC50 of compound 11 was found to be less than 0.1 μM. Compared to other known APE/Ref-1 inhibitors, compound 11 exhibited increased potency in inhibiting melanoma proliferation. As determined by luciferase reporter analyses, compound 2 was shown to effectively inhibit H2O2-activated AP-1 transcription activities. Targeting APE/Ref-1-mediated signaling using pharmaceutical inhibitors is a novel and effective strategy for melanoma treatment with potentially high impact.Item A pyrazinium-based fluorescent chemosensor for the selective detection of 2,4,6-trinitrophenol in an aqueous medium(RSC, 2022) Khungar, BhartiSensing nitroaromatic explosives has gained significant attention due to both increased terrorist threats and a need for environmental protection. In this regard, a fluorescent chemosensor, 1-benzyl-3,5-di(thiophen-2-yl)pyrazin-1-ium bromide (BTPyz), was synthesized and characterized via spectroscopic methods. The photophysical properties were investigated using absorption and emission spectral analysis. As a fluorescent chemosensor, BTPyz exhibited a selective response towards 2,4,6-trinitrophenol (TNP) with a detection limit of 11.6 nM and quenching constant (KSV) of 3.8 × 104 M−1. The fluorescence quenching mechanism was attributed to ground-state charge-transfer complex formation and resonance energy transfer, as evident from Uv-visible, fluorescence and NMR spectroscopy, single-crystal XRD studies, and density functional theory calculations. BTPyz was also employed for the contact mode detection of TNP on paper strips. The detection of TNP in real water and soil samples demonstrated BTPyz to be a promising detection tool toward environmental specimensItem Abnormal NHC Palladium(II) Complex Containing CNN Pincer Skeleton and Its Application to Suzuki-Miyaura Coupling of Aryl Chlorides in Water(Wiley, 2023-05) Khungar, BhartiThe excellent catalytic activities of abnormal NHC carbene complexes, where the C2 position remains unaffected, and coordination occurs at the C4 or C5 position of the imidazolium ring, is still a fascinating but scarce area of research. This present work reports a palladium complex (LPdBr) bearing abnormal NHC with CNN pincer architecture. It is synthesized from imidazolium-based quinoline ligand (LH) with Pd(OAc)2 via -NH and carbene deprotonation. The complex was fully characterized by NMR spectroscopy (1D and 2D) and high-resolution mass spectrometry (HRMS). The structure and abnormal coordination modes of the complex are further confirmed with the help of single-crystal X-ray diffraction. The studies revealed the abnormal coordination mode in LPdBr where C5 carbon of the imidazolium ring participates in bonding, leaving the C2 position unaffected. The catalytic potential of complex LPdBr was investigated in the Pd-catalyzed Suzuki-Miyaura coupling of various aryl/heteroaryl chlorides with different aryl/naphthyl/phenanthryl boronic acids. The catalyst LPdBr successfully activated various less-activated aryl chloride substrates. LPdBr also exhibited good catalytic activity at 1 mol% Pd loading under microwave irradiation and in green solvent water. The mechanism of the catalytic cycle is investigated and proposed by HRMS.Item Luminescent triazolo-fused pyrido[3,4-b]pyrazines as novel fluorophores(Elsevier, 2024-12) Khungar, Bharti; Sakhuja, RajeevA series of organic fluorophores based on novel [1,2,4]triazolo [4′,3':1,2]pyrido [3,4-b]pyrazine architecture were synthesized by a simple two-step protocol. Synthesized organic fluorophores exhibit blue-to-green fluorescence and their UV absorption and fluorescent emission properties were studied. The photophysical properties of synthesized derivatives were tuned by introducing functionalities of varying electronic nature on the core nucleus. The luminescence maxima of the synthesized compounds are found in the range from 427 nm to 503 nm, and the quantum yields ranging from 0.01 to 0.64 were calculated. Among various synthesized molecules, 3-(4-bromophenyl)-8,9-bis(4-methoxyphenyl)-[1,2,4]triazolo [4′,3':1,2]pyrido [3,4-b]pyrazine showed highest quantum yield (ΦF = 0.64), and was further explored for its solvatochromic, acidochromic, aggregation induced fluorescence studies along with theoretical HOMO-LUMO calculations