Browsing by Author "Jitendra Kumar Yadav"

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Axial ligand-induced high electrocatalytic hydrogen evolution activity of molecular cobaloximes in homo- and heterogeneous medium
(Royal Society of Chemistry, 2024) Jitendra Kumar Yadav; Baghendra Singh; Anjali Mishra; Sarvesh Kumar Pal; Nanhai Singh; Prem Lama; Arindam Indra; Kamlesh Kumar
Three new molecular cobaloxime complexes with the general formula [ClCo(dpgH)2L] (1-3), where L1 = N-(4-pyridylmethyl)-1,8-naphthalimide, L2 = 4-bromo-N-(4-pyridylmethyl)-1,8-naphthalimide, L3 = 4-piperidin-N-(4-pyridylmethyl)-1,8-naphthalimide, have been synthesized and characterized by UV-Vis, multinuclear NMR, FT-IR and PXRD spectroscopic techniques. The crystal structures of all complexes have also been reported. The electrocatalytic activity of complexes is investigated under two catalysis conditions: (i) homogeneous conditions in acetonitrile using acetic acid (AcOH) as a proton source and (ii) heterogeneous conditions upon immobilization onto the surface of activated carbon cloth (CC). Complex 3 exhibited high electrocatalytic HER activity under both homogeneous and heterogeneous conditions. It catalyses proton reduction to molecular hydrogen in acetonitrile solution at a lower overpotential (640 mV) with a high turnover frequency (TOF) of 524.57 s−1 and demonstrates good stability in acidic conditions. Furthermore, catalytic (working) electrodes are prepared by immobilizing the complexes onto the surface of activated carbon cloth (CC) for electrocatalytic HER under heterogeneous conditions. An impressive HER performance was again obtained with catalytic electrode 3@CC in 1.0 M KOH, achieving a current density of −10 mA cm−2 at an overpotential of 262 mV. Chronoamperometric (CA) studies showed no significant decay of the initial current density for 10 h, indicating the excellent stability of 3@CC. Additionally, UV-Vis and NMR spectral studies of the recovered catalyst after electrocatalysis revealed no structural changes, demonstrating its robustness under reaction conditions. © 2024 The Royal Society of Chemistry.
Challenges and Recent Advances of Novel Chemical Inhibitors in Medulloblastoma Therapy
(Humana Press Inc., 2022) Anand Maurya; Upendra Kumar Patel; Jitendra Kumar Yadav; Virender Pratap Singh; Alka Agarwal
Medulloblastoma is a common term used for the juvenile malignant brain tumor, and its treatment is exciting due to different genetic origins, improper transportation of drug across the blood-brain barrier, and chemo-resistance with various side effects. Currently, medulloblastoma divided into four significant subsections (Wnt, Shh, Group 3, and Group 4) is based on their hereditary modulation and histopathological advancement. In this chapter, we tried to combine several novel chemical therapeutic agents active toward medulloblastoma therapy. All these compounds have potent activity to inhibit the medulloblastoma. © 2022, The Author(s), under exclusive license to Springer Science+Business Media, LLC, part of Springer Nature.
Chlorocobaloxime containing N-(4-pyridylmethyl)-1,8-naphthalamide peripheral ligands: synthesis, characterization and enhanced electrochemical hydrogen evolution in alkaline medium
(Royal Society of Chemistry, 2022) Jitendra Kumar Yadav; Baghendra Singh; Sarvesh Kumar Pal; Nanhai Singh; Prem Lama; Arindam Indra; Kamlesh Kumar
Two new discrete cobaloxime based complexes with the general formula [ClCo(dioxime)2L] (1 and 2), L1 = N-(4-pyridylmethyl)-1,8-naphthalamide, L2 = 4-bromo-N-(4-pyridylmethyl)-1,8-naphthalamide have been synthesized and characterized by various spectroscopic techniques such as FT-IR, 1H, 13C{1H} NMR and PXRD. The molecular structures of both complexes have also been determined using single crystal X-ray crystallography. The solid state molecular structures revealed distorted octahedral geometry around the Co(iii) central metal ion with two dioximes in the equatorial plane and axial positions are occupied by chloro and pyridine nitrogen of N-(4-pyridylmethyl)-1,8-naphthalamide ligands. Both complexes exhibit weaker non-covalent interactions (C-H⋯O, C-H⋯Cl and C-H⋯π(Centroid) in complex 1 whereas C-H⋯O and C-H⋯Br in complex 2) resulting in the formation of dimeric and 1D supramolecular structures. Furthermore, these complexes are immobilized onto the surface of activated carbon cloth (CC) and their electrocatalytic performance for the hydrogen evolution reaction (HER) has been investigated in alkaline and acidic media as well as buffer solution. In alkaline medium, we found that complex 2 exhibited impressive electrocatalytic HER activity and produced a current density of −10 mA cm−2 at an overpotential of 260 mV, whereas complex 1 produced the same current density at an overpotential of 334 mV. An electrochemical impedance spectroscopy (EIS) spectral study revealed the faster charge transfer kinetics of complex 2 than that of complex 1. Similarly, the low Tafel slope (100 mV dec−1) for the HER with complex 2 indicates faster HER kinetics compared to complex 1. The chronoamperometric study showed that complex 2 is stable under electrocatalytic HER conditions for 5 h without losing the initial current density and it has also been established that the complex structure is retained after electrocatalysis. © 2023 The Royal Society of Chemistry.
Efficient: N -formylation of primary aromatic amines using novel solid acid magnetic nanocatalyst
(Royal Society of Chemistry, 2020) Jitendra Kumar Yadav; Priyanka Yadav; Satish K. Awasthi; Alka Agarwal
Sulfonic acid functionalized over biguanidine fabricated silica-coated heterogeneous magnetic nanoparticles (NP@SO3H) have been synthesized, well characterized and explored for the first time, as an efficient and recyclable catalyst for N-formylation of primary amines under mild reaction conditions. Exploiting the magnetic nature of Fe3O4, the prepared catalyst was readily recovered from the reaction mixture via an external magnet. The catalyst can be reused for up to six cycles without any substantial loss of catalytic activity. The cost effectiveness, simple methodology, wide substrate tolerance, excellent yield and easy work-up are the additional advantages of present catalytic system. This journal is © The Royal Society of Chemistry.
Homoleptic Ni(ii) dithiocarbamate complexes as pre-catalysts for the electrocatalytic oxygen evolution reaction
(Royal Society of Chemistry, 2022) Sarvesh Kumar Pal; Baghendra Singh; Jitendra Kumar Yadav; Chote Lal Yadav; Michael G. B. Drew; Nanhai Singh; Arindam Indra; Kamlesh Kumar
Four new functionalized Ni(ii) dithiocarbamate complexes of the formula [Ni(Lx)2] (1-4) (L1 = N-methylthiophene-N-3-pyridylmethyl dithiocarbamate, L2 = N-methylthiophene-N-4-pyridylmethyl dithiocarbamate, L3 = N-benzyl-N-3-pyridylmethyl dithiocarbamate, and L4 = N-benzyl-N-4-pyridylmethyl dithiocarbamate) have been synthesized and characterized by IR, UV-vis, and 1H and 13C{1H} NMR spectroscopic techniques. The solid-state structure of complex 1 has also been determined by single crystal X-ray crystallography. Single crystal X-ray analysis revealed a monomeric centrosymmetric structure for complex 1 in which two dithiocarbamate ligands are bonded to the Ni(ii) metal ion in a S^S chelating mode resulting in a square planar geometry around the nickel center. These complexes are immobilized on activated carbon cloth (CC) and their electrocatalytic performances for the oxygen evolution reaction (OER) have been investigated in aqueous alkaline solution. All the complexes act as pre-catalysts for the OER and undergo electrochemical anodic activation to form Ni(O)OH active catalysts. Spectroscopic and electrochemical characterization revealed the existence of the interface of molecular complex/Ni(O)OH, which acts as the real catalyst for the OER. The active catalyst obtained from complex 2 showed the best OER activity achieving 10 mA cm−2 current density at an overpotential of 330 mV in 1.0 M aqueous KOH solution. © 2022 The Royal Society of Chemistry.
Inherent Flexibility vis-à-vis Structural Rigidity in Chemically Stable Antimalarial Dispiro N-Sulfonylpiperidine Tetraoxanes
(Wiley-Blackwell, 2018) Chiranjeev Sharma; Kumkum Sharma; Jitendra Kumar Yadav; Alka Agarwal; Satish Kumar Awasthi
Structurally diverse and chemically stable tetraoxanes were formed by peroxidation of N-sulfonylpiperidones. X-ray analysis revealed that the crystal structures possess central spiro-2,5-disubstituted tetraoxane rings trans fused to 6-membered piperidine and cyclohexylidene substituents in classical chair conformations. The more flexible cycloheptane ring exhibited pseudorotation between chair and twist chair conformation. The two sulfonyl oxygen atoms act as hydrogen-bonding acceptors and participate in hydrogen bonding. Docking calculations showed that the tetraoxanes are aligned parallel to the plane of the porphyrin ring of heme so that the iron can attack the O−O bond to initiate redox-mediated reaction to render nanomolar antimalarial potency to these compounds against P. falciparum 3D7. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Insight into the interaction of benzothiazole tethered triazole analogues with human serum albumin: Spectroscopy and molecular docking approaches
(John Wiley and Sons Ltd, 2019) Priyanka Yadav; Jitendra Kumar Yadav; Arvind Kumar Dixit; Alka Agarwal; Satish Kumar Awasthi
The interaction of four benzothiazole tethered triazole analogues (MS43, MS70, MS71, and MS78) with human serum albumin (HSA) was investigated using various spectroscopic techniques (ultraviolet–visible (UV–vis) light absorption, fluorescence, circular dichroism (CD), molecular docking and density functional theory (DFT) studies). Fluorescence quenching constants (~1012) revealed a static mode of quenching and binding constants (Kb ~104) indicating the strong affinity of these analogues for HSA. Further alteration in the secondary structure of HSA in the presence of these analogues was also confirmed by far UV–CD spectroscopy. The intensity loss in CD studied at 222 nm indicated an increase in random coil/β-sheet conformations in the protein. Binding energy values (MS71 (−9.3 kcal mol−1), MS78 (−8.02 kcal mol−1), MS70 (−7.16 kcal mol−1) and MS43 (−6.81 kcal mol−1)) obtained from molecular docking revealed binding of these analogues with HSA. Molecular docking and DFT studies validated the experimental results, as these four analogues bind with HSA at site II through hydrogen bonding and hydrophobic interactions. © 2019 John Wiley & Sons, Ltd.
Insights into the interaction of potent antimicrobial chalcone triazole analogs with human serum albumin: Spectroscopy and molecular docking approaches
(Royal Society of Chemistry, 2019) Priyanka Yadav; Jitendra Kumar Yadav; Alka Agarwal; Satish K. Awasthi
Mechanistic insights into the interaction of five previously chemically synthesized triazole-linked chalcone analogs (CTs) with human serum albumin (HSA) were sought using various spectroscopic techniques (UV-visible absorption, fluorescence, and circular dichroism) and molecular docking. The fluorescence quenching experiments performed at three different temperatures (288, 298 and 308 K) revealed the static mode of quenching and the binding constants (Kb ∼ 106-9) obtained indicated the strong affinity of these analogs for HSA. Furthermore, significant changes in the secondary structure of HSA in the presence of these analogs were also confirmed by far UV-CD spectroscopy. The thermodynamic properties such as the enthalpy change (ΔH°), Gibbs free energy change (ΔG°) and entropy change (ΔS°) revealed that the binding process was spontaneous and exothermic. Theoretical studies, viz., DFT and molecular docking corroborated the experimental results as these five analogs could bind with HSA through hydrogen bonding and hydrophobic interactions. The present study provides useful information regarding the interaction mechanism of these analogs with HSA, which can provide a new avenue to design more potent chalcone triazole analogs for use in the biomedical field. © The Royal Society of Chemistry 2019.
Isonicotinate-Zn(ii)/Cd(ii) bridged dicobaloximes: synthesis, characterization and electrocatalytic proton reduction studies
(Royal Society of Chemistry, 2023) Jitendra Kumar Yadav; Anjali Mishra; Gaurav Kumar Mishra; Sarvesh Kumar Pal; Kedar Umakant Narvekar; Ahibur Rahaman; Nanhai Singh; Prem Lama; Kamlesh Kumar
Herein, we present the synthesis of two new dicobaloxime complexes, [{ClCo(dmgH)2(4-PyCOO)}2Zn(DMF)2] (1) and [{ClCo(dmgH)2(4-PyCOO)}2Cd(H2O)3(DMF)].4H2O (2) bridged by isonicotinate-Zn(ii) and Cd(ii) moieties. These complexes were synthesized upon reaction of a monomeric chlorocobaloxime [ClCo(dmgH)2(4-PyCOOH)] with Zn(NO3)2·6H2O and Cd(OAc)2·2H2O in a methanol/DMF solvent mixture. Both complexes are fully characterized by UV-Visible, FT-IR, and NMR (1H and 13C{1H}) spectral studies. The solid-state structures are also determined by single-crystal X-ray crystallography. In complex 1, Zn (ii) metal ions reside within a four coordinated distorted tetrahedral geometry (ZnO4) formed by two oxygen atoms of isonicotinate connected to cobaloxime units and two oxygen atoms of DMF molecules. In complex 2, the Cd(ii) metal ion exhibited distorted octahedral geometry (CdO6), with two oxygen atoms of isonicotinate that connect to cobaloxime units, one DMF, and three water molecules. The Co(iii) metal center of cobaloxime units in both complexes 1 and 2 displayed distorted octahedral geometry with two dmgH units in the equatorial plane whereas chloride ion (Cl−) and the nitrogen atom of isonicotinate occupy the axial coordination sites. The redox behaviour of both complexes was studied by cyclic voltammetry at variable scan rates in deoxygenated DMF/H2O (95 : 5) solution using 0.1 M TBAPF6 as the supporting electrolyte and a glassy carbon (GC) electrode as the working electrode. Both complexes exhibited similar redox properties and two redox couples CoIII/II and CoII/CoI are observed in the reductive scan. Furthermore, complexes are investigated as electrocatalysts for proton reduction in the presence of acetic acid (AcOH) and complex 1 exhibited impressive electrocatalytic activity compared to complex 2 and monomer. The stability study indicated the retention of molecular structural integrity during HER electrocatalytic experiments. © 2023 The Royal Society of Chemistry.
Molecular docking and density functional theory studies of potent 1,3-disubstituted-9H-pyrido[3,4-b]indoles antifilarial compounds
(Springer, 2021) Jitendra Kumar Yadav; Priyanka Yadav; Vinay Kumar Singh; Alka Agarwal
The interaction of three potent antifilarial compounds (4C, 4F, and 3F) with filarial proteins thioredoxin, glutathione s-transferase and cyclophilin were investigated using molecular docking and density functional theory (DFT) studies. Molecular docking was performed using YASARA tool, Hex 8.0.0 Cuda tool and PatchDock server and docked complex were visualized by Discovery Studio 3.0. The predicted binding energy of antifilarial compounds 4C (−247.6, −243.8, −256.8 kcal mol−1), 4F (−242.6, −246.4, −232.4 kcal mol−1) and 3F (−272.4, −248.5, −277.7 kcal mol−1) with filarial protein 4FYU, 5D73, and 1A33, respectively. Docking results were strongly supported by molecular dynamics data and molecular mechanics-generalized born surface area (MM-GBSA) calculations. The optimized geometries of all three compounds were used for calculating the energies of the frontier molecular orbitals highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO). The lowest HOMO–LUMO energy gap in compound 3F suggested that it is the most bioactive molecule among all these three compounds, which is in accordance with the docking results of these compounds. The interaction energies between ligand and protein are mainly due to hydrogen bonds, hydrophobic interactions, and van der Waals interactions which give the stability to the complex. The structural information and docking studies of different filarial proteins with antifilarials obtained from this study could aid in screening and designing new antifilarial or selective inhibitors for chemotherapy against filariasis. © 2021, The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.