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    A lead(II)-N′-isonicotinoylpyrazine-2-carbohydrazonamide complex system as a converter of aerial carbon dioxide to carbonate under electrochemical conditions with the formation of a single-component white light-emitting phosphor
    (Royal society of chemistry, 2024) Mahmoudi, Ghodrat; Garcia-Santos, Isabel; Labisbal, Elena; Castineiras, Alfonso; Alizadeh, Vali; Gomila, Rosa M.; Frontera, Antonio; Safin, Damir A.
    In this contribution, a novel binuclear heteroleptic complex [Pb2L2(CO3)]2CH(3)CN2MeOH (12CH(3)CN2MeOH) is reported, which was fabricated by electrochemical oxidation of a lead anode under an ambient atmosphere in a CH3CN : MeOH solution of N '-isonicotinoylpyrazine-2-carbohydrazonamide (HL). The CO32- anion was produced from the conversion of aerial CO2 by the Pb2+-L complex system under electrochemical conditions. In the structure of 1, ligand L exhibits a tridentate pincer-like N,N ',O-coordination mode, while the CO32- anion exhibits a tetradentate bridging coordination mode with one of the oxygen atoms exhibiting a bridging mu-coordination mode. The metal cations in the structure of 1 are in a five-membered N2O3 coordination environment, formed by covalent bonds. The molecular structure of 12CH(3)CN2MeOH is stabilized by a pair of intermolecular Pb & ctdot;N tetrel bonds formed with one of the NH2 nitrogen atoms of an adjacent complex molecule and with the acetonitrile nitrogen atom, and one Pb & ctdot;O tetrel bond formed with the carbonyl oxygen atom of the other adjacent complex molecule, yielding a 2D supramolecular sheet. This sheet is further stabilized by intermolecular N-H & ctdot;N-acetonitrile and N-H & ctdot;O-carbonate hydrogen bonds and pi(Pyrazine)& ctdot;pi(Pyridine) interactions. The optical properties of the complex were revealed by UV-vis spectroscopy and spectrofluorimetry in MeOH. It was established that the described complex is emissive upon excitation at 340 nm with a broad band from about 500 nm to 780 nm with a maximum at similar to 580 nm, accompanied by a shoulder at similar to 620 nm. The CIE-1931 chromaticity coordinates of (0.28, 0.36) fall within the white gamut of the chromaticity diagram. Thus, complex 1 is a single-component white light-emitting phosphor.
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    A Nanosized Porous Supramolecular Lead(II)-N′-phenyl(pyridin-2-yl)methylene-N-phenylthiosemicarbazide Aggregate, Obtained Under Electrochemical Conditions
    (American Chemical Society, 2024) Mahmoudi, Ghodrat; Garcia Santos, Isabel; Labisbal, Elena; Castineiras, Alfonso; Alizadeh, Vali; Gomila, Rosa M.; Frontera, Antonio; Safin, Damir A.
    A novel nanosized porous supramolecular nonanuclear complex [Pb9(HL)12Cl2(ClO4)](ClO4)3·15H2O·a(solvent) (1·15H2O·a(solvent)) is reported that was synthesized by electrochemical oxidation of a Pb anode under the ambient conditions in a CH3CN:MeOH solution of N′-phenyl(pyridin-2-yl)methylene-N-phenylthiosemicarbazide (H2L), containing [N(CH3)4]ClO4 as a current carrier. The supramolecular aggregate of 1 is enforced by a myriad of Pb···S tetrel bonds (TtBs) established with the thiocarbonyl sulfur atoms of adjacent species, which have been also analyzed by DFT calculations via 2D maps of ELF, Laplacian and RDG properties. Moreover, Pb···Cl TtBs with the central Cl- anion, and Pb···O TtBs with the three oxygen atoms of the ClO4- anion, were revealed. Notably, the molecular structure of 1 differs significantly from that recently reported by us [Pb2(HL)2(CH3CN)(ClO4)2]·2H2O (2·2H2O), which was obtained using a conventional synthetic procedure by reacting Pb(ClO4)2 with H2L in the same CH3CN:MeOH solution, thus highlighting a crucial role of the electrochemical conditions. The optical characteristics of the complex were investigated using UV-vis spectroscopy and spectrofluorimetry in methanol. The complex was found to be emissive when excited at 304 nm, producing a broad emission band ranging from approximately 420 to 600 nm with multiple peaks. The CIE-1931 chromaticity coordinates, calculated as (0.33, 0.24), suggest that the emission lies in the white region of the chromaticity diagram. Further investigation is needed to fully characterize the origin of this emission. © 2024 The Authors. Published by American Chemical Society.
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    A novel, extreme simple modification of low-cost pencil graphite electrode (PGE) by single-walled carbon nanotube/pyrenebutyric acid (SWCNT/PBA) nanostructure for sensitive and selective detection of adrenaline
    (Springer, 2025) Mahmoudi, Ghodrat; Hosseinifard, Mojtaba; Moghadam, Ahmad Jamali; Gargari, Masoumeh Servati; Alizadeh, Vali
    The electrochemical carbon nanotube (CNT)-based sensors may provide an effective answer to the growing need for qualitative and quantitative determination of biomolecules. However employing CNTs as interface nanomaterials in various electrode matrices has been challenging for researchers. The most important issues are uniform dispersion of CNTs due to their agglomeration and their interfacial connection with electrode matrices. The superiority of this work lies in its ability to overcome these shortcomings by simple and rapid procedures while remaining negligible sensor surface fouling, but also provides high sensitive, inexpensive, and selective determination of AD molecule. Our work presents the non-covalent functionalization of Single Wall Carbon Nanotubes (SWCNTs) by Pyrenebutyric Acid (PBA) through simple pi-stacking interaction for preserving their electronic structure and preventing their agglomeration in the dispersion step to develop a novel disposable sensor with many attractive analytical performance characteristics for Adrenaline (AD) determination. SWCNTs/PBA hybrid film on a low-cost PGE support have been developed involving soaking of greatly simplified solvent-treated GPE without any further pretreatment step into successfully dispersed SWCNTs/PBA in ethanol, which is a green solvent. The surface morphology of the SWCNTs/PBA nanostructured films were evaluated using Field-emission scanning electron microscopy (FE-SEM), being correlated with the electrochemical characteristics observed by cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS) techniques. The heterogeneous electron transfer rate constant (ks) values 0.09, 0.15 and 0.40 s-1 were obtained for Bare PGE, PGE/SWCNT, and PGE/SWCNT/PBA electrodes, respectively. The obtained ks values have been shown that modification of SWCNTs with PBA improves the analytical properties of the sensor more than those obtained at bare PGE and SWCNTs/PGE due to synergistic effects. The analytical performance of SWCNTs/PBA/PGE was evaluated for AD oxidation in optimum pH 7.0 of phosphate buffer solution in the presence of an excess amount of interfering compounds by DPV technique. The fabricated sensor showed good response with high sensitivity, low detection limit (40 nM), wide linear range (0.25-9 mu M), and excellent reproducibility and repeatability. Also, the simultaneous analyses of AD and Uric Acid (UA) reveal that the fabricated sensor could separate the electrooxidation peaks of these two mixtures and good response with low detection limit (95nM) was also obtained for UA detection. The practical applicability of the fabricated sensor has been successfully tested for the determination of AD in human serum and injection ampoule samples with 98-110% recoveries.
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    A pyrazinamide-benzenesulfonohydrazide hybrid N'-(phenylsulfonyl)pyrazine-2-carbohydrazonamide: Experimental and theoretical insights
    (Elsevier Ltd, 2024) Alizadeh, Vali; Garcia Santos, Isabel; Castiñeiras, Alfonso; Mahmoudi, Ghodrat; Safin, Damir A
    A pyrazinamide-benzenesulfonohydrazide hybrid N'-(phenylsulfonyl)pyrazine-2-carbohydrazonamide (1), which was studied by physical measurements and computational tools, is reported. Compound 1 was synthesized using a metallic Na-assisted interaction of 2-cyanopyrazine with benzenesulfonylhydrazine in dry methanol. Our newly developed synthetic approach allowed to obtain the title compound witht the yield of 74%, which is more than twice higher in comparison to the previously reported synthesis using pyrazine-2-carbohydrazonamide and benzenesulfonyl chloride. Molecules of the title compound are linked via N–H⋯O, C–H⋯Ph, S=O⋯2-pyrazine and π⋯π interactions. As it was found by the Hirshfeld surface analysis, molecules of 1 interact through H⋯X (X = H, C, N and O) contacts. Electronic properties of 1 were revealed using the Density Functional Theory (DFT) computations. 1 was expected to be a fourth-class toxicity, and it does not penetrate the blood-brain barrier, while can potentially be absorbed by the gastrointestinal tract. It was predicted that compound 1, which demonstrated the strongest activity against PLpro, Nsp3_range 207–379 MES and Nsp16_SAM site, are of interest to suppress activity of the SARS-CoV-2 proteins. Although the Ki value is slightly higher, the ligand efficiency scores for complex PLpro–1 were found to be characteristic for a Hit. © 2024 Elsevier Ltd
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    Aerial carbon dioxide conversion to carbonate mediated by a lead(ii) complex with tridentate bipyridine containing a hydrazide ligand under electrochemical conditions yielding single-component white-light-emitting phosphors
    (Royal Society of Chemistry, 2024) Mahmoudi, Ghodrat; Garcia Santos, Isabel; Labisbal, Elena; Castiñeiras, Alfonso; Alizadeh, Vali; Gomila, Rosa M.; Frontera, Antonio; Safin, Damir A.
    A novel tetranuclear complex [Pb4L4(CO3)2]·4H2O (1·4H2O) is reported, which was obtained through the electrochemical oxidation of a lead anode under an ambient atmosphere in a CH3CN : MeOH solution of N’-isonicotinoylpicolinohydrazonamide (HL). CO32− anions were formed through the conversion of aerial CO2via the Pb2+-L complex system under electrochemical conditions. The ligand L links two Pb2+ cations through the carbonyl oxygen atom, while the CO32− anion links two Pb2+ cations through two monodentate and one bidentate oxygen atoms. The molecular structure of 1 is stabilized by a pair of Pb⋯O tetrel bonds formed with the bidentate oxygen atom of the CO32− anion, while molecules of 1 are interlinked through reciprocal π(chelate ring)⋯π(chelate ring), π(chelate ring)⋯π(noncovalent ring) and Pb⋯π(noncovalent ring) interactions, yielding a 1D supramolecular chain. The same reaction but under a nitrogen atmosphere yielded a novel mononuclear complex [PbL2]·MeOH·2H2O (2·MeOH·2H2O). In the structure of 2, each ligand L exhibits a tridentate coordination mode. Molecules of 2 are also interlinked through reciprocal π(chelate ring)⋯π(chelate ring), π(chelate ring)⋯π(noncovalent ring) and Pb⋯π(noncovalent ring) interactions, similar to 1, yielding a 1D supramolecular chain. The energetic features of these assemblies were studied using DFT calculations. Additionally, QTAIM analysis was employed to characterize noncovalent contacts, including intermolecular Pb⋯N tetrel bonds. These tetrel bonds were further analyzed using the ELF and Laplacian of electron density 2D maps, which confirmed their noncovalent nature. The optical properties of the complexes were revealed using UV-vis and diffuse reflectance spectroscopy and spectrofluorometry. Both complexes were found to be emissive in a solution of MeOH. CIE-1931 chromaticity coordinates of (0.38, 0.37) and (0.31, 0.32) for 1·4H2O and 2·MeOH·2H2O, respectively, fall within the white gamut of the chromaticity diagram. © 2024 The Royal Society of Chemistry.