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Search results for: Β-DIKETIMINATE LIGAND
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Reactivity study of a β-diketiminate titanium(III) complex with a phosphanylphosphido ligand towards chlorophosphanes. A new method of synthesis of β-diketiminate titanium(IV) complexes with versatile phosphanylphosphinidenes
PublicationThe reactivity of ab-diketiminate titanium(III) complex with a phosphanylphosphido ligand, [MeNacNacTi(Cl){g2-P(SiMe3)-PtBu2}] (1)(MeNacNac= [Ar]NC(Me)CHC(Me)N[Ar]; Ar = 2,6-iPr2Ph), was investigatedtowards selected chlorophosphanes, such astBu2PCl,iPr2PCl, Cy2PCl, (Cy)tBuPCl, (Me)tBuPCl, (Ph)tBuPCl, Ph2PCl, (iPr2N)tBuPCl and (Et2N)2PCl. The reactions withtBu2PCl and Ph2PCl lead mainly to theearlier described complex [MeNacNacTi(Cl){g2-P-PtBu2}]...
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Synthetic, Structural, and Spectroscopic Characterization of a Novel Family of High-Spin Iron(II) [(β-Diketiminate)(phosphanylphosphido)] Complexes
PublicationThis work describes a series of iron(II) phosphanylphosphido complexes. These compounds were obtained by reacting lithiated diphosphanes R2PP(SiMe3)Li (R = t-Bu, i-Pr) with an iron(II) β-diketiminate complex, [LFe(μ2-Cl)2Li(DME)2] (1), where DME = 1,2-dimethoxyethane and L = Dippnacnac (β-diketiminate). While the reaction of 1 with t-Bu2PP(SiMe3)Li yields [LFe(η1-Me3SiPPt- Bu2)] (2), that of 1 with equimolar amounts of i-Pr2PP(SiMe3)Li,...
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Syntheses, Structures and Reactivity of Terminal Phosphido Complexes of Iron(II) Supported by a β-Diketiminato Ligand
PublicationWe report the synthesis of the first series of terminal phosphido iron complexes supported by a β‐diketiminato ligand (Dippnacnac) and their catalytic activity in dehydrocoupling of secondary phosphines. Anionic and neutral mono‐ or diphosphido complexes were obtained from the reaction of [(Dippnacnac)FeCl2Li(dme)2] with the R2PLi (R = iPr, tBu, Cy, Ph) phosphides by tuning the stoichiometric ratio, polarity of the solvent, and...
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Reactions of (Ph)tBuP-P(SiMe3)Li·3THF with [(PNP)TiCl2] and [MeNacNacTiCl2·THF]. Synthesis of first PNP titanium(IV) complex with phosphanylphosphinidene ligand [(PNP)Ti(Cl){η2-P-P(Ph)tBu}]
PublicationLithium derivative of diphosphane (Ph)tBuP-P(SiMe3)Li (1) was isolated for the first time and investigated in reactions with β-diketiminate (MeNacnac− = [Ar]NC(Me)CHC(Me)N[Ar]; Ar = 2,6-iPr2C6H3) and PNP-pincer (PNP = N[2-PiPr2-4-methylphenyl]2) Ti(III) complexes. The β-diketiminate titanium(III) complex containing phosphanylphosphido ligand [MeNacNacTi(Cl){η2-P(SiMe3)-P(Ph)tBu}] (2) was prepared in reaction of [MeNacNacTiCl2·THF]...
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Synthesis of compounds with C-P-P and C=P-P bond systems based on the phospha-Wittig reaction
PublicationA reactivity study of a β-diketiminate titanium(III) phosphanylphosphido complex [MeNacNacTi(Cl){η2-P(SiMe3)-PtBu2}] (1) towards ketones such as benzophenone, 9-fluorenone, acetophenone, cyclopentanone, cyclohexanone and cycloheptanone is reported. The reactions of 1 with aromatic ketones (without α-protons) directly lead to the Ti(III) complex [MeNacNacTi(μ2-Cl)(OSiMe3)] (5) as well as Ti(IV) complexes with the pinacol condensation...
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Reactions of Lithiated Diphosphanes R2P−P(SiMe3)Li (R = tBu and iPr) with [MeNacnacTiCl2·THF] and [MeNacnacTiCl3]. Formation and Structure of TitaniumIII and TitaniumIV β‑Diketiminato Complexes Bearing the Side-on Phosphanylphosphido and Phosphanylphosphinidene Functionalities
Publicationβ-Diketiminate complexes of TiIII-containing phosphanylphosphido ligands [MeNacnacTi(Cl){η2-P(SiMe3)- PR2}] (MeNacnac− = [Ar]NC(Me)CHC(Me)N[Ar]; Ar = 2,6- iPr2C6H3) were prepared by reactions of [MeNacnacTiCl2· THF] with lithium derivatives of diphosphanes R2P−P(SiMe3) Li (R = tBu, iPr) in toluene solutions. Surprisingly, reactions of [MeNacnacTiCl2·THF] with R2P−P(SiMe3)Li in THF solutions led to TiIV complexes containing phosphanylphosphinidene ligands...
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Molecular mechanism and energetics of coupling between substrate binding and product release in the F 1 -ATPase catalytic cycle
PublicationF1-ATPase is a motor protein that couples the rotation of its rotary γ subunit with ATP synthesis or hydrolysis. Single-molecule experiments indicate that nucleotide binding and release events occur almost simultaneously during the synthesis cycle, allowing the energy gain due to spontaneous binding of ADP to one catalytic β subunit to be directly harnessed for driving the release of ATP from another rather than being dissipated...
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Kompleksy metali przejściowych zawierające ligand R2P-P
PublicationBadania obejmują kompleksy metali przejściowych zawierające ligandy fosfanylofosfinidenowe oraz fosfanylofosfidowe. Kompleksy te są pochodnymi kompleksów fosfinidenowych oraz fosfidowych, gdzie grupa alkilowa została zastąpiona grupą fosfanylową (R’2P). W pracy można wydzielić trzy główne obszary badań. Pierwszym było zbadanie reaktywności R2PP(SiMe3)Li względem diamidowych bądź β-diketiminowych kompleksów cyrkonu zawierających...
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Phosphanylphosphido and phosphanylphosphinidene complexes of zirconium(IV) supported by bidentate N,N ligands
PublicationPhosphanylphosphido complexes of zirconium, [NacNacZrCl2(η2-R2P–PSiMe3)] (R = t-Bu, i-Pr), were synthesized in the reaction of R2P–P(SiMe3)Li·nTHF (R = t-Bu, i-Pr) with a β-diketiminate complex, [NacNacZrCl3], in toluene. Elimination of Me3SiCl from [NacNacZrCl2(η2-R2P–PSiMe3)] provided the phosphanylphosphinidene complexes [NacNacZrCl(η2-R2P–P)] (R = t-Bu, i-Pr). Moreover, the reaction of [NacNacZrCl2(η2-R2P–PSiMe3)] with R2P–P(SiMe3)Li·nTHF...
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Homoleptic mono-, di-, and tetra-iron complexes featuring phosphido ligands: a synthetic, structural, and spectroscopic study
PublicationWe report the first series of homoleptic phosphido iron complexes synthesized by treating either the β-diketiminato complex [(Dippnacnac)FeCl2Li(dme)2] (Dippnacnac = HC[(CMe)N(C6H3-2,6-iPr2)]2) or [FeBr2(thf )2] with an excess of phosphides R2PLi (R = tBu, tBuPh, Cy, iPr). Reaction outcomes depend strongly on the bulkiness of the phosphido ligands. The use of tBu2PLi precursor led to an anionic diiron complex 1 encompassing a planar...
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Mechanochemical Energy Transduction during the Main Rotary Step in the Synthesis Cycle of F1-ATPase
PublicationF1-ATPase is a highly efficient molecular motor that can synthesize ATP driven by a mechanical torque. Its ability to function reversibly in either direction requires tight mechanochemical coupling between the catalytic domain and the rotating central shaft, as well as temporal control of substrate binding and product release. Despite great efforts and significant progress, the molecular details of this synchronized and fine-tuned...
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Experimental and theoretical investigation of the reactivity of [(BDI*)Ti(Cl){η2-P(SiMe3)-PiPr2}] towards selected ketones
PublicationIn this work, we report a new type of reactivity of [(BDI*)Ti(Cl){η2-P(SiMe3)-PiPr2}] (1) towards ketones (BDI* = 2,6-diisopropylphenyl-β-methyldiketiminate ligand). In the reaction of 1 with acetone, cyclopentanone or cyclohexanone, a ketone moiety is inserted into Ti–Pphosphanyl or Ti–Pphosphido bonds to form complexes with a new C–P–P moiety, providing [(BDI*)Ti(Cl){η2-P(SiMe3)-PiPr2-C(Me)2O}] (2a), [(BDI*)Ti(Cl){η2-OC(Me)2P(SiMe3)-PiPr2}]...
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Emulsification alters simulated gastrointestinal proteolysis of β-casein and β-lactoglobulin
PublicationWe have studied the effect of the adsorption of milk proteins at the oil-water interface on their digestibility in simulated gastrointestinal environment. The investigations aimed to characterize how both the breakdown of the adsorbed proteins and the interactions with physiological surfactants, phosphatidylcholine (PC) and bile salts (BS), influence structural transformations of model, protein-stabilized food emulsions in the...
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Molecular mechanism of proton-coupled ligand translocation by the bacterial efflux pump EmrE
PublicationThe current surge in bacterial multi-drug resistance (MDR) is one of the largest challenges to public health, threatening to render ineffective many therapies we rely on for treatment of serious infections. Understanding different factors that contribute to MDR is hence crucial from the global “one health” perspective. In this contribution, we focus on the prototypical broad-selectivity proton-coupled antiporter EmrE, one of the...
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Anticancer Study on IrIII and RhIII Half-Sandwich Complexes with the Bipyridylsulfonamide Ligand
PublicationTwo non-platinum compounds, organometallic half-sandwich complexes [(η 5 -Cp)IrCl(L)]PF 6 (1) and [(η 5 -Cp)RhCl(L)]PF 6 (2) were prepared by treating pentamethylcyclopentadienyl chloride dimers of iridium(III) or rhodium(III) with the obtained 4-amino-N-(2,2'-bipyridin-5- yl)benzenesulfonamide ligand (L) and ammonium hexafluorophosphate. The crystal structures of ligand (L) and complexes 1 and 2 were obtained and then analyzed. Coordination...
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Computational methods for calculation of binding free energy for ligand-receptor complexes
PublicationAccurate description of the molecular complexes energetic influence is required for understanding of many biological functions carried out by proteins. Therefore, estimation of binding free energy for ligand-receptor complexes is of highest importance for structure-based ligand design and drug discovery approaches.Experimental methods of determination of difference in Gibbs'es free energy have many limitations. Thus, computational...
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Meiothermus ruber cells as β-galactosidase activity biocatalyst
PublicationThe current study allowed to establish the possibility of using whole cells of thermophilic bacteria Meiothermus ruber as a biocatalyst with β-galactosidase activity. β-galactosidases are used for hydrolysis of lactose as well as for oligosaccharides synthesis. The advantages of using whole bacterial cells catalysis is not only elimination of tedious, expensive protein isolation and/or purification but also stabilization of enzymes...
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Hydrothermal reactions: From the synthesis of ligand to new lanthanide 3D-coordination polymers
PublicationThe organic ligand 2,5-piperazinedione-1,4-diaceticacid (H2PDA) was synthesized under hydrothermal conditions starting from the iminodiacetic acid and catalyzed by oxalic acid. The X-ray powder diffraction data indicates that the compound crystallizes in the P21/c space group as reported in the literature. The ligand was also characterized by elemental analysis, magnetic nuclear resonance, infrared spectroscopy and thermogravimetric...
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Structure elucidation of carbamoylo-β-lactam diastereoisomers by ROESY and NOESY experiments
PublicationRecently we have focused in the problem of preparation of carbamoylo-β-lactams as a result of oxidative cyclization of malonyl enamides. In our experiments we obtain mixture of two main β-lactam products: as a result of subsequent elimination and a second as a product of substitution. All of the produced β-lactams have trans configuration what was confirmed by 1H coupling constants. However id should be stressed that in the case...
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Electroabsorption study of metal-to-ligand charge transfer in an organic complex of iridium (III).
PublicationW pracy zmierzono i zinterpretowano widmo elektroabsorpcji (EA) próżniowo naparowanych warstw organicznego kompleksu Ir(ppy)3, powszechnie stosowanego jako emiter fosforescencyjny w organicznych diodach elektroluminescencyjnych. Analiza widma EA potwierdziła fakt,że niskoenergetyczne stany elektronowe tego kompleksu związane są z przeniesieniem ładunku metal-ligand.
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Towards β-selectivity in functional estrogen receptor antagonists
PublicationBased on the benzo[b]naphtho[1,2-d]furan and benzo[b]naphtho[1,2-d]thiophene frameworks, a series of ligands with different basic side chains (BSCs) has been synthesized and pharmacologically evaluated. Also, their binding modes have been modelled using docking techniques. It was found that the introduction of a BSC in these systems brings about a decrease of affinity for both estrogen receptors α and β in an in vitro competitive...
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Improvement of opipramol base solubility by complexation with β-cyclodextrin
PublicationOpipramol (OPI), a tricyclic antidepressant and anxiolytic compound, is administered orally in the form of a dihydrochloride. Salt form of the drug has a higher solubility in water and hence bioavailability and stability. A similar effect can be achieved by closing the hydrophobic part of the drug molecule in the cyclodextrin cavity. The paper presents opipramol inclusion complexes with beta-cyclodextrin (β-CD) in 1:1 molar ratio....
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Ligand-Modified Boron-Doped Diamond Surface: DFT Insights into the Electronic Properties of Biofunctionalization
PublicationWith the increasing power of computation systems, theoretical calculations provide a means for quick determination of material properties, laying out a research plan, and lowering material development costs. One of the most common is Density Functional Theory (DFT), which allows us to simulate the structure of chemical molecules or crystals and their interaction. In developing a new generation of biosensors, understanding the nature...
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Studies on the influence of β-cyclodextrin derivatives on the physical stability of famotidine
PublicationThe usage of Fourier transform infrared spectroscopy, near infrared spectroscopy, differential scanning calorimetry and microscopy is presented in this work focused on the exploration of the effect of CD on the physical stability of famotidine (FAM). The most significant information was achieved by analysis of the second derivatives ofnear infrared (NIR) spectra recorded. Changes in the shape of spectra derivatives allow...
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New clicked full agonists of the estrogen receptor β
PublicationA click chemistry approach was used to synthesize a series of 1,4-diaryl-substituted 1,2,3-triazoles designed to behave as estrogen receptor (ER) ligands. We studied their affinities for both receptors α and β, their agonist activities in a cell-based luciferase reporter assay and their effect on the proliferation of the hormone-dependent MCF-7 cell line. We found two compounds (3a and 3c) that behave as selective full agonists...
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Rotation Triggers Nucleotide-Independent Conformational Transition of the Empty β Subunit of F1-ATPase
PublicationF1-ATPase (F1) is the catalytic portion of ATP synthase, a rotary motor protein that couples proton gradients to ATP synthesis. Driven by a proton flux, the F1 asymmetric γ subunit undergoes a stepwise rotation inside the α3β3 headpiece and causes the β subunits’ binding sites to cycle between states of different affinity for nucleotides. These concerted transitions drive the synthesis of ATP from ADP and phosphate. Here, we study...
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Comparative molecular dynamics study of dimeric and monomeric forms of HIV-1 protease in ligand bound and unbound state
PublicationHuman immunodeficiency virus type 1 protease (HIV-1 PR) is a viral-encoded enzyme that forms a homodimer. HIV-1 PR is essential for replication and assembly of the virus and inactivation of HIV-1 PR enzyme causes production of immature, noninfectious viral particles and thus HIV-1 PR is an attractive target in anti-AIDS drug design. In our current work, we performed molecular dynamics (MD) calculations (500 ns) for two different...
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Mechanochemically synthesized Mn3O4@β-cyclodextrin mediates efficient electron transfer process for peroxymonosulfate activation
PublicationThe rational surface engineering of heterogeneous catalysts is of great significance in advanced oxidation processes (AOPs) for eliminating refractory contaminants but remains challenging. In this study, β-cyclodextrin modified Mn3O4 (Mn3O4@β-CD) was prepared through a mechanochemical approach for peroxymonosulfate (PMS) activation, which achieved efficient bisphenol A (BPA) removal via electron transfer process (ETP). The reactive...
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Simple and novel synthesis of 3-(thio)phosphoryl-β-lactams by radical cyclization
PublicationRadical cyclization of phosphono-acetenamides promoted by manganese(III) acetate leads exclusively to the formation of 3-phosphoryl-β-lactams. The thiophosphoryl analogues were also prepared using this method. In particular, the presented protocol does not require the use of noble metals, while comparable methods do.
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Synthesis, crystal structure and cytotoxic activity of ruthenium(II) piano-stool complex with N,N-chelating ligand
PublicationA mononuclear compound of the general formula [(η6-p-cymene)RuIICl(2,2′-PyBIm)]PF6 has been synthesized from a bidentate N,N-donor ligand, viz. 2,-(2′-pyridyl)benzimidazole (2,2′-PyBIm) and the corresponding chloro-complex [(η6-p-cymene)Ru(μ-Cl)Cl]2 (precursor). The isolated coordination compound was characterized by IR, UV–vis and 1H, 13C NMR spectroscopies. The single crystal X-ray analysis of the complex reveals that the asymmetric...
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The role of centrifugal partition chromatography in the removal of β-asarone from Acorus calamus essential oil
PublicationΒ-asarone is a phenylpropane derivative present in the rhizomes of Acorus calamus, that was proved to exhibit toxic effects in humans. Because of its presence the whole plant that is commonly used in traditional medicine for its sedative, anti-inflammatory, neuroprotective and other properties has limited application nowadays. In the study, qualitative and quantitative analysis of a collection of nine essential oil (EO) samples...
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Characterization of immobilized Escherichia coli cells transformed by β-galactosidase gene from Pyrococcus woesei
PublicationThermostable β-galactosidase from Escherichia coli transformant containing theenzyme gene from Pyrococcus woesei was immobilized on alginate gel.The benefits of using whole bacterial cells not only exclude expensive, laborious proteinisolation and purification but also stabilize enzymes by cytosol components. Increase inproductivity of enzyme can be achieved by cells permeabilization. To increase permeability ofcytoplasmic membrane...
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Preparation and Characterization of Indomethacin Supramolecular Systems with β-Cyclodextrin in Order to Estimate Photostability Improvement
PublicationCyclodextrins have found wide application in contemporary chemistry, pharmacy andmedicine. Because of their unique properties, cyclodextrins are constantly used in research on solubility or stability improvement, as well as other physicochemical properties of medicinal substances. Indomethacin (IND) is a photolabile molecule that also attracts the interest of researchers due to its therapeutic potential and the need to...
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A new cold-active β-galactosidase from Arthrobacter sp. S3* - gene cloning, overexpression, purification and properties
PublicationA psychrotrophic bacterium producing a cold-active β-galactosidase was isolated from Spitsbergen soil and classified as Arthrobacter sp. S3*. The gene encoding β-galactosidase was isolated from the genomic DNA library, sequenced, cloned, expressed in Escherichia coli, purified by ion exchange chromatography and characterized. The Arthrobaster sp. S3* β-galactosidase is a homotrimeric enzyme composed of 74,4 kDa subunits. It is...
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The Interaction of Heptakis (2,6-di-O-Methyl)-β-Cyclodextrin with Mianserin Hydrochloride and Its Influence on the Drug Toxicity
PublicationOne tetracyclic antidepressant, mianserin hydrochloride (MIA), has quite significant side effects on a patients’ health. Cyclodextrins, which are most commonly used to reduce the undesirable features of contained drugs within their hydrophobic interior, also have the potential to alter the toxic behavior of the drug. The present paper contains investigations and the characteristics of interaction mechanisms for MIA and the heptakis...
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Study of Integer Spin S = 1 in the Polar Magnet β-Ni(IO3)2
PublicationPolar magnetic materials exhibiting appreciable asymmetric exchange interactions can potentially host new topological states of matter such as vortex-like spin textures; however, realizations have been mostly limited to half-integer spins due to rare numbers of integer spin systems with broken spatial inversion lattice symmetries. Here, we studied the structure and magnetic properties of the S = 1 integer spin polar magnet β-Ni(IO3)2...
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A new approach to β-decays studies impacting nuclear physics and astrophysics: The PANDORA setup
PublicationTheory predicts that lifetimes of β-radionuclides can change dramatically as a function of their ionization state. Experiments performed in Storage Rings on highly ionized atom have proven nuclei can change their beta decay lifetime up to several orders of magnitude. The PANDORA (Plasmas for Astrophysics, Nuclear Decay Observation and Radiation for Archaeometry) experiment is now conceived to measure, for the first time, nuclear...
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Synteza kompleksów β-diketiminowych oraz PNP tytanu(III) i tytanu(IV) z ligandem fosfanylofosfidowym i fosfanylofosfinidenowym. Badanie reaktywności β-diketiminowych kompleksów tytanu(III) z ligandem fosfanylofosfidowym
PublicationPierwszym głównym tematem prezentowanej pracy była synteza kompleksów β-diketiminowych (MeNacNac-; [ArNC(Me)CHC(Me)NAr]-) oraz PNP (bis[2-(diizopropylofosfino)-4-metylofenyloamina]) tytanu z ligandem fosfanylo-fosfidowym i fosfanylofosfinidenowym. Układy te otrzymuje się w reakcjach chlorkowych kompleksów β-diketiminowych oraz PNP z solami litowymi difosfanów (RR’P-P(SiMe3)Li) (R = tBu, iPr; R’ = tBu, iPr, Ph). Optymalizacja warunków...
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Convenient synthesis of 3-phosphono-β-lactams through the cyclization ofN-alkenyl-phosphonoacetamides
PublicationOxidative cyclization through the treatment by the transition metals is convenientsynthetic tool with a great number of applications. In the most cases the result is the formationof C-C bond between generated radical and unsaturated part of the same or another molecule.As it was presented by Trogolo it is also suitable way to obtain 4-membered heterocyclicβ-lactamic ring[1]. In this communicate we want to present new application...
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Foliate-Targeting Quantum Dots-β-Cyclodextrin Nanocarrier for Efficient Delivery of Unsymmetrical Bisacridines to Lung and Prostate Cancer Cells
PublicationTargeted drug delivery by nanocarriers molecules can increase the efficiency of cancer treatment. One of the targeting ligands is folic acid (FA), which has a high affinity for the folic acid receptors, which are overexpressed in many cancers. Herein, we describe the preparation of the nanoconjugates containing quantum dots (QDs) and β-cyclodextrin (β-CD) with foliate-targeting properties for the delivery of anticancer compound...
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Synthesis, structure, DNA binding and anticancer activity of mixed ligand ruthenium(II) complex
PublicationIn order to obtain a potential chemotherapeutic which is not affected on the normal BALB/3T3 cell line, a new arene ruthenium(II) complex {[RuCl(L1)(η6-p-cymene)]PF6}2 · H2O has been synthesized by a direct reaction of precursor, [{(η6-p-cymene)Ru(μ-Cl)}2Cl2], with N,N-chelating ligand (L1 - 2,2′-bis(4,5-dimethylimidazole). The compound has been fully characterized by elemental analysis, X-ray diffraction, IR, UV–Vis and 1H, 13C...
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The influence of magnetic particle incorporation on bisphenol A removal by β-cyclodextrin-derived sorbent
PublicationA novel, biomass-derived hybrid sorbent Ban-CD-EPI-Fe was successfully synthesized in a coprecipitation method, in which β-cyclodextrin copolymerized with banana peel extract and epichlorohydrin was grafted onto an iron oxide surface. The composition, presence of functional groups, morphology, thermal stability, and magnetic properties of the obtained material were characterized by Powder X-Ray Diffraction (XRD), X-Ray Photoelectron...
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Manganese(III) Promoted Cyclization of N-alkenyl-N-(2-hydroxyethyl) amides to Iso-Oxacepham Potent β-Lactamase Inhibitors
PublicationBackground: β-Lactams are still a subject of interest of organic chemists. The main reason for this interest is due to their application as a chemotherapeutic. β-Lactam antibiotics are still the most commonly used drugs in bacterial infections. Method: Methods using 4-exo-trig radical cyclization leading to β-lactams are an alternative to classical Staudinger`s β-Lactams formation. We prepared N-alkenyl-N-(2-hydroxyethyl)amides...
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Excited-state proton transfer and geminate recombination in the molecular cage of β-cyclodextrin
PublicationExcited-state proton transfer and geminate recombination in aqueous heptakis(2,6-di-O-methyl)-β-cyclodextrin have been compared with those in water by monitoring the photoinduced prototropic tautomerization of 6-hydroxyquinoline, which occurs via forming anionic intermediate. Enol deprotonation decelerates by 18 times whereas its reverse process accelerates slightly with encapsulation. The imine protonation of the intermediate...
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Otrzymywanie i właściwości preparatów unieruchomionej termostabilnej β-glukozydazy z Sulfolobus shibatae
Publicationβ-Glukozydaza z Sulfolobus shibatae, unieruchomiona poprzez katalizowane transglutaminazą sieciowanie na żelu krzemionkowym, charakteryzuje się niewielką wrażliwością na zmiany pH w zakresie odpowiadającym kwasowości mleka i serwatki. Duża termostabilność preparatu umożliwia jego zastosowanie do hydrolizy laktozy w reaktorze działającym w podwyższonej temperaturze hamującej lub znacznie ograniczającej rozwój niepożądanych drobnoustrojów.
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The Quaternization Reaction of 5-O-Sulfonates of Methyl 2,3-o-Isopropylidene-β-D-Ribofuranoside with Selected Heterocyclic and Aliphatic Amines
PublicationThe synthesis of N-((methyl 5-deoxy-2,3-O-isopropylidene-β-D-ribofuranoside)-5-yl) ammonium salts are presented. To determine the effect of the nucleophile type and outgoing group on the quaternization reaction, selected aliphatic and heterocyclic aromatic amines reacted with: methyl 2,3-O-isopropylidene-5-O-tosyl-β-D-ribofuranoside or methyl 2,3-O-isopropylidene-5-O-mesyl-β-D -ribofuranoside or methyl 2,3-O-isopropylidene-5-O-triflyl-β-D-ribofuranoside...
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The stereoselective formation of β-lactams with acyl ketenes generated from 5-acyl-Meldrum's acids
PublicationAcyl ketenes formed during thermal decompositions of 5-acyl-2,2-dimethyl-1,3-dioxa-4,6-diones undergo stereoselective [2+2] cycloaddition to chiral aldimines. We report the first example of optically active 3-acyl-β-lactams formation from Meldrum’s acid derivatives.
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Oznaczanie neurotoksyny, β-N-metylamino-L-alaniny (BMAA), w materiale biologicznym
Publicationβ-N-metylamino-L-alaniny (BMAA) jest naturalnie występującym niebiałkowym aminokwasem. W strukturze związku występuje grupa karboksylowa o pKa1 2,1 , pierwszorzędowa grupa aminowa o pKa2 6,5 i drugorzędowa grupa aminowa o pKa3 9,8. Przy fizjologicznych wartościach pH (7,4), w obecności CO2/HCo3-, BMAA tworzy węglanowe addukty (BMAA-α - NCO2 i BMAA-β-NCO2) o działaniu agonistycznym względem receptorów glumatinianu. Efektem jest...
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Cylindrical orifice testing in laminar flow with the orifice diameter ratio β = 0.5
PublicationThe paper presents the results of an experimental study of a cylindrical orifice with the orifice diameter ratio β = 0.5 and the flow opening length‑to‑diameter ratio L/d = 1, with hydraulic oil flowing in the DN50 measuring channel. The measurements of the values characterising the oil flow were made in the laminar flow regime, for the Reynolds numbers ranging between Re = 100 to 950. Based on the experimental tests, standard...
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THE GENE CLONING, OVEREXPRESSION, PURIFICATION AND BIOCHEMICAL CHARACTERISATION OF A NEW COLD-ADAPTED β–GALACTOSIDASE FROM ARTHROBACTER SP. VII-4
PublicationINTRODUCTION. β-Galactosidase [EC 3.2.1.23] is an enzyme that catalyzes the hydrolysis of O-glycosidic linkages in galactosides. It is commercially used in dairy industry for the production of milk with reduced lactose content. Potentially, the best method for lactose removal under cooling conditions should be carried out with a cold-adapted enzyme. AIM. The aim of this study was to determine the taxonomic affiliation of the isolate...