Search
Filters
total: 1682
filtered: 1395
-
Catalog
Chosen catalog filters
displaying 1000 best results Help
Search results for: LEWIS ACIDS
-
The Acid Strength of the Lewis‐Brønsted Superacids – A QSPR Study
Publication -
The acid strength of the HClO4/n(AlF3) and HClO4/n(SbF5) (n = 1–3) Lewis–Brønsted superacids containing the excess of the Lewis acid component
Publication -
Monomeric Triphosphinoboranes: Intramolecular Lewis Acid–Base Interactions between Boron and Phosphorus Atoms
PublicationHerein, we present the synthesis of the first fully characterized monomeric triphosphinoboranes. The simple reaction of boron tribromide with three equivalents of bulky lithium phosphide tBu2PLi yielded triphosphinoborane (tBu2P)3B. Triphosphinoboranes with diversified phosphanyl substituents were obtained via a two-step reaction, in which isolable bromodiphosphinoborane (tBu2P)2BBr is first formed and then reacts with one equivalent...
-
The acid strength of the HF/AlX3 Lewis-Brønsted complexes involving various electron acceptors as ligands
Publication -
Caralumane Superacids of Lewis and Brønsted Character
Publication -
Diphosphination of CO2 and CS2 mediated by frustrated Lewis pairs - catalytic route to phosphanyl derivatives of formic and dithioformic acid
PublicationThe first example of CO2 diphosphination is described. Reactions of unsymmetrical diphosphanes with CE2 (E = O, S) catalyzed by BPh3 insert a CE2 molecule into the P-P bond with formation of the products of the general formula R2P-E-C(=E)-PR2. The obtained CO2 adducts arise from synergistic interaction of diphosphane and borane with CO2 molecule.
-
The mechanisms of isobutene hydration yielding tert-butanol catalyzed by a strong mineral acid (H2SO4) and Lewis-Brønsted superacid (HF/SbF5)
Publication -
Dissociative electron attachment to HGaF4 Lewis–Brønsted superacid
Publication -
Mechanisms of carbon monoxide hydrogenation yielding formaldehyde catalyzed by the representative strong mineral acid, H2SO4, and Lewis–Brønsted superacid, HF/AlF3
Publication -
Theoretical estimation of acid–base properties of Lewis and Brønsted centres at the V-W-O catalyst surface: water molecule as the probe in DFT calculations
Publication -
The presence of two different central atoms increases the strength of Lewis-Brønsted superacids
Publication -
Matcha Green Tea: Chemical Composition, Phenolic Acids, Caffeine and Fatty Acid Profile
Publication -
Bioaccessibility of Phenolic Acids and Flavonoids from Buckwheat Biscuits Prepared from Flours Fermented by Lactic Acid Bacteria
Publication -
Strength of the Lewis–Brønsted Superacids Containing In, Sn, and Sb and the Electron Binding Energies of Their Corresponding Superhalogen Anions
Publication -
Fluorinated Boronic Acids: Acidity and Hydrolytic Stability of Fluorinated Phenylboronic Acids
Publication -
Novel Cell Permeable Polymers of N-Substituted L-2,3-Diaminopropionic Acid (DAPEGs) and Cellular Consequences of Their Interactions with Nucleic Acids
Publication -
Reactivity of bulky aminophosphanes towards small molecules: Activation of dihydrogen and carbon dioxide by aminophosphane/borane frustrated Lewis pairs
PublicationA series of mono- and bisaminophosphanes with formulas R2NPR’R’’ and (R2N)2PR’ (R = iPr, Cy; R’ = Ph, Cy; R’’ = iPr) were characterized by X-ray analysis, NMR spectroscopy and computational methods. The common structural futures of these species are short and polarized PAN bonds, a pyramidal geometry at the P atom and an almost planar geometry at the N atoms. According to DFT calculations, these...
-
Is the Fatty Acids Profile in Blood a Good Predictor of Liver Changes? Correlation of Fatty Acids Profile with Fatty Acids Content in the Liver
Publication -
Complexation of amino acids derivatives in water by calix[4]arene phosphonic acids
PublicationSeries of the calix[4]arene phosphonic acids with various substituents at the lower rim was synthesized. Complexing properties of these receptors towards methyl esters of six amino acids strongly depended on the calix[4]arene conformation flexibility. The complex formation processes were monitored using 1H NMR spectroscopy (deuterated phosphate buffer at pD 7.3, 22 oC) and association constant values were evaluated. Inherently...
-
Diphosphinoboranes as Intramolecular Frustrated Lewis Pairs: P–B–P Bond Systems for the Activation of Dihydrogen, Carbon Dioxide, and Phenyl Isocyanate
PublicationHerein, we present the first example of the activation of small molecules by P-B-P bond systems. The reactivity study involves reactions of two selected diphosphinoboranes, (tBu2P)2BPh (1’) and (Cy2P)2BNiPr2 (2), that differ in terms of their structural and electronic properties for the activation of dihydrogen, carbon dioxide, and phenyl isocyanate. Diphosphinoborane 1’ activates H2 under very mild conditions in the absence of...
-
Activation of N2O and SO2 by the P–B Bond System. Reversible Binding of SO2 by the P–O–B Geminal Frustrated Lewis Pair
PublicationHerein, we present the first transformation of borylphosphine into borylphosphinite using nitrous oxide. Borylphosphine reacts with N2O via insertion of a single oxygen atom into the P−B bond and formation of a P−O−B bond system. Borylphosphine and borylphosphinite capture SO2 and activate it in an irreversible and reversible manner, respectively.
-
Study on the concentration of acids by membrane distillation
Publication -
Chirality Measures of α-Amino Acids
Publication -
Chlorogenic acids – their properties, occurrence and analysis
Publication -
Modification of Bacterial Cellulose with Quaternary Ammonium Compounds Based on Fatty Acids and Amino Acids and the Effect on Antimicrobial Activity
Publication -
Boron Difluoride Complexes of Carbamoyl Meldrum's Acids
Publication5-[Hydroxy(aryl/alkylamino)methylene]-2,2-dimethyl-1,3-dioxane-4,6-diones react with BF3•Et2O in mild conditions leading to the formation of boron difluoride complexes of carbamoyl Meldrum's acids. The X-ray structure has been obtained for one representative complex. The obtained new compounds are fairly stable at standard ambient conditions and easily isolable.
-
Applications of Unnatural Amino Acids in Protease Probes
Publication -
Inhibitors of amino acids biosynthesis as antifungal agents
PublicationFungal microorganisms, including the human pathogenic yeast and filamentous fungi, are able to synthesize all proteinogenic amino acids, including nine that are essential for humans. A number of enzymes catalyzing particular steps of human-essential amino acid biosynthesis are fungi specific. Numerous studies have shown that auxotrophic mutants of human pathogenic fungi impaired in biosynthesis of particular amino acids exhibit...
-
Mechanism of the reaction of Lawesson's reagent with N-alkylhydroxamic acids
PublicationIdentyfikacja fosforowych produktów powstających w reakcji kwasów hydroksamowych z odczynnikiem Lawessona pozwoliła ustalić mechanizm tytułowej reakcji. Wykorzystano w tym celu spektroskopię 31P NMR. Wzorce labilnych produktów otrzymano na niezależnej drodze syntetycznej lub przeprowadzono je w trwałe pochodne, które wyizolowano z mieszanin reakcyjnych. Produktem przejściowym badanej reakcji okazał się odpowiedni O-ditiofosfonylowany...
-
S-thioacyldithiophosphates in the synthesis of thiohydroxamic acids and O-thioacylhydroxylamines
PublicationDitiofosforany tioacylu to trwałe, łatwo osiągalne z kwasów karboksylowych środki tioacylujące. Z powodu ich niskiej reaktywności wobec nukleofili tlenowych i wysokiej wobec nukleofili azotowych znalazły zastosowanie w syntezie kwasów tiohydroksamowych bezpośrednio z hydroksyloamin z niechronioną grupą hydroksylową. W przypadku dużej zawady przestrzennej można otrzymać O-tioacylohydroksyloaminy.
-
Propensity of salicylamide and ethenzamide cocrystallization with aromatic carboxylic acids
PublicationThe cocrystallization of salicylamide (2-hydroxybenzamide, SMD) and ethenzamide (2-ethoxybenzamide, EMD) with aromatic carboxylic acids was examined both experimentally and theoretically. The supramolecular synthesis taking advantage of the droplet evaporative crystallization (DEC) technique was combined with powder diffraction and vibrational spectroscopy as the analytical tools. This led to identification of eleven new cocrystals...
-
Ion Chromatography in Environmental Analysis of Selected Organic Acids
PublicationLow molecular mass carboxylic acids (LCAs) occur in many environmental compartments dueto natural processes and human activity. When volatile and nonvolatile acids are to be monitored then liquidchromatography, including ion chromatography seems a method of choice. At high pH the acids are inionized form and can be separated as carboxylats by means of anion exchange chromatography. LCAs canalso be separated at low pH by ion exclusion...
-
Biodegradability of modified emulsifiers - esters of polyols and fatty acids
PublicationBadano podatność na biodegradację wybranych emulgatorów estrów polioli i kwasów tłuszczowych przy użyciu testu zamkniętej butelki (OECD 301 D). Stwierdzono, że badane emulgatory nie mogą zostać uznane za łatwo ulegające biodegradacji. Najwyższy poziom rozkładu (57,3%) osiągnął emulgator C14Gna, najniższy (29,8%) AEGNa.
-
Bile Acids: Key Players in Inflammatory Bowel Diseases?
Publication -
Electric chips for rapid detection and quantification of nucleic acids
Publication -
Fatty acids as molecular carriers in cleavable antifungal conjugates
PublicationConjugates composed of C2-18 fatty acid (FA) residues as a molecular carrier and 5-fluorocytosine (5-FC) as an active agent, released upon the action of intracellular esterases on the ester bond between FA and “trimethyl lock” intramolecular linker, demonstrate good in vitro activity against human pathogenic yeasts of Candida spp. The minimal inhibitory concentrations (MIC) values for the most active conjugates containing caprylic...
-
Hyaluronic acid/tannic acid films for wound healing application
PublicationIn this study, thin films based on hyaluronic acid (HA) with tannic acid (TA) were investigated in three different weight ratios (80HA/20TA, 50HA/50TA, 20HA/80TA) for their application as materials for wound healing. Surface free energy, as well as their roughness, mechanical properties, water vapor permeability rate, and antioxidant activity were determined. Moreover, their compatibility with blood and osteoblast cells was investigated....
-
Immunosuppressive properties of amino acid and peptide derivatives of mycophenolic acid
PublicationMycophenolic acid (MPA) was coupled with amino acids and biologically active peptides including derivatives of tuftsin to modify its immunosuppressive properties. Both amino acid unit in the case of simple MPA amides and modifications within peptide moiety of MPA - tuftsin conjugates influenced the observed activity. Antiproliferative potential of the obtained conjugates was investigated in vitro and MPA amides with threonine methyl...
-
Synthesis and biological activity of mycophenolic acid-amino acid derivatives
Publication -
Synthesis and biological activity of mycophenolic acid-amino acid derivatives
PublicationIn search of new immunosuppressants, mycophenolic acid (MPA) was coupled with amino acid methyl esters followed by hydrolysis to analogs bearing free carboxylic groups. The obtained compunds were tested in vitro as growth inhibitors of lymphoid cell line (Jurkat) and human peripheral blood mononuclear cells (PBMC) from healthy donors. According to obtained results recovering of free carboxylic group increased their activity. Additionally,...
-
Anticancer Properties of Amino Acid and Peptide Derivatives of Mycophenolic Acid
PublicationBackground: Although Mycophenolic Acid (MPA) is applied as prodrugs in clinic as an immunosuppressant, it also possesses anticancer activity. MPA acts as Inosine-5’-Monophosphate Dehydrogenase (IMPDH) inhibitor, where the carboxylic group at the end of the side chain interacts with Ser 276 of the enzyme via hydrogen bonds. Therefore, MPA derivatives with other polar groups indicated high inhibition too. On the other hand, potent...
-
α-Amino Acids In Water: A Review Of VCD And ROA Spectra
Publication -
Hydrogen and chalcogen bonds in crystals of chalcogenadiazolecarboxylic acids – competition or cooperation?
PublicationThis article presents crystal structures of chalcogenadiazolecarboxylic acids bearing both a hydrogen and a chalcogen bond donor. The selected molecules varied in the size of the aromatic unit, the chalcogen atom and/or the position of the carboxyl group in the core structure. The most common synthons in their lattice are "R" _"2" ^"2" (8) self-complementary acid dimers or four-membered [Ch···N]2 rings. Supramolecular synthons...
-
Determination and identification of organic acids in wine samples. Problems and challenges.
PublicationFor long time, organic acids were underestimated. However, during last two decades there is an increasing interest of natural compounds having antioxidant, antimicrobial and anti-inflammatory properties thus organic acids are very preferable. Wine stands as one of the sources of organic acids since they are responsible for its organoleptic and aestethic character. Nevertheless, it is important to not exceed acceptable level of...
-
Composition of fatty acids in selected sorts of biscuits, offered for children
PublicationThe fatty acid (FA) composition, especially total trans-fatty acids (TFA) content in 12 assortments of biscuits offered for children, produced by four different companies, were determined by gas chromatography. Total fat content of the biscuit samples ranged from 2.2 to 22.8 g/100 g of product. The major FAs were palmitic C16:0, oleic C18:1, and linoleic C18:2 acids. Depending on the biscuit type, the total saturated fatty acids...
-
Peroxidative metabolism of fatty acids in the course of tick-borne encephalitis
Publication -
Applicability of phenolic acids as effective enhancers of cocrystals solubility of methylxanthines
PublicationApplicability of phenolic acids as potential cocrystal formers for methylxanthine derivatives was analyzed both in terms of cocrystallization probabilities and solubility advantage. The cocrystal formation abilities were evaluated using mixing enthalpy estimated within the conductor like screening model for real solvents (COSMO-RS) framework. The solubility improvement of potential cocrystals was estimated by formulation of the...
-
Occurrence and Determination of Volatile Fatty Acids in Wastewater of Different Origin
PublicationOpracowano metodykę oznaczania krótkołańcuchowych alifatycznych kwasów monokarboksylowych w ściekach rożnego pochodzenia stosując ekstrakcję za pomocą eteru metylo-tert-butylowego na etapie przygotowania próbek i chromatografię gazową z kolumną kapilarną Stabilwax-DA i Rtx-624, natomiast na etapie detekcji stosowano spektrometr mas.
-
Capillary Electrophoresis in Determination of Low Molecular Mass Organic Acids
PublicationThis paper presents overviews the capabilities of capillary electrophoretic techniques to determine low molecular mass organic acids in a variety of aqueous, gas and solid samples. It mainly focuses on short - chain carboxylic acids containing one or more carboxylic groups and possibly some other functional groups (hydroxyl, keto-, amino- etc.). Finally the procedures applied to the determine the acids in different matrices are...
-
Calibration of POCIS and PASSIL passive samplers – influence of humic acids
Publication