Artykuły (WCh)

Stały URI dla kolekcjihttp://hdl.handle.net/11652/155

Przeglądaj

Teraz wyświetlane 1 - 20 z 188

Propedeutyka kierunkowych oddziaływań międzycząsteczkowych. Wiązania wodorowe, oddziaływania asocjacji warstwowej i wiązania halogenowe
(Wydawnictwo Politechniki Łódzkiej, 2011) Kruszyński, Rafał
The review presents the typical bonding intermolecular interactions: hydrogen bonds, halogen bonds and stacking interactions. The first part describes the specific types of intermolecular interactions, including their definitions, energy and selected properties. The second part deals with the application of quantum-mechanical methods to study of intermolecular interactions, especially the appliance of the natural bond orbitals method, and usage of ab intio calculations for solving of structural problems appearing during the above mentioned studies. All above referred interactions have been presented in orbital terms. The third part describes the novel employment of graph theory to characterise the motifs formed by intermolecular interactions in the solid state.
Indanthrone dye revisited after sixty years
(2014) Kotwica, Kamil; Bujak, Piotr; Wamil, Damian; Materna, Mariusz; Skórka, Łukasz; Gunka, Piotr A.; Nowakowski, Robert; Golec, Barbara; Łuszczyńska, Beata; Zagórska, Małgorzata; Pron, Adam
Indanthrone, an old, insoluble dye can be converted into a solution processable, self-assembling and electroluminescent organic semiconductor, namely tetraoctyloxydinaptho[2,3-a:20,30-h]phenazine (P-C8), in a simple one-pot process consisting of the reduction of the carbonyl group by sodium dithionite followed by the substitution with solubility inducing groups under phase transfer catalysis conditions
Decomposition of Azo Dye C.I. Direct Yellow 86 by the Fenton Process in the Presence of Nanoparticles of Iron Oxides
(Instytut Biopolimerów i Włókien Chemicznych (IBWCh) , Łódź, Polska, 2014) Kos, Lech; Sójka-Ledakowicz, Jadwiga; Michalska, Karina; Perkowski, Jan
The aim of the study was to determine the efficiency of decomposition of azo dye C.I. Direct Yellow 86 by the Fenton method in the presence of nanoparticles of iron oxides and to compare it with the classical Fenton method. Water solutions of the dye were subjected to the classical purification method with the application of ferrous sulfate and – for comparison – to a process in which iron (II,III) oxide nanopowder was added to the ferrous sulfate. Analysis of the effect of the ferrous sulfate, iron (II,III) oxide nanopowder, hydrogen peroxide and the pH of the solution on the treatment efficiency showed that the process was optimised. The use of iron oxide nanopowder increased the efficiency of dye decomposition.
A Convenient Approach to a Novel Group of Quaternary Amino Acids Containing a Geminal Bisphosphonate Moiety
(2014) Dzięgielewski, Marek; Hejmanowska, Joanna; Albrecht, Łukasz
Quaternary amino acids containing a geminal bisphosphonate moiety have been synthesized for the first time. The developed two-step reaction sequence utilizes the Michael addition of α-substituted azlactones to a vinylidene bisphosphonate as the key step. The reaction proceeds under catalytic conditions with excellent regioselectivity. Subsequent, acid-mediated azlactone ring opening affords the target quaternary amino acids with good overall yields. Attempts to develop an enantioselective version of the synthetic strategy are described.
Role of water in metal catalyst performance for ketone hydrogenation: a joint experimental and theoretical study on levulinic acid conversion into gamma-valerolactone
(2014) Carine, Michel; Jérémie, Zaffran; Ruppert, Agnieszka M.; Matras-Michalska, Joanna; Jędrzejczyk, Marcin; Grams, Jacek; Sautet, Philippe
While Ru is a poor hydrogenation catalyst compared to Pt or Pd in the gas phase, it is efficient under aqueous phase conditions in the hydrogenation of ketones such as the conversion of levulinic acid into gamma-valerolactone. Combining DFT calculations and experiments, we demonstrate that water is responsible for the enhanced reactivity of Ru under those conditions.
Erratum: “How accurate is the strongly orthogonal geminal theory in predicting excitation energies? Comparison of the extended random phase approximation and the linear response theory approaches” [J. Chem. Phys.140, 014101 (2014)]
(American Institute of Physics, 2014) Pernal, Katarzyna; Chatterjee, Koushik; Kowalski, Piotr H.
How accurate is the strongly orthogonal geminal theory in predicting excitation energies? Comparison of the extended random phase approximation and the linear response theory approaches
(American Institute of Physics, 2014) Pernal, Katarzyna; Chatterjee, Koushik; Kowalski, Piotr H.
Performance of the antisymmetrized product of strongly orthogonal geminal (APSG) ansatz in describing ground states of molecules has been extensively explored in the recent years. Not much is known, however, about possibilities of obtaining excitation energies from methods that would rely on the APSG ansatz. In the paper we investigate the recently proposed extended random phase approximations, ERPA and ERPA2, that employ APSG reduced density matrices. We also propose a time-dependent linear response APSG method (TD-APSG). Its relation to the recently proposed phase including natural orbital theory is elucidated. The methods are applied to Li2, BH, H2O, and CH2O molecules at equilibrium geometries and in the dissociating limits. It is shown that ERPA2 and TD-APSG perform better in describing double excitations than ERPA due to inclusion of the so-called diagonal double elements. Analysis of the potential energy curves of Li2, BH, and H2O reveals that ERPA2 and TD-APSG describe correctly excitation energies of dissociating molecules if orbitals involved in breaking bonds are involved. For single excitations of molecules at equilibrium geometries the accuracy of the APSG-based methods approaches that of the time-dependent Hartree-Fock method with the increase of the system size. A possibility of improving the accuracy of the TD-APSG method for single excitations by splitting the electron-electron interaction operator into the long- and short-range terms and employing density functionals to treat the latter is presented.
Thermal properties of diene elastomers
(2014) Rybiński, Przemysław; Kucharska-Jastrząbek, Agnieszka; Janowska, Grażyna
The paper presents the results of investigating the effect of the macromolecule chemical structure and the spatial network structure of butadiene (BR), butadiene-styrene (SBR) and butadiene-acrylonitrile (NBR) rubbers on their thermal properties. The rubbers were cross-linked by the conventional method by means of dicumyl peroxide or sulfur as well as by the non-conventional way using iodoform (CH3I). The rubber and their vulcanizates were assessed by the derivatographic method (under air) and by means of differential scanning calorimetry (DSC) under inert gas. The thermal cross-linking degree of the polydienes and the efficiency of the cross-linking processes, dependent on both the chemical structure of elastomer macromolecules and their spatial network structure were determined. The cross-linking of elastomers with iodoform changes the thermal properties of polymers, significantly increasing their glass transition temperature during both sample heating and cooling, which results from the increase in mutual interaction of macromolecules connected with their modification with iodine compounds.
Theoretical predictions of isotope effects versus their experimental values for an example of uncatalyzed hydrolysis of atrazine
(Royal Society of Chemistry, 2014) Grzybkowska, Anna; Kamiński, Rafał; Dybała-Defratyka, Agnieszka
Kinetic isotope effects are one of the most powerful experimental techniques for establishing the nature of a chemical process. However their interpretation very often seeks support from electronic structure calculations in order to get detailed information regarding the transition state which is not experimentally available. For an example of atrazine hydrolysis we have shown how the match between experimentally and theoretically determined magnitudes of carbon, nitrogen and chlorine kinetic isotope effects can be used to discuss the mechanism under different reaction conditions. Two different density functionals combined with the explicit presence of solvent molecules and a continuum solvation model revealed that although the reaction proceeds via the same concerted mechanism regardless of the reaction conditions the transition state structure for an acid and base-catalyzed pathway is different.
Organocatalytic Enantioselective Approach to Spirocyclic Δβ,γ-Butenolides
(2014) Hejmanowska, Joanna; Dzięgielewski, Marek; Kowalczyk, Dorota; Albrecht, Łukasz
A novel method for the preparation of the spirocyclic Δβ,γ-butenolides is presented. The developed strategy is based on a trienamine-mediated [4+2]-cycloaddition between (E)-3-alkylidene- 5-arylfuran-2(3H)-ones and 2,4-dienals. Target products containing three contiguous centres including one quaternary are efficiently formed in a highly enantiomerically enriched form in the presence of the silyl-protected diphenylprolinol aminocatalyst.
Simulation of diffusion in a crowded environment
(Royal Society of Chemistry, 2014) Polanowski, Piotr; Sikorski, Andrzej
We performed extensive and systematic simulation studies of two-dimensional fluid motion in a complex crowded environment. In contrast to other studies we focused on cooperative phenomena that occurred if the motion of particles takes place in a dense crowded system, which can be considered as a crude model of a cellular membrane. Our main goal was to answer the following question: how do the fluid molecules move in an environment with a complex structure, taking into account the fact that motions of fluid molecules are highly correlated. The dynamic lattice liquid (DLL) model, which can work at the highest fluid density, was employed. Within the frame of the DLL model we considered cooperative motion of fluid particles in an environment that contained static obstacles. The dynamic properties of the system as a function of the concentration of obstacles were studied. The subdiffusive motion of particles was found in the crowded system. The influence of hydrodynamics on the motion was investigated via analysis of the displacement in closed cooperative loops. The simulation and the analysis emphasize the influence of the movement correlation between moving particles and obstacles.
Dielectric Properties and Characterisation of Titanium Dioxide Obtained by Different Chemistry Methods
(Hindawi Publishing Corporation, 2014) Wypych, Aleksandra; Bobowska, Izabela; Tracz, Milena; Opasińska, Agnieszka; Kadłubowski, Sławomir; Krzywania-Kaliszewska, Alicja; Grobelny, Jarosław; Wojciechowski, Piotr
We made comparison of titanium dioxide powders obtained from three syntheses including sol-gel and precipitation methods as well as using layered (tetramethyl)ammonium titanate as a source of TiO2. The obtained precursors were subjected to step annealing at elevated temperatures to transform into rutile form. The transformation was determined by Raman measurements in each case. The resulting products were characterised using Raman spectroscopy and dynamic light scattering. The main goal of the studies performed was to compare the temperature of the transformation in three titania precursors obtained by different methods of soft chemistry routes and to evaluate dielectric properties of rutile products by means of broadband dielectric spectroscopy. Different factors affecting the electrical properties of calcinated products were discussed. It was found that sol-gel synthesis provided rutile form after annealing at 850°C with the smallest particles size about 20 nm, the highest value of dielectric permittivity equal to 63.7, and loss tangent equal to 0.051 at MHz frequencies. The other powders transformed to rutile at higher temperature, that is, 900°C, exhibit lower value of dielectric permittivity and had a higher value of particles size. The correlation between the anatase-rutile transformation temperature and the size of annealed particles was proposed.
Versatile Synthesis of 4-Methylidenepyrazolidin-3-ones Using a Horner–Wadsworth–Emmons Approach
(2014) Modranka, Jakub; Jakubowski, Rafał; Janecki, Tomasz
A new, versatile method for the synthesis of, so far unknown, variously substituted 4-methylidenepyrazolidin-3-ones as potential cytotoxic agents is described. Target compounds were synthesized from the corresponding 4-diethoxyphosphorylpyrazolidin-3-ones which were used as Horner–Wadsworth–Emmons reagents for the olefination of formaldehyde. 4-Phosphorylpyrazolidin-3-ones were, in turn, obtained starting from the sodium salt of ethyl 2-diethoxyphosphoryl-3-hydroxy-2-propenoate, ethyl 2-acyl-2-diethoxyphosphorylacetates, or 3-methoxy-2-diethoxyphosphorylacrylate and monosubstituted or 1,2-disubstituted hydrazines.
Chemical synthesis of the 5-taurinomethyl(-2-thio)uridine modified anticodon arm of the human mitochondrial tRNALeu(UUR) and tRNALys
(Cold Spring Harbor Laboratory Press, 2014) Leszczyńska, Grażyna; Leonczak, Piotr; Woźniak, Karolina; Małkiewicz, Andrzej
5-Taurinomethyluridine (τm5U) and 5-taurinomethyl-2-thiouridine (τm5s2U) are located at the wobble position of human mitochondrial (hmt) tRNALeu(UUR) and tRNALys, respectively. Both hypermodified units restrict decoding of the third codon letter to A and G. Pathogenic mutations in the genes encoding hmt-tRNALeu(UUR) and hmt-tRNALys are responsible for the loss of the discussed modifications and, as a consequence, for the occurrence of severe mitochondrial dysfunctions (MELAS, MERRF). Synthetic oligoribonucleotides bearing modified nucleosides are a versatile tool for studying mechanisms of genetic message translation and accompanying pathologies at nucleoside resolution. In this paper, we present site-specific chemical incorporation of τm5U and τm5s2U into 17-mers related to the sequence of the anticodon arms hmt-tRNALeu(UUR) and hmttRNALys, respectively employing phosphoramidite chemistry on CPG support. Selected protecting groups for the sulfonic acid (4-(tert-butyldiphenylsilanyloxy)-2,2-dimethylbutyl) and the exoamine function (-C(O)CF3) are compatible with the blockage of the canonical monomeric units. The synthesis of τm5s2U-modified RNA fragment was performed under conditions eliminating the formation of side products of 2-thiocarbonyl group oxidation and/or oxidative desulphurization. The structure of the final oligomers was confirmed by mass spectroscopy and enzymatic cleavage data.
Oncologic photodynamic diagnosis and therapy: confocal Raman/fluorescence imaging of metal phthalocyanines in human breast cancer tissue in vitro
(Royal Society of Chemistry, 2014) Abramczyk, Halina; Brożek-Płuska, Anna; Surmacki, Jakub; Musiał, Jacek; Kordek, Radzisław
Raman microspectroscopy and confocal Raman imaging combined with confocal fluorescence were used to study the distribution and aggregation of aluminum tetrasulfonated phthalocyanine (AlPcS4) in noncancerous and cancerous breast tissues. The results demonstrate the ability of Raman spectroscopy to distinguish between noncancerous and cancerous human breast tissue and to identify differences in the distribution and aggregation of aluminum phthalocyanine, which is a potential photosensitizer in photodynamic therapy (PDT), photodynamic diagnosis (PDD) and photoimmunotherapy (PIT) of cancer. We have observed that the distribution of aluminum tetrasulfonated phthalocyanine confined in cancerous tissue is markedly different from that in noncancerous tissue. We have concluded that Raman imaging can be treated as a new and powerful technique useful in cancer photodynamic therapy, increasing our understanding of the mechanisms and efficiency of photosensitizers by better monitoring localization in cancer cells as well as the clinical assessment of the therapeutic effects of PDT and PIT.
A Tandem Conjugate Addition–Intramolecular Horner–Wadsworth–Emmons Olefination Approach to the Synthesis of Cyclopentene[c]chroman-2-ones and Cyclopent-1-enecarboxylates
(2014) Deredas, Dariusz; Huben, Krzysztof; Maniukiewicz, Waldemar; Krawczyk, Henryk
A strategically new approach to cyclopentene[c]chroman- 2-ones and cyclopent-1-enecarboxylates by tandem Michael– Horner–Wadsworth–Emmons reaction of 2,5-hexanedione with 3-(diethoxyphosphoryl)coumarins is described. The products were obtained as single diastereoisomers in high yields.
Nowe absorbery organiczne do modyfikacji wyrobów z włókien celulozowych przeznaczonych na środki ochrony indywidualnej przed promieniowaniem nadfioletowym
(2014) Sójka-Ledakowicz, Jadwiga; Czajkowski, Wojciech; Lewartowska, Joanna; Mamnicka, Justyna; Kudzin, Marcin H.; Lota, Wiesława
Najważniejszym elementem ochrony skóry przed szkodliwym wpływem promieniowania ultrafioletowego naturalnego i emitowanego przez źródła sztuczne jest odzież wykonana z materiałów włókienniczych o odpowiednich właściwościach barierowych i użytkowych. W niniejszej pracy przedstawiono wyniki badań właściwości barierowych przed promieniowaniem ultrafioletowym dzianiny bawełnianej modyfikowanej nowymi organicznymi absorberami UV opartymi na 1,3,5-triazynie typu reaktywnego i bezpośredniego. Skuteczność modyfikacji dzianiny bawełnianej, także po wielokrotnym praniu i ekspozycji na promieniowanie UV, sprawdzana była na dwuwiązkowym spektrofotometrze UV-Vis. Zbadano także właściwości użytkowe barierowej dzianiny bawełnianej przeznaczonej na środki ochrony indywidualnej, takie jak rękawiczki, koszulki z długim rękawem, nakrycia głowy.
New Eco-friendly Method for Paper Dyeing
(Institute of Biopolymers and Chemical Fibres, 2014) Blus, Kazimierz; Czechowski, Jacek; Koziróg, Anna
For economical and environmental reasons, the paper industry has shifted the production of paper products towards dyed products made from pulp grades with a high content of recovered paper. The basic method for dyeing paper products is pulp colouring with direct and basic dyes. Disadvantages of this method include coloured white water and so-called „bleeding” processes when using those products. „Bleeding” processes are undesired when using tissue products. A new eco-friendly method for dyeing pulp with adducts of reactive dyes and selected cationic aliphatic polyamine compouds was developed. A reactive dye is added to refined pulp and then a cationic polyamine compound. The dyeing substance is adsorbed on the entire surface of refined cellulose based semi finished products in a water medium with a pH near to neutral. After web consolidation, an uniform dye penetrated paper product is obtained, with high colour life and strength. Reactive dyes contain 3’-carboxypyridine-1,3,5-triazine systems that react with cellulose in a medium near to neutral and at a temperature similar to web drying. As polyamine compounds, polycondensates of guanidine with hexamethylene-1.6-diamine and octamethylene-1,8-diamine were used. As was proved by a test done on coloured paper, these compounds are characterised by bactericidal and fungicidal properties, which are advised for tissue paper. The polyamine compounds mentioned cause the quantitative adsorption of dyes on cellulose based pulp, increasing the retention of cellulose fibre fines, and the white water is practically colourless. In principle, this dyeing method does not change the strength, optical, structural and dimensional properties of selected paper products.
Effect of Formic Acid on Pollutant Decomposition in Textile Wastewater Subjected to Treatment by the Fenton Method
(Instytut Biopolimerów i Włókien Chemicznych (IBWCh) , Łódź, Polska, 2014) Kos, Lech; Michalska, Karina; Żyłła, Renata; Perkowski, Jan
The aim of this research was to determine the effect of formic acid on pollutant decomposition in textile wastewater subjected to treatment by the Fenton method. To estimate the effect of formic acid on treatment efficiency for different types of textile wastewater tested, COD reduction in mixtures of wastewater and formic acid was calculated. The values of COD calculated were then compared with COD values obtained experimentally during the oxidation of samples of wastewater-formic acid mixtures in the Fenton process. It was found that the presence of formic acid did not deteriorate the conditions of wastewater treatment in the Fenton process. Thus the presence of formic acid in textile wastewater is more advantageous than that of acetic acid.
Cytochrome P450-catalyzed dealkylation of atrazine by Rhodococcus sp. strain NI86/21 involves hydrogen atom transfer rather than single electron transfer
(Royal Society of Chemistry, 2014) Meyer, Armin H.; Dybała-Defratyka, Agnieszka; Alaimo, Peter J.; Geronimo, Inacrist; Sanchez, Ariana D.; Cramer, Christopher J.; Elsner, Martin
Cytochrome P450 enzymes are responsible for a multitude of natural transformation reactions. For oxidative N-dealkylation, single electron (SET) and hydrogen atom abstraction (HAT) have been debated as underlying mechanisms. Combined evidence from (i) product distribution and (ii) isotope effects indicate that HAT, rather than SET, initiates N-dealkylation of atrazine to desethyl- and desisopropylatrazine by the microorganism Rhodococcus sp. strain NI86/21. (i) Product analysis revealed a non-selective oxidation at both the αC and βC-atom of the alkyl chain, which is expected for a radical reaction, but not SET. (ii) Normal 13C and 15N as well as pronounced 2H isotope effects (εcarbon: −4.0‰ ± 0.2‰; εnitrogen: −1.4‰ ± 0.3‰, KIEH: 3.6 ± 0.8) agree qualitatively with calculated values for HAT, whereas inverse 13C and 15N isotope effects are predicted for SET. Analogous results are observed with the Fe(IV)[double bond, length as m-dash]O model system [5,10,15,20-tetrakis(pentafluorophenyl)porphyrin-iron(III)-chloride + NaIO4], but not with permanganate. These results emphasize the relevance of the HAT mechanism for N-dealkylation by P450.