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1
Content available remote Thin films of copper phthalocyanine deposited by solution processing methods
EN
In this work, we show and discuss the surface structure picture of copper phthalocyanine (CuPc) thin films deposited from trifluoroacetic acid (TFA) solvent onto silicon substrates at ambient conditions by four solution processing methods, namely drop-casting, dip-coating, spin-casting and spray-coating. The CuPc films were studied by AFM, as the main technique, and complemented by micro-Raman spectroscopy. Essentially, such thin films consist of CuPc molecular nanoribbons of a fixed ~1 nm thickness. CuPc molecules are arranged in an in-plane direction and formed in stacks under a defined tilt angle with respect to the substrate surface (monolayer) or underlying CuPc layer (multilayer). The film morphology takes various forms depending on the solution concentration, number of layers, and the deposition method. For instance, the morphology varies from very wide (~600 nm) but flat (~1 nm) ribbons for films prepared by dip-coating to crystallized rod-like features (multi-layered ribbons) when obtained by spray-coating. The factors studied in this paper should be taken into consideration in designing and controlling the criteria for rigorous CuPc film architecture.
EN
The aim of the research was to analyse the influence of the initial heat treatment of polyacrylonitrile fibres on their sorption properties in relation to selected basic and disperse dyes, in order to select the dyeing variants most beneficial from the point of view of increasing the sorption capacity of commonly used dyes and improving the dyeing process. Research was carried out on a fibre produced on an industrial scale, using dyes of basic application importance, which differ in the diffusion properties of the molecules and the mechanism of binding with the fibre material. Thermal treatment of the fibre was carried out in various media (air, water, steam), with various variants of the temperature and its duration, i.e. under the conditions commonly used in fibre preprocessing processes and their "improvement". During the research, several different measurement methods were used to assess changes in the molecular and supramolecular structure of the fibre material: the infrared absorption spectroscopy method, the critical fibre dissolution measurement method, the densitometric method, and the interferential polarisation microscopy method. Fibre sorption changes resulting from the modification of the structure of the fibre under the influence of thermal treatment were analysed from the point of view of improving the efficiency of dye use and shortening the dyeing time based on commonly accepted values of the sorption index Cb and kinetic sorption index: t0.5 for basic dyes and t0.7 for disperse dyes.
PL
Celem badań było określenie wpływu wstępnej obróbki cieplnej badanych włókien poliakrylonitrylowych na ich właściwości sorpcyjne w stosunku do wybranych barwników zasadowych i zawiesinowych. Badania prowadzono na włóknach produkowanych w skali przemysłowej, używając barwników o dużym znaczeniu aplikacyjnych, różniących się właściwościami dyfuzyjnymi cząsteczek oraz mechanizmem wiązania z tworzywem włókna. Obróbkę termiczną prowadzono w różnych mediach (powietrze, woda, para wodna), w różnych wariantach temperatury i czasu jej trwania. W badaniach zastosowano metody pomiarowe, pozwalające oceniać zmiany parametrów budowy cząsteczkowej i nadcząsteczkowej tworzywa włókien: metodę spektroskopii absorpcyjnej w podczerwieni, metodę pomiaru krytycznego czasu rozpuszczania włókien, metodę densytometryczną oraz metodę mikroskopii interferencyjno-polaryzacyjnej. Zmiany zdolności sorpcyjnej włókien analizowano z punktu widzenia poprawy efektywności wykorzystania barwników i skrócenia czasu barwienia w oparciu o wartości wskaźnika sorpcji Cb oraz kinetycznych wskaźników sorpcji: t0,5 dla barwnika zasadowego i t0,7 dla barwników zawiesinowych.
EN
High nitrogen organic compounds (N>50 wt.%) are important for chemical industries because they can provide clean products with generally low-molecular weight product gases and enormous energy release. The density of these materials at or near room temperature is an important physical property for the assessment of their detonation and combustion performances. A novel method is introduced here for the prediction of the density of various classes of organic compounds, including different derivatives of triazole, tetrazole, triazine, tetrazine, furazan, and some organic nitrogen-containing chains. The core model is based on elemental composition, where its reliability has been improved by considering some molecular fragments including specific functional groups. The high reliability of these simple model has been compared with the output from two complex quantum mechanical approaches. For 91 high nitrogen compounds, the values of the standard deviation (SD) of the core and improved correlations were 0.076 and 0.047 g·cm–3. For a further 32 materials, the values of SD were 0.057 and 0.042 g·cm–3 for the core and improved correlations, respectively. These data are close to core and improved quantum mechanical methods, i.e. 0.056 and 0.042 g·cm–3, respectively, where the calculated data from complex quantum mechanical approaches were available.
EN
Aluminized melt cast formulations based on 2,4,6-trinitrotoluene (TNT) deliver an enhanced blast effect because the secondary combustion process of aluminum (Al) occurs beyond the detonation zone. A new method is introduced to assess the detonation performance and characteristics of aluminized TNT explosives on the basis of the laser-induced breakdown spectroscopy (LIBS) technique, in both air and argon (Ar) atmospheres. The plasma emissions of the prepared samples were recorded, where the atomic lines of Al, C, O and H as well as the molecular bands of AlO, CN and C2 were identified. A good discrimination and separation between the samples was possible using LIBS and principle component analysis (PCA), although they had similar atomic compositions. The quantitative calibration curve obtained using the relative intensity of Al/O was used to determine the detonation velocity/pressure and aluminum content of the TNT/Al samples. Comparisons between experimental and theoretical spectra were made using a Nelder–Mead temperature program for CN bands, which provided good agreement with the fitted spectra. Finally, CN vibrational temperatures were calculated from these spectral fittings. These temperatures have higher values in an Ar atmosphere than in an air atmosphere. Thus, increasing the oxygen concentration can decrease these temperatures in TNT/Al standard samples.
EN
The aim of the paper is to assess the range and the mechanisms of transformations of the molecular structure and the physical microstructure of polyacrylonitrile (PAN) fibers produced by various manufacturers under the influence of thermal treatment in different conditions. The thermal treatments were carried out in different media (such as air, water, and steam), at various temperatures, and using different periods of treatment. Changes in the molecular structure were assessed using infrared (IR) absorption spectroscopy and evaluation of the differences in molecular cohesion energy of the fiber material during the dissolution processes. Changes in the fibers’ physical microstructure were investigated using densitometric, IR spectrophotometric, and X-ray diffraction methods; for assessment of both the reconstruction process of the paracrystalline matter of the fibers and the changes in the fibers’ total orientation, interferential polarization microscopy was used.
EN
In this study, a new and reliable model is derived for predicting the density of tetrazole N-oxide salts using molecular structure descriptors through multiple linear regression methods (MLR). The proposed model is based on the elemental, functional group and type of molecule descriptors. The coefficient of determination (R2) of the model was 0.9321 for 36 energetic tetrazole N-oxides with different molecular structures as an exploratoryset. The predictive ability of this model has been checked using a cross validation method (Q2 LOO = 0.9325 and Q2 LMO = 0.9324). The new correlation had a root mean square deviation (RMSD) of 0.033 g·cm−3 and an average absolute deviation (AAD) of 0.025 g·cm−3. This correlation also gave good predicted results for a further 10 energetic tetrazole N-oxides as a test set. The new reliable model can also be appliedfor designing novel energetic tetrazole N-oxides.
EN
Polyether ionophore antibiotics (ionophores) represent a large group of naturally- occurring lipid-soluble compounds isolated from actinomycetes strains of Streptomyces genus. Ionophores are able to form complexes with the metal cations, especially sodium and potassium, and transport them across the lipid membranes according to electroneutral or electrogenic transport mechanism. This process disturbs the intercellular Na+/K+ concentration gradient and intracellular pH, leads to the mitochondrial injuries, cell swelling, vacuolization and finally to programmed cell death (apoptosis). For this reason, ionophore antibiotics found commercial use in veterinary medicine as coccidiostatic agents and non-hormonal growth promoters. In addition to the industrial use of ionophores, some of them effectively and selectively inhibit properties of different cancer cells as well as enhance the anti-cancer effects of radio- and/or chemotherapy. In this group, particularly interesting is salinomycin because of its potent anti-microbial and anti-cancer activity, including efficiency against multi-drug resistant cancer cells and cancer stem cells. A very interesting direction of research is the chemical modification of ionophore antibiotics, which can lead to obtaining various derivatives with better biological activity and lower toxicity than those of the starting substances. Because biological activity of ionophore antibiotics and their derivatives is strictly connected with the ability to form characteristic pseudocyclic structures around the complexed cations (host-guest complex), it is also important to establish the detailed information on these structures. In this context, our review article is focused on the possible role of salinomycin and its derivatives in anti-microbial as well as anti-cancer therapy, and gives an overview of the properties of this antibiotic.
8
Content available Betainy jako akceptory protonu
EN
Ammonium alkanoates (ammonioalkanocarboxylates) are zwitterions (or inner salts, or betaines), because they possess formally charged ammonium and carboxylate groups separated by one or more sp3 carbon atoms. The chemistry of betaines has become a subject of particular interest due to their applications in biological research, especially with regard to their important role in aminoacid synthesis as methyl transfer agents. The crystals of many betaine complexes display interesting physical properties, exhibiting phase transitions with ferroelectric, antiferroelctric and ferroelastic behavior. Betaines containing a hydrophobic chain in the range of 8–20 carbon atoms show the unique properties characteristic for amphoteric surfactants and their current industrial application is in toiletries and personal care products. The conformational structure of zwitterionic molecules depends on several factors. The electrostatic attraction between two charged groups depends strongly on arm flexibility (energy differences between rotational trans and gauche isomers), bulkiness and hydration of charged groups preventing their close approach, solvent and arm electrical properties which control electrostatic attraction between two opposite charged groups, and polarization of solvent around the molecule caused by the dielectric discontinuity between solvent and solute interior (image charge effect). Electrostatic interaction is the common determinant and probably the most important element in structure-reactivity correlation in organic and biological systems. On the other hand, organic compounds are thought to be pure even though they may be a mixture of conformational isomers. This is because the isomers covert rapidly with each other at room temperature and their individual reactivates are little known. Occasionally the conformers may be stabilized in the crystallographic matrixes of polymorphic structures. This article describes structures of seven groups of aliphatic, aromatic and alicyclic betaines and numbers of their new hydrogen-bonded complexes with mineral and organic acids.
PL
Najczęściej stosowanym obecnie modyfikatorem asfaltu w różnego rodzaju budowlanych wyrobach hydroizolacyjnych jest kopolimer styren-butadien-styren (SBS).W przemyśle materiałów wodochronnych zarówno ilość, rodzaj, jak i jakość substancji użytej do modyfikacji asfaltu określana jest na podstawie obserwacji praktycznych. Przedstawione badania określają wpływ budowy kopolimeru SBS (liniowy lub rozgałęziony) na właściwości reologiczne asfaltu. Wskazano w nich optymalne proporcje mieszaniny złożonej z wymienionych kopolimerów.
EN
Nowadays, the most commonly used asphalt modifier in various kinds of building articles waterproofing is a styrene-butadiene-styrene ( SBS). In industry, waterproof materials, both the quantity, type and quality of the material used in asphalt modification, is determined on the basis of practical observations. Introduced investigations define the influence of SBS copolymer (linear or arborescent) on rheology properties of the asphalt. In research is indicated optimal, mutual proportions of the mixture composed from these copolymers.
PL
W pracy dokonano teoretycznej analizy własności optycznych oraz struktury molekularnej materiałów opartych na silikonach stosowanych do produkcji implantów w postaci soczewek wewnątrzgałkowych. Badania teoretyczne struktury i właściwości optycznych wykonane zostały w pakiecie ADF w oparciu o półempiryczną metodę DFT bazującą na podejściu Kohn-Shama. Na podstawie przeprowadzonych badań teoretycznych określono parametry struktury badanych polimerów, takie jak: kąty dihedralne oraz odległości miedzyatomowe. Wyznaczone widma absorpcyjne zostały zestawione z rozkładami wrażliwości fotoreceptorów. Na podstawie uzyskanych wyników stwierdzono obecność maksimum absorpcyjnego w zakresie promowania widzialnego dla związku para-(thio)phensulfaphenylu. Obecność takiego maksimum w zakresie światła widzialnego jest niepożądana i może prowadzić do zaburzeń w postrzeganiu barw.
EN
The paper presents a theoretical analysis of the optical properties and molecular structure of the silicone-based materials used for the manufacture of implants in the form of intraocular lenses. Theoretical studies of the structure and optical properties has been made in the ADF package based on semi-empirical method based on DFT Kohn-Sham approach. On the basis of theoretical studies the structure parameters of investigated polymers has been determined, such as: dihedral angles and interatomic distances. Designated absorption spectra were exhibited together with the photoreceptor sensitivity distributions. Obtained results revealed the presence of absorption maximum in the visible wave range for the para-(thio)phensulfaphenyle. The presence of such a maximum is undesirable and may lead to disturbances in the color perception.
EN
The elements creating a friction pairs are described to be very difficult in terms of defining all optimal parameters in an unequivocal way. The research on stability of friction pairs is focused on the surface and the top layer of surface in the parts concerned. The main goal is to find new design solutions and materials, thereby achieving one million kilometers of mileage to main repair in the case of internal combustion engines. The biggest structural difficulties are noticeable in friction pairs where it can be observed sliding and returning motion, which is also connected with sealing function. A typical example of such pair is piston ring – cylinder sleeve in piston – rings - cylinder unit in an internal combustion engine. Engineers are currently seeking an additional factor, which would enable gaining the reduction of tangential force by reducing the friction coefficient in elements of friction pair during operations. The surface free energy may be such factor - it results from molecular structure and nature of the bonds between the molecules present in the material. Components of surface free energy determine the tribological properties of the material, which is reflected in the stability of the units. Energy state of the surface, which is connected with chemistry and characteristics in the material, is the first step to consider about the impact on wearing in internal combustion engine. This is the main topic of this article.
EN
Structural changes induced in crystals by photochemical reactions were presented. The changes concern: a) the distances between neighbouring reactant molecules and their mutual orientation in the case of intermolecular reactions, b) the distances and angles between fragments of a molecule for intramolecular reactions, c) the position of molecules in crystals, d) geometry of hydrogen bonds, e) cell constants, and f) the content of product molecules in crystals. For most intramolecular reactions, the distances between reactive atoms are constant for a long time in phototransformation and decrease rapidly at its end (Figs. 3 and 5). In the case of intermolecular reactions, the distances between reactive atoms of reactant molecules decrease linearly along with the phototransformation of crystals (Fig. 7). Additionally, unreacted molecules become, to a certain degree, similar to product molecules in terms of their shape (Figs, 4 and 8). Reactant and product molecules do not assume a fixed place in crystals. Product molecules change their orientation towards that of which is observed in a pure product crystal and reactant molecules gradually move away from the position they took in pure reactant crystals. All this has an influence on the geometry of hydrogen bonds existing in crystals (Fig. 9). The above-mentioned structural transformations find their expression in values of cell constants (Fig. 10). The factors influencing the photoreactivity of molecules in crystals were also described. Knowledge of crystal and molecular structures of partly reacted crystals, determined thanks to X-ray structure analysis which is a branch of crystallography, reveals the behaviour of molecules in crystals in which photochemical reactions proceed and helps to understand a pathway of these reactions.
PL
W artykule przedstawiono wpływ dodatków (nanorurki węglowe jako nanonapełniacz, montmorylonit oraz pigment) na proces starzenia izotaktycznego polipropylenu (iPP). Kompozyty otrzymano metodą interkalacji w stopie poprzez wprowadzanie określonego dodatku do stopionej matrycy polimerowej. Badania prowadzono w celu scharakteryzowania wpływu wybranych napełniaczy na proces starzenia, pod kątem zmian w barwie i strukturze cząsteczkowej materiału. Charakterystykę przebiegu procesu starzenia prowadzono w określonych odstępach czasu ekspozycji na zadane warunki symulujące starzenie atmosferyczne. Dokonano także porównania zmian zachodzących w polipropylenie i kompozycie polipropylenu z glinokrzemianem przy różnych parametrach starzenia. Instrumentalną zmianę barwy prowadzono w celu oszacowania stopnia zniszczenia powierzchni (wpływ na estetykę wyrobów z iPP), a zmiany zachodzące w materiałach na poziomie cząsteczkowym (zanik pierwotnej struktury i pojawienie się nowych ugrupowań) kontrolowano przy zastosowaniu spektroskopii w podczerwieni z transformacją Fouriera (FTIR).
EN
The paper presents effect of additives (carbon nonotubes as nanofiller, montmoryllonites, pigment) on the process of isotactic polypropylene degradation. The composites were obtained by the melt intercalation by introducing certain additive into the molten polymer matrix. The study was conducted to characterize the influence of selected fillers on the aging process for changes in color and molecular structure of the material. The characteristic of the aging process was carried out at defined intervals of exposure, the answer to aging simulating atmospheric conditions. The changes in polypropylene and polypropylene composite with aluminosilicate that have occured at different parameters of aging was also compared. Instrumental color change was carried out to estimate the degree of surface damage (impact on the aesthetics of the iPP), and the changes occuring in materials at the molecular level (loss of the original structure and the emergence of new groups) was monitored using FTIR spectroscopy.
PL
W ostatnich latach związki polifenolowe zyskują coraz większe zainteresowanie konsumentów i wytwórców żywności. Wyniki badań epidemiologicznych wskazują na prozdrowotne efekty spożywania żywności bogatej w polifenole przede wszystkim ze względu na ich właściwości przeciwutleniające i przeciwrodnikowe. Do tej grupy związków należą hydroksylowe pochodne kwasu benzoesowego. W pracy przedstawiono badania podatności na biodegradację soli wybranych fenolokwasów, różniących się ilością oraz położeniem grup hydroksylowych w cząsteczce oraz toksyczność ostrą w stosunku do wybranych organizmów wskaźnikowych. Stopień biodegradacji oceniano na podstawie redukcji wskaźników zanieczyszczeń tj. RWO i BZT. Określono strukturę analizowanych związków posługując się metodami spektroskopowymi (UV-VIS, FT-IR) oraz teoretycznymi obliczeniami kwantowo-mechanicznymi.
EN
Nowadays phenols are compounds of an increasing interest of costumers and food producers. Results of epidemiological researches indicate a health promoting effect of eating foods rich in polyphenols, mainly due to their anti-free radicals and antioxidant properties. Hydroxyl derivatives of benzoic acid belong to this group of compounds. In this paper investigations of biodegradability and the acute toxicity toward indicator organisms of selected phenolic acids differing in the number and location of hydroxyl groups in the molecule and their salts were presented. The degree of biodégradation was determined based on reduction of pollution indicators such as DOC and BOD. The molecular structures of studied compounds were determined by spectroscopic method (UV-VIS, FT-IR) and using quantum-mechanical calculations.
EN
Condensation of meta-cresol with ethyl acetoacetate in dehydrated phosphoric acid is slow enough to observe formation and disappearance of the in termediates viz 1,2- di -hydro-4,7-dimethyl-4-(4-hydroxy-2-methylphenyl)-coumarin (3) and 1,2- di hydro- 4,7-dimethyl-4-(2-hydroxy-4-methylphenyl)-coumarin (4). GCMS analyses of the reaction mixtures indicated that 4,7-dimethylcoumarin (5) was formed from 3 and 4 by elimination of meta-cresol molecule. The compounds 3 and 4 were isolated by the column chromatography. Their structures were elucidated by the spectroscopic methods but unequivocal assignment of the structure to the particular isomer was not possible. The structures were resolved by X-ray diffraction studies.
PL
W pracy przedstawiono wyniki badań strukturalnych, spektroskopowych i magnetycznych dwóch grup kompleksów metali: pierwsza grupa zawiera związki z jonem chinolino-2-karboksylanowym, a druga zawiera związki z jonem 9,10-dihydro-9-okso-10-akrydynooctanowym. Otrzymano 21 nowych związków, a dla 16 przeprowadzono analizę rentgenostrukturalną. Kompleksy scharakteryzowano metodami spektroskopii oscylacyjnej, spektroskopii elektronowej, spektroskopii elektronowego rezonansu paramagnetycznego, spektroskopii Mossbauera oraz zbadano ich właściwości magnetyczne. Kompleksy z pierwszej grupy są monomerami i we wszystkich przypadkach jon chinolino-2-karboksylanowy jest ligandem chelatujacym, a grupa karboksylanowa koordynuje w formie monodentnej. W kryształach tych związków obserwuje się różnorodne struktury supramolekularne, których budowa zależy od geometrii sfery koordynacyjnej w kompleksie, rodzaju wspólliganda i związków współ-krystalizujących. Wyjątkowo efektywna kooperacja pomiędzy oddziaływaniami międzycząsteczkowymi (wiązania wodorowe, oddziaływania typu pi-pi i C-H-pi) występuje w kryształach kompleksów [Mn(quin-2-c)2(H20)2]. 2Ade i [Mn(quin-2-c)2(H20)2] 4CH3COOH. Oddziaływania międzyczą-steczkowe istotnie wpływają na charakterystykę oscylacyjną monodentnej grupy karboksyla-nowej, a także umożliwiają słabą wymianę magnetyczną między centrami paramagnetycznymi. W drugiej grupie związków ligand 9,10-dihydro-9-okso-10-akrydynooctanowy łączy się z jonami metali w różnorodny sposób, grupa karboksylanowa koordynuje jako monodentna, chelatująca lub mostkowa, otrzymane związki są monomerami lub polimerami. W kryształach tych związków występują struktury supramolekularne z dużym udziałem oddziaływań stackingowych i wiązań wodorowych. Analiza budowy kryształów obu grup związków dowodzi, że słabe oddziaływania typu pi-pi i C-H--pi-odgrywają ważna rolę w procesach samoskupiania związków koordynacyjnych.
EN
A large group of metal coordination compounds containing quinoline-2-carboxylate (quin-2-c") and 9,10-dihydro-9-oxo-10-acridineacetate (CMA~) ions was studied. Ancilliary ligands such as water, alcohols, imidazole and chloride ions have been incorporated in these complexes. Quinoline-2-carboxylic acid and 9,10-dihydro-9-oxo-10-acridineacetatic acid exhibit biological activity. The first compound is the tryptophan metabolite, whereas the second one is the powerful interferon inducer. Fifteen new complexes with quinoline-2-carboxylate ion and six new complexes with 9,10-dihydro-9-oxo- 10-acridineacetate ion were obtained and characterized by analytical, spectrosopic and magnetic methods. Sixteen compounds were obtained in the form suitable for single crystal X-ray analysis. The first group of complexes are molecular compounds in which the quin-2-c" ligand chelates the metal ions by the quinoline nitrogen atom and the oxygen atom from monodentate carboxylate group. The coordination sphere of the metal ions in these compounds mimics the structure of the metal centers in the corresponding mononuclear iron and manganese enzymes in regard to the coordination number, donor groups, geometry and the spin state. In the second group of complexes, the monomers, polymers and cluster were found. The CMA~ ion coordinates metal ions through the oxygen atoms from the carboxylate group in the various modes: monodentate, chelating or bridging. In the crystals of all compounds studied, the ID, 2D or 3D supramolecular structures generated by in-termolecular interactions of 0-H-O, N-H-O, N-H--N, C-H-O, C-Hxx and tv-k type have been found. The results of the structural analysis show that the coordination compound containing the groups essential for hydrogen bond's formation, located close to the coordination sphere, are efficient substrates in the selfassembly processes. The architecture of the crystals greatly depenas on the strong hydrogen bond systems, however the weak interactions between aromatic rings also play important role in the compounds studied. Very effective cooperation of various intermolecular interactions is found in the crystals of [Mn(quin-2-c)2(H20)2]-2Ade and [Mn(quin-2-c)2(H20)2]-4CH3COOH. The adenine ribbons of unique type have been found in the crystal of the first compound. Adenine molecules are connected by simuta-neas Watson-Crick and Hoogsteen hydrogen bonds. The second compound is a very interesting example of tetrasolvate which becomes amorphous when it looses the solvent and rebuilds the crystal structure after resolvation. This compound can be used as a safe and efficient store of acetic acid. The results of the spectroscopic and magnetic studies on the complexes with quin-2-c" and CMA" ions are presented. The magnetic properties of the compounds containing the Fe(II) high-spin ions testify the weak magnetic exchange taking place by the systems of strong hydrogen bonds. The EPR and UV-Vis spectroscopic data support the results of the X-ray studies. The detailed magnetic and spectroscopic investigations of [Ni(CMA)2(Him)2(MeOH)2] (UV-Vis, HFHFEPR and magnetic measurements) combined with the structural information provide reliable experimental data for determination of the electronic structure of nickel center in the bacterial enzyme Glioxalase I. The studies of the IR spectra have shown that the vibrational frequencies of the monodentate carboxylate group are considerably influenced by the hydrogen bonding involving this group. When the monodentate carboxylate group is involved in hydrogen bonding the A v = vas(COO) - vs(COO) value is several dozen cm"' smaller than that in the absence of hydrogen bonds. This observation shows that the determination of the type of coordination of the carboxylate group cannot be made solely on the basis of the IR spectra.
17
Content available remote Effect of high hydrostatic pressure on structure of gelatin gels
EN
The present contribution reports on the rheological investigations concerning influence of high hydrostatic pressure on the molecular structure of gelatin gels. For the purpose of the study, a torsional shear wave rheometer for in-situ investigations of viscoelastic substances under high pressure was developed. Small amplitude vibrations generated by piezoelectric elements are used to determine the storage modulus of the investigated medium. The system is able to stand pressures up to 300 MPa. The experiments have been carried out with household gelatin (0.1 w/w aqueous solution). The gelification curves revealed similar time course. However, the values of G' obtained for the gels curing 300 minutes under 100 MPa and 200 MPa were observed to be respectively 2.1 and 4 times higher than at ambient conditions. The increased number of triple helix junction zones is hypothesised to be the cause of this phenomenon as a result of reinforcement of the hydrogen bonds due to pressure. An attempt to cognize the characteristic dimensions of the molecular structure based on the theory of rubber elasticity is made.
EN
This paper presents research into the influence of UV radiation on the molecular and supermolecular structure of first-, second-, and third-generation manmade cellulose fibres, differing from each other in their initial structures and containing dulling agents.
EN
An attempt has been undertaken to assess the effect of UV radiation on the structure of polyamide and polypropylene fibres, which are characterised by various macroscopic features, colours and additives. Based on the measurements we performed, we were able to conclude that UV radiation under the exposure conditions used brings about changes in both the fibre structure and mechanical properties. The extent of these changes is clearly dependent on the initial fibre structure, added modifiers and macroscopic features.
20
Content available remote The formation of macrocyclic compounds with O,O- and O,N-acetal units
EN
Poly(acetal)s are prepared in polycondensation of methyl a-D-mannopyranoside (IX) and terephthalaldehyde (IV) or 1,4-bis(formylphenoxy)butanes (XIV) catalyzed by acid. The composition highly depends on the reaction conditions, structure of comonomers and nature of catalyst leading to the formation of chiral macrocycles and linear macromolecules. The regioselective polycondensation was examined by 1H NMR spectroscopy. The structures of polycondensation products were also identified by electrospray mass spectrometry (ESI-MS) and MALDI-TOF mass spectroscopy. The polycondensation of terephthalaldehyde with 2-amino-2-hydroxymethyl-1,3-propanediol [or 2,2'(1,4-phenylene)-bis-1,3-(4,4-dihydroxymethyl)oxazolidine (bis-oxazolidine)] and 2-amino-2-methyl-1,3-propanediol under acidic catalysts leads to the formation of macrocyclic compounds. ESI-MS measurements were used to study the details of polymer structure and support the nature of oxazolidine-acetal and 2-(1',4'-phenylene)-5-methyl-1-aza-3,7-dioxabicyclo[3.3.0]octane as the repeating units in all macromolecules (both cyclic and linear).
PL
Przedstawiono podsumowanie wyników opublikowanych prac własnych nad otrzymywaniem w wyniku polikondensacji związków makrocyklicznych z jednostkami wymienionymi w tytule. Omówiono poliacetale uzyskane z metylo-a-D-mannopiranozydu [wzór (IX)] i aldehydu tereftalowego [wzór (IV)] lub 1,4-bis(formylofenoksy)butanów [wzór (XIV), schemat C i D] w obecności kwasu jako katalizatora. Produkty polikondensacji analizowano metodami NMR, desorpcji-jonizacji promieniem laserowym z matrycy (Matrix-Assisted Laser Desorption Ionisation Time of Flow - MALDI-TOF; rys. 1) oraz elektrorozpylaniem (Electroscopray Ionisation - ESI; rys. 2). Opisano także polikondensację (IV) z 2-amino-2-hydroksymetylo-1,3-propanodiolem [wzór (XVIII), schemat E] lub 2,2'-(1,4-fenyleno)-bis-1,3-(4,4-dihydroksymetylo)oksazoli- dyną oraz z 2-amino-2-metylo-1,3-propanodiolem [wzór (XXIII), schemat F] katalizowaną kwasami. Za pomocą metody spektroskopii mas ESI (ESI-MS) analizowano budowę makrocząsteczek (liniowych i cyklicznych) zawierających ugrupowania 1,3-oksazolidynowe lub 2-(1',4'-fenyleno)-5-metylo-1-aza-3,7-dioksabicyclo[3.3.0]oktanu (rys. 3-5). Do modelowania uzyskanych cząsteczek z ugrupowaniami O,O- i O,N-acetali użyto programu "CHEM SKETCH", który umożliwił obserwację ilości giętkich konformacji w pseudo-rotacji każdej z monomerycznych jednostek w makrocząsteczkach zarówno liniowych, jak i cyklicznych [wzory (XXII), (XXIX), (XXX)]. Zdolność tego typu związków makrocyklicznych do samoorganizacji może mieć duże znaczenie w syntezie i pozwala na lepsze zrozumienie wysokiego stopnia zróżnicowania oraz funkcjonalizacji nowych typów materiałów.
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