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1

Transformacje strukturalne w kryształach wywołane reakcjami fotochemicznymi

Turowska-Tyrk I., Bąkowicz J.

Wiadomości Chemiczne

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2014

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[Z] 68, 5-6

381--402

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.

2

Struktura pochodnych benzo[ b]furanu i kumaryny oraz ich kompleksów z miedzią (II) i cynkiem(II)

Drzewiecka A.

Wiadomości Chemiczne

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2012

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[Z] 66, 3-4

355-369

EN

Selected benzo[b]furan and coumarin derivatives with proven and potential antibacterial, anticancer and antiarrhythmic activities have been investigated [1–3] (Figs. 1 and 2). The stereochemical description of their molecules in the solid and gas phase as well as intra- and intermolecular-interactions in crystals have been determined [4–6]. The structural studies of analyzed molecules indicated the planarity of the benzo[b]furan and coumarin ring systems. The oxygen or carbon atoms of the substituents, –OH, –OCH3, –C(=O)CH3 and –COO H, are nearly coplanar with the aromatic ring. The hydroxyl and acetyl groups, being in the ortho position, are coplanar with the aromatic ring and the formation of the intramolecular O–H…O hydrogen bond in all three states of matter is observed. Its strength is around 18 kcal/mol. Several conformers of studied compounds, differing in the orientation of the methoxy, acetyl and/or carboxyl groups, were analyzed. Next, the electrochemical method was used to synthesize novel copper and zinc complexes with the oxygen donor benzo[b]furan and coumarin derivatives. The Cu(II) and Zn(II) complexes have been obtained with carboxylic acids as ligands whereas hydroxy ligands reacted only with copper [6]. The geometry of metal-ligand interaction of new compounds has been determined using a single crystal X-ray crystallography and an X-ray absorption spectroscopy [7, 8]. The combination of these two methods revealed that for some compounds cation environment could depend on the form of the solid sample. In the microcrystalline zinc complexes (studied by EXAFS) the cation is penta-coordinated (ZnO5) with the Zn–O distances being ca 1.98(3) Ĺ. In the recrystallized complex (analyzed by the X-ray diffraction) it was found that zinc is tetra-coordinated (ZnO4). The Cu(II) cation in the singlecrystal form of the complex with the carboxylic acid 5 is penta-coordinated to the carboxylate groups and the ethanol molecule. The bridging COO – groups stabilize the dinuclear complex center Cu2O10. The powdered form of this complex is based on the Cu2O8 units, indicating the absence of the ethanol molecule in the coordination sphere. In the series of the Cu(II) complexes with the hydroxy derivatives of benzo[b]furan and coumarin a centrosymmetric coordination polyhedron of metal exhibits a square-planar geometry (CuO4). Two ligands are bonded to the copper cation via the acetyl and deprotonated hydroxyl O atoms.

3

High-temperature phenomena in RbD2PO4 and CsH2PO4 . Polymeric transformations or polymorphic phase transitions?

Bronowska W.

Materials Science Poland

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2006

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Vol. 24, No. 1

229--236

EN

X-ray analysis has been performed for RbD2PO4 and CsH2PO4 over the temperature range from 288 K to 537 K and 507 K, respectively. The refinement of the crystal structure of RbD2PO4 at 430 K has revealed that the high-temperature paraelectric phase of this crystal is isomorphic with the monoclinic P21/m paraelectric phase of CsH2PO4. The X-ray diffraction CCD images obtained for RbD2PO4 have proved that the high-temperature paraelectric phase is stable up to approximately 525 K. At this temperature, polycrystallisation of the single-crystal samples and their subsequent decomposition has been observed. CsH2PO4 undergoes a structural phase transition at 504 K, from the monoclinic paraelectric phase to a cubic superionic phase (P21/m transforms to Pm-3m symmetry). The reversibility of the superionic phase transition in the crystals is a strong evidence for a polymorphic character of this solid-solid transition.

4

Bi8V2O17 - a stable phase in the Bi2O3-V2O5 system

Wrobel W., Krok F., Abrahams I., Kozanecka-Szmigiel A., Malys M., Chan S.C.M., Dygas J.R.

Materials Science Poland

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2006

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Vol. 24, No. 1

23--30

EN

Bi8V2O17 is commonly observed as an intermediate phase in the synthesis of compounds in ternary systems of the type Bi2O3-V2O5-MexOy. It is also seen as an end product at particular compositions in these systems. A rhombohedral substructure model for this phase is presented along with electrical parameters. Evidence from the Arrhenius plot suggests a phase transition at around 550 °C. The existence of a limited solid solution of Bi8V2O17 with ZrO2 is also discussed.

5

Structure types formed in the Ln-Al-{Si, Ge} systems.

Melnyk I., Pikus S., Kuprysyuk V., Semuso N., Gladyshevskii R.

Archives of Materials Science

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2005

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Vol. 26, nr 4

279-301

EN

This paper reviews the different structure types observed for alumosilicides and alumogermanides of rare earth metals. The analysis is based mainly on the coordination polyhedra around the atoms of the smallest size and on the stacking of segments cut from simple structure types. The 24 different structure types in which the 145 known rare-earth alumosilicides and alumogermanides can be crystallized are described in detail.

6

Wzrost i struktura kryształów roztworów stałych SrAl0,5Ta0,5O3: LaAlO3.

Berkowski M., Fink-Finowicki J., Byszewski P., Diduszko R., Aleksiyko R., Kikalejshvili-Domukhovska R.

Archiwum Nauki o Materiałach

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2003

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T. 24, nr 4

571-582

PL

Wzrost kryształów (SrAl0,5Ta0,5O3)1-x (LaAlO3)x ((SAT)1-x(LA)x) metodami Czochralskiego i topienia strefowego został zbadany w całym zakresie koncentracji poszczególnych składników; struktura otrzymanych kryształów została zbadana metodami dyfrakcji rentgenowskiej. Zaproponowano schematyczny diagram fazowy tych materiałów; roztwory stałe istnieją w zakresie koncentracji 0 mniejsze lub równe x mniejsze lub równe 0,5, w którym kryształy mają strukturę regularną. Metodą Czochralskiego można otrzymać monokryształy w zakresie koncentracji x=0,23/0,41. W otrzymanych kryształach nie stwierdzono występowania przejść fazowych ani zbliźniaczeń niskokątowych. Odpowiedni zakres wartości stałych sieci, wysoka temperatura topnienia tych materiałów wynosząca blisko 1850 stopni Celsjusza wskazuje na ich dobrą termiczną i chemiczną stabilność przy wykorzystaniu jako podłoży dla epitaksji HTSc perowskitów manganowych i GaN.

EN

Crystals of (SrAl0,5Ta0,5O3)1-x (LaAlO3)x ((SAT)1-x(LA)x) were obtained by the Czochralski and floating zone method in whole composition range; structure of these crystals was investigated by X-ray measurements. A schematic phase diagram of this solution is proposed; it was found that solid solutions exist at concentration 0 lto x lto 0.5 and crystals adopt cubic structure. The Czochralski method was successfully used to grow of single crystals with x=0.23/0.41. Structural phase transitions and tendency to formation of twins were no stated. The proper range of lattice parameters and high melting point close to 1850 degrees centigrade indicate their high thermal and chemical stability. Therefore these crystals may be used as substrates for the growth of HTSc, manganites or GaN epitaxial layers.

7

Realna struktura kryształów BaTiO3 otrzymywanych metodą krystalizacji z roztworów stopionych soli i tlenków

Borodin V.Z., Fesenko E.G., Skulski R., Surowiak Z.

Archiwum Nauki o Materiałach

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2003

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T. 24, nr 3

245-273

PL

Przedstawiono proces hodowli kryształów BaTiO3 metodą krystalizacji z roztworów stopionych soli i tlenków (odmianą metody Remeiki). Sklasyfikowano obserwowane defekty wzrostu kryształów i zaproponowano najbardziej prawdopodobne mechanizmy ich powstawania. Podsumowano wyniki badań statyki struktury domenowej kryształów BaTiO3 w temperaturze pokojowej, tzn. w fazie tetragonalnej, a także wyniki badań procesu formowania się 90 i 180 stopniowych domen podczas przemiany fazowej w bezgradientowym i gradientowym polu temperatur. Metodami mikroskopii optycznej, mikroskopii elektronowej oraz dyfrakcji rentgenowskiej zbadano strukturę krystaliczną wyhodowanych kryształów BaTiO3. W większości badanych kryształów zaobserwowano obecność makro- i mikrobloków, typowych dla struktur mozaikowych. Wskazano na wzajemne relacje struktury domenowej i struktury mozaikowej otrzymanych kryształów BaTiO3.

EN

The process of BaTiO3 single crystals obtaining from melted salts and oxides (modified Remeika method) is presented in this paper. The observed defects of crystal growth are classified and the most probable mechanisms of their arising are proposed. The results of static domain structure investigations at room temperature (i.e. in tetragonal phase), as well as 90 and 180 degrees domain structures formation in gradient and gradient-free fields of temperatures are reviewed. Using the methods of optical microscopy, electron microscopy and X-ray diffraction the crystal structure of grown crystals has been investigated. In the majority of investigated crystals the presence of macro- and microblocks typical for mosaic structures was stated. The mutual correlation's between domain and mosaic structures have been found.

8

Modyfikowanie polipropylenu jarzącymi wyładowaniami małej częstotliwości w powietrzu

Rishina L. A., Yizen E. I., Shibryaeva L. S., Sosnovskaya L. N., Veretennikova A. I., Lodygina T. A., Gilman A. B.

Polimery

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1998

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T. 43, nr 1

34-39

PL

PP, otrzymany w obecności układów katalitycznych: (a) heterogenicznego δ-TiCl3-AlEt2Cl w obecności wodoru lub (b) homogenicznego rac-Et(Ind)2ZrCl2 metyloaluminoksan, modyfikowano jarzącymi wyładowaniami małej częstotliwości w powietrzu. W cienkiej warstwie powierzchniowej mody-fikowanego PP stwierdzono pojawienie się zawierających tlen grup funkcyjnych (wodoronadtlenki). W pewnych warunkach cała struktura PP ulegała zmianie, co przejawiało się znacz-nym wzrostem ciężaru cząsteczkowego (M) i temperatury to-pnienia (Tt). Zmiany te były szczególnie widoczne w PP syn-tetyzowanym w obecności metalocenu (b): M zwiększał się 10-krotnie, a Tt wzrastała z 134°C do 164°C. Ponadto zawar-tość frakcji PP nierozpuszczalnej w n-heptanie rosła z 7% do 96%, czyli zwiększał się stopień izotaktyczności PP. Struktura krystaliczna modyfikowanego PP wykazała obecność odmian α. oraz γ, przy czym pod wpływem wyładowań odmiana y ulegała częściowej przemianie w odmianę *. Czynnikiem powodującym zmiany struktury PP było przy-puszczalnie zawarte w plazmie promieniowanie UV

EN

PP prepared (a) over a δ-TiCl3-AlEt2Cl heterogeneous catalytic system in the presence of hydrogen and (b) rac-Et(Ind)2ZrCl2-methylalumoxane homogeneous system, was modified by low-frequency glow discharges in air. Functional groups containing oxygen were found to appear in a min surface layer. Under some conditions changes of the whole structure of PP were determined, evident in a great increase in the molecular mass (M) and melting temperaturę (Tm). The structural modification is especially considerable for the PP synthesized with the metallocene system b. M rose by a factor of ~10, the melting temperature rose from 130°C to 164°C, stereoregularity parameters enhanced and the fractional composition changed. The boiling n-heptane-soluble fraction increased from 7 to 96% (PP became highly iso-tactic). The crystalline structure of this PP was found to consist of the α- and the γ-modifications, the latter passing into the former when exposed to plasma. The UV-component of the plasma is believed to be responsible for the modifications observed.