Wyniki wyszukiwania - Biblioteka Nauki

1

Complex lag synchronization of two identical chaotic complex nonlinear systems

100%

Mahmoud E. , Abualnaja K.

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nr 1

63-69

EN

Much progress has been made in the research of synchronization for chaotic real or complex nonlinear systems. In this paper we introduce a new type of synchronization which can be studied only for chaotic complex nonlinear systems. This type of synchronization may be called complex lag synchronization (CLS). A definition of CLS is introduced and investigated for two identical chaotic complex nonlinear systems. Based on Lyapunov function a scheme is designed to achieve CLS of chaotic attractors of these systems. The effectiveness of the obtained results is illustrated by a simulation example. Numerical results are plotted to show state variables, modulus errors and phase errors of these chaotic attractors after synchronization to prove that CLS is achieved.

2

Complexation of poly(ethylene glycol) with poly(ethyl methacrylate-co-N-vinyl-2-pyrrolidone) gel based on hydrogen bonds

100%

Liu G. , Xie D. , Guan C.

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tom Vol. 15, nr 3

85-90

EN

The complexes of poly(ethyl methacrylate-co-N-vinyl-2-pyrrolidone) (P(EMA-co-VP)) gel with poly- (ethylene glycol) (PEG) stabilized by the hydrogen bonds were prepared. It was found that both the concentration and the molecular weight of PEG have a strong effect on the P(EMA-co-VP) gel. When PEG was introduced into the P(EMA-co-VP) gel, the glass transition temperatures (Tg) of the complexes decreases with the decreasing of PEG molecular weight. In such a system, the maximum molecular weight of PEG required for the complex formation is no more than 2000, and P(EMA-co-VP)/PEG complexes are a homogeneous amorphous phase, which was studied by FTIR, XRD, TEM, and DSC.

3

Spectrophotometric study of thermodynamics and kinetics of charge-transfer complexation of dibenzopyridino-18-crown-6 with iodine in chloroform solution

88%

Zolgharnein J. , Shamsipur M.

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tom Vol. 72, nr 11

2486-2492

EN

The charge-transfer complexation reaction between iodine and dibenzopridino-18-crown-6 (DBPY18C6) has been investigated spectrophotomertically in chloroform solution at different temperatures. The resulting comlex was formulated as (DBPY18C6...I(+))I(-/3).The enthalpy and entropy of the complex formation were evaluated from the temperature dependence of the formation constant. The resulting charge-transfer complex is both enthalpy and entropy stabilized. The rate constants at various temperatures and the activation parameters were evaluated.

4

Czeska koncepcja zdrady jako element mitu monachijskiego

75%

Kubok B.

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nr 12

EN

The Czech concept of betrayal as an element of the Munich mythThis article explores the cultural significance of the “Munich myth”, focusing on the concept of “Western betrayal” and its connotations associated with the idea of destiny and sacrifice. It also examines how the myth influenced the formation of Czech national identity, especially during and shortly after the Second World War. Opening with an analysis of a poem by František Halas written in the midst of the Munich Conference, it also reviews a number of writings which increased the popularity of the ideas of betrayal and sacrifice and, as a result, have made them synonymous with the “Czech fate”: excerpts from the memoirs of Zdeněk Štĕpánek and Edvard Beneš, essays by Karel Kosík and Milan Kundera, and Bedřich Fučík’s literary criticism. The article concludes with a discussion of the key findings of the book Mnichovský komplex (The Munich Complex) by Jan Tesař, a polemic study discrediting and deconstructing the myth of the “Munich betrayal”. Czeska koncepcja zdrady jako element mitu monachijskiegoArtykuł dotyczy fenomenów kulturowych zawartych w micie monachijskim, szczególnie takich, jak koncepcja zdrady i powiązane z nią konotacje (figura ofiary, losu, teatralizacja życia społecznego). Przedstawia także proces formowania się wojennej oraz powojennej czeskiej tożsamości narodowej pod wpływem tego mitu. W artykule poddano analizie wiersze Františka Halasa z okresu wydarzeń monachijskich, a także te fragmenty wspomnień (Zdenĕk Štĕpánek, Edvard Beneš), eseistyki (Karel Kosík, Milan Kundera) i krytyki literackiej (Bedřich Fučík), które przyczyniły się do rozpowszechnienia koncepcji zdrady i ofiary jako czynnika konstytuującego „czeski los”. Artykuł kończy prezentacja najważniejszych tez zawartych w książce pt. Monachijski kompleks autorstwa Jana Tesařa o charakterze polemicznym i dekonstrukcyjnym wobec mitu „zdrady monachijskiej”.

5

Control of operability of Peltier modules in cooling systems based on the analysis of transient operating modes

75%

Kuzichkin O. R. , Konstantinov I. S. , Vasilyev G. S. , Surzhik D. I.

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tom Vol. 42, no 2

31--42

EN

The paper is devoted to the control of operability of Peltier modules based on the analysis of transient modes of their operation. Advantages of using low-power thermoelectric modules for the development of thermoelectric plants with adaptive control systems for the needs of the agricultural complex, which significantly reduce their cost characteristics, are shown. The problem of using the stationary mode of their operation, associated with the low efficiency of the modules, as well as the dynamic mode, associated with the presence of transient processes, is indicated. It is noted that overcoming this problem requires solution of the task of automation of reliability providing the well-known approaches to its solution are shown, for which the key advantages and disadvantages are given. An approach is proposed to complex control of the operability and quality of thermoelectric modules during their expluatation in three components of the physical process of thermoelectric conversion (Peltier thermoelectric effect, electrical and thermal transfer phenomena) by analyzing transients in the system based on identification algorithms. To justify it, the necessary equations and mathematical relations are given. Aprobating of the proposed approach was carried out experimentally by determining the time constants for operable and defective commercially available modules and showed its significant advantages over the standard verification procedure.

6

Voltammetric Study of Interaction of Copper with Some Methyl-Substituted Ethylenediimine Compounds Using Nonlinear Least-Squares-Excel-Solver

75%

Fotouhi L. , Bahmanpour T. , Ghasemi J. , Dehghanpour S. , Heravi M.

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2006

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tom Vol. 80, nr 3

483-489

EN

The complex formation of Cu2+ with some recently synthesized methyl-substituted ethylenediimines in binary dimethylformamide-ethanol mixtures was studied by differential pulse voltammetry. The stoichiometry and the stability of the complexes were determined by monitoring the increasing complex peak current against the ligand concentration using nonlinear least squares-Excel solver. In all studied cases, it was found that the stability of the resulting 1:1 complex decreases by increasing the amount of ethanol in the binary mixtures. The observed stability order is discussed in terms of the solvent binary mixtures and the nature of the substituted ethylenediimine structure.

7

Poezja Stanisława Piętaka w zwierciadle psychoanalizy materialnej Gastona Bachelarda. Rekonesans badawczy

63%

Wieliczko-Paluch K.

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tom 33

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nr 1

EN

The study presents the analysis of representative images in Stanisław Piętak’s writing. The methodology is based on Gaston Bachelard’s psychoanalysis of fundamental material elements of poetic imagination. The first part of article reminds main theses of French philosopher’s conception, formed by ancient Greek philosophy and modified ideas of Freud and Jung. The next parts of the text concern three sets of literary motifs and images characteristic of Piętak. The analysis included: a great complex: water – woman – moon – mirror – death; selected descriptions of sky, flight and birds; a few poetic visions of home. The research leads to the conclusion that discussed creations correlate with Bachelard’s theory and proves that Piętak’s poetic imagination was dominated by archetypal material imaginations, connected with three of the four Empedocles’ classical elements: water, air and earth.

PL

W artykule dokonano analizy obrazów literackich reprezentatywnych dla twórczości Stanisława Piętaka, opierając się na psychoanalitycznej koncepcji wyobraźni poetyckiej Gastona Bachelarda, nawiązującej do koncepcji czterech żywiołów. Pierwsza część pracy stanowi przypomnienie głównych tez francuskiego uczonego, ukształtowanych przez filozofię starożytnej Grecji oraz zmodyfikowane idee Freuda i Junga. Kolejne partie tekstu dotyczą trzech układów motywów i obrazów literackich charakterystycznych dla Piętaka. Analizie poddano egzemplifikację wielkiego zespołu obrazowego: woda – kobieta – księżyc – lustro – śmierć, a także wybrane opisy nieba, lotu i ptaków oraz niektóre poetyckie wizje rodzinnego domu. Badania prowadzą do konkluzji na temat związku między omawianymi kreacjami literackimi a teorią Bachelarda, dowodząc, iż poetycką wyobraźnię Piętaka zdominowały archetypowe obrazy, powiązane z trzema z czterech Empedoklesowych żywiołów: wodą, powietrzem i ziemią.

8

Vibronic behaviour of octahedral Cu(II) complexes in Cu(2-benzoylpyridine)2(NO3)2x2H2O crystal with a weak superexchange coupling. Temperature EPR studies

63%

Hoffmann S. K. , Goslar J. , Hilczer W. , Goher M. A. S.

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2000

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tom Vol. 48, No. 4

397-409

EN

Octahedral [Cu(2-benzoylpyridine)2 (H20)2] complexes in the Cu(2-Bzpy)2-(NO3)2 .2H2O are very dynamical and Cu(II) ions are very weakly coupled as it is shown by the single crystal EPR measurements in the temperature range 4.2-300 K. Rigid lattice limit (9 K) of spin-Hamiltonian parameters are: gx = 2.137, gy = 2.014, gz = 2.306 as determined by decoupling of exchange merged EPR lines. The ground state is predominantly Ix(2) -y(2)) with 8% of the Iz(2)) state. This mixing is produced by zero-point motions in the ground vibrational state and results in g x > gy with strong lowering of the gy-value. The decoupling procedure gave superexchange coupling parameter J = 0.0040 cm(1), which unexpectedly is temperature independent in contrast to other weakly coupled Cu(II) paramagnets. The g-factors show relatively strong temperature variations with gy practically not affected by temperature and a tendency to averaging of the g x and gz with room tem-perature parameters: g x = 2.161, gy = 2.013, gz = 2.285. This is explained as the pseudo Jahn-1eller effect with dynamical transitions between two elongated octahedral axes, i.e. O-Cu-O (x-axis) and H2O-Cu-H2O (z-axis) with N-Cu-N (y-axis) direction ill the in-plane coordination with pyridine nitrogen not affected by vibronic dynamics. The vibronic effect can be described by two-well model in the temperature range 80-150 K only with energy difference between the ground vibronic state in the well being 220 cm-l. At lower temperatures Cu(II) complexes are strongly localized in the deepest potential well, whereas at higher temperatures, the vibronic g-factor averaging is dominated by the other mechanism.

9

Improvement of enzyme stability via non-covalent complex formation with dextran against temperature and storage lifetime

63%

Altikatoglu M. , Kuzu H.

Polish Journal of Chemical Technology

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2010

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tom Vol. 12, nr 1

12-16

EN

The optimal methodology to prepare the novel modified enzyme, polymer-enzyme complex, was developed to give a high catalytic activity in aqueous solution. The non-covalent complexes of two different enzymes (horseradish peroxidase and glucose oxidase) were prepared with various molar ratios (nD/nE 0,05; 0,1; 1; 5; 10; 15; 20) by using 75kDa dextran. The thermal stabilities of the obtained complexes were evaluated with the activities determined at different temperatures (25, 30, 35, 40, 50, 60, 70, 80°C) applying 60 minutes incubation time for pH 7. The complexes with the molar ratio nD/nHRP: 10 and nD/nGOD: 5 showed the highest thermal stability. Its activity was very high (ca. 1,5-fold higher activity than pure enzyme for HRP-dextran complexes) and almost the same between applying one hour incubation time and without incubation, and could also be measured at high temperatures (70, 80 °C). We finally succeeded in preparing dextran-enzyme complexes which showed higher activity than pure enzyme in aqueos solution at all temperatures for pH 7. In addition, the mentioned complexes at pH 7 had very long storage lifetime compared to purified enzyme at +4 °C; which is considered as a good feature for the usage in practice.

10

Synthesis and spectroscopic studies of tin(IV) complexes of biologically active Schiff bases of sulpha drugs and heterocyclic aldehydes/ketones

63%

Gupta M. K. , Singh H. L. , Tripaathi U. D. , Varshney A. K.

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2000

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tom Vol. 48, No. 3

195-201

11

Derivative spectrophotometric methods for the determination of rhodium, palladium and platinum in mixtures

51%

Balcerzak M. , Bystrońska D. , Święcicka E.

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tom Vol. 46, No. 4

547-560

EN

Derivative spectrophotometric methods allowing direct determination of rhodium, palladium and platinum in binary mixtures have been developed. The complexes of the metals with tin(II) chloride make the basis of spectrophotometric measurement. The determination of the metals can be carried out in aqueous solutions or after extraction into 1,2-dichloroethane in the form of the ion-associates Rh(Pd, Pt)-SnCl(3)-diantipirylme-thane (DAM). Palladium and platinum in spent autocatalyst have been determined by the developed methods.

PL

Opracowano bezpośrednie metody oznaczania rodu, palladu i platyny w podwójnych mieszaninach z wykorzystaniem techniki spektrofotometrii pochodnej. Kompleksy metali z chlorkiem cyny(II) stanowiły podstawę spektrofotometrycznego pomiaru. Metale można oznaczać w roztworze wodnym lub po ekstrakcji 1,2-dichloroetanem w postaci asocjatów jonowych Rh(Pd,Pt)-SnCl(3)-diantypirylometan (DAM). Opracowane metody zastosowano do oznaczania palladu i platyny w zużytym katalizatorze samochodowym.

12

Studies of the equlibria of complexes of Pr(III), Nd(III), Eu(III), Gd(III), Dy(III) and Er(III) with quercetin-5'-sulfonic acid in aqueous solutions

51%

Kopacz M. , Bujonek B. , Nowak D. , Kopacz S.

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tom Vol. 46, No. 5

621-631

EN

The equilibria of the dissociation reaction of QSA as well as those of the complexation of QSA with Pr(III), Nd(III), Eu(lII), Gd(IlI), Dy(III) and Er(III) in aqueous solutions were investigated. The composition and formation constants of the complexes were determined by the spectrophotometric and potentiometric methods. The spcctrophoto-metric method was suggested to determine the above lanthanides with QSA.

PL

Zbadano równowagi reakcji dysocjacji kwasu kwercctyno-5'-sulfonowego (QSA) oraz reakcji komplcksowania QSA z jonami Pr(III),Nd(III), Eu(lII), Gd(III), Dy(III) i Er(III) . w roztworach wodnych. Skład i stale tworzenia kompleksów wyznaczono metodą spek-trofotometryczną i metodą potcncjometryczną. Zaproponowano metodą speklrofoto-metryczną do oznaczania wyżej wymienionych jonów lantanowców za pomocą QSA.

13

Structural and vibrational studies of the molecular crystal formed by benzenamine with trifluoroacetic acid

51%

Baran J. , Barnes A. J. , Barycki J. , Pietraszko A. , Ratajczak H.

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2001

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tom Vol. 49, No. 2

115-124

EN

The crystal structure of benzenamine-trifluoroacetic acid has been found to belong to the P2i space group of the monoclinic system, with Z = 8, o = 10.294(2) A, b = 9.126(2) A, c = 20.603(4) A, and Beta = 98.77(3)°. In the crystal the amine is protonated and the resulting benzenammonium and trifluoroacetate ions are interlinked by a network of N—H- • -O hydrogen bonds. The observed infrared spectrum is in accordance with such a structure.

14

Electrochemical studies of trans-dichloro-bis(diphenylphosphino) methane rhenium complex

51%

Rabia M. K. M.

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2001

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tom Vol. 49, No. 4

265-277

EN

Electrochemical studies of the fraras-dichloro-bis (diphenylphosphino) methane rhenium in tetrabutylammonium perchlorate/dichloromethane have been performed using cyclic and convolution potential sweep voltammetry. At room temperature, it was found that the complex isomerises on oxidation from the irons- to the cis-isomer and returns back to the original complex form on reduction at lower potentials. The electrode mechanisms were proposed and discussed on the basis of the "square-scheme". Upon cooling to 233 K, the cyclic voltammetric behaviour shows a single reversible couple in the region expected for the oxidation of trans-[ReC\2 (dppm)2]. Furthermore, the homogeneous and heterogeneous rate constants of the isomerisation reaction were evaluated.

15

Methodology of the hydrocarbon pools prognosing by the complex of geophysical data

51%

Pylypyshyn B. , Khavenzon I.

Wiertnictwo, Nafta, Gaz

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2008

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tom T. 25, z. 2

609-614

EN

The proposed methodology is worked out for the aims of oil and gas geology and can be used at investigation of terrigenous, terrigenous-carbonate and carbonate sections. It can also be used at prospecting and exploration of coal, ore, diamond deposits and underground water, as well as at the solving the tasks that need the detailed knowledge of the section structure (gas storages, slide dangerous zones etc.). The methodology includes the new methods and techniques of processing and interpretation of geophysical data. It is realized as a programme-methodical complex (PMC) "Seismocyclit" and "AFCM" - amplitude-frequency characteristic of medium, computed according to the noise constituent of wave field. It is based on the theory of sedimentary cyclicity - lithology (the teaching about rock-formations associations) and on the assumption of discompaction and compaction zones existence (the zones of reservoirs and cap rocks development). The uniting of the known geophysical methods and techniques, which were tested by time with the worked out by us techniques of processing and interpretation have led to creation of the new instrument for geological investigations. The advantages of our methodology in comparison with the commonly used methods consist in the possibility of obtaining the new qualitative data as to geological structure of the studied areas, which permit to carry out the forecast of hydrocarbons pools.

PL

Zaproponowana metodologia została opracowana na potrzeby geologii naftowej i gazowej i może być wykorzystana do badania części terygenicznych, terygeniczno-węglanowych i węglanowych. Może ona być także wykorzystana do poszukiwań za węglem, rudami, złożami diamentów i wód gruntowych, jak również przy rozwiązywaniu zadań wymagających dogłębnej wiedzy na temat struktury danej części (zbiorniki gazu, niebezpieczne strefy osuwisk itp.). Zaprezentowana metodologia obejmuje nowe metody i techniki przetwarzania i interpretacji danych geofizycznych. W praktyce przyjmuje to postać kompleksu programowo-metodycznego "Seismocyclit" oraz charakterystyki amplitudowo-częstotliwościowej ośrodka "AFCM", obliczonej zgodnie ze składową hałasu pola fal. Podstawą jest teoria sedymentacyjnej cykliczności litologicznej (nauki o związkach skał i formacji) oraz założenie istnienia stref dekompakcji i kompakcji (stref rozwoju zbiornika i nadkładu skalnego). Połączenie znanych metod i technik geofizycznych, które zostały sprawdzone za pomocą opracowanych przez autorów technik przetwarzania i interpretacji doprowadziło do stworzenia nowego instrumentu do badań geologicznych. W porównaniu z innymi, powszechnie stosowanymi metodami, przedstawiona autorska metoda ma zaletę polegającą na możliwości otrzymywania nowych danych jakościowych na temat struktury geologicznej badanych obszarów, umożliwiających wykonanie prognoz dotyczących złóż węglowodorów.

16

Opinia matek na temat doświadczeń komunikacyjnych ich dzieci z zespołem Downa i złożonymi potrzebami komunikacyjnymi

51%

Pudełko W. , Wilewska Ł.

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nr 2

173-186

EN

The article discusses issues related to the specificity of speech development of people with Down syndrome and speech therapy, with particular emphasis on augmentative and alternative communication therapy (AAC). Stories (case studies) of three people with Down syndrome and intellectual disability are presented, based on conversations with their mothers. Data analysis allowed for the collection of extensive research material indicating difficulties associated with the process of speech therapy of patients with complex communication needs. Moreover, collected data allowed us to recognize the need to combine classic speech therapy with augmentative and alternative communication therapy and to educate society more broadly about AAC. The article presents examples of good practices aimed at improving the communication situation of people with complex communication needs and their families.

PL

W artykule zostały omówione zagadnienia dotyczące specyfiki rozwoju mowy osób z zespołem Downa oraz terapii logopedycznej, ze szczególnym uwzględnieniem terapii komunikacji wspomagającej i alternatywnej (AAC). Przedstawiono historie (studium przypadku) trzech osób z zespołem Downa i niepełnosprawnością intelektualną, które opisano na podstawie rozmów z ich matkami. Analiza danych pozwoliła na zgromadzenie obszernego materiału badawczego wskazującego na trudności związane z procesem terapii logopedycznej pacjentów ze złożonymi potrzebami komunikacyjnymi. Zebrane dane pozwoliły również dostrzec potrzebę łączenia klasycznej terapii logopedycznej z terapią komunikacji wspomagającej i alternatywnej oraz szerszego edukowania społeczeństwa w zakresie AAC. W niniejszym artykule zaprezentowane zostały przykłady dobrych praktyk, których celem jest poprawa sytuacji osób ze złożonymi potrzebami komunikacyjnymi oraz ich rodzin w zakresie komunikacji.

17

Determination of sulfite by ion pair chromatography using pre-column derivatization with iron(III)-1,10-phenanthroline complex

51%

Janovskiene G. , Paliulionyte V. , Padarauskas A.

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tom Vol. 47, No. 6

847-854

EN

An ion-pair chromatographic (IP-HPLC) method was developed for the selective and sensitive determination of sulfite. The proposed method is based on the pre-column derivatiza-tion of sulfite with iron(III)-l,10-phenathroline complex (Fe(phen)(3+/(3) and direct photometric detection of Fe(phen)(2+)(3) formed. The optimized separations were carried out on a C(18) column using acetonitrile-water (60:40) mobile phase containing 50 mmol L(-1) NaClO4 and 5 mmol L(-1) acetate buffer (pH 5.0) and direct photometric detection at 510 nm. The optimal conditions for the derivatization reaction were established by varying pH, concentration of Fe(phen)(3+)/3 and reaction temperature. Valid calibration (r2 = 0.998) is demonstrated in the range 2 x 10(-6)-5 x 10(-4) mol L(-4) of sulfite. The detection limit (S/N = 3) was 5 x 10(-7) mol L(-1). The proposed system was applied to the determination of free sulfite in wines. The recovery tests established for wine samples were within the range 94-105%. The IP-HPLC results agree with those obtained by iodometric titration technique.

PL

Opracowano selektywną i czułą metodę oznaczania siarczynów przy pomocy chromatografii par jonowych (IP-HPLC). Proponowana metoda jest oparta na przedkolumnowej derywaty-zacji siarczynu przy użyciu kompleksu żelazo(III)-1, 10-fenantrolina Fe(phen)(+3/3 Utworzony jon Fe(phen)j+jest bezpośrednio mierzony fotometrycznie przy długości fali 510 nm. Optymalizację rozdziału przeprowadzono na kolumnie C(18) z fazą ruchomą acetonitryl-woda (60:40) z dodatkiem 50 mmol L(-1) NaClO(4) i 5 mmol L(-1) buforu octanowgo (pH 5,0). Optymalne warunki reakcji derywatyzacji ustalano zmieniając wartości pH, stężenie Fe(phen)(+3)/(3) oraz temperaturę. Liniową zależność kalibracyjną (r2 = 0,998) uzyskano w zakresie stężeń 2 x 10(-6) -5 x 10(-4) mol L(-1) siarczynów. Granica wykrywalności (S/N = 3).

18

Study on the stability and formation rate of the complex compounds of Ni(II), Cu(II), Hg(II) with PAN by potentiometric and spectrophotometric methods

51%

Gorodkiewicz E. , Figaszewski Z.

Chemia Analityczna

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2000

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tom Vol. 45, No. 6

867-877

EN

A simple titrimetric method was developed for the determination of some drugs acting on the central nervous system, namely, phenobarbital, thiopental sodium and the hydrochlo-ride salts of chlorpromazine, promazine, trifluoperazine and pyritinol. The method is based on titrating these drugs using either sodium hydroxide, mercury(II) chloride or silver nitrate. The end point was located conductimetrically. The proposed method was successfully applied to the determination of the studied compounds in some pharmaceutical preparations and the results obtained were in agreement with those obtained using official or reference methods.

PL

Opracowano prostą, miareczkową metodę oznaczania kilku substancji farmaceutycznych, działających na ośrodkowy układ nerwowy, tj. fenobarbitalu, soli sodowej tio-pentalu i chlorowodorków chloropromazyny, promazyny, trifluoperazyny oraz pirytynolu. Zasadą metody jest miareczkowanie roztworu analitu roztworem wodorotlenku sodu, chlorku rtęci(II) lub azotanu srebra. Punkt końcowy wyznaczano potencjometrycznie. Opracowaną metodę zastosowano do oznaczania badanych substancji w preparatach farmaceutycznych. Otrzymano wyniki zgodne z metodami odniesienia.

19

Thermal and long period stability of series of V(V), V(IV) and V(III) complex with Schiff base ligands in solid state

51%

Szklarzewicz J. , Jurowska A. , Hodorowicz M. , Gryboś R.

Science, Technology and Innovation

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2019

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tom Vol. 4, no. 1

30--36

EN

The synthesis and physicochemical properties of three new complexes of vanadium at +5, +4 and +3 oxidation state are described and discussed. The octahedral surrounding of vanadium for V(III) complexes of [V(L1)(HL1)] general formula is filled with two ONO tridentate ligand L, for V(IV) one ONO ligand L, oxido ligand and 1,10-phenanthroline (phen) as a co-ligand are presented in complexes of [VO(L2)(phen)]. For V(V) the complexes of [VO2(L1)(solv)] type were formed. As ligands, the H2L Schiff bases were formed in reaction between 5-hydroxysalcylaldehyde and phenylacetic hydrazide (H2L1) and 3,5- dichlorosalicyaldehyde and 4-hydroxybenzhydrazide (L2). The magnetic moment measurements, in 8 year period, show, that V(III) complexes slowly oxidise to V(IV) with preservation of the nonoxido character of the complexes, while V(IV) complexes were found to be stable. The TG and SDTA measurements indicate, that thermal stability depends mainly on the oxidation state of vanadium. The less thermally stable are the V(V) complexes, while V(IV) and V(III) are stable up to ca. 200oC. In solution, at pH 2 (similar to that in human digestion system), again the V(IV) are the most stable, only at pH 7.0 V(III) complexes had higher stability. The most stable, thus best for pharmaceutical use, are V(IV) complexes.