Wyniki wyszukiwania - Biblioteka Nauki

1

A Conformational Study of Some Secondary 1-Methyl-2-pyrrolecarbothioamides

100%

Jagodziński T. S. , Dziembowska T. , Jagodzińska E. , Rozwadowski Z.

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2001

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tom Vol. 75, nr 12

1853-1861

2

Transformation of the 3-oxoazabicyclo[2.2.2]octane pentachlorophenol complex into the 3-hydroxy-3-methoxyazabicyclo[2.2.2]octane pentachlorophenolate

100%

Majerz I. , Malarski Z. , Lis T.

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1998

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tom Vol. 72, nr 2

325-334

EN

The transformation of the 3-oxoazabicyclo[2.2.2]octane pentachlorophenol complex in methanol (and CH3OD) solution into the 3-hydroxy-3-methoxy-azabicyclo[2.2.2]octane pentachlorophenolate is described. The presence of the acidic phenol proton were sufficient to promote such a reaction. The crystal structure of the 3-hydroxy-3-methoxyazabicyclo[2.2.2]octane pentachlorophenolate and its deuterated analoque were determined by X-ray method. IR spectra indicate an ionic character of the complexes and a moderately strong N(+)-H...O(-) and N(+)-D...O(-) hydrogen bonds with the isitopic ratio v(NH)/v(ND) equal to 1.22. Weaker intermolecular O-H...O(-) and O-D...O(-) hydrogen bridges exhibit the isotopic ratio v(OH)/v(OD) 1.34.

3

Spectroscopic studies of Zn(II) halides complexes with 5,7-disubstituted derivatives of 1,2,4-triazolo-[1,5a]-pyrimidine

100%

Szłyk E. , Grodzicki A. , Pazderski L. , Sitkowski J.

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1998

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tom Vol. 72, nr 1

55-60

EN

Complexes of ZnX2 (X=Cl, Br, I, SCN) with 5,7-dimethyl-1,2,4-triazolo-[1,5a]-pyrimidine, 5,7-diphenyl-1,2,4-triazolo-[1,5a]-pyrimidine and 5,7-di-tert-butyl-1,2,4-triazolo-[1,5a]-pyrimidine were prepared and characterized by IR (100-4000 cm-1) and 1H, 13C, 15N NMR spectroscopies. Spectral data suggest pseudo-tetrahedral configuration around Zn(II) atom with N-3 bonded heterocycles. Halides and thiocyanates (N bonded) are in terminal positions.

4

Synthesis and Characterization of First Row Transition Metal Complexes of a Schiff Base Hydrazone Containing Quinoxaline Moiety

100%

Anantha Lakshmi P. V. , Shyamala B. S. , Jayatyaga Raju V.

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2009

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tom Vol. 83, nr 9

1555-1563

EN

A series of new chromium(III), manganese(II), iron(III), cobalt(II), nickel(II) and copper(II) complexes of the Schiff base hydrazone (HDHAHQO), synthesized from 3-hydrazinoquin oxaline-2-one (HQO) and dehydroacetic acid (DHA) were prepared and characterized. The Schiff base exhibits biambidenticity. It be haves as a monobasic tridentate ONN donor in iron(III) and copper(II) complexes and ONO donor in chromium(III), manganese(II), cobalt(II) and nickel(II) complexes. The nature of bonding and the stereochemistry of the complexes have been deduced from elemental analyses, thermal, infrared, electronic spectra, magnetic susceptibility and conductivity measurements. An octahedral geometry was suggested for all the complexes. The Schiff base ligand, HDHAHQO, and its complexes were tested against one strain Gram+ve bacteria (Staphylococcus aureus), Gram-ve bacteria (Escherichia coli). The prepared metal complexes exhibited higher antibacterial activities than the parent ligand.

5

Cobalt(II), Nickel(II) and Copper(II) Complexes of Some 2'-Hydroxychalcones

100%

Karamunge K. G. , Vibhute Y. B.

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2008

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tom Vol. 82, nr 3

559-564

EN

Complexes of Co(II), Ni(II) and Cu(II) with 1-(2'-hydroxy-3'- iodo-5'- methylphenyl)- 3-(3,4-methylenedioxyphenyl)-2-propen-1-one (L1), 1-(2'- hydroxy-3'-bromo-5'- chlorophenyl)- 3-(3,4- methylenedioxyphenyl)-2-propen-1-one (L2) and 1-(2'- hydroxy-3'-iodo- 4'-methyl-5'-chlorophenyl)-3- (3,4-methylene dioxyphenyl)-2- propen-1- one (L3) have been prepared and characterized with the help of elemental analyses, molar conductivity, magnetic measurement, electronic spectra, infrared spectra, ESR and thermal analysis. Elemental analyses confirmed a 1:2 (metal:ligand) stoichiometry. The conductivity data show that all these complexes are non-electrolytes. The infrared spectral data indicate that the L1, L2 and L3 act as mononegative bidentate ligands with all the metal ions and the electronic spectral data suggest that all Co(II), Ni(II) complexes have pseudooctahedral geometry whereas Cu(II) complexes have square planar geometry. Presence of coorinated water molecules in Co(II), and Ni(II) complexes is confirmed by TGA studies. ESR parameters of Cu(II) complexes have been calculated and relevant conclusions have been drawn with respect to the nature of bonds present in them.

6

Information Content in Linear Dichroism Spectra

100%

Thulstrup P. W.

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2008

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tom Vol. 82, nr 4

901-920

EN

Spectroscopy with linearly polarized light on aligned samples (LD spectroscopy) is a useful technique that may greatly enhance the possibilities for determining sample structure, making spectral assignments, and several other tasks, generally based on a determination of transition moment directions. However, the technique does not provide the same amount of information in all cases; this depends strongly on the molecular symmetry. The almost ideal case is that of D2h, D2, or C2v symmetry, when only 3 different (perpendicular) transition moment directions are possible. When the molecular symmetry decreases, the information that may be obtained becomes less precise. If the molecule has a plane of symmetry left, the transition moment may be located perpendicular to the symmetry plane or at any direction in the plane, and much useful information may still be extracted. In the case of a molecule with no symmetry at all the information that can be obtained often becomes highly qualitative, unless special information happens to be available. Unfortunately, this severe limitation is sometimes overlooked when low-symmetry molecules are studied, and the spectra are evaluated the same way spectra for symmetrical molecules are. This is an obvious source of error, and conclusions based on such an analysis are hardly reliable. In this paper, the spectroscopic technique, assumptions commonly made, and the mathematical treatment of IR and UV spectra are briefly summarized for different molecular symmetries. This is illustrated by a few examples, including new IR LD spectra of limonene, a very difficult, low symmetry case.

7

Thermal decomposition and IR-spectra of Mg(II) Complexes with G-picoline

100%

Mojumdar S. , Melnik M. , Jóna E.

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1999

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tom vol. 73 nr 2

293-297

EN

The thermal decomposition of the complexes Mg(Clac)2(pic)2×3H20 (I), Mg(Cl2ac)2(pic) × 4H20 (II) and Mg(Cl3ac)2(pic)2 × 3H2O (III), where Clac = ClCH2COO-, Cl2ac = Cl2CHCOO-, Cl3ac = Cl3CCOO- and pic = g-picoline had been investigated in air by TG and DTA. The possible scheme of destruction of the complexes is suggested. The final product was MgO for the complex I-III. The thermal stability of the complexes can be ordered in the sequence: I = III < II. IR data suggest a unidentate coordination of carboxylates to Mg (II) in complexes I-III and g-picoline coordination with Mg(II) through the nitrogen atom of its heterocyclic ring.

8

Badania procesów identyfikacji zgorzeli słonecznej w skałach bazaltowych.

100%

Góralczyk S. , Filipczyk M.

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2008

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tom Vol. 121, nr 50

85-94

PL

W artykule przedstawione zostały nowe kierunki badań nad zjawiskiem zgorzeli słonecznej skał bazaltowych podjęte w Zakładzie Górnictwa Skalnego Instytutu Mechanizacji Budownictwa i Górnictwa Skalnego w Warszawie. Podstawowym celem prac było opracowanie wstępnych założeń metodyki badawczej pozwalającej w sposób jednoznaczny zintensyfikować i zidentyfikować zgorzel słoneczną. W tym celu zaproponowano nowe, innowacyjne metody badawcza, jak również podjęto próbę modyfikacji obecnie stosowanych metod normowych.

EN

"Sunburn" examination was begun in Institute of Rock Mining in Institute of Mechanised Construction and Rock Mining last year. Main target was Iooking for initial ideas for new undoubtful method of testing basaltic rocks. We try to find the way to intensive and identifi "sunburn" in basaltic rocks. For this purpose we propose new innovative research method and try to modify standard methods using nowadays.

9

Synthesis of New 2-Aminobenzimidazole Derivatives. Part 4. Reactions of 2-Arylideneaminobenzimidazole with Selected -Ketoesters

100%

Nawrocka W. P. , Kowalska M. W. , Sztuba B. , Dryś A. , Wietrzyk J. , Filip B.

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2007

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tom Vol. 81, nr 10

1753-1753

EN

Schiff bases 2–6 obtained from 2-aminobenzimidazole 1 with p-(N,N-diethylamino)-, p-chloro-, p-bromo-, 2,4-dimethoxy-, and 3,4-dimethoxybenzaldehyde were subjected to the reaction with 1,3-ketoester: methyl-, ethyl-, benzyl-, and t-butylacetoacetate to form derivatives of pyrimido[1,2-a]benzimidazole 7–23. 1H NMR spectra recorded for the compounds 20–23 in DMSO solution indicate the presence of two conformational forms. Compounds 2, 7–23 were examined for their antiproliferative activity in vitro against the cells of human lung cancer cell lines A549.

10

Spectroscopic and thermal studies of light lanthanide complexes with 2,6-dihydroxybenzoic acid

88%

Brzyska W. , Rzączyńska Z. , Kula A. , Jaroniec M.

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1998

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tom Vol. 72, nr 9

2087-2092

EN

The complexes of light lanthanides (La-Eu) with 2,6-dihydroxybenzoic acid have been prepared and their IR spectra and thermal decomposition have been investigated. The complexes Ln(C7H5O4)3 x nH2O, where n=4 for La-Sm and n=6 for Eu, when heated lose the crystallization water molecules in one (La-Pr), two (Nd, Sm) or three (Eu) steps and then anhydrous compounds decompose to Ln2O3, CeO2 and Pr6O11 with intermediate formation of instable Ln(C7H5O4)(C7H4O4), except of lanthanum complees, which forms additionally La2O2CO3.

11

ZSM-5 zeolite modified with thallium ions

88%

Romotowski T. , Komorek J. , Stoch J. , Mikołajczyk M.

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1998

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tom Vol. 72, nr 11

2450-2454

EN

ZSM-5 zeolite modified with Tl has been investigated with XRD, IR and XPS spectroscopies. Thallium Tl(+) ions were introducted in the exchange reaction in water medium, accompanied by exchange of Na(+) with H(+). From XPS results follows that more likely thallium atoms have been incorporated to the ZSM-5 zeolite lacctice as Tl(+) species. All TlHNa-ZSM-5 zeolite samples catalyzed ammoxidation of m-xylene. X-ray diffractograms before and after ammoxidation proved the preservation of the ZSM-5 zeolite structure.

12

Preparation and Some Properties of Lithium Vanadium Bronzes

88%

El-Sayed A. , Mousa S.

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2006

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tom Vol. 80, nr 5

773-781

EN

Lithium vanadium bronzes with composition formula LixV2O5 (0.04 _ x _ 0.92) have been prepared by solid-state reaction at 650graduate C in argon atmosphere. The obtained products were characterized by X-ray powder diffraction and IR spectroscopy. The results reveal that four phases are present in the range from x = 0.04 to 0.92 namely alfa,beta ,beta' , and gamma phase. The magnetic susceptibility for the investigated samples was measured using the conventionalGouy'smethod. The effectivemagnetic moments as calculated from experimental data indicate the presence ofV4+ ions in all samples. The electrical conductivity as a function of temperature and lithium content was measured from room temperature to 483 K. The electrical conductivity of the samples is found to be affected by lithium content. The electrical conductivity increases with temperature and both electronic and ionic conduction are discussed.

13

Studies on Cobalt(II), Nickel(II), Copper(II) and Zinc(II) Complexes Involving a Bidentate Schiff Base Ligand

88%

Sivasankaran Nair M. , Joseyphus R. S. , Dhanaraj C. J.

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2009

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tom Vol. 83, nr 9

1529-1535

EN

Co(II), Ni(II), Cu(II) and Zn(II) complexes of Schiff base, derived by the condensation of indole-3-carboxaldehyde and beta-alanine, were synthesized and characterized by elemental analysis, conductance measurements, IR, electronic spectra, magnetic measurements and powder XRD. The analytical data show the composition of the metal complex to be ML2, where L is the Schiff base ligand. The conductance data indicate that all the complexes are non-electrolytes. IR results demonstrate the bidentate binding of the Schiff base ligand in volving azomethine nitrogen and carboxylato oxygen atom. The electronic spectral measurements indicate that Co(II) and Ni(II) complexes have pseudo tetrahedral geometry, while Cu(II) complex is square planar. The magnetic measurements show paramagnetic behaviour for Co(II), Ni(II) and Cu(II) complexes. The powder XRD studies show that Ni(II) and Zn(II) complexes are crystalline, while the Co(II) and Cu(II) complexes are amorphous. The crystallite size of the Zn(II) complex was found to be in the nanocrystalline regime. Antimicrobial studies indicate that the metal complexes are found to be more active than the ligand. Among the metal complexes, the Co(II) and Cu(II) complexes were more active compared to that Ni(II) and Zn(II) complexes.

14

Hydrazinium Complexes of Lanthanide and Transition Metal Squarates

88%

Vairam S. , Govindarajan S.

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2006

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tom Vol. 80, nr 10

1601-1614

EN

Reaction of the ligands, squaric acid and hydrazine with Ln(NO3)3 where Ln(III) = La, Pr, Nd, Sm, Gd and Ce results in the formation of the complexes of the formula, N2H5[Ln(C4O4)2]xH2O where x = 3, 5 and 6 and their reaction with transition metal nitrates, M(NO3)2xH2O, where M(II) = Co, Ni, Cu, Zn and Cd in aqueous solution yields the squarates of the types, [(N2H5)3M(C4O4)2.5]2H2O where M(II) = Co, Ni and Cd; [(N2H5)2Zn(C4O4)2]2H2O and [(N2H5)Cu(C4O4)1.5 ]. Neutralization of the acid with hydrazine hydrate gives dihydrazinium squarate hydrate, (N2H5)2(C4O4)H2O. All the above complexes, except Cd, are sparingly soluble in water and are characterized by IR, UV-visible, ESR and thermoanalytical methods. The squarates appear to behave as bis-monodentate and tetrakis-monodentate bridged ligands in transition metal and lanthanide complexes respectively. Hydrazinium cation acts as a coordinating ligand in transition metal complexes whereas it is a charge compensating species in lanthanide squarates. This fact is revealed from their IR spectra by displayingN-N frequency at 1000 cm–1 in the former case and at 950 cm–1 in the latter. Squarate compounds exhibit very high exothermic decomposition. Hydrazinium lanthanide squarates show weight losses due to dehydration and dehydrazination from 68 graduate C to 258 graduate C and a strong exothermic decomposition between 176 graduate C and 700 graduate C leading to the formation of metal oxides/oxy carbonates as the end products possibly via H[Ln(C4O4)2] intermediate. Transitionmetal compounds loose water and hydrazine in the range of 50–275 graduate C, and then undergo strong exothermic decomposition above 200 graduate C with no stable intermediate formation. Simple hydrazinium salt decomposes completely exothermally at 179 graduate C. The electronic spectra indicate the coordination number (CN) and geometry; CN 8 with square anti-prism for lanthanides and CN 6 with octahedral arrangement for transition metals. The geometry of the complexes is substantiated by their electronic spectra, magnetic

15

The Role of Steric Hindrance in Molecular recognition Process of 1,4-Diols Obtained from Tartaric Acid

88%

Szczęsna B. , Urbańczyk-Lipkowska Z.

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2000

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tom Vol. 74, nr 4

495-501

EN

X-ray structure analysis has been done and compared with already known crystal structure of host compound. The lack of complexing properties of the former could be explained by differences in intermolecular hydrogen bonding pattern, expressed by sterically hindered and strain free hydroxy groups. respective solution and solid state IR spectra show the same effect in both media.

16

Preparation, spectral properties and antimicrobial effects of new Cu(II) compounds with some bio-active ligands

88%

Mojumdar S. , Hudecova D. , Melnik M.

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1999

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tom vol. 73 nr 5

759-764

EN

The compounds [Cu(ac)2(Et2na)]2 × Et2na × 2H20 (I), Cu(Clac)2(Et2na)3 (II), Cu(Cl2ac)2(Et2na)2 × 2H20 (III), [Cu(ac)2mpc]2 × 2CH3OH (IV), Cu(Clac)2(mpc) (V), Cu(Cl2ac)2(mpc)2 (VI), Cu(Cl3ac)2(mpc)2 (VII), Cu(pc) × 5h2O (VIII), where ac=CH3Coo-, Clac=ClCH2COO-, Cl2ac=Cl2CHCOO-, Cl3ac=Cl3CCOO-, Et2na=N,N-diethylnicotinamide, mpc= methyl-3-pyridyl carbamate and pc=2,6-pyridinedicarboxylate have been prepared and characterized by elemental analysis, IR, EPR and electronic spectra. Their antimicrobial effects have been tested on various fungal strains. Significant morphological changes of Botrytic cinerea were observed by the compounds V and VII. The highest antimicrobial effects were manifested by compound IV. IC50 and MIC of that compound are 220 and 1000 mg/ml against Rhizopus oryzae, 250 and 500 mg/ml against Microsporum gypseum, respectively. IR data suggest a unidentate coordination of carboxylate to Cu(II). Et2na and mpc were coordinated through the N atom of the heterocyclic rings. EPR spectra suggest a diametric structure of complexes I and IV and monomeric structure of complexes II, III, V-VIII.

17

DFT calculation and assignment of vibrational spectra of aryl and alkyl chlorophosphates

88%

Anishchenko V. , Rybachenko V. , Chotiy K. , Redko A.

Open Chemistry

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2014

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tom 12

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nr 2

153-163

EN

DFT calculations of vibrational spectra of chlorophosphates using wide range of basis sets and hybrid functionals were performed. Good agreement between calculated and experimental vibrational spectra was reached by the combination of non-empirical functional PBE0 with both middle and large basis sets. The frequencies of the stretching vibrations of the phosphate group calculated using semi-empirical functional B3LYP for all basis sets deviate significantly from the experimental values. The number of polarization functions on heavy atoms was shown to be a key factor for the calculation of vibrational frequencies of organophosphates. The importance of consideration of all the stable rotamers for a complete assignment of fundamental modes was shown.

18

Structure of 3-Hydroxy-3-methyl-pyrido[2,1-c][1,4]dihydrooxazinium Chloride Studied by X-ray, FTIR, 1H, 13C and 15N NMR and DFT Methods

88%

Szafran M. , Nowak-Wydra B. , Katrusiak A. , Dega-Szafran Z.

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2006

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tom Vol. 80, nr 7

1039-1053

EN

2-Hydroxymethyl-pyridine with chloroacetone gave 3-hydroxy-3-methyl-pyrido[2,1-c] [1,4]dihydrooxazinium chloride (1). Its crystal structure was determined by X-ray diffraction and confirmed by FTIR and NMR spectra. In DMSO and D2O solutions this compound exists in some equilibrium mixture with N-acetonyl-2-hydroxymethyl-pyridinium chloride (2). The equilibrium mixture was proved by FTIR, 1H and 13C NMR spectra. Two of the most stable conformers of both compounds (1 and 2) were analyzed by the B3LYP calculations. Correlations between the experimental 1H and 13C NMR chemical shifts for 1 and 2 and the GIAO/B3LYP/6-31G(d,p) calculatedmagnetic isotropic shielding tensors (sigma cal), delta exp= a + b x sigma calc, are reported. Agood linear relationship between the experimental and calculated data was obtained only for carbons.

19

Synthesis of New tetraoxacyclophanes Containing Benzophenone Units

75%

Kuś P. , Jones P.

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2000

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tom Vol. 74, nr 7

965-977

EN

4,4'-Dihydroxybenzophenone was used as a precursor for synthesis of macrocyclic compounds.

20

Studies of Au(I) complexes with perfluorinated carboxylates and trimethylphosphine

75%

Łakomska I. , Grodzicki A. , Szłyk E.

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1998

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tom Vol. 72, nr 3

492-497

EN

Au(I) complexes of the type RCOOAuL, where R=C6F13, C7F15, C8F17, C9F19, C6F5, OOC(C3F6) and L - trimethylphosphine (Me3P) were synthesized and characterized by spectroscopic (IR, (13)C, (19)F, (31)P NMR) and thermal methods. Spectroscopic results favour two coordinated Au(I) with unidentate bonded trimethylphosphine and carboxylates, whereas in the case of hexafluoroglutarate a dimeric structure has been found. The mode of carboxylates binding was proposed basing on the chemical shift of COO group in (13)C NMR spectra and splitting of COO asymmetric and symmetric vibrations bands. Thermal decomposition proceeds in a multistage way that results in metallic gold. Decomposition temperatures and thermal stability of the studied complexes depend on the length of the perfluorinated chain.