Wyniki wyszukiwania - Biblioteka Nauki

1

Chiral calixarenes Derived from Resorcinol : Part 5 : Crystal Structure of Chiral Aminomethyl Derivative of Resorcarene

100%

Iwanek W.

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1999

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tom Vol. 73, nr 11

1777-1782

2

Synthesis of New Co(III) Hetero-Ligand Complexes with Imidazole and 1-Methylimidazole and Their H, C, and Co NMR Spectra

100%

Danilczuk E. , Grzelakowska A. , Michalska M.

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2000

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tom Vol. 74, nr 2

181-189

EN

Cis-[Co(en)2(1-Melm)2]Cl3, fac-[Co(dien)(ImH)3]X3 (X=Cl-, NO3-,ClO4-) and fac-[Co(dien)(1-Melm)3]Cl3 complexes were prepared and characterized by absorption, 1H NR, 13C NR and 59Co NMR spectra, where en, dien, imH and 1-elm denote ethylenediamine, diethylenetriamine, imidazole and 1-methylimidazole, respectively. Calculated coordination-induced shifts ranged from +0.62 to -0.03 pp for 1H and +7.11 to -1,19 ppm for 13C nuclei of imidazole ligands. The influence of imidazole methylation on 59Co NMR spectra was considered.

3

1H and 13C Nuclear Magnetic Shielding in Gaseous and Liquid Propene

100%

Kubiszewski M. , Makulski W.

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2008

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tom Vol. 82, nr 7

1457-1457

EN

Propylene, C3H6, was studied by high resolution NMR spectroscopy in liquid and gaseous state at 300 K. Extrapolation of gas-phase 1H and 13C chemical shifts to the ero-den sity limit permit ted the determinations of absolute nuclear magnetic shielding in the isolated propylene molecule. These new experimental results were used in a reliable verification of ab in itio calculations of proton and carbon nuclear magnetic shielding. The analogous pure liquid propylene spectra were also measured. The second virial coefficients and gas-to-liquid shifts were discussed in the context of intermolecular inter actions in gas and association in liquid phase.

4

Theoretical studies on the electronic structures and spectra of single silicon-doped SWCNTs

88%

Gao P. , Yu Y. , Ni Z. , Teng Q.

Open Chemistry

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2010

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tom 8

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nr 3

587-593

EN

The equilibrium geometries and electronic structures of a series of SWCNTs doped with a silicon atom were studied by using density function theory (DFT). The most stable doping site of silicon predicted at B3LYP/6-31G(d,p) level was located near the boundary of the SWCNTs. The energy gaps of (3,3) C48, (3,3) C60 and (3,3) C72 were respectively decreased by 0.43, 0.25 and 0.14 eV after doping. Based on the B3LYP/6-31G(d) optimized geometries, the electronic spectra of the doped SWCNTs were computed using the INDO/CIS method. The first UV absorption at 973.9 nm of (5,5)-Si(L) (C59Si) compared with that at 937.5 nm of (5,5) (C60) was red-shifted. The 13C NMR spectra and nuclear independent chemical shifts (NICS) of the doped SWCNTs were investigated at B3LYP/6-31G(d) level. The chemical shift at 119.4 of the carbon atom bonded with the silicon atom in (3,3)-Si(L) (C59Si) in comparison with that at 144.1 of the same carbon atom in (3,3) (C60) moved upfield. The tendency of the aromaticity (NICS = −0.1) for (3,3)-Si(H) (C47Si) with respect to that of the anti-aromaticity (NICS = 6.0) for (3,3) (C48) was predicted. [...]

5

New Congeners of 1-Picryl-2-phenyl-2-(para-picramidophenyl)-diazenium Betaine whose Picramido Groups Are Replaced by 4-Cyano-2,6-dinitrophenyl Analogs

88%

Covaci I.

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2001

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tom Vol. 75, nr 10

1427-1440

EN

By analogy with our previously described 1-picryl-2-phenyl-2-(para-picramidophenyl)- diazenium betaine (4a), three new congeners were synthesized in which either one, or the other, or both of the picryl groups have one 4-nitro group replaced by a cyano group. The spectral properties of these new compounds are described, and they prove that the cyanodinitrophenyl group behaves like a slightly less powerful electron-withdrawing group than a picryl group. The dipotassium salt of 1-picryl-2-phenyl-2-(4-picrylaminophenyl)- hydrazine (5a) forms a supramolecular complex, 13, with 18-crown-6 ether, which can be mono- or dialkylated with methyl iodide, resulting in a monomethyl and dimethyl derivative 14 and 15, respectively. The monomethyl derivative, 14, has the methyl attached to the diarylamino nitrogen atom, since oxidation by potassium permanganate converts it into a stable hydrazylic radical, 17.Abyproduct in the synthesis of betaine 4a, when an excess of DPPH is used over N-methoxypicramide, was proved to be 2-(4-methoxyphenyl)-2-phenyl-1-picrylhydrazine, 12. In order to avoid the formation of such byproducts and to allow simpler purification procedures, it is recommended to use equimolar ratios of reactants, in the presence of potassium permanganate.

6

Synthesis, spectroscopic characterization and antimicrobial evaluation of some (E)-N-(4-substitutedbenzylidene)-4-fluorobenzenesulfonamides

88%

Jayanthi P. , Jesu Retna Raj G. , Sekar M. , Thanikachalam V.

World News of Natural Sciences

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2017

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tom 13

101-112

EN

In the present study, six numbers of Schiff bases (1-6) have been synthesized by the condensation of 4-fluorobenzenesulfonamide and substituted aromatic aldehyde. The purities of these Schiff bases have been checked by their physical constants, IR, 1H NMR and 13CNMR spectral data. The antimicrobial activities of these Schiff bases have been evaluated using Bauer-Kirby method.

7

The role of the side group in reactions involving 1-propyl-2-methylimidazole and 1-propyl-2-imidazole-carboxaldehyde and Co(II), Ni(II), Cu(II) and Zn(II) ions

88%

Barszcz B. , Kulig J. , Jezierska J. , Lisowski J.

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1999

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tom vol. 73 nr 3

447-456

EN

The complexing properties of 1-propyl-2-methylimidazole (1-Pr-2-CH3Im) and 1-propyl-2-imidazolecarboxaldehyde (1-Pr-2-CHOIm) with CoII, NiII, CuII and ZnII were investigated pH-metrically at 25oC and at the ionic strength of 0.5 mol dm-3(KNO3). The stability constans calculated indicate the formation of complexes with metal: ligand ratio of 1:1, 1:2, 1:3, and 1:4. The stability of the metal complexes with both imidazoles depends mostly on the substituent situated between the nitrogen atoms of the imidazole ring. It was found that the carboxalaldehyde oxygen atom participates in the formation of the coordination bond. The formation of the weak chelate copper (II)-1-propyl-2-imidazolecarboxaldehyde complexes was confirmed by EPR spectra. The electronic spectra reveal that the cobalt(II) forms both tetrahedral and octahedral species with 1-Pr-2-CH3Im, but 1_Pr-2-CHIIm forms only six-coordinated compounds. The NMR spectra of 1_Pr-2-CHOIm indicate that hydration of the CHO takes place when Zn(II) ions are introduced into the ligand solution at pH5.03.

8

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.

9

Synthesis, structure and Tuberculostatic Activity of N'-(amino-pyridyl-methylene)-hydrazinecarbodithioic Acid Methyl Esters

75%

Orlewska C.

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2001

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tom Vol. 75, nr 9

1237-1245

EN

The methods of preparation of the title esters from imidates or amidrazones are described, and structures of the compounds are elucidated on the basis of 1H, 13C-NMR, 2D-NMR spectra and X-ray diffraction method. Tuberculotic activity was also studied.

10

Structure and Hydrogen Bonding of Solid N1-Alkyl-N2-(2-hydroxy, 4- or 5-methylphenyl)thioureas

75%

Wawer I. , Anulewicz-Ostrowska R. , Maciejewska D. , Koleva V.

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2000

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tom Vol. 74, nr 6

823-835

EN

Crystalline N1-alkyl-N2-arylthioureas with ortho hydroxyl and para or meta methyl substituents to the phenyl ring were studied by single crystal X-ray diffraction, IR and solid state 13C cP MAS NMR. Two different modes of association were found: i) intermolecular N1H...S bonds and N2H not involved in hydrogen bonding in N1-methyl-N2-(2-hydroxy, 5-metylphenyl)thuiourea 1, ii) cyclic dimers with two N2H...S hydrogen bonds (S...N2 distance of 3.332 A) and N1H engaged in intermolecular N1H...O bond in N1-methyl-N2-(2-hydroxy,4 methylphenyl)thiourea 2. Changes of carbon chemical shifts between solution and solid state result mainly from the reorientation of the aromatic ring with respect to the thiourea fragent.

11

Growth kinetics of CdSe nanoparticles synthesized in reverse micelles using bis(trimethylsilyl) selenium precursor

75%

Emin S. , Dushkin C. , Nakabayashi S. , Adachi E.

Open Chemistry

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2007

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tom 5

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nr 2

590-604

EN

We first focus on the kinetics of nanoparticle growth in a microemulsion synthesis of CdSe semiconductor nanocrystals. The process consists of a fast initial stage of typical time constant of the order of 103 s followed by a slow stage of time constant of the order of 104s. Growth proceeds similarly to that described for the hot-matrix synthesis of CdSe, underlining the generality of the two-stage growth mechanism, irrespective of the matrix type and synthesis conditions. However, the time constant of each stage in the microemulsion synthesis is much larger than in the hot-matrix one. Also, the ratio between the fast and slow time constant is appreciably bigger. We also prove that larger size reverse micelles, obtained by increasing the water:surfactant ratio, generally lead to larger CdSe nanoparticles. Bis(trimethylsilyl) selenium is the crucial precursor for the CdSe nanoparticle synthesis. An intermediate stage of the chemical reaction limiting the bis(trimethylsilyl) selenium production is described theoretically. [...]

12

Synthesis of 4-aryloxy-7-nitrobenzofurazan derivatives from 4-chloro-7-nitrobenzofurazan and various phenoxide anions (including pharmaceuticals) in the presence of crown ethers

75%

Bem M. , Caproiu M. , Stoicescu D. , Constantinescu T. , Balaban A.

Open Chemistry

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2003

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tom 1

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nr 3

260-276

EN

4-Chloro-7-nitrobenzofurazan reacts by nucleophilic substitution with phenoxide anions derived from estriol (2c), ethynylestradiol (2d), phenol (3e), guaiacol (3f), 2,6-dimethoxyphenol (3g), eugenol (3h), isoeugenol (3i), the cytostatic Etoposide (4), and Reichardt’s betaine (5) in the presence of crown ethers affording the corresponding 4-aryloxy-7-nitrobenzofurazan derivatives 6c, 6d, 7e-7i, 8, and 9. The structure of these compounds was confirmed by NMR spectra. Hydrophobicity/hydrophilicity parameters were investigated by reverse phase thin-layer chromatography.

13

Hydrogen Bonds and Electrostatic Interactions in N-(Ethoxycarbonylmethyl)-quinuclidinium Chloride Dihydrate

63%

Dega-Szafran Z. , Katrusiak A. , Szafran M.

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2009

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tom Vol. 83, nr 5

723-735

EN

N-(Ethoxycarbonylmethyl)-quinuclidinium chloride crystallizes as dihydrate, QNBEźClź2H2O. The crystals are monoclinic, space group C2/c. Water molecules interact with the chloride an ions and form a cyclic oligomer, through the O–HźźźCl and O–HźźźO hydrogen bonds. The chloride an ions and water molecules addition ally interact electrostically with the positively charged nitrogen atom of the quinuclidinium moiety. The optimized structure of QNBEźClź2H2O by the B3LYP/6-31G(d,p) level of the ory reproduces well the molecular aggregation observed in the crystal. The FTIR spectrum of the solid compound is consistent with the X-ray structure.

14

Solid Fly-ash:PTS catalyzed synthesis, spectral studies and antimicrobial activities of some 1,3-diarylpropenones

63%

Arulkumarana R. , Vanangamudia G. , Kamalakkannana D. , Sundararajana R. , Vijayakumara S. , Thirumurthyb K. , Mayavelb P. , Thirunarayanan G.

Annales Universitatis Mariae Curie-Skłodowska, sectio AA – Chemia

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2012

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tom 67

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nr 1-2

45-77

EN

The green catalyst Fly-ash:PTS has been prepared and characterized by IR and SEM analysis. Using this catalyst some aryl chalcones have been synthesized by aldol condensation of aryl methyl ketone and substituted benzaldehydes. It has been observed that this reaction yields more than 85% of the product. These chalcones have been characterized by their physical constants and spectral data following the procedures published in literature. The effect of substituents on the spectral data of the chalcones, synthesized, has been studied using single and multi-regression analysis with Hammett equation. The antibacterial and antifungal activities of these chalcones have been studied using Bauer-Kirby method.

15

Wodorozcieńczalne kationomery poliuretanowe syntezowane z 4,4'-diizocyjanianu difenylometanu lub diizocyjanianu izoforonu, poliestrów i N-metylo- lub N-butylodietanoloaminy — analiza struktury i wybranych właściwości otrzymywanych powłok

51%

Król P. , Król B.

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2012

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tom T. 57, nr 11-12

799-811

PL

Poliuretanowe kationomery syntezowano w reakcji MDI, IPDI, poliestrów i trzeciorzędowych amin alifatycznych, które po wbudowaniu do prepolimeru w reakcji z kwasem mrówkowym lub bromkiem butylu tworzyły kationy alkiloamoniowe. Otrzymane prepolimery izocyjanianowe przedłużano w środowisku wodnym przy użyciu 1,6-heksametylenodiaminy, uzyskując trwałe dyspersje wodne. Metodą spektroskopii 1H NMR potwierdzono struktury chemiczne syntezowanych kationomerów i podjęto próby ilościowej oceny polarności otrzymanych z nich powłok, na podstawie specjalnie w tym celu obliczanego parametru kdośw. Wykorzystując modele van Ossa-Gooda i Owensa-Wendta oraz pomiary kątów zwilżania powierzchni kationomerów poliuretanowych za pomocą cieczy wzorcowych o różnej polarności, wyznaczono swobodną energię powierzchniową (SEP) wytwarzanych powłok. Dyskutowano wpływ struktury chemicznej oraz polarności kationomerów poliuretanowych na wartości SEP i jej składowe: polarną, dyspersyjną i kwasowo-zasadową. Stwierdzono, że istotną rolę odgrywa w tym przypadku zarówno rodzaj diizocyjanianu, poliestru, jak i jego ciężar cząsteczkowy oraz struktura segmentu jonowego. Powłoki o małej hydrofilowości (SEP ok. 38 mJ/m2) wytwarzano z kationomerów syntezowanych z MDI i poli(etylenoadypiniano)diolu 1000, zawierających ugrupowania jonowe otrzymane w wyniku wbudowania do łańcuchów poliuretanowych N-butylodietanoloaminy wraz z bromkiem butylu.

EN

Polyurethane cationomers were synthesized in the reaction of MDI, IPDI, polyesters and tertiary aliphatic amines, which were incorporated into the prepolymer and converted to alkylammonium cations by reacting with formic acid or butyl bromide. The obtained isocyanate prepolymers were extended in aqueous medium using 1,6-hexamethylenediamine resulting in the formation of stable aqueous dispersions. Chemical structures of the synthesized cationomers were confirmed by 1H NMR spectroscopy. Attempts were made to quantitatively evaluate the polarity of coatings made from them using specially calculated for that purpose kcalc. parameter. The surface free energy (SFE) of the obtained coatings was determined using van Oss — Good and Owens — Wendt models as well as contact angle measurements of cationomer surfaces by means of standard liquids with various polarity. The effect of chemical structure and polarity of polyurethane cationomers on SFE as well as on its polar and acid-base components was discussed. It was concluded that these parameters are highly influenced by both diisocyanate and polyester type as well as molecular weight and ionic segment structure. Coatings with low hydrophobicity (SFE about 38 mJ/m2) were prepared from the cationomers made from MDI and poly(ethylene adipate) diol 1000, containing ionic groups obtained by incorporation of N-butyldiethanolamine together with butyl bromide into the polyurethane chains.