Library

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    Electronic Resource
    Electronic Resource
    Structure of the deoxytetranucleotide d-pApTpApT and a sequence-dependent model for poly(dA-dT)Supplementary material on observed and calculated structure factors for d-pApTpApT is available from the authors. (1982)
    New York : Wiley-Blackwell
    Biopolymers 21 (1982), S. 513-533 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The x-ray structure of the hydrated ammonium salt of the deoxytetranucleotide d-pApTpApT was determined by Patterson and direct methods at a resolution of 1 Å. The crystal structure contains right-handed double-helical segments formed by complementary Watson-Crick-type hydrogen bonding between the adenine and thymine bases of neighboring molecules. The minihelix contains two base pairs. The chains are antiparallel. The A-T and T-A sequences have different phosphodiester conformations. The deoxyribose-pucker and the sugar-base orientation alternate along the chain depending on the nature of the base (3′-endo for purine and 2′-endo for pyrimidine). The extended structure is stabilized by base-base, base-sugar, and hydrogen-bond interactions. The minihelix of two base pairs provides starting coordinates for model-building studies of the dA-dT polymer. A B-DNA-type polymer structure is described, which has sequence-dependent alternations of both the deoxyribose pucker and the phosphate diester bridge conformation. Such sequence-dependent DNA structures, if present locally in regions such as operator sequences, could facilitate sequence-specific interactions. The crystal study also suggests possible geometrical parameters for the replication fork.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360210304
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    Zur Reaktion von Diphenoxyphosphorylchlorid mit N,N-disubstituierten Harnstoffen - Bildung von phosphorylierten Biuret-VerbindungenProfessor Gisbert Großmann zum 60. Geburtstag gewidmet (1991)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 594 (1991), S. 146-156 
    Details
    ISSN: 0044-2313
    Keywords: Diphenoxyphosphorylchloride ; N′,N′-dialkyl-N-diphenoxyphosphoryl urea ; N-diphenoxyphosphoryl-N″,N″-dipropyl biuret ; X-ray crystal structure analysis ; n.m.r. spectra ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Reaction of Diphenoxyphosphorylchloride with N,N-disubstituted Ureas - Formation of Phosphorylated Biuret CompoundsN′,N′-disubstituted N-diphenoxyphosphorylureas, (PhO)2P(O)—NH—CO—NR1R2 (R1 = R2 = Et, 1; n-Pr, 2; n-Bu, 3; i-Bu, 4; R1 = Me and R2 = Ph, 5) as well as phosphorylated biuret compounds, (PhO)2P(O)—NH—CO—NH—CO—NR1R2 are obtained in the reaction of diphenoxyphosphorylchloride with N,N-disubstituted ureas and triethylamine. The biuret derivatives are formed via (PhO)2P(O)NCO. Their yield rises if the reaction is carried out without amine. The X-ray crystal structure analysis of (PhO)2P(O)—NH—CO—NH—CO—NPr2, 8, shows that dimers exist in the crystal with intermolecular as well as intramolecular hydrogen bonds. The framework formed by atoms P—N1—C1(O4)—N2—C2(O5)—N3(C3)C6 is planar. The existence of a rotation barrier along the bond C2-N3 was detected by NMR spectroscopy.
    Notes: Bei der Umsetzung von Diphenoxyphosphorylchlorid mit N,N-disubstituierten Harnstoffen in Gegenwart von Triethylamin treten neben N′,N′-disubstituierten N-Diphenoxyphosphorylharnstoffen, (PhO)2P(O)—NH—CO—NR1R2 (R1 = R2 = Et, 1; n-Pr, 2; n-Bu, 3; i-Bu, 4; R1 = Me u. R2 = Ph, 5), immer auch N″,N″-disubstituierte N-Diphenoxyphosphorylbiuret-Verbindungen, (PhO)2P(O)—NH—CO—NH—CO—NR1R2 auf. Sie entstehen über intermediär gebildetes (PhO)2P(O)NCO. Die Ausbeute an Biuretderivaten steigt, wenn ohne Aminzusatz gearbeitet wird. Die Röntgen-Kristallstrukturanalyse von (PhO)2P(O)—NH—CO—NH—CO—NPr2, 8, zeigt, daß im Kristall Dimere mit sowohl inter- als auch intramolekularen Wasserstoffbrücken vorliegen. Das Gerüst von 8 mit der Atomfolge P—N1—C1(O4)—N2—C2(O5)—N3(C3)C6 ist nahezu planar. NMR-Untersuchungen beweisen die Existenz einer Rotationsbarriere um die Bindung C2-N3.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/zaac.19915940118
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    Polysulfonylamine. XXIV. Darstellung und Kristallstrukturen von Bis(dimesylamino)dimethylsilan und Bis(dimesylamino)dimethylstannan (1991)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 601 (1991), S. 111-119 
    Details
    ISSN: 0044-2313
    Keywords: Sulfonyl amines ; bis(dimesylamino)dimethyl silane ; bis(dimesylamino)dimethyl stannane ; preparation ; crystal structures ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Polysulfonyl Amines. XXIV. Preparation and Crystal Structures of Bis(dimesylamino)dimethyl Silane and Bis(dimesylamino)dimethyl StannaneThe new compounds (CH3)2E[N(SO2CH3)2]2 with E = Si (3), m.p. 162 °C, and E = Sn (4), m.p. 194-196 ° were prepared by metathesis of AgN(SO2CH3)2 with (CH3)2ECl2 and subjected to X-ray structure determinations. 3 crystallizes in the monoclinic space group C2/c with a = 1714.3(4), b = 679.6(2), c = 1389.9(4) pm, β = 97.50(2)° and Z = 4, 4 in the same space group with a = 2093.8(8), b = 1320.7(6), c = 1443.9(6) pm, β = 124.28(3)° and Z = 8. The crystals of both compounds consist of discrete monomeric molecules, in which the central atom E is bonded to two carbon and two nitrogen atoms in an approximately tetrahedral geometry for 3 [angles at Si in the range (105.5⃛111.9)°] and in a severely distorted tetrahedral arrangement in 4 [CSnC 128.8°; NSnN 107.8°; NSnC in the range (99.9⃛109.4)°]. Details of the molecular structures suggest that in each molecule two intramolecular E⃛O dipole-dipole interactions are stereochemically significant [Si⃛O 291.4 pm (2x); Sn⃛O 300.9 and 303.1 pm]. The molecule of 3 displays an exact, that of 4 an approximate twofold symmetry.
    Notes: Die neuen Verbindungen (CH3)2E[N(SO2CH3)2]2 mit E = Si (3), Schmp. 162 °C, und E = Sn (4), Schmp. 194-196 °C, wurden durch Metathese von AgN(SO2CH3)2 mit (CH3)2ECl2 erhalten und röntgenstrukturanalytisch charakterisiert. 3 kristallisiert in der monoklinen Raumgruppe C2/c mit a = 1714,3(4), b = 679,6(2), c = 1389,9(4) pm, β = 97,50(2)° und Z = 4, 4 in der gleichen Raumgruppe mit a = 2093,8(8), b = 1320,7(6), c = 1443,9(6) pm, β = 124,28(3)° und Z = 8. Die Kristallpackung beider Verbindungen besteht aus diskreten monomeren Molekülen, in denen das Zentralatom E an zwei Kohlenstoff- und zwei Stickstoffatome gebunden ist. 3 weist eine annähernd tetraedrische Geometrie auf [Winkel am Siim Bereich (105,5⃛111,9)°], 4 hingegen eine stark verzerrte Tetraedergeometrie [CSnC 128,8°; NSnN 107,8°; NSnC im Bereich (99,9⃛109,4)°]. Eine Betrachtung der Molekülstrukturen legt nahe, daß in beiden Fällen je zwei intramolekulare (E⃛O)-Wechselwirkungen vom Dipol-Dipol-Typ die Stereochemie beeinflussen [Si⃛O 291,4 pm (2x) Sn⃛O 300,9 und 303,1 pm]. Das Molekül von 3 besitzt eine strenge, das von 4 eine annähernde zweizählige Symmetrie.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/zaac.19916010113
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 4
    Electronic Resource
    Electronic Resource
    Tris(trimethylsilyl)methanselenenylhalogenide und -chalkogenideProfessor Heinrich Nöth zum 65. Geburtstage gewidmet (1993)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 619 (1993), S. 1693-1698 
    Details
    ISSN: 0044-2313
    Keywords: Tris(trimethylsilyl)methaneselenenyl halides ; Tris(trimethylsilyl)methaneselenyl chalcogenides ; 1H, 13C, 77Se n.m.r. sprectra ; crystal structure ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Tris(trimethylsilyl)methaneselenenyl Halides and Chalcogenides.Ditrisyldiselenide (1) (trisyl = TSi = (Me3Si)3C) reacts with SOCl2, Br2 and I2 to provide trisylselenenyl halides TSiSeX (2: X = Cl; 3: X = Br, 4: X = I). Insertion of S and Se into the Se—Se bond of 1 to yield (TSiSe)2Sn (5: n = 1; 6: n = 2) and (TSiSe)2Sen (7: n = 1; 8: n = 2) was catalysed by iodine. 5 was isolated in pure state and examined by X-ray diffraction. Triselenide 7 can be cleaved by I2 in CS2 to give 4 and Se2I2 (9). From 2 with Me3SiCN and Me3SiNCS, the new selenenyl pseudohalides TSiSeCN (10) and TSiSeSCN (11) were prepared. The compounds were characterised by 1H, 13C- and 77Se n.m.r. spectra.
    Notes: Ditrisyldiselenid (1) (Trisyl  -  Tsi  -  (Me3Si)3C—) reagiert mit SOCl2, Br2 und I2 zu Trisylselenenylhalogeniden TSiSeX (2: X = Cl; 3: X = Br, 4: X = I). Die Einschiebung von Schwefel und Selen in die Se—Se-Bindung von 1 zu (TSiSe)2 Sn (5: n = 1; 6: n = 2) bzw. (TSiSe)2Sen (7: n = 1; 8: n = 2) läßt sich mit Iod katalysieren. 5 wurde in reiner Form isoliert und durch Röntgenstrukturanalyse untersucht. Das Triselenid 7 wird durch Iod in CS2 zu 4 und Se2I2 (9) gespalten. Aus 2 lassen sich mit Me3SiCN bzw. Me3SiNCS das Trisylselenocyanat TSiSeCN (10) bzw. Trisylselenenylthiocyanat TSiSeSCN (11) gewinnen. 1H, 13C- und 77Se-NMR Spektren von 1 - 11 sind im Einklang mit den Strukturvorschlägen.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/zaac.19936191011
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...