Covalent Analogues of DNA Base-Pairs and Triplets V. Synthesis of Purine-Purine and Purine-Pyrimidine Conjugates Connected by Diverse Types of Acyclic Carbon Linkages

2002 ◽  
Vol 67 (10) ◽  
pp. 1560-1578 ◽  
Author(s):  
Michal Hocek ◽  
Hana Dvořáková ◽  
Ivana Císařová
Keyword(s):  
Single Crystal ◽  
Crystal Structures ◽  
Base Pair ◽  
Cross Coupling ◽  
X Ray Diffraction ◽  
Base Pairs ◽  
X Ray ◽  
Dna Base ◽  
Dna Base Pairs ◽  
Purine Pyrimidine

The title 1,2-bis(purin-6-yl)acetylenes, -diacetylenes, -ethylenes and -ethanes were prepared as covalent base-pair analogues starting from 6-ethynylpurines and 6-iodopurines by the Sonogashira cross-coupling or oxidative alkyne-dimerization reactions followed by hydrogenations. 6-[(1,3-Dimethyluracil-5-yl)ethynyl]purine (11) was prepared analogously and hydrogenated to the corresponding purine-pyrimidine conjugates linked via vinylene and ethylene linkers. Unlike the cytostatic bis(purin-6-yl)acetylenes and -diacetylenes, the purine-pyrimidine conjugates were inactive. Crystal structures of bis(purin-6-yl)acetylene 6a, -diacetylene 8a and -ethane 5a were determined by single-crystal X-ray diffraction.

Covalent Analogues of DNA Base-Pairs and Triplets VII. Synthesis and Cytostatic Activity of Bis(purin-6-yl)acetylene and -diacetylene Nucleosides

2004 ◽  
Vol 69 (10) ◽  
pp. 1955-1970 ◽  
Author(s):  
Petr Nauš ◽  
Ivan Votruba ◽  
Michal Hocek
Keyword(s):  
Acetic Acid ◽  
Base Pair ◽  
Cross Coupling ◽  
Cytostatic Activity ◽  
Coupling Reactions ◽  
Base Pairs ◽  
Cross Coupling Reactions ◽  
Dna Base ◽  
Dna Base Pairs

The title bis(purin-6-yl)acetylene and -diacetylene nucleoside derivatives were prepared as covalent base-pair analogues starting from acyl-protected 6-ethynylpurine and 6-iodopurine nucleosides by the Sonogashira cross-coupling or oxidative alkyne-dimerization reactions followed by deprotection. The key starting acyl-protected 6-ethynylpurine nucleosides were prepared by a sequence of cross-coupling reactions of protected 6-halopurine nucleosides with (trimethylsilyl)acetylene followed by a modified desilylation with TBAF in presence of acetic acid. Surprisingly, the acyl-protected nucleosides exhibited significant cytostatic activity higher than the fully deprotected title compounds.

Crystal structures of (S)- and (R,S)-2,2′-bipyridine-3,3′-dicarboxylic acid 1,1′-dioxides and of their barium salts: absolute configuration and molecular distortion enforced by supramolecular self-assembly

1997 ◽  
Vol 212 (3) ◽  
Author(s):  
P. Vojtíšek ◽  
I. Císařová ◽  
J. Podlaha ◽  
Z. Žák ◽  
S. Böhm ◽  
...  
Keyword(s):  
Single Crystal ◽  
Dicarboxylic Acid ◽  
Crystal Structures ◽  
Absolute Configuration ◽  
Self Assembly ◽  
Barium Salt ◽  
X Ray Diffraction ◽  
X Ray

AbstractCrystal structures of the title compounds were determined by single crystal X-ray diffraction. Absolute configuration of the barium salt of (+)-(

Die Kristallstrukturen der isotypen Verbindungen Ba3[MoN4] und Ba3[WN4] / The Crystal Structures of the Isotypic Compounds Ba3[MoN4] and Ba3[WN4]

1991 ◽  
Vol 46 (5) ◽  
pp. 566-572 ◽  
Author(s):  
Axel Gudat ◽  
Peter Höhn ◽  
Rüdiger Kniep ◽  
Albrecht Rabenau
Keyword(s):  
Transition Metals ◽  
Single Crystal ◽  
Crystal Structures ◽  
Structure Type ◽  
X Ray Diffraction ◽  
X Ray ◽  
Ternary Compounds ◽  
The Third

The isotypic ternary compounds Ba3[MoN4] and Ba3[WN4] were prepared by reaction of the transition metals with barium (Ba3N2, resp.) under nitrogen. The crystal structures were determined by single crystal X-ray diffraction: Ba3[MoN4] (Ba3[WN4]): Pbca; Z = 8; a = 1083.9(3) pm (1091.8(3) pm), b = 1030.3(3) pm (1037.5(3) pm), c = 1202.9(3) pm (1209.2(4) pm). The structures contain isolated tetrahedral anions [MN4]6- (M = Mo, W) which are arranged in form of slightly distorted hexagonal layers and which are stacked along [010] with the sequence (···AB···). Two of the three Ba atoms are situated between, the third one is placed within the layers of [MN4]-groups. In this way the structures can be derived from the Na3As structure type.

An Intramolecular Boron Nitrogen Lewis Acid Base Pair on a Rigid Naphthyl Backbone

2012 ◽  
Vol 67 (6) ◽  
pp. 589-593 ◽  
Author(s):  
Daniel Winkelhaus ◽  
Beate Neumann ◽  
Norbert W. Mitzel
Keyword(s):  
Nmr Spectroscopy ◽  
Single Crystal ◽  
Lewis Acid ◽  
Elemental Analysis ◽  
Base Pair ◽  
Ring System ◽  
X Ray Diffraction ◽  
Acid Base ◽  
X Ray ◽  
Boron Nitrogen

The reaction of (C6F5)2BCl with 8-lithio-N,N-dimethyl-1-naphthylamine (1) afforded the fivemembered ring system 8-bis(pentafluorophenyl)boryl-N,N-dimethyl-1-naphthylamine (2) with an intramolecular dative B-N bond. The compound was characterised by elemental analysis, NMR spectroscopy and single-crystal X-ray diffraction.

Lewis-Base Adducts of Group 1B Metal(I) Compounds. XXI The Crystal and Molecular Structures of the Unsolvated Forms of Dibromotris(triphenylphosphine)dicopper(I) and 'step' Tetrabromotetrakis(triphenyl-phosphine)tetracopper(I)

1985 ◽  
Vol 38 (8) ◽  
pp. 1243 ◽  
Author(s):  
JC Dyason ◽  
LM Engelhardt ◽  
C Pakawatchai ◽  
PC Healy ◽  
AH White
Keyword(s):  
Single Crystal ◽  
Crystal Structures ◽  
Molecular Structures ◽  
Lewis Base ◽  
Crystal Data ◽  
X Ray Diffraction ◽  
Triphenyl Phosphine ◽  
X Ray ◽  
Crystal And Molecular Structures

The crystal structures of the title compounds have been determined by single-crystal X-ray diffraction methods at 295 K. Crystal data for (PPh3)2CuBr2Cu(PPh3) (1) show that the crystals are iso-morphous with the previously studied chloro analogue, being monoclinic, P21/c, a 19.390(8), b 9.912(5), c 26.979(9) Ǻ, β 112,33(3)°; R 0.043 for No 3444. Cu( trigonal )- P;Br respectively are 2.191(3); 2.409(2), 2.364(2) Ǻ. Cu(tetrahedral)- P;Br respectively are 2.241(3), 2.249(3); 2.550(2), 2.571(2) Ǻ. Crystals of 'step' [PPh3CuBr]4 (2) are isomorphous with the solvated bromo and unsolvated iodo analogues, being monoclinic, C2/c, a 25.687(10), b 16.084(7), c 17.815(9) Ǻ, β 110.92(3)°; R 0.072 for No 3055. Cu( trigonal )- P;Br respectively are 2.206(5); 2.371(3), 2.427(2) Ǻ. Cu(tetrahedral)- P;Br are 2.207(4); 2.446(2), 2.676(3), 2.515(3) Ǻ.

scholarly journals Crystal structures of two novel iron isocyanides from the reaction of 2,6-dimethylphenyl isocyanide, CNXyl, with bis(anthracene)ferrate(−1)

2022 ◽  
Vol 78 (1) ◽  
Author(s):  
William W. Brennessel ◽  
John E. Ellis
Keyword(s):  
Crystal Structure ◽  
Single Crystal ◽  
Crystal Structures ◽  
Tridentate Ligand ◽  
Reductive Cyclization ◽  
X Ray Diffraction ◽  
X Ray

The reaction of the [K(18-crown-6)(thf)2]1+ (thf is tetrahydrofuran) salt of bis(anthracene)ferrate(−1), or [Fe(C14H10)2]−, with 2,6-dimethylphenyl isocyanide (CNXyl) in thf resulted in the formation of two new iron isocyanide complexes, namely, [(1,2,3,4-η)-anthracene]tris(2,6-dimethylphenyl isocyanide)iron, [Fe(C14H10)(C9H9N)3] or [Fe(1,2,3,4-η-C14H10)(CNXyl)3], and {5,6-bis(2,6-dimethylanilino)-3-(2,6-dimethylphenyl)-1,2,7-tris[(2,6-dimethylphenyl)imino]-3-azoniahept-3-ene-1,4,7-triido}tris(2,6-dimethylphenyl isocyanide)iron tetrahydrofuran disolvate, [Fe(C54H56N6)(C9H9N)3]·2C4H8O or [Fe(C54H56N6)(CNXyl)3]·2C4H8O, which were characterized by single-crystal X-ray diffraction. The former is likely an intermediate along the path to the known homoleptic [Fe(CNXyl)5], while the latter contains a tridentate ligand that is formed from the `coupling' of six CNXyl ligands. A third crystal structure from this reaction, (7-methylindol-1-ido-κN)(1,4,7,10,13,16-hexaoxacyclooctadecane-κ6 O)potassium, [K(C9H8N)(C12H24O6)] or [K(C9H8N)(18-crown-6)], contains a 7-methylindol-1-ide anion, in which one CNXyl ligand has shed a proton during its reductive cyclization.

Die neuen Oxobismutate(III) Cs6Bi4O9, K9Bi5O13 und A2Bi4O7 (A = Rb, Cs) / The New Oxobismutates(III) Cs6Bi4O9, K9Bi5O13 and A2Bi4O7 (A = Rb, Cs)

2002 ◽  
Vol 57 (10) ◽  
pp. 1090-1100
Author(s):  
Franziska Emmerling ◽  
Caroline Röhr
Keyword(s):  
Single Crystal ◽  
Crystal Structures ◽  
Alkali Metals ◽  
Mixed Valence ◽  
Three Dimensional ◽  
X Ray Diffraction ◽  
X Ray ◽  
Trigonal Bipyramidal ◽  
Mixed Valence Compound

AbstractThe title compounds were synthesized at a temperature of 700 °C via oxidation of elemental Bi with the hyperoxides AO2 or via reaction of the elemental alkali metals A with Bi2O3. Their crystal structures have been determined by single crystal x-ray diffraction. They are dominated by two possible surroundings of Bi by O, the ψ-trigonal-bipyramidal three (B) and the ψ-tetrahedral four (T) coordination. Cs6Bi4O9 (triclinic, spacegroup P1̄, a = 813.82(12), b = 991.60(14), c = 1213.83(18) pm, α = 103.658(2), β = 93.694(3), γ = 91.662(3)°, Z = 2) contains centrosymmetric chain segmentes [Bi8O18]12- with six three- (T) and two four-coordinated (B) Bi(III) centers. K9Bi5O13 (monoclinic, spacegroup P21/c, a = 1510.98(14), b = 567.59(5), c = 2685.6(2) pm, β = 111.190(2)°, Z = 4) is a mixed valence compound with isolated [BivO4]3- tetrahedra and chains [BiIII4O9]6- of two T and two B coordinated Bi. In the compounds A2Bi4O7 (A = Rb/Cs: monoclinic, C2/c, a = 2037.0(3) / 2130.6(12), b = 1285.5(2) / 1301.9(7), c = 1566.6(2) / 1605.6(9) pm, β = 94.783(3) / 95.725(9)°, Z = 8) ribbons [Bi4O6O2/2]2- are formed, which are condensed to form a three-dimensional framework.

Crystal structures of some eriostyl/nitrobenzoate derivatives

1980 ◽  
Vol 33 (2) ◽  
pp. 313 ◽  
Author(s):  
PR Jefferies ◽  
BW Skelton ◽  
B Walter ◽  
AH White
Keyword(s):  
Charge Transfer ◽  
Solid State ◽  
Single Crystal ◽  
Crystal Structures ◽  
X Ray Diffraction ◽  
X Ray ◽  
Structure Determinations

Following the suggestion made earlier, on the basis of solution spectroscopy, that a number of eriostyl/nitrobenzoate compounds form charge-transfer self-complexes, a number of these have been investigated structurally by single-crystal X-ray diffraction methods in order to ascertain the presence or otherwise of such interactions in the solid state. The substances thus studied were eriostyl 3,5-dinitrobenzoate (1), eriostyl p-nitrobenzoate (2), tetrahydroeriostyl 3,5-dinitrobenzoate (3), and eriostemyl 3,5-dinitrobenzoate (4);* structure determinations in all cases, although displaying the presence of strong charge-transfer interactions from the two moieties of each molecule, show that the interactions in the solid state are intermolecular in nature.

scholarly journals Darstellung und Kristallstrukturen von (PH4P)4Sb8I28 und (Ph4P)Sb3I10(Ph = C6H5) / Synthesis and Crystal Structures of (PH4P)4Sb8I28 and (Ph4P)Sb3I10(Ph = C6H5)

1987 ◽  
Vol 42 (12) ◽  
pp. 1493-1499 ◽  
Author(s):  
Siegfried Pohl ◽  
Wolfgang Saak ◽  
Detlev Haase
Keyword(s):  
Single Crystal ◽  
Crystal Structures ◽  
Diffraction Data ◽  
Lone Pair ◽  
X Ray Diffraction ◽  
Triclinic Space Group ◽  
X Ray ◽  
Molar Ratios ◽  
Polymeric Chains ◽  
Bond Strengths

AbstractThe compounds (Pn4P)4Sb8I28 (1) and (Ph4P)Sb3I10 (2) were prepared by the reaction of SbI3 and Ph4PI in acetonitrile (molar ratios 2:1 and 3:1 respectively). The structures of 1 and 2 were determined from single crystal X-ray diffraction data.1 crystallizes in the triclinic space group P1̄ with a - 1321.7(5). b = 1346.7(5), c = 2201.8(8) pm, α = 104.18(2). β = 99.92(2), γ = 100.33(2)°; 2: monoclinic, C2/c, a = 2371.1(2), b = 745.0(1), c = 2495.1(2) pm, β = 100.75(1)°.Whereas 1 exhibits isolated Sb8I284- ions, the anions of 2 are built up of polymeric chains [Sb3I10- ]∞. In both compounds the distorted Sbl6 octahedra are linked by common edges. The Sb-I distances are in the range between 277.4 and 354.8 pm (1) and between 277.4 and 342.4 pm (2). The observed structures do not only depend on stoichiometry, the nature of the counter cations, and the possibility of oligomerisation but also on the wide variety of the Sb-I bond strengths and the different bridges formed by iodine.The lone pair of Sb(III) seems to be predominantly 5 s2.

scholarly journals Asymmetric base-pair opening drives helicase unwinding dynamics

2019 ◽  
Vol 116 (45) ◽  
pp. 22471-22477 ◽  
Author(s):  
Francesco Colizzi ◽  
Cibran Perez-Gonzalez ◽  
Remi Fritzen ◽  
Yaakov Levy ◽  
Malcolm F. White ◽  
...  
Keyword(s):  
Base Pair ◽  
Double Helix ◽  
The Other ◽  
Base Pairs ◽  
Dna Helicases ◽  
Cellular Processes ◽  
Dna Base ◽  
Dna Base Pairs ◽  
Opening And Closing ◽  
Base Pair Opening

The opening of a Watson–Crick double helix is required for crucial cellular processes, including replication, repair, and transcription. It has long been assumed that RNA or DNA base pairs are broken by the concerted symmetric movement of complementary nucleobases. By analyzing thousands of base-pair opening and closing events from molecular simulations, here, we uncover a systematic stepwise process driven by the asymmetric flipping-out probability of paired nucleobases. We demonstrate experimentally that such asymmetry strongly biases the unwinding efficiency of DNA helicases toward substrates that bear highly dynamic nucleobases, such as pyrimidines, on the displaced strand. Duplex substrates with identical thermodynamic stability are thus shown to be more easily unwound from one side than the other, in a quantifiable and predictable manner. Our results indicate a possible layer of gene regulation coded in the direction-dependent unwindability of the double helix.

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