ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

Your email was sent successfully. Check your inbox.

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

Proceed reservation?

Export
Filter
  • crystal structure  (45)
  • Springer  (45)
  • American Meteorological Society
  • 1995-1999  (45)
  • 1990-1994
  • 1940-1944
  • 1998  (45)
  • 1941
Collection
Keywords
Publisher
Years
  • 1995-1999  (45)
  • 1990-1994
  • 1940-1944
Year
  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Journal of chemical crystallography 28 (1998), S. 11-15 
    ISSN: 1572-8854
    Keywords: Mebendazole–propionic acid complex ; molecular complex ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Recrystallization of the anthelmintic drug mebendazole from propionic acid yields a 1:1 molecular complex which crystallizes in the triclinic system space group $${P\bar 1}$$ , a = 5.928(2), b = 11.066(2), c = 14.337(6)Å, α = 94.89(3), β = 101.56(3), γ = 96.18(2)°, and Z = 2 complex units in the unit cell. An x-ray diffraction study revealed an R 2 2 (8) hydrogen bonding system in the complex, involving the unprotonated imidazole N and amide N–H function of the drug and the acid carboxylic group. Complex molecules form centrosymmetric dimers by intermolecular N–H···O hydrogen bonding involving the protonated imidazole N atom and the benzoyl O atom of the drug molecule.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 2
    ISSN: 1572-8854
    Keywords: Cu(II) complex ; crystal structure ; EPR spectra
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The title compound, Cu(glyglygly)Br·1·5H2O, crystallizes in the space group C2/c, with a = 21.468(7), b = 6.716(5), c = 16.166(6) Å, β = 98.39°, and Z = 8. The tripeptide is bonded to one Cu(II) ion through the nitrogen [Cu–N=1.97(1)Å] and oxygen [Cu–O=2.019(8)Å] atoms of the amino end glycine residue and to another Cu(II) through one oxygen atom [Cu–O=1.931(9)Å] of the terminal carboxyl group. This give rise to covalently bonded and infinite ···–Cu–tripeptide–Cu–··· chains. These chains are linked to one another by a network of H-bonds involving the water molecules and bromide ions. The Cu(II) ion is in a distorted tetragonal pyramidal coordination polyhedron. At the corner of the base of the pyramid are the terminal glycine nitrogen and oxygen atoms of one tripeptide, a carboxylic oxygen of another tripeptide and a bromide ion. The fivefold coordination is completed with a water molecule at the top of the pyramid [Cu–Ow=2.286(9)Å]. For all orientations of the applied magnetic field the single crystal EPR spectra display a single anisotropic exchange collapsed resonance without hyperfine structure. Its position was measured in three perpendicular planes and the crystal g-tensor evaluated from the data. This tensor is interpreted in terms of the contributing Cu(II) complexes in the unit cell to deduce the principal values g1 = 2.273, g2 = 2.050 and g3 = 2.131 for the molecular gyromagnetic tensor. We also discuss the magnitude of the exchange interaction between neighboring copper ions in the lattice on the basis of the features in the EPR spectra and the structural information.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 3
    ISSN: 1572-8854
    Keywords: 2-Methylnaphthalene ; hexachlorocyclopentadiene ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract 2-Methylnaphthalene undergoes Diels-Alder addition and substitution with hexachlorocyclopentadiene to give two products, 1,2,3,4,5,6,7,8,13,13,14,14-dodecachloro-1,4,4a,4b,5,8,8a,12b-octahydro-10-methyl-1,4;5,8-dimethanotriphenylene 1 and 1,2,3,4,5,6,7,8,13,13,14,14-dodecachloro-1,4,4a,4b,5,8,8a,12b-octahydro-10-(1′,2′,3′,4′,5′-pentachlorocyclopentadienyl)methyl-1,4;5,8-dimethanotriphenylene 2. The molecular structure of 2 has been characterized by X-ray crystallography: C26H9Cl17, monoclinic, space group P21/c, with a = 15.316(3), b = 13.698(3), c = 16.116(3) Å, β = 96.113(3)°, and Z = 4.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 4
    ISSN: 1572-8854
    Keywords: Halobismuthate(III) ; phenanthroline ; synthesis ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The reaction between bismuthate oxide and phen (1,10-phenanthroline) in acid medium led to the isolation of the unusual [(PhenH)(PhenH2)][BiCl6]·2H2O derivative, which has been characterized by X-ray analysis and IR spectroscopy. The compound crystallizes in the triclinic space group $$[\text[P\bar 1]]$$ with a = 8.313(2), b = 9.349(2), c = 9.807(3) Å, α = 86.39(3), β = 110.27(3) and γ = 106.48(3)°. The crystal structure is made of [BiCl6]3− anions and [(PhenH)(PhenH2)]3+ cations. A network of hydrogen bond interactions involving the two clathrated water molecules, the phenanthroline moiety and the chlorines characterizes the entire structure.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 5
    ISSN: 1572-8854
    Keywords: Lanthanum complex ; hexamethylenetetramine ; IR spectra ; thiocyanates ; coordination number nine ; tricapped trigonal prism ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The title compound (LaC15H42N11O9S3) was prepared and characterized by means of X-ray, IR and Raman measurements. The crystals are orthorhombic: Pnma (No. 62), a = 21.117(2), b = 14.736(2), c = 10.082(1) Å, and Z = 4. The structure consists of polyhedra with a La(III) ion in the center of them and hexamethylene molecules, which link these polyhedra. Each La(III) ion coordinates seven molecules of water and two thiocyanate ions via nitrogen atoms. The IR and Raman spectra, which have been obtained and interpreted, are in good agreement with X-ray results.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 6
    ISSN: 1572-8854
    Keywords: Cerium(IV) ; β-diketonate ; volatility ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The cerium(IV) β-diketonate compounds [Ce(β-diket)4] [where β-diket = tmhd (2,2,6,6-tetramethylheptane-3,5-dionate) 1, pmhd (1-phenyl-5-methylhexane-1,3-dionate) 2] were prepared by reacting cerium(IV) ammonium nitrate [CAN; Ce(NH4)2(NO3)6] with the respective Na(β-diket) compound in ethanol, and structurally characterized by single crystal X-ray diffraction. Compound 1 crystallizes in the triclinic space group $$P \bar 1$$ with a = 12.472(4), b = 19.972(5), c = 21.436(3) Å, α = 97.05(7), β = 90.16(2), γ = 106.55(3)°, V = 5076(2) Å3, Z = 4, T = 150(2) K. Compound 2 crystallizes in the monoclinic space group P21/n. with a = 14.817(6), b = 17.123(6), c = 19.146(3) Å, β = 105.46(4)°, V = 4682(3) Å3, Z = 4, T = 150(2) K. Crystals of 1 contain two independent [Ce(tmhd)4] molecules, with four chelating tmhd ligands bonded to each metal in a distorted dodecahedral arrangement; the cerium atom in 2 is also bonded to four chelating pmhd ligands but in this case the coordination geometry is closer to square antiprism. Both complexes are air and moisture stable. Sublimation studies reveal that 1 sublimes almost quantitatively, while 2 is comparatively involatile.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 7
    ISSN: 1572-8854
    Keywords: Nickel(II) complex ; crystal structure ; Schiff base
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract A nickel(II) complex of the pyridine-2-aldehyde Schiff base of S-methyldithiocarbazate (HNNS) has been synthesized and characterized by means of elemental analysis, IR and UV-vis spectra. The crystal structure of the complex has been determined by single-crystal X-ray diffraction. The complex crystallizes in the monoclinic, space P21/c, with a = 14.092(2), b = 16.886(2), c = 8.857(2)Å; β = 105.78(3) °, V = 2028.2(6) Å3, and Z = 4. The nickel atom is octahedrally coordinated by two uninegatively charged tridentate Schiff base in a mer-configuration via the pyridine nitrogen atom, azomethine nitrogen atom, and mecaptide sulfur atom.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Journal of chemical crystallography 28 (1998), S. 885-892 
    ISSN: 1572-8854
    Keywords: Benztropine mesylate ; crystal structure ; thermal analysis ; dehydration kinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The crystal structure of benztropine mesylate has been determined. It is orthorhombic, Pbca, with a = 12. 885(8)Å, b = 32.012(9)Å, and c = 10.027(3) Å. It exhibits similar packing to that seen in the previously reported crystal structure of benztropine mesylate monhydrate. X-ray powder diffraction patterns have been used to identify the anhydrous and monohydrate forms. The dehydration of the monohydrate follows a first-order reaction mechanism with activation energy of 92(8) kJ mol−1.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Journal of chemical crystallography 28 (1998), S. 521-527 
    ISSN: 1572-8854
    Keywords: Cadmium ; crown ether ; 15-crown-5 ; 18-crown-6 ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Reaction of 15-crown-5 or 18-crown-6 in 3:1 (v/v) CH3CN:CH3OH with Cd(NO3)2·4H2O followed by slow evaporation produces [Cd(NO3)2(15-crown-5)] or [Cd(NO3)2(18-crown-6)]. Crystals of [Cd(NO3)2(15-crown-5)] are orthorhombic with space group Pbca and cell parameters a = 13.562(5), b = 15.941(9), and c = 15.011(7) Å at 295 K. [Cd(NO3)2(18-crown-6)] crystallizes in the monoclinic space group C2/c with a = 11.235(2), b = 11.196(5), c = 15.385(3) Å, and β = 99.89(2)° at 295 K. The metal center in [Cd(NO3)2(15-crown-5)] rests atop the macrocyclic donor array with two cis-bound nitrate anions and adopts a distorted tricapped trigonal prismatic geometry. [Cd(NO3)2(18-crown-6)] resides on an equatorial two-fold rotation axis with Cd2+ coordinated in the 18-crown-6 cavity and the nitrate anions oriented in twisted trans positions.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Journal of chemical crystallography 28 (1998), S. 577-579 
    ISSN: 1572-8854
    Keywords: (−)—Crinine ; Pancratium ; alkaloid ; Amaryllidaceae ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract (−)—Crinine, C16H17NO3, is an alkaloid extracted from the bulbs of Pancratium maritimum L. (Amaryllidaceae). The compound crystallizes in the space group P212121 with cell dimensions a = 6.040(1), b = 12.382(1), c = 17.861(2) Å, with Z = 4. The molecule has five rings and an OH group. The N-containing, five-membered ring and the D ring have envelope conformations. The A and B rings have distorted chair and half-chair conformations, respectively.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 11
    Electronic Resource
    Electronic Resource
    Springer
    Journal of chemical crystallography 28 (1998), S. 217-220 
    ISSN: 1572-8854
    Keywords: Metal carbonyl complexes ; chelate complexes ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The x-ray crystal structure of the complex η2-PDOW(CO)4 (five-membered ring, PDO = 2, 2, 4, 7, 7-pentamethyl-3,6-dithiaoctane) is reported. The complex crystallizes in the monoclinic crystal system, space group P21/c, [#14] with unit cell parameters a = 14.002(14) Å, b = 9.340(10) Å, c = 15.094(12) Å, β = 92.67(4)°, V = 1972(3) Å3; Z = 4. The arrangement of the ligands around the metal atom is distorted from octahedral geometry. Large C–O bond distances and short W–C bond distances of the carbonyl groups located at a trans position with respect to PDO is indicative of a trans influence. The W–S(1) and W–S(2) bond distances of 2.545(3) and 2.545(2) Å, respectively, are shorter than observed for closely related complexes.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 12
    ISSN: 1572-8854
    Keywords: Triphenylsiloxy ; silanol ; borane ; crystal structure ; adduct
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The title compound crystallizes in the triclinic space group $$P \bar 1$$ , with a = 14.458(6), b = 14.630(5), c = 14.721(8) Å, α = 79.75(2), β = 80.11(3), γ = 80.50(3)°, and Z = 2. The crystal structure consists of molecules of (Ph3SiO)3B and Ph3SiOH linked by an weak B···(silanol) acceptor-donor bond, additionally stabilized by OH(silanol)···O(siloxy) hydrogen bonds. The average B–O, Si–O distances and B–O–Si angle are 1.369, 1.649 Å and 137.2°, respectively.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 13
    ISSN: 1572-8854
    Keywords: Steroid ; pregnadiene ; x-ray diffraction ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The title compound is C29H34O4, tetragonal, P43, a = b = 10.310(1), c = 23.871(2)Å. The A, B, C, and D rings adopt envelope, half-chair, chair, and distorted chair conformations, respectively. The phenyl ring is planar. The methyl substituents at the A/B, C/D, and at C(17) are axial; and the –OCOCH3 group at C(17) and phenyl ring at C(16) are equatorial. The molecules in the crystal are held together by van der Waals forces and several C–H···O hydrogen bond interactions.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 14
    Electronic Resource
    Electronic Resource
    Springer
    Journal of chemical crystallography 28 (1998), S. 539-543 
    ISSN: 1572-8854
    Keywords: Antimalarial ; crystal structure ; peroxy bridge
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The crystal and molecular structure of the antimalarial compound Artemisinin (formerly known as Qinghaosu), C15H22O5 has been determined by direct methods. Crystals are orthorhombic colorless needles, space group P212121, Z = 4. D c = 1.299 g cm −3, with unit cell parameters a = 6.3543(9), b = 9.439(3), c= 24.066(4) Å. The molecule incorporates a fused ring system containing a six-membered ring C which includes an oxygen bridge and a peroxy-bridge. The ring C has a distorted boat conformation and the C - O - O - C torsion angle is 47.8(2)°. Rings A and D have symmetrical chair and distorted chair conformations, repectively. Ring junctions A/B, A/D, and C/D are cis, junction B/D is trans. All inter-molecular contacts are van der Waals. The absolute configuration of Artemisinin was determined from the refined value of the Flack x parameter. [The atomic coordinates given in a previous structure analysis, “Crystal Structure and Absolute Configuration of Qinghaosu,” Qinghaosu Research Group, Institute of Biophysics, Academica Sinica, Scientia Sinica, Vol. XXIII No. 3, 380 (1980), do not display the molecule in its absolute configuration.]
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 15
    ISSN: 1572-8862
    Keywords: Ruthenium ; thioether macrocycle ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract The reaction of a mixture of cis-3,7,11-trimethyl-1,5,9-trithiacyclododecane, cis-Me312S3, 1 and trans-3,7,11-trimethyl-l,5,9-trithiacyclododecane, trans-Me312S3, 2, with Ru6(CO)17(μ 6-C), 3, yielded three new cluster compounds Ru6(CO)13(μ-η3-cis-SCH2CHMe(CH2SCH2CHMe)2CH2)(μ 6-C) 4, and two isomers of Ru6(CO)13(μ-η3-cis-SCH2CHMe(CH2SCH2CHMe)2CH2)(μ 6-C) 5a and 5b. The molecular structures of 4 and 5b were established by single crystal X-ray diffraction analyses. In both complexes, the macrocycles have adopted tridentate coordination with one of the sulfur atoms in a bridging position. Two carbonyl ligands occupy bridging positions in each compound. Crystal Data for 4·Me2CO: space group=P21/n, a=11.295(1) Å, b=17.547(3) Å, c=20.318(3) Å, β=93.71(1)°, Z=4, 2900 reflections, R=0.025. Crystal Data for 5b·1.5 C6H6: space group=Pbca, a=31.8900(8) Å, b=23.4330(6) Å, c=21.6240(4) Å, Z=16, 12163 reflections, R=0.040.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 16
    ISSN: 1572-8862
    Keywords: Mixed-metal cluster ; crystal structure ; magnetic properties
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract The preparation, magnetic properties, and crystal structure of [(salen)Cu]4[(salen)Fe(H2O)2]2(ClO4)2 via hydrogen bonding are described [salen=N,N′-ethylenebis (salicylideneiminate)]. Crystals are triclinic, of space group $$\rm P\bar 1$$ , with cell constants a=12.853(3), b=13.921(3), c=14.251(3) Å, α=68.68(3)°, β=87.86(3)°, γ=86.82(3)°, and Z=1. The structure was solved and refined to R=0.064 and R′=0.068. The structure comprises the hexanuclear units which result from the linking of four mononuclear fragments [(salen)Cu] and two mononuclear fragment [(salen)Fe(H2O)]+, through Cu -O ⋯ H -O -Fe -O -H ⋯ O -Cu hydrogen bonds of coordinating H2O. In this complex, FeIII ions are in almost square-planar surroundings. The temperature dependences of the magnetic susceptibilities of the complex have been studied in the 4.2–300 K range, indicating the presence of an antiferromagnetic interactions between metal ions.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 17
    ISSN: 1572-8862
    Keywords: Dynamic disorder ; crystal structure ; ruthenium cluster
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract The disorder in the X-ray crystal structures of Ru3(CO)11(L), L=CN t Bu 1 and PMe3 3 has been re-examined. Crystallographic data for 1 at 100 K: C16H9NO11Ru3, space group P21/n, a=11.796(5), b=11.748(2), c=16.040(7) Å, β=109.81(3)°, Z=4, 6077 reflections, R=0.028. For 3 at 223 K: C14H9O11PRu3, space group P21/n, a=8.5971(15), b=12.391(7), c=40.345(8) Å, β=94.43(2)°, Z=8, 7966 reflections, R=0.031. The disorder present in 1 and 3 at room temperature disappears reversibly on cooling, showing that it is dynamic in origin. The ligator atoms of the isonitrile and phosphine ligands move by a maximum of ∼0.8 Å, indicating that the whole cluster does not rotate intact within the crystal lattice, but rather that the Ru3 triangle effectively oscillates within a relatively rigid ligand polyhedron. The crystal structure of Ru3(CO)9{P(OMe)3 3} 7, which crystallizes in triclinic (7-t) and monoclinic (7-m) modifications is also reported. Both modifications have two independent molecules in the asymmetric unit, and both modifications display dynamic disorder in the metal framework. Crystalllographic data for 7-t at 173 K: C18H27O18P3Ru3, space group P-1, a=11.8085(18), b=15.915(2), c=17.350(3) Å, α=99.929(14), β=101.811(14), γ=90.630(12)°, Z=4, 11242 reflections, R=0.048. For 7-m at 120 K: C18H27O18P3Ru3, space group P21/c, a=11.708(8), b=15.922(5), c=33.950(10) Å, β=99.29(4), Z=8, 10191 reflections, R=0.027.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 18
    Electronic Resource
    Electronic Resource
    Springer
    Journal of applied electrochemistry 28 (1998), S. 559-563 
    ISSN: 1572-8838
    Keywords: electroless Ni–Co–B alloy ; dimethylamineborane ; complexing agent ; deposition rate ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Electrical Engineering, Measurement and Control Technology
    Notes: Abstract Fundamental aspects of electroless Ni–B, Co–B and Ni–Co–B alloys have been systematically examined. The composition, crystal structure and deposition rate of the alloys were determined as a function of the concentration of reducing agent (dimethylamineborane) and complexing agents (tartrate, citrate, malonate and succinic acid), bath pH and Ni2+/Co2+ ratio. Changes in the deposition rate and metallurgical features of the alloys induced by the change in plating parameters are discussed, based on electrochemical polarization data and the formation enthalpy of the nickel and cobalt borides.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 19
    ISSN: 1572-8854
    Keywords: Copper ; 1,10-phenanthroline ; trifluoroacetate ; crystal structure ; magnetic exchange
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The compound [Cu(phen)(O2CCF3)2]n (phen = 1,10-phenanthroline) has been synthesized and its crystal structure determined. It crystallizes in monoclinic space group C2/c, with a = 19.229(7), b = 11.281(5), c = 7.621(2) Å, β = 104.305(12)°, and Z = 4. The crystal structure is polymeric, being built from infinite zigzag chains of trifluoroacetate bridged copper(II), with the phenanthroline ligands being stacked between the chains. The variable-temperature (13–300 K) magnetic susceptibility and ESR data are reported and a weak ferromagnetic exchange interaction is observed with the exchange parameter estimated as J = 2.9 cm−1.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 20
    Electronic Resource
    Electronic Resource
    Springer
    Journal of chemical crystallography 28 (1998), S. 839-841 
    ISSN: 1572-8854
    Keywords: π-allyl ; carbonyl ; nitrile ; chloro ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The title compound crystallizes in the monoclinic spacegroup P21/m with a = 6.796(9), b = 12.145(14), c = 7.749(8)Å, β = 101.86(1)°, and Z = 2. The crystal structure consists of molecules of [MoCl(CO)2(NCMe)2(η3-C3H4Me-2)] with crystallographically imposed Cs symmetry and has a pseudo-octahedral geometry, with the π-allyl group trans- to the chloro group and the two cis-carbonyl and acetonitrile groups occupying the equatorial plane.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 21
    ISSN: 1572-8854
    Keywords: 1,10-Phenanthroline ; bis-phenanthrolineprotium ; adduct ; crystal structure ; hydrogen bonding
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Herzog's reported bis-1,10-phenanthrolineammonium perchlorate, [(phen)2(NH4)](ClO4) is in fact the known 2:1 adduct of l,10-phenanthroline (phen) with perchloric acid, [(phen)2H](CIO4). Its crystal structure, mode of formation, and properties are described. The compound crystallizes in the triclinic space group with $$P\bar 1$$ , a = 7.2510(8), b = 13.120(2), c = 22.083(12) Å, α = 77.4550(12), β = 84.45(2), γ = 82.204(14)°, V = 2026.7(6) Å3, Z = 4, and D c = 1.510 g cm−3. It contains cationic columns of alternating 1,10-phenanthroline and its conjugate acid.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 22
    Electronic Resource
    Electronic Resource
    Springer
    Journal of chemical crystallography 28 (1998), S. 645-648 
    ISSN: 1572-8854
    Keywords: 2-Bromoleptoclinidinone ; marine alkaloid ; cytotoxic ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract 2-Bromoleptoclinidinone methanol solvate, C18H8BrN3O·CH4O, crystallizes in the orthorhombic space group Pbca with a = 15.7013(2), b = 7.3308(1), and c = 26.9326(1) Å. The molecule is essentially planar, with the largest deviations occurring at bromine (−0.21 Å), carbonyl oxygen O(l) (+0.19 Å) and in ring-A (C(9) −0.15 Å, C(10) −0.15 Å). Methanol occupies the 1,10-phenanthroline-like metal binding site of the title compound.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 23
    Electronic Resource
    Electronic Resource
    Springer
    Journal of chemical crystallography 28 (1998), S. 925-929 
    ISSN: 1572-8854
    Keywords: Quinoline ; chloroquine ; antimalarial ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The preparation of N12-(7-chloro-4-quinolinyl)-N 1,N 1-diethyl-1,12-diaminododecane, AQ-40, was accomplished by a five-step process in 80% overall yield from 12-aminododecanoic acid and 4,7-dichloroquinoline. AQ-40 crystallizes as a monohydrate from reagent grade chloroform/ diethyl ether mixtures in the triclinc space group P-1 with a = 8.667(2), b = 8.9425(10), c = 17.217(3) Å, α = 99.34(1), β = 99.89(2), γ = 91.56(1)°, V = 1295.0 Å3 and Z = 2. The l2-(N 1,N 1-diethylamino)dodecyl side chain is in the fully extended conformation and the water molecule forms hydrogen bonds to the two tertiary nitrogen atoms as well as with the secondary amino group. The nitrogen of the secondary amino group bound to the four-position of the quinoline moiety is virtually planar. This together with the rather short C–N distance of 1.347(3) Å to the quinoline moiety suggests involvement of the lone pair on this nitrogen with the π system of the ring.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 24
    Electronic Resource
    Electronic Resource
    Springer
    Journal of chemical crystallography 28 (1998), S. 69-72 
    ISSN: 1572-8854
    Keywords: Co(III) complex ; crystal structure ; kinetics ; steric effects
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The title compound crystallizes in the orthorhombic space group Pnma, with a = 7.9209(5), b = 9.818(1), c = 16.867(2) Å, and Z = 4. The structure was solved employing 1864 independent x-ray reflections with I〉2σ(I) by Patterson and difference Fourier techniques and refined by full-matrix least-squares to R = 0.036. The trans-[CO(NH3)4(NH2CH3)Cl](ClO4)2 molecule is on a crystallographic mirror plane. The cobalt ion is in an elongated octahedral coordination with four equatorial ammonia ligands [average Co–N distance equal to 1.966(2) Å], an axial methylamine [Co–N=1.965(3)Å], and an axial chlorine ion [Co–Cl=2.2771(9)Å]. Kinetic steric effects of the complex are interpreted in terms of structural results.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 25
    Electronic Resource
    Electronic Resource
    Springer
    Journal of chemical crystallography 28 (1998), S. 209-212 
    ISSN: 1572-8854
    Keywords: Bismuth ; crystal structure ; inorganic polymer
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The ethylenediammonium pentachlorobismuthate(III) dihydrate salt is monoclinic with the following unit cell dimensions: a = 10.902(8)Å, b = 7.926(6)Å, c = 15.199(6)Å, β = 96.40(1)°, space group P21/n with Z = 4. The structure shows a layer arrangement parallel to the $$\vec a$$ axis: planes of the [Bi2Cl10]4− bioctahedra alternate with planes of [NH3(CH2)2NH3]2+ dications. The [Bi2Cl10]4− bioctahedra are connected through O(W)–H··· Cl hydrogen bonds, so that infinite unidimensional chains of composition [Bi2Cl10(H2O)2] n 4n− are formed in the structure parallel to the $$\vec a$$ axis. These chains are themselves interconnected by means of the N–H···Cl bonds originating from the [NH3(CH2)2NH3]2+ entities, forming a three-dimensional network.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 26
    ISSN: 1572-8854
    Keywords: Strontium ; triphenylsiloxy ; crystal structure ; ammonia
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The title complex [Sr2(OSiPh3)4(NH3)5]·0.5C7H8 was prepared by the reaction of strontium metal granules with triphenylsilanol in an ammoniacal-toluene solution at −40°C. It crystallizes in monoclinic space group P21/n with a = 14.465(3), b = 20.715 (6), c = 25.199(6) Å, β = 95.98(2)°, and Z = 4. The complex has a dimeric structure with one terminal and three bridging triphenylsiloxy ligands, the remaining coordination sites being occupied by five ammonia molecules. The central Sr2O4N5 moiety adopts a distorted M2X9 face-sharing bioctahedral arrangement.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 27
    ISSN: 1572-8854
    Keywords: Mixed rubidium–ammonium acid sulfate ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The structure of Rb0.7(NH4)0.3HSO4 has been determined by X-ray analysis. The mixed compound crystallizes in the monoclinic space group P21/n with unit cell parameters a = 14.374(6) Å, b = 4.618(6) Å, c = 14.412(2) Å, β = 118.03(2)°, V = 844.4(4) Å3, and D cal = 1.536 g cm−3 for Z = 8. The mixed compound Rb0.7(NH4)0.3HSO4 is a chain-based structure. The Rb+ and NH4 + cations are intercalated between chains, formed of HSO4 - groups linked with OH⋯O hydrogen-bonding. Rb0.7(NH4)0.3HSO4 presents a new type of structural arrangement different from those of pure RbHSO4 and NH4HSO4.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 28
    ISSN: 1572-8854
    Keywords: 2-[1,5-Dimethyl-4-hexenyl]-6-hydroxy-5-methyl-1,4-benzoquinone ; 2-[1,5-dimethyl-4-hexenyl]-6-amino-3-hydroxy-5-methyl-1,4-benzoquinone ; 2-[1,5-dimethyl-4-hexenyl]-3-amino-6-hydroxy-5-methyl-1,4-benzoquinone ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The crystal structures of isoperezone (1), aminoperezone (2), and isoaminoperezone (3) have been determined by single-crystal X-ray diffraction. Compound (1) yields orange crystals, orthorhombic space group P212121 with unit cell dimensions a = 6.271(6), b = 30.373(7), c = 7.257(1) Å, and Z = 4; compound (2) yields purple crystals, orthorhombic space group P212121 with unit cell dimensions a = 6.498(3), b = 7.500(1) c = 29.200(6) Å, and Z = 4; compound (3) yields purple crystals, monoclinic space group P21 with unit cell dimensions a = 7.354(1), b = 7.511(1), c = 13.283(1) Å, β = 102,07(1)°, and Z = 2. The side chains in (1)–(3) are oriented out of the plane of the quinone ring at an angle of 124, 144, and 97°, respectively. The molecules in the crystal are held together by hydrogen-bonding networks and van der Waals interactions.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 29
    Electronic Resource
    Electronic Resource
    Springer
    Journal of chemical crystallography 28 (1998), S. 639-643 
    ISSN: 1572-8854
    Keywords: Tungsten(II) ; diiodo ; carbonyl ; trimethylphosphite ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract [WI2(CO)3{P(OMe)3}2]crystallizes in the orthorhombic space group Pca21, with a = 26.924(5), b = 10.726(2), c = 14.136(3) Å, and Z = 8. There are two molecules in the asymmetric unit, the metal atoms in each case being seven-coordinate with a capped fac-(CO)3 octahedral geometry. The molecular dimensions in the two molecules are nearly identical. The W–P distance to the capping atom 2.397 Å (average) is significantly shorter than the other W–P distance, 2.525 Å (average).
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 30
    ISSN: 1572-8854
    Keywords: Pyrimidine ; carboxamide ; sulfonyl ; chiral ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Three novel dihydropyrimidine compounds N8,6-di(4-nitrophenyl)-(3R)-ethyl-(7R)-methyl-5-oxo-2,3,6,7-tetrahydrooxazolo[3,2,c] pyrimidine-8-carboxamide (2), N8,6-di((4-methylphenyl)-sulfonyl)-(3R)-ethyl-5-oxo-(7R)-phenyl-2,3,6,7-tetrahydrooxazolo [3,2,c]pyrimidine-8-carboxamide (3) and N8,6-di ((4-methylphenyl)sulfonyl)-(3R)-ethyl-(7R)-methyl-5-oxo-2,3,6,7-tetrahydrooxazolo[3,2,c] pyrimidine-8-carboxamide (4) have been prepared (from 2-amino-1-butanol of 64.4% e.e.) and structurally characterized by X-ray crystallography. All three compounds contain stereogenic centers, but the crystal of (2) chosen was found to be racemic whilst those of (3) and (4) were found to be homochiral. Compound (2) crystallizes in the monoclinic space group P21/c, with a = 17.958(4), b = 12.431(2), c = 9.653(2) Å, β = 96.20(3)°, U = 2142.3(7) Å3, Z = 4, and D c = 1.449 g cm−3. Compounds (3) and (4) both crystallize in the monoclinic space group P21, with a = 9.349(2), b = 5.824(5), c = 26.513(8) Å, β = 99.43(2)°, U = 1424.1(13) Å3, Z = 2 and D c = 1.389 g cm−3 for (3), and a = 5.9526(9), b = 16.3521(10), c = 13.2263(11) Å, β = 92.81(12)°, U = 1285.9(2) Å3, Z = 2 and D c = 1.378 g cm−3 for (4).
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 31
    ISSN: 1572-8854
    Keywords: Heterotrimetallic sulfido cluster ; linear ; synthesis ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The complex Cu(PPh3)3I reacts with [Et4N]2MoS4 and FeBr2 to give the heterotrimetallic complexes [Et4N][(Ph3P)2{CuS2MoS2Fe}Br2] (1). [Et4N][(Ph3P)2{CuS2MoS2Fe}Br2] (1) crystallizes in the triclinic space group P-1, a = 13.537(4), b = 15.316(4), c = 12.381(4) Å, α = 105.16(2), β = 93.27(3), γ = 101.18(2)°, and V = 2415.0(12) Å3 for Z = 2. The three metal atoms of the structure [Et4N][(Ph3P)2{CuS2MoS2Fe}Br2] (1) are nearly distributed along a line, where three metal atoms (Mo, Cu, Fe) are each in an approximate tetrahedral coordination, the lengths Mo-Fe and Mo-Cu distances are 2.772(2) and 2.798(2) Å, respectively.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 32
    Electronic Resource
    Electronic Resource
    Springer
    Journal of chemical crystallography 28 (1998), S. 447-452 
    ISSN: 1572-8854
    Keywords: Bimetallic EDTA complex ; crystal structure ; antimony
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The synthesis and crystal structure of a new EDTA complex, [CaSb2(EDTA)2(H2O)8]n, are reported. This compound crystallizes in the monoclinic space group P21/n, with a = 7.132(1) Å, b = 21.893(3) Å, c = 10.891(2) Å, β = 91.15(2)°. Sb(EDTA) entities are connected through carboxylate bridges to the calcium atoms resulting in layers parallel to the (101) plane. These layers are linked through a weak Sb···O bond (3.171 Å). Pyrolysis of this complex under sulfur vapor, between 400 and 800°C, leads to a mixture of the monometallic sulfides. Pyrolysis in air above 700°C allows the easy preparation of the mixed oxide CaSb2O6.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 33
    ISSN: 1572-8854
    Keywords: 1-1′-Diphosphaferrocene conformation ; P···P secondary bonding ; bis-[W(CO)5](l,l′-diphosphaferrocene system) ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The structures of (3,3′,4,4′-tetramethyl-1,1′-diphosphaferrocen-2-yl)carboxylic acid (1) and its bis-[W(CO)5] pentane solvate complex (2) have been determined by X-ray analysis. The compound 1 crystallizes in the monoclinic P21 /n space group with Z = 4; a = 7.8404(9), b = 14.9441(16), c = 11.7730(14) Å, β = 92.773(10)°, V = 1377.8(3) Å3, and Dcalc = 1.553 g cm−3. The compound 2 crystallizes in the triclinic $$P\bar 1$$ space group with two complex molecules and one pentane molecule in the unit cell. Cell parameters: a = 10.7070(2), b = 12.577(2), c = 13.239(3) Å, α = 84.00(2), β = 77.58(1), γ = 66.06(1)°, V = 1591.0(5) Å3, and Dcalc = 2.100 g cm−3 .The fully eclipsed conformation of the phospholyl rings with P···P secondary bonding of 3.353(1) Å is observed in 1 and a partially eclipsed conformation is found in 2. The 10 possible conformations of 1,1′-diphosphaferrocenes were described as the function of conformational parameter θ and observed geometry of the phospholyl rings.7 We suppose that the earlier conclusions concerning the destabilizing nature of 1,1′-diphosphaferrocene conformations with θ 〈 100° cannot be considered as general. The mode of W – P coordination, the structural changes of 1 by W(CO)5 coordination, the structural effect of phospholyl rings substitution by the –COOH group, and hydrogen bonds are analyzed.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 34
    Electronic Resource
    Electronic Resource
    Springer
    Journal of chemical crystallography 28 (1998), S. 635-638 
    ISSN: 1572-8854
    Keywords: Cobalt(II) ; 2-aminobenzenethiol ; trimethylphosphite ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract A cobalt-thiolato-phosphite complex [Co(o-SC6H4NH2){P(OMe)3}3]PF6 has been prepared and characterized by X-ray crystallography. The complex crystallizes in the triclinic space group $$P\bar 1$$ with a = 10.590(4), b = 11.122(3), c = 13.577(5) Å, α = 101.85(1), β = 108.50(1), γ = 101.75(1)°, V = 1420.6(8) Å3, and Z = 2. The structure comprises discrete [Co(o-SC6H4NH2){P(OMe)3}3]+ cations and PF 6 − anions where the metal atom is coordinated in a highly distorted square-pyramidal environment by one chelate o-SC6H4NH 2 − (abt) and two P(OMe)3 ligands in the basal positions, and a third P(OMe)3 in the axial site with Co–N,, 1.847(5), Co–S, 2.166(2), Co–P, 2.157(2), 2.147(2), and 2.125(2) Å.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 35
    ISSN: 1572-8862
    Keywords: Silver cluster ; crystal structure ; tetrameric cluster
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract The sought-after member of the [(PDBP) n AgX] m (n, m=1,4; 2,2; 3,1; PDBP=5-Phenyldibenzophosphole, X=halides) series, the tetrameric [(PDBP)AgCl]4 cluster has been prepared and structurally characterized. The [P4Ag4Cl4] cluster core of [(PDBP)AgCl]4 bears striking similarity to that of [(Ph3P)AgCl]4.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 36
    ISSN: 1572-9001
    Keywords: 1-Acetyl-indoline ; crystal structure ; electronic structure ; AM1 calculation ; CI calculation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The crystal and molecular structures of the following molecules have been determined: 1-acetyl-indoline, 1-acetyl-5-nitro-indoline, l-acetyl-5-nitro-7-bromo-indoline, 1-acetyl-5-bromo-7-nitroindoline, and l-acetyl-5-bromo-7-nitro-indol. Molecular orbital calculations are performed for these compounds and two related species.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 37
    ISSN: 1572-8951
    Keywords: hydrogen bond ; ferrocenyl carbonyl proanoic ; supermolecule ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Selective recognition in the title compound, (C14H14FeO3)2 ċ (C10H8N2), between ferrocenyl carbonyl propanoic acid and 4,4'-bipyridine through strong O–-HċN intermolecular hydrogen bonds results in a novel supramolecular architecture. Its crystal structure has been solved by single-crystal X-ray diffraction methods while its characterization has been studied by IR and DSC.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 38
    Electronic Resource
    Electronic Resource
    Springer
    Structural chemistry 9 (1998), S. 39-45 
    ISSN: 1572-9001
    Keywords: Enantioselective chromatographic technique ; chiral selector ; ergot alkaloid derivative ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The structure of (+)1-(3-allylpropyl)-(5R,8S,10R)-N,N-diethyl-N′-[6-methylergolin-8-yl]urea, C22H33N4O (allyl-terguride), has been determined as part of a study on the chiral recognition mechanism of ergot alkaloids when they are used as the chiral stationary phase for the separation of racemic mixtures in liquid chromatographic methods. At the pH of the solution used for the crystallization, the molecules of allyl-terguride are protonated at N(6). All bond distances and angles are in the expected ranges. In the asymmetric unit one hydroxide ion is present. Hydrogen bonds join molecules of allyl-terguride in pairs along the b axis, connecting O(2) of the hydroxide ion to O(1) of one molecule and to N(2) and N(6) of another.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 39
    Electronic Resource
    Electronic Resource
    Springer
    Journal of sol gel science and technology 13 (1998), S. 987-990 
    ISSN: 1573-4846
    Keywords: mullite ; MnO ; crystal structure ; electronic paramagnetic resonance (EPR) ; sol-gel chemistry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Gels were synthesized from solutions of tetraethylorthosilicate (TEOS) and aluminium nitrate (with and without manganese nitrate). The structural evolution of the gels as a function of manganese content and heat-treatment temperature was studied by visible spectrophotometry (VIS), electron paramagnetic resonance (EPR), X-ray diffraction (XRD) and scanning electron microscopy (SEM). The results show that the presence of manganese can induce mullitization at lower temperatures. However, the effect of manganese depends on its content and how it enters into the mullite structure.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 40
    ISSN: 1573-4943
    Keywords: Artificial neural network ; crystal structure ; statistics ; tetanus toxin ; botulinum neurotoxin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Earlier studies used Rost and Sander's artificial neural network [(1993a), J. Mol. Biol. 232, 584–599] to predict the secondary structures [Lebeda and Olson (1994), Proteins 20, 293–300] and residue solvent accessibilities [Lebeda and Olson (1997), J. Protein Chem. 16, 607–618] of the clostridial neurotoxins. Because the X-ray crystal structure of the 50-kDa C-terminal half of the heavy chain of tetanus toxin was recently determined, this report evaluates the accuracy of these network-derived predictions. For this predominantly β-strand-containing fragment, predictions, on a per-residue basis, for both secondary structure and solvent accessibility were about 70% accurate. A more flexible and realistic analysis based on overlapping segments yielded accuracies of over 80% for the three-state secondary structure and for the two-state accessibility predictions. Because the accuracies of these predictions are comparable to those made by Rost and Sander using a dataset of 126 nonhomologous globular proteins, our predictions provide a quantitative foundation for gauging the results when building by homology the structures of related proteins.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 41
    ISSN: 1573-5079
    Keywords: bacterial photosynthesis ; crystal structure ; electron transfer ; proton transfer
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Structural features that have important implications for the fundamental process of transmembrane proton transfer are examined in the recently published high resolution atomic structures of the reaction center (RC) from Rhodobacter sphaeroides in the dark adapted state (DQAQB) and the charged separated state (D+QAQB −); the latter is the active state for proton transfer to the semiquinone. The structures have been determined at 2.2 Å and 2.6 Å resolution, respectively, as reported by Stowell et al. (1997) [Science 276: 812–816]. Three possible proton transfer pathways (P1, P2, P3) consisting of water molecules and/or protonatable residues were identified which connect the QB binding region with the cytoplasmic exposed surface at Asp H224 & Asp M240 (P1), Tyr M3 (P2) and Asp M17 (P3). All three represent possible pathways for proton transfer into the RC. P1 contains an uninterrupted chain of water molecules. This path could, in addition, facilitate the exchange of quinone for quinol during the photocycle by allowing water to move into and out of the binding pocket. Located near these pathways is a cluster of electrostatically interacting acid residues (Asp-L213, Glu-H173, Asp-M17, Asp H124, Asp-L210 and Asp H170) each being within 4.5 Å of a neighboring carboxylic acid or a bridging water molecule. This cluster could serve as an internal ‘proton reservoir’ facilitating fast protonation of QB − that could occur at a rate greater than that attainable by proton uptake from solution.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 42
    ISSN: 1573-6881
    Keywords: Terminal oxidase ; redox coupling ; electrochemical gradient ; electron transport ; energy transduction ; proton translocation ; crystal structure ; site-directed mutagenesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Physics
    Notes: Abstract One of the challenging features of energy-transducing terminal oxidases, like the aa 3 cytochrome c oxidase of Paracoccus denitrificans, is the translocation of protons across the cytoplasmic membrane, which is coupled to the transfer of electrons to oxygen. As a prerequisite for a more advanced examination of the enzymatic properties, several amino acid residues, selected on the basis of recent three-dimensional structure determinations, were exchanged in subunit I of the Paracoccus enzyme by site-directed mutagenesis. The properties of the mutated oxidases were analyzed by different methods to elucidate whether they are involved in the coupled and coordinated transfer of protons via two different pathways either to the site of oxygen reduction or through the enzyme from the cytoplasm to the periplasmic side.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 43
    ISSN: 1572-9605
    Keywords: GdBa2Cu3O7−δ ; Ca substitution ; Mo substitution ; Hf substitution ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract The structural and superconducting properties of (Gd1−x−y Ca y M x )Ba2Cu3O z with M = Mo, Hf are investigated using X-ray diffraction, electrical resistivity, and oxygen content measurements. The effect of increasing the Mo concentration in (Gd1−x Mo x )Ba2Cu3O z changes the structure from orthorhombic to tetragonal accompanied by a large increase in resistivity and a fast decrease in T c at the rate of 1.9 K per at.% of Mo, unlike that of Hf substitution in (Gd1−x Hf x )Ba2Cu3O z , which maintains the orthorhombic structure and decreases T c very slowly at the rate of 0.6 K per atm.% of Hf with nearly no change in resistivity. The suppression of T c by M = Mo, Hf can be counterbalanced by hole doping by Ca which increases T c with increasing Ca content showing maximum compensation for Mo. A comparative study of M = Mo, Hf doped samples in (Gd1−x−y Ca y M x )Ba2Cu3O z indicates that the valence of the dopant M = Mo4+,6+, Hf4+ and its ionic radius play an important role in controlling the structural and superconducting properties of the systems.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 44
    Electronic Resource
    Electronic Resource
    Springer
    Journal of inclusion phenomena and macrocyclic chemistry 31 (1998), S. 357-365 
    ISSN: 1573-1111
    Keywords: calixarenes ; crystal structure ; supramolecular assembly
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract p-Benzylcalix[5]arene.3py (py = pyridine) (1) crystallizes in the triclinic space group P1, a = 10.641(3), b = 13.975(3), c = 24.052(12) Å, α = 94.60(4), β = 91.51(4), γ = 111.46(2)°, V = 3312(4) Å3, Z = 2. Refinement led to a final conventional R value of 0.065 for 5457 reflections. The calixarene is in a distorted cone conformation. Two pyridine molecules are hydrogen bonded to phenolic oxygen atoms and one of them is included in the hydrophobic cavity of the neighboring calixarene molecule along the a axis.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 45
    Electronic Resource
    Electronic Resource
    Springer
    Journal of inclusion phenomena and macrocyclic chemistry 30 (1998), S. 13-19 
    ISSN: 1573-1111
    Keywords: THF clathrate ; Schiff base macrocycle ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract A new clathrate inclusion compound of 2,3:11,12:20,21:29,30-tetrabenzo-1,13,16,19,31,34-hexaoxa-5,6,8,9,23,24,26,27- octaaza-7,25-dithioketone-2,3:4,5:9,10:11,12:22,23:27,28:29,30-cyclo-[36]ene([ 36]eneO6N8), which contains THF, has been prepared and crystallizes in the monoclinic space group P21/n with a = 9.829(5)Å, b = 24.23(1)Å, c = 10.181(9)Å, β = 92.93(5)-. Each unit cell contains two [36]ene-O6N8 molecules and four THF molecules. The [36]ene-O6N8 molecule lies on the crystallographic centre of symmetry and a pair of the THF molecules with half-chair conformation are located within rectangular channels formed by the macrocycle molecules.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...