Space groupP212121 Witha Research Articles

A novel structure of secondary alcohol derived from (+)-Δ3-carene with pseudo three-fold symmetry

The crystal structure of C12OH20 (lR-6R-4R-2 R-3,7,7-trimethyl-4-(2-hydroxyethyl) bicyclo [4.1.0] hept-2-ene) has been determined by X-ray diffraction. The compound crystallizes in space group P212121 witha = 5.893(1),b = 22.572(2), c = 26.164(3) A,V = 3480.3 A3, Z= 12. The structure was solved by modified direct methods and refined to anR value of 0.081 for 607 unique reflections. Each asymmetric unit has three molecules which are held together through intermolecular hydrogen bonds resulting in a novel spiral-type arrangement of molecules. The six-membered ring has a half-chair conformation.

Molecular structure of 3-phenyl-5-methyl-4-isoxazolyl-penicillin sulfone (oxacillin sulfone): C19H19N3O8S

The crystal structure of oxacillin sulfone has been determined by single-crystal X-ray diffraction techniques and refined by full-matrix least squares. The penicillin molecule cocrystallizes with H2O in an orthorhombic space groupP212121 witha=10.303(7) A,b=26.735(17) A, andc=7.384(4) A. The calculated density is 1.526 g cm−3, with aZ value of 4. FinalR-factor is 0.035. The oxidation of the sulfur atom is discussed in terms ofS1 conformation of the penam moiety and in terms of hydrogen-bond formation between one oxygen of the sulfur atom and the amidic hydrogen of the C6 side-chain. A comparison with oxacillin and cloxacillin sulfoxide is also made.

Structure of the 1?1?1 complex between 1,4,7,10,13,16-hexaoxacyclooctadecane (18-crown-6), 2,3-dichlorophenol, and water

The structure of the title compound, C12H24O6·C6H4OCl2·H2O, has been determined by X-ray diffraction methods. The crystals are monoclinic, space groupP21 witha=8.628(2),b=13.767(4),c=9.676(2), β=96.38(2)°, andD x =1.295 Mg m−3 forZ=2; 2355 reflections were recorded on a CAD4 diffractometer using CuKα radiation atT=243° K. The structure was solved usingMultan andShelx. The finalR value based on 1901 reflections is 0.071. The 18-crown-6 molecule has approximatelyD3d symmetry. The host molecule (18-crown-6), the guest molecule (dichlorophenol), and water form a super-molecule. Binding between host and guest is effected by bridging water molecule: the water and dichlorophenol molecule are linked by a very strong hydrogen bond (O⋯O=2.58 A); weaker interactions exist between water and oxygens of the crown ether (O⋯O distances 2.85 and 2.90 A).

Crystal structure of tetramethylammoniuml-histidinatobis (thiocyanato) vanadyl (IV) monohydrate

The title compound, [(CH3)4N] [VO(l-His)(NCS)2]·H2O, has been prepared by the reaction of [(CH3)4N]4[VO(NCS)4]2·H2O with histidine in aqueous solution. The crystal is orthorhombic, space groupP212121 witha=9.839(6),b=11.835(5),c=17.366(6) A,Z=4. The structure was solved by direct methods and refined by full-matrix least-squares to anR of 0.073 for 1067 reflections. In the complex anion VO2+ was coordinated by two thiocyanate groups and al-histidine which functions as a tridentate chelate.

Crystal structure of the phenylacetylene-choleic acid

Deoxycholic acid (C24H40O4, M r =392.58) and phenylacetylene (C8H6, M r =102.14) form a 2:1 inclusion compound which crystallizes in space groupP212121 witha=25.542(6),b=13.662(5),c=7.227(2) A,Z=4. The finalR is 0.071 for 2168 observed reflections withI>1.5σ(I). The crystal packing is characterized by an assembly of antiparallel pleated bilayers of deoxycholic acid molecules which leave empty channels running alongc. Phenylacetylene molecules are accommodated within the cavities in an ordered fashion and are very probably arranged in only one orientation, which was determined by means of Van der Waals energy calculations. Atoms of deoxycholic acid belonging to ring A and to the side-chain are engaged in binding interactions with the guest molecule. The arrangement of the guest molecules supports the experimental results of γ irradiation, which show a failure of the phenylacetylene molecules to undergo inclusion polymerization.

Crystal and molecular structure of hydroxyjatrophone C

The structure of the title compound has been established by means of the x-ray diffraction method on a single crystal. The crystals are othorhombic, space groupP212121 (No. 19) witha=10.222(4),b=10.622(2),c=16.434(3) A,z=4. Full-matrix least squares refinement led toR=4.9%. The molecular stereochemistry, bond distances, bond angles, torsion angles, and hydrogen bond scheme have all been determined.

The x-ray crystal and molecular structure of glechomafuran

The X-ray crystal structure of glechomafuran (1β,10α,4α,5β-diepoxy-7,8-furanogermacrane), a natural product obtained from seeds ofSmyrnium olusatrum L., has been determined in order to establish the correct relative configuration of the molecule. Crystals are monoclinic, space groupP21 witha=6.785(4),b=12.325(9),c=16.390(6) A,β=97.89(4)°, and four molecules in the unit cell. The two epoxides are found to be α,β-attached, and the associated methyl groups are positionedsyn to each other. The furan ring is essentially flat, and shows no evidence of any double bond delocalization.

The structure of bis[(o-hydroxyphenoxy)ethoxy]ethane monohydrate

The title compound (C18H22O6·H2O) crystallizes in space groupP212121 witha=25.909(5),b=8.542(3),c=8.187(3) A,Z=4. The structure was determined from 1538 X-ray diffractometer data and refined toR=8.05%. The polyether adopts an annular structure with the water molecule at the center, and is slightly folded like the wings of a butterfly. As usual, all torsion angles about C−O aretrans and about C−C aregauche. This complex displays 3 three-center (bifurcated) and 1 two-center hydrogen bonds, between phenolic hydroxyl and water oxygen. The latter is involved in an infinite homodromic chain O(1)−H...OW−H...O(1)−H...

Crystal structure of the 2:1 inclusion compound between deoxycholic acid and quadricyclane

The 2:1 inclusion compound formed between deoxycholic acid (C24H40O4,Mr=392.58) and quadricyclane (C7H8,Mr=92.14) crystallizes in space groupP212121 witha=27.150(7),b=13.359(3),c=14.161(4) A,Z=4. The structure was refined toR=0.086 andRw=0.088 for 2079 observed reflections withI>2.5σ(I). The crystal packing is very similar to that found in the norbornadiene-deoxycholic acid inclusion compound and is characterized by an assembly of antiparallel pleated bilayers, formed by molecules of deoxycholic acid held together through hydrogen bonds. Quadricyclane occupies approximately the same position of norbornadiene and its atoms give rise to good van der Waals interactions with some methyl groups of deoxycholic acid.

Conformational analysis of 13-hydroxy-α-isolupanine epimers

13α-Hydroxy-α-isolupanine (I) and 13β-hydroxy-α-isolupanine (II) crystallize in the space groupP212121 witha=13.123(2),b=13.221(3),c=8.224(1) A,Z=4 anda=9.745(2),b=11.383(1),c=12.710(2) A,Z=4, respectively. Structural differences between the epimeric molecules are concentrated around ringA. In (I) ringA has a half-chair conformation, and in (II) it is a distorted sofa. TheA/B ring junction configuration isquasi-trans in the case of (I) andquasi-cis in (II). The above differences can be explained by the different intermolecular interactions observed in these two structures.

Crystal and molecular structures of the 3?-acetoxy and 3?-benzoxy derivatives of ?-amyrin

Crystals of the 3β-acetoxy derivative of α-amyrin are monoclinic, space groupP21 witha = 8.021(1),b = 11.474(1),c = 15.564(2) A, and β = 100.496(3) °. Crystals of the 3β-benzoxy derivative are orthorhombic, space groupP212121, witha = 6.752(1),b = 12.974(1), andc = 36.664(3) A. Both structures have been solved by direct methods and refined by full-matrix least-squares, using data collected on an automated four-circle diffractometer. The final residuals for the acetoxy and benzoxy structures are 0.055 (2274 significant independent reflections) and 0.152 (1220 significant independent reflections) respectively. The geometry of the α-amyrin skeleton in both structures is similar to that found in other triterpene structures containing a system of five condensed six-membered rings. RingC has a C(8)β-sofa conformation due to the presence of the double bond at C(12)-C(13) whereas in the remaining rings thechair conformation predominates.

Conformation of uncomplexed natural antamanide crystallized from CH 3 CN/H 2 O

Natural antamanide, a cyclic decapeptide from Amanita phalloides, has been shown to have the same conformation for the backbone and comparable side groups as the biologically active synthetic [Phe(4), Val(6)]antamanide. Packing in the crystal is quite different for the two compounds. Large channels with a polar lining are formed in the crystals of [Phe(4), Val(6)]antamanide, whereas in natural antamanide large channels in the crystal are completely surrounded by the lipophilic side groups of the Pro, Phe, and Ala residues. Antamanide, C(64)H(78)N(10)O(10).8H(2)O.X, crystallizes in space group P2(1)2(1)2(1) with a = 15.88 A, b = 34.88 A, and c = 13.61 A.

Crystal and molecular structure of pisatin

(+)-Pisatin, C17H14O6, a lipophilic substance with antifungal activity, has been isolated fromPisum sativum L. following fungal inoculation. Orthorhombic crystals of the monohydrate belong to the space groupP212121 witha = 6.910(3),b = 9.006(2),c = 24.253(4) A, andZ = 4. The structure was solved by direct methods from diffractometer data measured with CuKα radiation. Refinement with anisotropic temperature factors given to the non-hydrogen atoms converged atR = 0.058 for the 1255 observed terms. The molecular conformation is similar to the conformation recently reported for phaseollin, a related phytoalexin. Hydrogen bonds involving the water and pisatin molecules link the latter into infinite spirals extending alongb.

Nucleic acid conformation: Crystal and molecular structure of deoxyguanosine (5′) phosphate (disodium salt)—Agauche-trans (gt) conformation about the C(4′)-C(5′) bond and O(1′) puckering of the furanose ring

The crystal structure of deoxyguanosine (5′) phosphate, disodium salt, (5′-dGMP Na2 4H2O) has been determined from three dimensional single crystal x-ray data collected by multiple film, equi-inclination, Weissenberg method using CuKa radiation. The crystal belongs to the monoclinic space groupP21 witha=16.002±0.003 A,b=10.730±0.003 A,c=5.575±0.005 A andβ=101.9°. The structure was solved by symbolic addition method using the program Multan, the reliability index being 0.090. The guanine base is in the usualanti conformation about the C (1′)-N (9) bond withxCN=52.3°. The structure shows two unique conformational features not observed in any nucleotide structure reported so far. The deoxyribose moiety shows O (1′)endo puckering with respect to the best four atom plane defined by C(1′)-C(2′)-C(3′)-C(4′). The conformation about the C(4′)-C(5′) bond isgauche-trans with o00=62.5° and ooc=174.8°. This is the first nucleotide structure where agt conformer similar to that found in the Watson-Crick double helical DNA model has been experimentally observed. These two conformational features have also direct relevance to the concept of ‘a conformationally rigid nucleotide unit’ developed by Sundaralingam. The nine membered guanine ring is essentially planar. Bases of molecules related by a ‘c’ cell translation tend to overlap, the shortest distance being 3.51 A between the atoms N (3) and C(8). One of the sodium atoms Na(1) has an octahedral coordination with four water oxygens and O(6) and O(3′) atoms occupying the corners at distances ranging from 2.35 A to 2.55 A.

Crystal and molecular structure of bicuculline

The crystal and molecular structure of the phthalide isoquinoline alkaloid bicuculline, C20H17NO6, has been determined by X-ray diffraction methods. The compound crystallizes in the orthorhombic space groupP212121 (No. 19) witha = 14·49,b = 10·90 andc = 10·43 A. The atomic parameters were refined by least squares to give a conventionalR-factor of 0·0437 for 1557 symmetry independent reflections.

The structure of vitamin B 12 - VII. The X-ray analysis of the vitamin B 12 coenzyme

The three-dimensional molecular structure of coenzyme B 12 (5'-deoxyadenosylcobalamin) has been determined by X-ray diffraction. The crystals, as grown from an acetone-water solution and photographed wet, are orthorhombic (space group P 2 1 2 1 2 1 ) with a = 27·93, b = 21·73 and c = 15·34 Å. Four coenzyme molecules (C 72 H 100 O 17 N 18 PCo) and about 68 water molecules make up the unit cell. 3068 Bragg reflexions, extending to a spacing of 0·9 Å, were measured with the crystals in contact with their mother liquor. The intensities were estimated visually from Weissenberg films taken with Cu Kα radiation. The cobalt atoms were easily located from the Patterson synthesis. The structure was solved in three steps, using first cobalt alone, then cobalt and 53 light atoms, and in the third approximation, 106 atoms, which included nearly the full asymmetric unit, except for water and hydrogen. Refinement of the atomic coordinates was accomplished initially by calculation of difference syntheses and finally by differential synthesis. The atomic positions have standard deviations of about 0·04 Å. The conformation of the molecule is very similar to cyanocobalamin. The principal differences are in the orientation of the acetamide and propionamide side chains. Factors which influence the conformation of the corrin nucleus are analysed by comparing several corrinoids of known structure. Features of the molecule which have been examined in detail include the pucker in the pyrroline rings, the bend in the corrin macrocycle, the conformation of the nucleotide and nucleoside moieties and the orientation of the deoxyadenosine moiety with respect to the corrin nucleus. The packing of the molecules and the hydrogen bonding is discussed and compared with that found in the wet and dry vitamin B 12 crystals. Each coenzyme molecule participates in 18 direct intermolecular hydrogen bonds.