The Crystal and Molecular Structure of 11,12‐dibromo‐ 7,8—benzo‐1,5‐di(p—tolylsulphonyl)‐1,5‐diazacyclononan

The crystal structure of the title compound, C₂₅H₂₆Br₂N₂O₄S₂ was determined by single crystal X‐ray diffraction technique. The crystals are monoclinic, space group C 2/c, with a=20.7142(2) Å b=11.7910(2) Å, c= 10.6735(3) Å, β=98.549(2)°, V=2577.94(9) ų, Z=4. The structure was solved by direct methods and refined by least‐squares methods to a final R=0.046 for 1866 observed reflections with I>2sigma(I). The title compound, displays disordered geometry around the C1 atom located almost on twofold axis. The nine‐membered heterocylic ring is close to the half‐chair conformation. The dihedral angle between phenyl rings is 34.2(1)°.     

Crystal Structure of N-methyl Crotananinium Iodide — A Pyrrolizidine Alkaloid

The crystal structure of N-methyl crotananinium iodide has been determined by X-ray structure analysis. The compound crystallizes in the orthorhombic space group P2₁2₁2₁ with cell parameters a = 19.37(2), b = 7.70(2), c = 13.38(2) Å. The structure has been solved by Patterson and successive Fourier methods and refined by full matrix least-squares methods to an R-index of 0.075. The structural features of the title compound are noted and are compared with those of similar others of such pyrrolizidine alkaloids.     

Refined Crystal and Molecular Structure of Andrographolide — Diterpene

A refined crystal structure of andrographolide has been obtained by X-ray anaysis using CuKα radiation. It crystallizes in the monoclinic crystal system with unique b-axis in space group P2₁. The unit cell parameters are a = 6.552(2) Å, b = 8.009(1) Å, c = 17.989(1) Å and interaxial angle β = 97.32(1)°. The structure has been solved by direct methods and was refined up to R = 0.041, ωR = 0.0464. Both the cyclohexane rings are in chair conformation with the furan ring in twist conformation. The crystal structure is stabilized by hydrogen bonding.     

Crystal and Molecular Structure of Diterpenoid Alkaloid 3-Acetylaconitine

Abstract  3-Acetylaconitine (1), C₃₆H₄₉NO₁₂, was isolated from the ammonium hydroxide wetted root of A. szechenyianum Gay. X-ray diffraction analysis demonstrated that it consists of four-six-membered rings A, B, C, D and two-five-membered rings E, F. The fused-ring system A, B, C and D are in chair, chair, chair and boat conformations, respectively; ring E is in a half-chair; and ring F is in an envelope confirmation. The crystal of 3-acetylaconitine is in orthorhombic crystal system with space group P2₁2₁2₁, lattice constants: a = 9.2002(8) ?, b = 11.06454(9) ?, and c = 33.072(3) ?, V = 3543.3(5) ?³, Z = 4. Index Abstract  3-Acetylaconitine, C₃₆H₄₉NO₁₂, was isolated from the ammonium hydroxide wetted root of A. szechenyianum Gay, and its crystal and molecular structure was determined by X-ray diffraction analysis.      

Crystal Structure of 5,6‐Dinitrobenzimidazole.monohydrate

The title compound (C₇H₆N₄O₅) crystallizes in the monoclinic space group P2₁/c with a=8.566(1) Å, b=14.493(3) Å, c=7.583(1) Å, β=87.75(1)°, V=940.7(3) ų, Z=4, D_x=1.597 g.cm^‐3. The structure was solved by direct methods and refined by full‐matrix least‐squares method (R=0.0696). The title compound consists of an imidazole ring with the two NO₂ groups and one water molecule. The short inter‐ molecular N‐H^…N [2.03(5) Å] and O_water‐H^…O [1.98(5) Å] hydrogen bonds are highly effective in holding the molecule in a stable state as a whole.     

The Molecular and Crystal Structure of 3β-O-(2′,3′ -O-isoropylidene-α-L-rhamnopyranosyl) — digitoxigenin

3β-O-(2′,3′ -O-isoropylidene-α-L-rhamnopyranosyl) — digitoxigenin crystallizes in the monoclinic space group P 2₁ with two molecules C₃₂H₄₈O₈ per unit cell and the lattice constants a = 7.865, b = 6.470, c = 29.803 Å, β = 93.95°. The structure was solved by direct methods of phases determination and subsequently refined by least squares technique to the final R-value 0.06. The position of the lactone ring is disordered in the crystal.     

Crystal Structure of 2‐methyl cinnamanilide and 2‐methoxy cinnamanilide

The crystal structures of two cinnamanilide derivatives 2‐methyl cinnamanilide (C₁₆ H₁₅ N O – compound I) and 2‐methoxy cinnamanilide (C₁₆ H₁₅ N O₂ – compound II) are reported. In both crystal structures, the cinnamamide group is almost planar. The inter‐planar angle between the two phenyl rings are 71.6(1)° for compound I and 7.5(1)° for compound II. The N‐H…O and C‐H…O type of hydrogen bond interactions between the amide group and the carbonyl group stabilizes the molecular packing as chains in the crystal lattice.     

The Crystal and Molecular Structure of tert‐Butoxycarbonyl ‐ α‐aminoisobutyryl ‐ isoleucyl ‐methylester

The crystal structure of the synthetic peptide Boc — Aib — Ile ‐ OMe (C₁₆ H₃ 0 N₂ O₅ ) has been determined from three‐dimensional X — ray diffraction data. The peptide crystallizes in triclinic space group P1 with a = 9.570(9), b = 10.261(7), c = 10.610(2) Å , α = 101.9(0), β = 91.7(0), γ = 98.6(0)° V = 1006.1(12) ų, Z = 2, D_calc = 1.09 Mg m^‐3. The structure was solved by direct methods and refined by full‐matrix least‐squares method to an R value of 0.072 (λ = 1.5418Å). The conformation of Aib residue in molecule A is αL and in molecule B is αR. The Ile residue in molecule A adopts folded conformation, while in molecule B it is in the extended region. The peptide units are trans and show significant deviations from planarity.     

Crystal Structure of Rabdoternin A

Abstract  

Rabdoternin A is a natural diterpenoid isolated from Rabdosia rubescen and its crystal structure was determined by X-ray single crystal diffraction. The compound compactly packs in an orthorhombic unit cell in the P2₁2₁2₁ space group with unit cell dimensions a = 7.9200(10) ?, b = 11.2411(14) ?, c = 20.474(2) ?, V = 1822.8(4) ?³ and Z = 4. Two intermolecular hydrogen bonds assemble the title compound into infinite two-dimensional networks along (001) plane.     

Crystal structure of a daturalactone – A withanolide

The crystal structure of a daturalactone derivative has been determined by X-ray structural analysis. The compound crystallizes in orthorhomic space group P2₁2₁2₁ with cell parameters a - 15.141(1) Å, b - 18.425(1) Å, c - 19.251(2) Å. The structure was solved by direct methods and refined to R - 0.082. The asymmetric unit contains two non-equivalent molecules. Extensive hydrogen bonding is present. The conformations of the rings are A: a distorted half-chair, B: a perfect half-chair, C: a chair, D: an envelope-half chair and E: a twist boat. Ring junctions A/B, B/C, C/D are all trans fused. Methyl carbons C(18), C(19), C(27) and the lactone moiety is β-oriented whereas the methyl carbons C(21) and C(28) are α-oriented.     

Static fatigue in glass — A reappraisal

The delayed failure of soda-lime glass was tested after different surface and heat treatments and at different humidities. It was found that the treatment history of the glass strongly influenced the characteristics times of failure and the effect of humidity on these times. However, the functional dependence of log failure time on relative stress was similar for most treatments. Analysis of the distributions of failure times at particular stresses showed that the log failure time was not linear with applied stress, as often assumed. The experimental data fit better inverse proportionality between log time and relative stress. Analysis of previous data on crack propagation (‘K - ν curves’) in glass also showed this proportionality. Some theoretical reasons for these results are examined.     

Bulk modulus — volume — ionicity relationship in tetrahedrally bonded semiconductors

It is shown that the bulk modulus of all diamond, zincblende and wurtzite structure compounds can be evaluated by means of the simple relation B = b₀a^−m(1 – g₀f_i) where a is the lattice parameter, f_i the spectroscopically defined bond ionicity and b₀, m and g₀ are constants having the same values for all compounds. This bulk modulus relation is used to estimate the bulk moduli for those zincblende and wurtzite structure compounds for which no experimental measurements have been made until now.     

Crystal and molecular structure of 14-desoxy-14ß-azido-digitoxigenin-3-acetate

The crystal and molecular structure of 14-desoxy-14ß-azido-digitoxigenin-3-acetate was determined by X-ray analysis. The compound crystallizes in the orthorhombic space group P 2₁2₁2₁ with four molecules C₂₅H₃₅N₃O₄ in the unit cell. The lattice parameters are a = 8.975, b = 13.698, and c = 18.958 Å. The structure was solved by direct methods and refined by least-squares procedures up to the discrepancy factor R = 0.041.     

Orthorhombic Polymorph of ErP5O14, Crystal Structure and Characterization

Erbium pentaphosphate crystals have been characterized and the structure of the orthorhombic polymorph (type III) determined by X-rays. It has been found that the orthorhombic samples of ErP₅O₁₄, space group Pnma, crystallize mainly at higher temperatures and usually are much larger than monoclinic crystals, space group C2/c, obtained from lower-temperature crystallizations. Differences in fluorescence and upconversion properties between orthorhombic and monoclinic polymorphs have been detected.