30 1995 5 1 629-636 Refined Crystal and Molecular Structure of Andrographolide -Diterpene A refined crystal structure of andrographolide has been obtained by X-ray anaysis using CuKa radiation. It crystallizes in the monoclinic crystal system with unique b-axis in space group P2,. The unit cell parameters are a = 6.552(2)8,, b = 8.009(1)& c = 17.989(1)8, and interaxial angle p = 97.32(1)". The structure has been solved by direct methods and was refined up to R = 0.041, wR = 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.
C12H17SO3N, Mr = 255.33, Orthorhombic, P212121, a = 11.703(1) Å, b = 14.797(3) Å, c = 14.971(2) Å, V = 2592.52 Å3, Z = 8, Dm = 1.309 Mgm−3, Dc = 1.308 Mgm−3, mμ = 21.57 cm−1, F(000) = 1088, T = 290 K, final R = 0.080 for 2416 unique reflections. There are two crystallographically independent molecules in the unit cell of the title compound.
IntroductionThe present study is part of series of structural studies on compounds with pharmacological activity. The compound is used for producing different degrees of depression for the central nervous system ranging from mild sedation to general anaethesia. The compound possesses anticonvulsant activity and is used for slightly decreasing the blood pressure, heart rate during the normal sleep. Single crystals of the compound were prepared by the reaction between barbituric acid, ethanol, and ammonium hydroxide. An X-ray analysis was carried out to establish the stereochemistry, to confirm geometry around C(3) atom and the chemical structure. ExperimentalA crystal of dimensions 2.8 x 2.2 x 4.5 mm was used for data collection on an automatic Enraf Nonius four circle CAD4 diffractometer using monochromatized CuKa radiation. The unit cell parameters were obtained by least squares treatment of 25 high angle reflections, which were individually centered on the diffractometer. Intensity data were collected with w -20 scan mode. The intensities of three standard reflections (801, 921, 870) were monitored after every 63 reflections during the data collection to check the crystal stability. The crystal data do not show any crystal deterioration. This confirmed that the crystal is stable to X-rays. 1410 reflections were recorded over the range of indices 0 5 h 5 32, 0 5 k 5 32, 0 5 1 5 7 of which 1341 with Kin, = 0.0183 were unique reflections. 1205 reflections with I 2 341) were obtained and used in calculations.The data were corrected for Lorentz polarisation and semi-empirical absorption effects but not for extinction effects.The crystallographic data are summarised in Table 1 (see next page). Structure determination and refinementThe structure was solved using the SHELXS86 (SHELDRICK 1986) program and refined by the use of SHELX76 (SHELDRICK 1976 and anisotropically R = 0.09. All the hydrogen atoms were affixed geometrically and not refined further. The inclusion of the affixed hydrogen atoms in the model refinement with their positional and isotropic temperature factors with the use of unit weights gave the final value of R = 0.080. Scattering Factors were contained in SHELX76 itself. PARST (NARDELLI) was used for geometrical calculations. All calculations were carried out on a Vax V.M.S computer. DiscussionThe fractional coordinates and equivalent isotropic temperature factors for the compound with non-hydrogen atoms for two independent molecules are presented in Table 2. Bond distances and bond angles for non-hydrogen atoms with e.s.d's in parentheses are given in .5174(1) .5830( 1) .5233( 1) .6171 (0) 4.7(4) 5.0(4) 4.0(3) 3.2(4) 3.9(4) 3.2(4) 3.9(4) 3.1(3) 3.0(4) 4 3 5 ) 6.5(7) 5.1(6) 5.0 (5) 4.6(4) 6.6(6) 4.0(3) 2.914) 3.6(4) 4.2(5) 3.9(4) 3.4(4) 5.3(6) 7.4(8) 4.9(6) 9.0(9) 3.4(4) B,, = 1/3 Bija:afo,aj L J
The compound crystallizes in the monoclinic crystal system with the space group P2,, having cell parameters u = 8.533 (2) A, b = 10.388(2) A, c = 6.195(2) A, B = 92.17(1)". The structure has been solved by direct methods and refined upto R = 0.076. The six membered cyclo hexane ring is in chair conformation with maximum deviation 0.2296 8, for the C(1) atom. The molecules are held together by hydrogen bonding.* All communications to be sent.
The crystal structure of trichloro benzyl methyl carbinyl acetate has been determined by X‐ray analysis. The compound crystallises in the monoclinic crystal system with the space group P21/a, with cell parameters a = 12.821(1) Å, b = 7.735(2) Å, c = 13.304(2) Å, β = 1117.15(1)°. The structure has been solved by direct methods and refined up to R = 0.064. The six membered benzene ring is planar with maximum deviation 0.0048 Å for the C(3) atom. The molecules are held together by van der Waals interactions.
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