Lattice-Dynamical Calculation of Second-Order Thermal Diffuse Scattering in Molecular Crystals

A computer procedure has been developed to calculate second-order thermal diffuse scattering (TDS) intensity for molecular crystals from latticedynamical calculations with an atom-atom potential in the Born-von K~irmfin formalism. It is applied to monoclinic phenothiazine and different contributions to second-order TDS intensity, acoustic-acoustic, acoustic-optic and optic-optic, are compared. Calculations are also performed in the long-wave approximation allowing for dispersion (LWD) and correction factors of Bragg intensities due to TDS contribution in the LWD approximation are, generally but not always, lower than lattice-dynamical ones; the ratio between LWD and 'exact' factors ranges from 0.4 to 1.4 for reflections considered

Structure of 1,3-Dihydro-4-[(2R)-2,5-dihydro-2-furyl]-3-phenyl-l-(p-tolyl)-2H-imidazole- 2-thione, C20HlsN2OS

Mr=334.4, orthorhombic, P212~2 ~, a= 9.366(4), b=20.616(5), c=9.137(4)A, V= 1764 (1) A 3, Z = 4, D x = 1.26 Mg m -3, 2(Mo Ka) = 0.7107 A, g = 0.18 mm -~, F(000) = 704, T= 300 K, final R--0.056 (wR =0.052) for 1979 observed reflections [I > 2a(/)]. The furanose ring is approximately planar because of the double bond, 1.289 (9) A, which affects the conformation of the ring. The dihedral angle between the furanose and imidazole least-squares planes is 69.9 (2) °. A possible C--H...O hydrogen bond has been detected involving C and O atoms in the furanose ring, giving infinite helical chains along [001 ]

Lattice Dynamical Calculation of First-Order Thermal Diffuse Scattering in Phenothiazine

A computer program has been developed to calculate first-order thermal diffuse scattering (TDS) intensity from eigenvectors and eigenvalues of the dynamical matrix obtained within the harmonic approximation with an atom-atom potential function and the external Born-yon Kfirmfin formalism. It is applied to monoclinic phenothiazine and correction factors of Bragg intensities due to TDS contribution are calculated and compared with the long-wave approximation. A Fourier difference synthesis is performed in order to reveal the influence of TDS contributions in electron density maps. A least-squares process is carried out to obtain the changes in structural parameters due to TDS contribution

Lattice Dynamics and Thermal Crystallographic Parameters in Phenothiazine

A computer program has been developed to study the lattice dynamics of molecular crystals in the harmonic approximation with the external Born-yon KS.rm~n formalism and an atom-atom potential function. Dispersion curves are obtained for monoclinic phenothiazine together with frequency distribution functions and external mode contribution to thermodynamic functions. Lattice dynamical T, L and S rigid-body tensors are obtained and individual thermal tensors are compared with experiment. The disagreement with respect to experimental results is of the same order as the disagreement with a Schomaker-Trueblood fit of experimental data

Structure of 4-(~-D-Erythrofuranosyl)-3-methyl- l-(p-tolyl)-4-imidazoline-2-thione Monohydrate, C 15H18N203S.H20

Mr=324.4, orthorhombic, P212t2 ~, a= 32.150(5), b=10.215(1), c=4.805(1)A, V= 1578.0 (4)/~3, Z = 4, D x = 1.36 Mg m -a, 2(Cu Ka) = 1.5418A, #=1.953mm -1, T=300K, final R= 0.050 for 1361 observed [I>2tr(I)] independent reflexions. The sugar ring adopts a conformation intermediate between envelope 2E and twist 2T forms. The orientation of the imidazoline ring with respect to the furanose is anti; the glycosidic angle is 24.6 (7) °. The crystal packing is due to hydrogen bonds involving the hydration water molecules

First- and Second-Order Thermal Diffuse Scattering (TDS) Intensity in Molecular Crystals: Influence on Crystal Structure Parameters

First- and second-order thermal diffuse scattering (TDS) intensities are calculated in the long-wave approximation allowing for dispersion (LWD) in monoclinic phenothiazine from polarization vectors and lattice-mode frequencies obtained from lattice dynamical calculations within the harmonic approximation and the external Born-von K~irmfin formalism using an atom-atom potential function in the form V(r) =-A/r6+ B exp (-Cr). The influence of firstand second-order TDS intensity on electronic density maps is analysed and compared. Least-squares refinements of positional and thermal parameters are carried out in different ranges of sin 0/A taking into account both first- and second-order TDS contributions and the results are discussed

Structure of l-(p-Ethoxyphenyl)-1,3-dihydro-3-phenyl-2H-benzimidazole-2-thione, C2IHlaN2OS

Mr=346-4, orthorhombic, P212121, a= 7.600(1), b= 11.132(2), c=20.767 (3)A, v= 1756.9(5)A 3, z=4, Dx=1.31Mgm -3, 2(CuKct) =.1.5418/k, /~= 1.67mm -1, F(000)=728, T= 300 K. Final R = 0.049 for 1531 observed independent reflections. The benzimid~zole bicycle is quasi-planar, the dihedral angle between the two fused rings being 1.6 (2) °. The unsubstituted phenyl ring is planar while the phenyl ring with the ethoxy substituent deviates significantly from the expected planar conformation

Structure and Absolute Configuration of 4-(a-D-Erythrofuranosyl)-1,3-dihydro-3-methyll-( p-tolyl)-2H-imidazole-2-thione, C 15 H18N2038

M r = 306.4, monoclinic, P21, a = 14.686 (6), b=5.359(4), c=9.439(3) A, fl=98.68(3) ° , V= 734.4 (7)/I,3, Z = 2, D x = 1.38 Mg m -3, 2(Mo Kct) = 0.7107 A, /t = 0-22 mm -1, F(000) = 324, T= 300 K, final R=0.042 (wR=0.037) for 1987 observed independent reflections. The sugar ring has a conformation intermediate between 3T 2 and 3E. The configuration of the imidazole ring with respect to the furanose ring is anti, the glycosidic angle being -9.3 (4) ° . The crystal packing is governed by hydrogen bonds involving OH groups and S atoms, forming infinite chains along [001]

Association of HLA-B*41:02 with Henoch-Schönlein Purpura (IgA Vasculitis) in Spanish individuals irrespective of the HLA-DRB1 status

INTRODUCTION: To determine whether the human leukocyte antigen (HLA) B alleles are implicated in the susceptibility to Henoch-Schönlein purpura (HSP) in the largest series of Caucasian HSP patients ever assessed for genetic studies. METHODS: The study population was composed of 349 Spanish patients diagnosed with HSP fulfilling the American College of Rheumatology and the Michel et al. classification criteria, and 335 sex and ethnically matched controls. HLA-B phenotypes were determined by sequencing-based typing (SBT) and analyzed by chi-square or Fisher exact test. RESULTS: A statistically significant increase of HLA-B*41:02 allele in HSP patients when compared with controls was found (8.3% versus 1.5% respectively; p = 0.0001; OR (odds ratio) =5.76 [2.15-19.3]). These results remained statistically significant after adjusting for Bonferroni correction (p = 0.0028). An internal validation also confirmed the susceptibility effect on HSP associated with HLA-B*41:02 (OR = 5.70 [1.98-16.44]). Since a former study described an association between HLA-DRB1*01:03 and HSP susceptibility, we also evaluated the implication of HLA-B*41:02 independently of HLA-DRB1*01:03. Interestingly, the association remained statistically significant (p = 0.0004, OR = 4.97 [1.8-16.9]). No HLA-B association with specific HSP clinical features was found. CONCLUSIONS: Our study indicates that HLA-B*41:02 is associated with the susceptibility to HSP in Spanish patients irrespective of HLA-DRB1 status