(2Z)-2-Benzylidene-4-octadecyl-3,4-dihydro-2H-1,4-benzothiazin-3-one

The octadecyl chain in the title compound, C33H47NOS, is in the `fully extended' conformation. A puckering analysis of the thiazine ring was performed. The molecules form micellar blocks in the crystal by intercalation of the extended octadecyl chains and association of the dihydro benzothiazine units through C—H...O hydrogen bonds. These blocks are associated through intercalation of the pendant phenyl groups which reside on the outer edges of each block.

Comparison of the crystal structures of methyl 4-bromo-2-(methoxymethoxy)benzoate and 4-bromo-3-(methoxymethoxy)benzoic acid

The title compounds, C10H11BrO4, (I), and C9H9BrO4, (II), are derivatives of bromo–hydroxy–benzoic acids. Compound (II) crystallizes with two independent molecules (AandB) in the asymmetric unit. In both (I) and (II), the O—CH2—O—CH3side chain is not in its fully extended conformation; the O—C—O—C torsion angle is 67.3 (3) ° in (I), and −65.8 (3) and −74.1 (3)° in moleculesAandB, respectively, in compound (II). In the crystal of (I), molecules are linked by C—H...O hydrogen bonds, formingC(5) chains along [010]. The chains are linked by short Br...O contacts [3.047 (2) Å], forming sheets parallel to thebcplane. The sheets are linkedviaC—H...π interactions, forming a three-dimensional architecture. In the crystal of (II), moleculesAandBare linked to formR22(8) dimersviatwo strong O—H...O hydrogen bonds. These dimers are linked into ...A–B...A–B...A–B... [C22(15)] chains along [011] by C—H...O hydrogen bonds. The chains are linked by slipped parallel π–π interactions [inter-centroid distances = 3.6787 (18) and 3.8431 (17) Å], leading to the formation of slabs parallel to thebcplane.

Characterizing the denatured state ensemble of ubiquitin under native conditions using replica exchange molecular dynamics

The representative structures of the denatured state ensemble of ubiquitin under a native condition and heat-denatured ubiquitin simulated from a fully extended conformation.

Crystal structures of eight mono-methyl alkanes (C26–C32)viasingle-crystal and powder diffraction and DFT-D optimization

The crystal structures of eight mono-methyl alkanes have been determined from single-crystal or high-resolution powder X-ray diffraction using synchrotron radiation. Mono-methyl alkanes can be found on the cuticles of insects and are believed to act as recognition pheromones in some social species,e.g.ants, waspsetc. The molecules were synthesized as pureSenantiomers and are (S)-9-methylpentacosane, C26H54; (S)-9-methylheptacosane and (S)-11-methylheptacosane, C28H58; (S)-7-methylnonacosane, (S)-9-methylnonacosane, (S)-11-methylnonacosane and (S)-13-methylnonacosane, C30H62; and (S)-9-methylhentriacontane, C32H66.All crystallize in space groupP21. Depending on the position of the methyl group on the carbon chain, two packing schemes are observed, in which the molecules pack together hexagonally as linear rods with terminal and side methyl groups clustering to form distinct motifs. Carbon-chain torsion angles deviate by less than 10° from the fully extended conformation, but with one packing form showing greater curvature than the other near the position of the methyl side group. The crystal structures are optimized by dispersion-corrected DFT calculations, because of the difficulties in refining accurate structural parameters from powder diffraction data from relatively poorly crystalline materials.

Crystal structure of ethyl (6-hydroxy-1-benzofuran-3-yl)acetate sesquihydrate

In the title hydrate, C12H12O4·1.5H2O, one of the water molecules in the asymmetric unit is located on a twofold rotation axis. The molecule of the benzofuran derivative is essentially planar (r.m.s. deviation for the non-H atoms = 0.021 Å), with the ester group adopting a fully extended conformation. In the crystal, O—H...O hydrogen bonds between the water molecules and the hydroxy groups generate a centrosymmetricR66(12) ring motif. TheseR66(12) rings are fused, forming a one-dimensional motif extending along thec-axis direction.

X-ray studies on crystalline complexes involving amino acids and peptides. XXXVIII. Crystal structures of the complexes of L-arginine and L-histidine with glutaric acid and a comparative study of amino acid–glutaric acid complexes

The complexes of glutaric acid with L-arginine and L-histidine (two crystal forms) exhibit different stoichiometries and ionization states. The aggregation patterns in two of the crystals are remarkably similar to those observed earlier in similar structures, while the pattern in the remaining one has not been seen earlier. The variability in the ionization state and stoichiometry observed in amino acid–dicarboxylic acid complexes appears to represent subtle differences in the response of a molecule to the presence in its neighbourhood of another type of molecule. The glutaric acid molecules (or glutarate or semiglutarate ions) in their complexes and in other crystals favour a fully extended conformation, albeit with frequent departures from it. The change in the chirality of the component molecules in the complex could lead to drastic changes in the aggregation pattern; alternatively, the effects of the change are accommodated through small adjustments in essentially the same pattern.