7,385 research outputs found

    O-H...O, C-H...O and C-H...[pi]arene intermolecular interactions in (2S)-2-(1-oxo-1H-2,3-dihydroisoindol-2-yl)pentanoic acid and (2S)-3-methyl-2-(1-oxo-1H-2,3-dihydroisoindol-2-yl)butanoic acid

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    In the first of the title compounds, (2S)-2-(1-oxo-1H-2,3-dihydroisoindol-2-yl)pentanoic acid, C₁₃H₁₅NO₃, prepared from L-norvaline, a hydrogen-bonded network is formed in the solid state through O-H...O=C, C-H...O=C and C-H...πarene intermolecular interactions, with shortest O...O, C...O and C...centroid distances of 2.582 (13), 3.231 (11) and 3.466 (3) Å, respectively. In the L-valine derivative, (2S)-3-methyl-2-(1-oxo-1H-2,3-dihydroisoindol-2-yl)butanoic acid, C₁₃H₁₅NO₃, O-H...O=C and Carene-H...O=C intermolecular interactions generate a cyclic R²₂(9) motif through cooperativity, with shortest O...O and C...O distances of 2.634 (3) and 3.529 (5) Å, respectively. Methylene C-H...O=Cindole interactions complete the hydrogen bonding, with C...O distances ranging from 3.283 (4) to 3.477 (4) Å

    Entry point into new trimeric and tetrameric imide-based macrocyclic esters derived from isophthaloyl dichloride and methyl 6-aminonicotinate

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    The one-step reaction of isophthaloyl dichloride with the 2-aminopyridine derivative (methyl 6-aminonicotinate) yields (i) a trimer-based macrocycle (EsIO)3 and (ii) a tetramer-based macrocycle (EsIO)4 in modest isolated synthetic yields (total of 25%), together with (iii) longer open-chain oligomers. The macrocyclisation relies on the semi-flexible imide hinge formed by reaction of the 2-amino(pyridine) functional group with two acyl chloride functional groups. The determining factors in macrocycle synthesis are (a) imide formation using the heteroaromatic ortho-N functionality; (b) the inherent ability of the imide to twist by 85-115 degrees from planarity (as measured by the CO...CO imide torsion angles and from computational calculations), thereby providing a hinge for macrocyclic ring closure or potentially (non)helical assembly in oligomer/polymer formation and (c) the conformational flexibility of the isophthaloyl group with meta-related carbonyl groups to twist and adopt either syn- or anti-conformations, although the syn-conformation is observed structurally for all isophthaloyl groups in both (EsIO)3 and (EsIO)4 macrocycles

    (2RS)-3-(4-Hydroxyphenyl)-2-(1-oxo-1H-2,3-dihydroisoindol-2-yl)propanoic acid monohydrate

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    The title compound, C₁₇H₁₅NO₄·H₂O, derived from DL-tyrosine crystallizes as an unusual hydrogen-bonded acid-monohydrate dimer. The asymmetric unit contains two organic molecules and two water molecules. Dimers link through (aryl)O-H...O=C hydrogen bonds along the [101] direction, forming a one-dimensional chain of rings, and further associated via inversion centres (forming a chain of rings aligned in the opposite direction) generating columns. Ruffled sheets arise from interlocking of isoindole rings via π-π(arene) stacking and C-H...π(arene) interactions; C-H...O interactions generate a three-dimensional network

    Structural systematic studies and conformational analyses of a 3x3 isomer grid of fluoro-N-(pyridyl)benzamides; physicochemical correlations, polymorphism and isomorphous relationships

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    The effect of fluorine and pyridine N atom substitution patterns on molecular structure and conformation is probed in a 3 3 isomer grid (Scheme 1) of fluoro-N-(pyridyl)benzamides (Fxx) (C12H9N2OF, x = para-/meta-/ortho-) to evaluate and correlate structural relationships between the solid-state and ab initio calculations. Physicochemical comparisons are analysed with an extended series of three related 3 x 3 isomer grids. Our analysis integrates crystal structure analyses, computational chemistry and conformational analyses together with NMR data and physicochemical trends such as melting point analysis. This study concludes structural systematics survey of four fluoro/methyl substituted benzamide/pyridinecarboxamide isomer grids

    (2S)-4-Methyl-2-(1-oxo-1H-2,3-dihydroisoindol- 2-yl)pentanoic acid.

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    The title compound, C14H17NO3, exhibits carboxylic acid group disorder about the C—CO2 axis, with site occupancies of 0.79 (5):0.21 (5). Molecules are linked by intermolecular O—H O Ciso, C—H O Ciso and C—H (arene) interactions (iso = isoindolinone)

    3-Fluoro-N-(3-fluorobenzoyl)-N-(2-pyridyl)benzamide

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    The title compound, C19H12F2N2O2, a 2:1 product of the reaction of 3-fluorobenzoylchloride and 2-aminopyridine crystallizes with a disordered 3-fluorobenzene ring adopting two conformations [ratio of occupancies 0.959 (4):0.041 (4)]. In the crystal structure, there are no classical hydrogen bonds and interactions comprise C-H...O in the form 2(C-H)...O=C [with motif R21(5)]; C-H...[pi](arene) interactions are also present

    The Commission, the Community Method, and the Smaller Member States

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    This Article discusses several developments concerning the position of the Commission in the institutional structures of the European Union ( EU ) that have occurred since then. It does not touch on the many other matters that influenced the debate on the draft Constitutional Treaty, leading to its failure at referendum in France and the Netherlands; these matters include the scope of the draft Treaty, questions concerning its economic, social, and political benefits or disadvantages, the working of the Stability Pact in the Eurozone and the ongoing debate on freedom of services legislation, the purposes for which the EU was originally created and their modification, further enlargement of the EU, and so on. These subjects require separate treatment

    Variability of developmental timings of the knee in young American children as assessed through Pyle and Hoerr's radiographic atlas

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    This study examines the accuracy of the Pyle and Hoerr radiographic atlas technique in an effort to document the extent of normal variation associated with developmental timings in the knee for purposes of age estimation. The atlas has been previously tested; however, accuracy rates were produced from a dataset, which spread in age from mostly 7–16 years. This study took a closer look at the younger age groups, examining radiographs from 297 children (147 female and 150 male) from birth to 6 years. Standard deviations representing the difference between the skeletal and chronological age were calculated according to two groupings. Each group represents episodes, or time periods, of differential developmental rates as expressed through the number of plates within the atlas dedicated to documenting each year of life. The beginning year of life is characterized by the most rapid of development as represented by the numerous image plates used to depict this time period. Individuals assigned to plates with a skeletal age between birth and 1 year were grouped collectively to document the variation associated with such rapidly changing morphology (SD = 2.5 months in female children; 2.3 months in male children). Years 1–3.8 years (female) and 1–4.5 years (male) were represented by two or three images within the atlas, and therefore, individuals assigned to plates with a skeletal age falling within this range were placed within a second grouping (SD = 5.2 months in female children; 7.0 months in male children). As expected, variation was observed to decrease as developmental processes accelerated in the younger children. The newly calculated standard deviations offer tighter predictions for estimating age in young children while at the same time maintaining an acceptable width that accounts for normal variation in developmental timings.</p
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