Anhydrous DL-Glutamic Acid

Dunitz, J.D.; Schweizer, W. B.

doi:10.1107/s0108270195001648

Cited by 14 publications

(13 citation statements)

References 2 publications

(2 reference statements)

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“…There are well‐documented cases in which the conformations of enantiomers are influenced by crystal packing forces. Structures of enantiopure and racemic amino acids have provided several interesting examples 8. Structures of (+)‐ and (±)‐ketopinic acids revealed a total of eight conformationally distinct contributors to the two structures, and these result from the low barriers to carboxyl rotation in this molecule 9…”

Section: Introductionmentioning

confidence: 99%

Crystal-Driven Distortion of Ligands in Copper Coordination Complexes: Conformational Pseudo-Enantiomers

Xu¹,

Maresca²,

Das³

et al. 2002

Chem. Eur. J.

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A 3D graphene architecture can be prepared via an in situ self‐assembly of graphene prepared by a mild chemical reduction. Fe3O4 nanoparticles are homogeneously dispersed into graphene oxide (GO) aqueous suspension and a 3D magnetic graphene/Fe3O4 aerogel is prepared during the reduction of GO to graphene. This provides a general method to prepare 3D graphene/nanoparticle composites for a wide range of applications including catalysis and energy conversion.

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Section: Introductionmentioning

confidence: 99%

Crystal-Driven Distortion of Ligands in Copper Coordination Complexes: Conformational Pseudo-Enantiomers

Xu¹,

Maresca²,

Das³

et al. 2002

Chem. Eur. J.

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“…Anhydrous DL-glutamic acid (Dunitz and Schweizer 1995) is monoclinic, whereas DL-glutamic acid monohydrate (Ciunik and Glowiak 1983;Flaig et al 2002) is orthorhombic. In all glutamic acid crystals, there is only one molecule in the asymmetric unit (assuming gauche conformation, Fig.…”

Section: Glutamic Acidmentioning

confidence: 99%

Amino Acid Structures

Fleck

Petrosyan

2014

Salts of Amino Acids

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Although this book deals with salts of amino acids, this chapter discusses the structures of pristine amino acids, since these molecular structures are also found in salts, and factors as solubility and conditions of crystal growth are important for the synthesis of amino acid salts as well as the pure form. In this context, the impact of minimal changes in conditions (such as impurities) on the growth of amino acid crystals is noted. The structural variation is very high, as not only amino acids differ from each other, but many amino acids exist in more than one form. This refers to the fact that enantiopure crystals can be grown as well as racemates (so-called DL-amino acids). Moreover, often more than one hydration state is found: Anhydrous forms are common, but many amino acids form hydrated crystals. For some amino acids (e.g., glycine, proline, methionine), more than one polymorph of the same hydration state is found. Some of these polymorphs form at ambient condition, often due to minuscule changes in conditions. For others, variation in temperature and pressure has been found to be the cause of the formation of different polymorphs. High-pressure data are available for some amino acids (e.g., alanine, serine, cysteine). Most amino acids are found to form a so-called head-to-tail motif, where acid and amino groups connect to form infinite chains. In some of the larger, nonpolar amino acids, a bilayer pattern is found, where polar groups of opposing molecules face each other, forming a layer, with the hydrophobic side chain facing outward (this motif is found in phenylalanine, methionine, leucine, or isoleucine). Not all amino acids crystallize readily, as is proved by the crystal structure of L-arginine, which could be determined only very recently, and that of lysine, which could not be solved at all to date. In addition to the standard 20, some nonstandard amino acids are discussed. Finally, notes on remarkable physical effects (such as piezoelectric data) or possible applications (as for instance the interactions of amino acids with carbon nanotubes) are presented.

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“…with scattering length b j and position vector r j was calculated by importing the crystallographic information file (CIF) (Dunitz & Schweizer, 1995) of the phase of LGA from the Crystallography Open Database (COD) (Downs & Hall-Wallace, 2003;Gražulis et al, 2009Gražulis et al, , 2012 to the Visualization for Electronic and Structural Analysis (VESTA) program (Momma & Izumi, 2011). However, because VESTA does not support the calculation of proton-polarized samples, the hydrogen scattering length was changed manually by adjusting the occupancy at hydrogen sites in the CIF data to calculate FðQ; P H 6 ¼ 0%Þ.…”

Section: Calculation Of Crystal Structure Factormentioning

confidence: 99%

Development of spin-contrast-variation neutron powder diffractometry for extracting the structure factor of hydrogen atoms

et al. 2021

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A spin-contrast-variation neutron powder diffractometry technique that extracts the structure factor of hydrogen atoms, i.e. the contribution of hydrogen atoms to a crystal's structure factor, has been developed. Crystals of L-glutamic acid were dispersed in a D-polystyrene matrix containing 4-methacryloyloxy-2,2,6,6,-tetramethyl-1-piperidinyloxy to polarize their proton spins dynamically. The intensities of the diffraction peaks of the sample changed according to the proton polarization, and the structure factor of the hydrogen atoms was extracted from the proton-polarization-dependent intensities. This technique is expected to enable analyses of the structures of hydrogen-containing materials that are difficult to determine with conventional powder diffractometry.

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Anhydrous DL-Glutamic Acid

Cited by 14 publications

References 2 publications

Crystal-Driven Distortion of Ligands in Copper Coordination Complexes: Conformational Pseudo-Enantiomers

Crystal-Driven Distortion of Ligands in Copper Coordination Complexes: Conformational Pseudo-Enantiomers

Amino Acid Structures

Development of spin-contrast-variation neutron powder diffractometry for extracting the structure factor of hydrogen atoms

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