X-ray studies on crystalline complexes involving amino acids and peptides. XXV. Structures of DL-proline hemisuccinic acid and glycyl-L-histidinium semisuccinate monohydrate and a comparative study of amino-acid and peptide complexes of succinic acid

Abstract

(1), Dx = 1.48 g cm -3, R =0.027 for 1610 observed reflections. Normal amino-acid and dipeptide aggregation patterns are preserved in the structures in spite of the presence of succinic acid/semisuccinate ions. In both the structures, the amino-acid/dipeptide layers stack in such a way that the succinic acid molecules/semisuccinate ions are enclosed in voids created during stacking. Substantial variability in the ionization state and the stoichiometry is observed in amino-acid and peptide complexes of succinic acid. Succinic acid molecules and succinate ions appear to prefer a planar centrosymmetric conformation with the two carboxyl (carboxylate) groups trans with respect to the central C--C bond. Considerable variation is seen in the departure from and modification of normal aminoacid aggregation patterns produced by the presence of succinic acid. Some of the complexes can be described as inclusion compounds with the amino acid/dipeptide as the 'host' and succinic acid/ semisuccinate/succinate as the 'guest'. The effects of change in chirality, though very substantial, are not the same in different pairs of complexes involving DL and L isomers of the same amino acid.

X-ray Studies on Crystalline Complexes Involving Amino Acids and Peptides. XXVII. Effect of Chirality, Specific Interactions and Characteristic Aggregation Patterns in the Structures of Arginine and its Complexes with Formic Acid

“…This is in addition to their intrinsic importance as models for interactions involving carboxyl groups in proteins. In this context, we have already obtained results of considerable interest from amino acid and peptide complexes of succinic and acetic acids (5)(6)(7)(8)(9)(10)(11)(12). Here we present the crystal structures ofthe complexes ofDL-and L-arginine with formic acid, and the hitherto unreported crystal structure of DL-arginine, which was determined to facilitate appropriate comparisons.…”

Crystal structure and vibrational analysis of novel nonlinear optical L‐histidinium tetrafluoroborate (L‐HFB) single crystals

“…In particular, L-histidine is an interesting molecule from the crystal engineering as well as supramolecular point of view [6]. The crystallographic data for other L-histidine complexes exists in the literature are salts of L-histidine formate, L-histidine acetate, L-histidine oxalate, L-histidine maleate, L-histidine L-tartarate, L-histidine dihydrogen arsenate orthoarsenic acid, L-histidine perchlorate, L-histidine succcinic acid and L-histidine tetraflurosuccinate [7][8][9][10][11][12][13][14][15]. All of these compounds are stabilized by extensive networks of hydrogen bonds.…”

The salt of l‐prolinium picrate

“…These bifurcated hydrogen bonds are very similar to that observed in other picrate [12] or nitrophenolate [13]. The pyrrolidine ring demonstrates a conformation intermediate between an envelope and half-chair, as observed in l-proline monohydrate [1], dl-proline monohydrate [5] and dl-proline hemisuccinic acid [4]. The C(2) atom assumes a trans position with respect to the carboxyl group.…”

“…The crystal structures of l-proline monohydrate [1], dl-proline hydrochloride [2], dl-homoproline tetrahydrate [3], proline hemisuccinic acid [4], dl-proline monohydrate [5], bis(l-proline) hydrogen perchlorate [6], bis(lproline) hydrogen nitrate [7] and l-proline hydrogen tartarate [8] have been reported. As proline is a very important amino acid, more examples of X-ray crystallographic work are needed to investigate its unique conformation in different situations.…”