Hydrogen bonding in enantiomeric versus racemic mono-carboxylic acids; a case study of 2-phenoxypropionic acid

2003 ◽  
Vol 59 (1) ◽  
pp. 132-140 ◽  
Author(s):  
Henning Osholm Sørensen ◽  
Sine Larsen
Keyword(s):  
Hydrogen Bond ◽  
Hydrogen Bonding ◽  
Crystal Structures ◽  
Carboxylic Acids ◽  
Crystal Packing ◽  
Cyclic Dimer ◽  
Optically Pure ◽  
Pure Enantiomer ◽  
Hydrogen Bonded

The structural and thermodynamic backgrounds for the crystallization behaviour of racemates have been investigated using 2-phenoxypropionic acid (PPA) as an example. The racemate of PPA behaves normally and forms a racemic compound that has a higher melting point and is denser than the enantiomer. Low-temperature crystal structures of the pure enantiomer, the enantiomer cocrystallized with n-alkanes and the racemic acid showed that hydrogen-bonded dimers that form over crystallographic symmetry elements exist in all but the structure of the pure enantiomer. A database search for optically pure chiral mono-carboxylic acids revealed that the hydrogen-bonded cyclic dimer is the most prevalent hydrogen-bond motif in chiral mono-carboxylic acids. The conformation of PPA depends on the hydrogen-bond motif; the antiplanar conformation relative to the ether group is associated with a catemer hydrogen-bonding motif, whereas the more abundant synplanar conformation is found in crystals that contain cyclic dimers. Other intermolecular interactions that involve the substituent of the carboxylic group were identified in the crystals that contain the cyclic dimer. This result shows how important the nature of the substituent is for the crystal packing. The differences in crystal packing have been related to differences in melting enthalpy and entropy between the racemic and enantiomeric acids. In a comparison with the equivalent 2-(4-chlorophenoxy)-propionic acids, the differences between the crystal structures of the chloro and the unsubstituted acid have been identified and related to thermodynamic data.

A Comparison of the Enamino Carbonyl Conjugation Efficiency for Hydrogen Bonding Formation in Pyridone and Dihydropyridone Systems

2000 ◽  
Vol 55 (1) ◽  
pp. 5-11 ◽  
Author(s):  
Teresa Borowiak ◽  
Irena Wolska ◽  
Artur Korzański ◽  
Wolfgang Milius ◽  
Wolfgang Schnick ◽  
...  
Keyword(s):  
Hydrogen Bond ◽  
Hydrogen Bonding ◽  
Hydrogen Bonds ◽  
Crystal Structures ◽  
Steric Hindrance ◽  
Crystal Packing ◽  
Intermolecular Hydrogen Bond ◽  
Asymmetric Unit ◽  
Intermolecular Hydrogen Bonds

The crystal structures of two compounds containing enaminone heterodiene systems and forming intermolecular hydrogen bonds N-H·O are reported: 1) 3-ethoxycarbonyl-2-methyl-4-pyridone (hereafter ETPY) and 2) 3-ethoxycarbonyl-2-phenyl-6-methoxycarbonyl-5,6-di-hydro-4-pyridone (hereafter EPPY). The crystal packing is controlled by intermolecular hydro­ gen bonds N-H·O = C connecting the heteroconjugated enaminone groups in infinite chains. In ETPY crystals the intermolecular hydrogen bond involves the heterodienic pathway with the highest π-delocalization that is effective for a very short N·O distance of 2.701(9) Å (average from two molecules in the asymmetric unit). Probably due to the steric hindrance, the hydrogen bond in EPPY is formed following the heterodienic pathway that involves the ester C = O group, although π-delocalization along this pathway is less than that along the pyridone-part pathway resulting in a longer N·O distance of 2.886(3) Å

Ferrocene Mono- and Di-Sulfonates as Building Blocks in Hydrogen-Bonded Networks

2007 ◽  
Vol 60 (8) ◽  
pp. 578 ◽  
Author(s):  
Jingli Xie ◽  
Brendan F. Abrahams ◽  
Tobias J. Zimmermann ◽  
Arindam Mukherjee ◽  
Anthony G. Wedd
Keyword(s):  
Hydrogen Bond ◽  
Hydrogen Bonding ◽  
Crystal Structures ◽  
Crystalline State ◽  
Building Blocks ◽  
The Individual ◽  
Secondary Bonding ◽  
Hydrogen Bonded

The structure directing influence of a variety of hydrogen-bonding cations on the arrangement of ferrocene mono- and di-sulfonate anions within the crystalline state is reported. The crystal structures of four different networks of composition A[Fe(η5-C5H5)(η5-C5H4SO3)] (A = imidazolium or N-methylimidazolium) and B2[Fe(η5-C5H4SO3)2] (B = imidazolium or pyridinium) are presented. The imidazolium ions are able to act as hydrogen bond bridges in the generation of layer-type structures similar to those found for guanidinium analogues. Secondary bonding interactions exert a powerful structure-directing influence within these networks even though the individual interactions appear to be rather weak.

Interplay between steric and electronic factors in determining the strength of intramolecular N—H...O resonance-assisted hydrogen bonds in β-enaminones

2006 ◽  
Vol 62 (6) ◽  
pp. 1112-1120 ◽  
Author(s):  
Valerio Bertolasi ◽  
Loretta Pretto ◽  
Valeria Ferretti ◽  
Paola Gilli ◽  
Gastone Gilli
Keyword(s):  
Hydrogen Bond ◽  
Hydrogen Bonding ◽  
Hydrogen Bonds ◽  
Crystal Structures ◽  
Structural Features ◽  
Membered Ring ◽  
Resonance Assisted Hydrogen Bond ◽  
Electronic Resonance ◽  
Hydrogen Bonded

The crystal structures of five β-enaminones are reported: (2Z)-3-(benzylamino)-1,3-diphenyl-prop-2-en-1-one, (2Z)-3-(benzylamino)-3-(2-hydroxyphenyl)-1-phenyl-prop-2-en-1-one, (2Z)-3-(benzylamino)-3-(4-methoxyphenyl)-1-(3-nitrophenyl)-prop-2-en-1-one, 2-{1-[(4-methoxyphenyl)amino]ethylidene}cyclohexene-1,3-dione and 2-{1-[(3-methoxyphenyl)amino]ethylidene}cyclohexene-1,3-dione. The structures were analysed and compared with those of similar compounds in order to establish which factors determine the range (2.53–2.72 Å) of N...O hydrogen-bond distances in intramolecularly hydrogen-bonded β-enaminones. It has been shown that, beyond electronic resonance-assisted hydrogen-bond effects modulated by substituents, the necessary requirements to produce very short N—H...O hydrogen bonding are steric intramolecular repulsions, including the embedding of an enaminonic C—C or C—N bond in an aliphatic six-membered ring. By considering the structural features it is possible to expect the strength of N—H...O hydrogen bonds adopted by specific β-enaminones.

Hydrogen-bonded chains in threecis-dichloridoplatinum(II) complexes bearing piperidine and amine ligands

2014 ◽  
Vol 70 (3) ◽  
pp. 297-301 ◽  
Author(s):  
Chi Nguyen Thi Thanh ◽  
Ngan Nguyen Bich ◽  
Luc Van Meervelt
Keyword(s):  
Hydrogen Bonding ◽  
Crystal Structures ◽  
Crystal Packing ◽  
Stacking Interactions ◽  
Hydrogen Bonding Interactions ◽  
Π Stacking ◽  
Amine Ligands ◽  
Hydrogen Bonded

The crystal structures ofcis-dichlorido(ethylamine-κN)(piperidine-κN)platinum(II), [PtCl2(C2H7N)(C5H11N)], (I),cis-dichlorido(3-methoxyaniline-κN)(piperidine-κN)platinum(II), [PtCl2(C5H11N)(C7H9NO)], (II), andcis-dichlorido(piperidine-κN)(quinoline-κN)platinum(II), [PtCl2(C5H11N)(C9H7N)], (III), have been determined at 100 K in order to verify the influence of the nonpiperidine ligand on the geometry and crystal packing. The crystal packing is characterized by N—H...Cl hydrogen bonding, resulting in the formation of chains of molecules connected in a head-to-tail fashion. Hydrogen-bonding interactions play a major role in the packing of (I), where the chains further aggregate into planes, but less so in the case of (II) and (III), where π–π stacking interactions are of greater importance.

scholarly journals Formation of quinol co-crystals with hydrogen-bond acceptors

2005 ◽  
Vol 61 (1) ◽  
pp. 46-57 ◽  
Author(s):  
Iain D. H. Oswald ◽  
W. D. Samuel Motherwell ◽  
Simon Parsons
Keyword(s):  
Hydrogen Bond ◽  
Hydrogen Bonding ◽  
Crystal Structures ◽  
Guest Molecule ◽  
Crystal Packing ◽  
Strong Hydrogen Bond ◽  
Hydrogen Bond Acceptor ◽  
Guest Molecules ◽  
Sterically Hindered

The crystal structures of eight new co-crystals of quinol with pyrazine, piperazine, morpholine, pyridine, piperidine, 4,4′-bipyridine, N-methylmorpholine and N,N′-dimethylpiperazine are reported. Quinol forms 1:1 co-crystals with pyrazine, piperazine and N,N′-dimethylpiperazine, but 1:2 co-crystals with morpholine, 4,4′-bipyridine, N-methylmorpholine, pyridine and piperidine. This difference can be rationalized in most cases by the presence of, respectively, two or one strong hydrogen-bond acceptor(s) in the guest molecule. The exception to this generalization is 4,4′-bipyridine, which forms a 1:2 co-crystal, possibly to optimize crystal packing. All structures are dominated by hydrogen bonding between quinol and the guest molecules. A doubly bridging motif, which connects pairs of quinol and guest molecules via NH...O or CH...O interactions, is present in all but the sterically hindered N,N′-dimethylpiperazine and N-methylmorpholine co-crystals.

Supramolecular assembling using synthons with NH—CO(S)—CS—NH and NH—CO—CO—NH functionalities: crystal structures of (S,S)-N,N′-monothiooxalyldileucine methyl ester and its dithio analogue

2004 ◽  
Vol 60 (1) ◽  
pp. 90-96 ◽  
Author(s):  
Biserka Kojić-Prodić ◽  
Berislav Perić ◽  
Zoran Štefanić ◽  
Anton Meden ◽  
Janja Makarević ◽  
...  
Keyword(s):  
Hydrogen Bond ◽  
Hydrogen Bonding ◽  
Methyl Ester ◽  
Crystal Structures ◽  
Hydrogen Bond Network ◽  
Asymmetric Unit ◽  
Orthorhombic Space Group ◽  
Space Group ◽  
Bond Network ◽  
Bonding Systems

To compare the structural properties of oxalamide and thiooxalamide groups in the formation of hydrogen bonds suitable for supramolecular assemblies a series of retropeptides was studied. Some of them, having oxalamide bridges, are gelators of organic solvents and water. However, retropeptides with oxygen replaced by the sp 2 sulfur have not exhibited such properties. The crystal structures of the two title compounds are homostructural, i.e. they have similar packing arrangements. The monothio compound crystallizes in the orthorhombic space group P212121 with two molecules in the asymmetric unit arranged in a hydrogen-bond network with an approximate 41 axis along the crystallographic b axis. However, the dithio and dioxo analogues crystallize in the tetragonal space group P41 with similar packing patterns and hydrogen-bonding systems arranged in agreement with a crystallographic 41 axis. Thus, these two analogues are isostructural having closely related hydrogen-bonding patterns in spite of the different size and polarity of oxygen and sulfur which serve as the proton acceptors.

scholarly journals Crystal structures of three 3,4,5-trimethoxybenzamide-based derivatives

2016 ◽  
Vol 72 (5) ◽  
pp. 675-682 ◽  
Author(s):  
Ligia R. Gomes ◽  
John Nicolson Low ◽  
Catarina Oliveira ◽  
Fernando Cagide ◽  
Fernanda Borges
Keyword(s):  
Hydrogen Bond ◽  
Hydrogen Bonding ◽  
Crystal Structures ◽  
Methoxy Group ◽  
Combined Effect ◽  
Donor Group ◽  
Methoxy Substituent ◽  
A Chain ◽  
Benzamide Derivatives

The crystal structures of three benzamide derivatives,viz. N-(6-hydroxyhexyl)-3,4,5-trimethoxybenzamide, C16H25NO5, (1),N-(6-anilinohexyl)-3,4,5-trimethoxybenzamide, C22H30N2O4, (2), andN-(6,6-diethoxyhexyl)-3,4,5-trimethoxybenzamide, C20H33NO6, (3), are described. These compounds differ only in the substituent at the end of the hexyl chain and the nature of these substituents determines the differences in hydrogen bonding between the molecules. In each molecule, them-methoxy substituents are virtually coplanar with the benzyl ring, while thep-methoxy substituent is almost perpendicular. The carbonyl O atom of the amide rotamer istransrelated with the amidic H atom. In each structure, the benzamide N—H donor group and O acceptor atoms link the molecules intoC(4) chains. In1, a terminal –OH group links the molecules into aC(3) chain and the combined effect of theC(4) andC(3) chains is a ribbon made up of screw relatedR22(17) rings in which the ...O—H... chain lies in the centre of the ribbon and the trimethoxybenzyl groups forms the edges. In2, the combination of the benzamideC(4) chain and the hydrogen bond formed by the terminal N—H group to an O atom of the 4-methoxy group link the molecules into a chain ofR22(17) rings. In3, the molecules are linked only byC(4) chains.

Polymorphs of phenazine hexacyanoferrate(II) hydrate: supramolecular isomerism in a 2D hydrogen-bonded network

2021 ◽  
Vol 77 (2) ◽  
pp. 211-218
Author(s):  
Ivica Cvrtila ◽  
Vladimir Stilinović
Keyword(s):  
Hydrogen Bonding ◽  
Hydrogen Bonds ◽  
Crystal Structures ◽  
The Other ◽  
Two Dimensional ◽  
Structural Motifs ◽  
Supramolecular Isomerism ◽  
Other Hand ◽  
Π Stacking ◽  
Hydrogen Bonded

The crystal structures of two polymorphs of a phenazine hexacyanoferrate(II) salt/cocrystal, with the formula (Hphen)3[H2Fe(CN)6][H3Fe(CN)6]·2(phen)·2H2O, are reported. The polymorphs are comprised of (Hphen)2[H2Fe(CN)6] trimers and (Hphen)[(phen)2(H2O)2][H3Fe(CN)6] hexamers connected into two-dimensional (2D) hydrogen-bonded networks through strong hydrogen bonds between the [H2Fe(CN)6]2− and [H3Fe(CN)6]− anions. The layers are further connected by hydrogen bonds, as well as through π–π stacking of phenazine moieties. Aside from the identical 2D hydrogen-bonded networks, the two polymorphs share phenazine stacks comprising both protonated and neutral phenazine molecules. On the other hand, the polymorphs differ in the conformation, placement and orientation of the hydrogen-bonded trimers and hexamers within the hydrogen-bonded networks, which leads to different packing of the hydrogen-bonded layers, as well as to different hydrogen bonding between the layers. Thus, aside from an exceptional number of symmetry-independent units (nine in total), these two polymorphs show how robust structural motifs, such as charge-assisted hydrogen bonding or π-stacking, allow for different arrangements of the supramolecular units, resulting in polymorphism.

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