Recrystallization of Enantiomers from Conglomerates

Dupray, Valérie

doi:10.5772/33746

Cited by 7 publications

(7 citation statements)

References 31 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Racemic compounds can yield either chiral or achiral crystal structures, and can theoretically be arranged in any one of the 230 space groups, 1 although around 95% of the known racemic compounds crystallize as centrosymmetric achiral crystal structures. 2 In this paper, we report the structural study of (4-(dimethylamino)phenyl)(phenyl)(thiophen-2-yl)methanol (1, see Figure 1), a chiral molecule which was synthesized as a racemic mixture from achiral precursors in the course of ongoing research. This compound was designed by our group to be used as an OFF/ON optical chemodosimeter for nerve agent mimics, due to the changes in its optical properties in the presence of these toxic compounds.…”

Section: ■ Introductionmentioning

confidence: 99%

“…Racemic mixtures of chiral molecules can crystallize as racemic compounds (the most common situation, a single crystalline phase with both enantiomers in a 1:1 ratio in the elementary cell), as conglomerates of chiral crystals (mechanical mixture of enantiomerically pure crystals; about 10% of the time), or as pseudoracemates (or racemic solid solutions). Racemic compounds can yield either chiral or achiral crystal structures, and can theoretically be arranged in any one of the 230 space groups, although around 95% of the known racemic compounds crystallize as centrosymmetric achiral crystal structures …”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Racemic Triarylmethanol Derivative Crystallizes as a Chiral Crystal Structure with Enantiomeric Disorder, in the Sohncke Space Group P2₁

Chulvi

Costero

Ochando

et al. 2015

Crystal Growth & Design

View full text Add to dashboard Cite

The X-ray crystal structure of a racemic triarylcarbinol derivate ((±)-1) was determined. Compound (±)-1 crystallizes as a chiral structure in the noncentrosymmetric Sohncke space group P2 1 and the crystals show a special case of enantiomeric disorder with two molecules of opposite handedness sharing many of the atomic positions in the asymmetric unit. The corresponding (R)-and (S)-enantiomers of 1 were separated by chiral HPLC, and crystallized independently yielding single crystals of both of them. The X-ray diffraction analysis of the crystals allowed the determination of the absolute configuration of both enantiomers (R)-1 and (S)-1. Both enantiomers establish intermolecular hydrogen bonds in the solid state, which induce significant differences in their molecular arrangement when compared to racemic crystal (±)-1. ■ INTRODUCTIONRacemic mixtures of chiral molecules can crystallize as racemic compounds (the most common situation, a single crystalline phase with both enantiomers in a 1:1 ratio in the elementary cell), as conglomerates of chiral crystals (mechanical mixture of enantiomerically pure crystals; about 10% of the time), or as pseudoracemates (or racemic solid solutions). Racemic compounds can yield either chiral or achiral crystal structures, and can theoretically be arranged in any one of the 230 space groups, 1 although around 95% of the known racemic compounds crystallize as centrosymmetric achiral crystal structures. 2 In this paper, we report the structural study of (4-(dimethylamino)phenyl)(phenyl)(thiophen-2-yl)methanol (1, see Figure 1), a chiral molecule which was synthesized as a racemic mixture from achiral precursors in the course of ongoing research. This compound was designed by our group to be used as an OFF/ON optical chemodosimeter for nerve agent mimics, due to the changes in its optical properties in the presence of these toxic compounds. 3 We have found that (±)-1 crystallizes as an ordered racemic crystal structure in the noncentrosymmetric space group P2 1 . This space group is one of 65 Sohncke space groups, which are the groups allowed for chiral crystal structures, containing only symmetry operations of the first kind (rotations and translations). 4 Actually, around of 5.2% of the CSD structures (of a total of 682 999) belong to a P2 1 space group. 5 Racemic mixtures that happen to crystallize as chiral crystal structures in Sohncke space groups are a very unusual case, and few examples have been reported in the literature. 6−9 Furthermore, the corresponding R and S enantiomers of 1 were separated by chiral HPLC, and crystallized independently yielding single crystals of both of them suitable for X-ray diffraction.■ EXPERIMENTAL SECTION X-ray Diffraction Analysis. Appropriate colorless acicular crystals of compound (±)-1 3 were grown from heptane/2-propanol as solvent at 4°C by means of liquid−liquid diffusion and analyzed by X-ray diffraction technique. The crystallization of the enantiomers, (S)-1 (1a) and (R)-1 (1b), was carried out at 4°C by the slow evaporation method...

show abstract

Section: ■ Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Racemic Triarylmethanol Derivative Crystallizes as a Chiral Crystal Structure with Enantiomeric Disorder, in the Sohncke Space Group P2₁

Chulvi

Costero

Ochando

et al. 2015

Crystal Growth & Design

View full text Add to dashboard Cite

show abstract

“…Unfortunately, the solids collected showed no optical activity. To ascertain unequivocally the nature of such a racemate, we turned the attention to second harmonic generation (SHG), a non-linear method that is reliable enough for spotting conglomerates, based on signal detection at /2 wavelengths (Galland et al 2009;Dupray 2012). Detection of SHG signals may be indicative of non-centrosymmetric crystals, which point to either conglomerates or racemic compounds crystallizing in non-centrosymmetric space groups.…”

Section: Boron Coordinationmentioning

confidence: 99%

On the Plausibility of Pseudosugar Formation in Cometary Ices and Oxygen-rich Tholins

Lavado¹,

Авалос²,

Babiano³

et al. 2015

Orig Life Evol Biosph

View full text Add to dashboard Cite

We revisit herein the formation and structure of dihydroxy dioxanes, which can be obtained from prebiotically available precursors and can be regarded as primeval sugar surrogates. Previous studies dealing with the heterogeneous composition of interstellar bodies point to the existence of significant amounts of small polyalcohols along with oxygen-containing oligomers. Even though such derivatives did not give rise to nucleosides and oligonucleotides, nor they were incorporated into subsequent metabolic routes, molecular chimeras based on sugar-like species could be opportunistic scaffolds in pre-evolutionary scenarios. We could figure out that pseudosugars, assembled by hemiacetalic bonds from available precursors in both interstellar and terrestrial scenarios, were presumably more abundant than thought. Moreover, these species share some key features with naturally-occurring sugar rings, such as anomeric preferences, coordinating ability, and the prevalent occurrence of racemic compounds.

show abstract

“…extent of the deformation of the amide group observed in the solid-state is mainly governed by effects of crystal packing.Since racemic mixtures tend to form centrosymmetric crystal structures[25], it is interesting to note that the crystal structure of 1b is chiral (Sohnke space group), i.e. comprises only one conformational enantiomer of the axially chiral molecule, and the crystal structures of 1c and 1f are polar.…”

mentioning

confidence: 99%

A structural study of seven N-acylindolines and their Pd(II)-mediated intramolecular oxidative coupling reactions for the synthesis of pyrrolophenanthridone alkaloids

Feilcke

Goddard

Imming

et al. 2019

Journal of Molecular Structure

View full text Add to dashboard Cite

Direct synthesis of the pyrrolophenanthridone scaffold was explored using an intramolecular Pd(II)-mediated coupling reaction of different N-acylindolines via CH activation, Amaryllidaceae alkaloids of the lycorine type belong to this type. Depending on the substitution pattern of the starting materials, the pathway yielded different product patterns and yields. Introduction of electron-withdrawing substituents into the 6-position of the indoline moiety did not improve coupling. Seven N-acylindoline precursors were structurally characterized by X-ray crystallography and NMR spectroscopy. The crystal structure of the lycorine type alkaloid oxoassoanine is reported for the first time.

show abstract

Recrystallization of Enantiomers from Conglomerates

Cited by 7 publications

References 31 publications

Racemic Triarylmethanol Derivative Crystallizes as a Chiral Crystal Structure with Enantiomeric Disorder, in the Sohncke Space Group P2₁

Racemic Triarylmethanol Derivative Crystallizes as a Chiral Crystal Structure with Enantiomeric Disorder, in the Sohncke Space Group P2₁

On the Plausibility of Pseudosugar Formation in Cometary Ices and Oxygen-rich Tholins

A structural study of seven N-acylindolines and their Pd(II)-mediated intramolecular oxidative coupling reactions for the synthesis of pyrrolophenanthridone alkaloids

Contact Info

Product

Resources

About

Recrystallization of Enantiomers from Conglomerates

Cited by 7 publications

References 31 publications

Racemic Triarylmethanol Derivative Crystallizes as a Chiral Crystal Structure with Enantiomeric Disorder, in the Sohncke Space Group P21

Racemic Triarylmethanol Derivative Crystallizes as a Chiral Crystal Structure with Enantiomeric Disorder, in the Sohncke Space Group P21

On the Plausibility of Pseudosugar Formation in Cometary Ices and Oxygen-rich Tholins

A structural study of seven N-acylindolines and their Pd(II)-mediated intramolecular oxidative coupling reactions for the synthesis of pyrrolophenanthridone alkaloids

Contact Info

Product

Resources

About

Racemic Triarylmethanol Derivative Crystallizes as a Chiral Crystal Structure with Enantiomeric Disorder, in the Sohncke Space Group P2₁

Racemic Triarylmethanol Derivative Crystallizes as a Chiral Crystal Structure with Enantiomeric Disorder, in the Sohncke Space Group P2₁