Mapping the structural boundaries of quasiracemate fractional crystallization using 2-substituted diarylamides

Tinsley, Ian C.; Spaniol, Jacqueline M.; Wheeler, Kraig A.

doi:10.1039/c7cc01638g

Cited by 7 publications

(10 citation statements)

References 20 publications

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“…This data is summarized in Figure 2 and shows the outcomes from both successful cocrystallization experiments (blue) and those that result in conglomerate formation (grey). In contrast to the previous 2-substituted diarylamides [32], where 34 of 55 entries formed quasiracemates, the 3-(18 of 45) and 4-substituted (10 of 45) systems show fewer instances of cocrystal formation. Furthermore, unlike the prior report, not all enantiomeric pairs resulted in racemic compounds.…”

Section: Hot Stage Thermomicroscopycontrasting

confidence: 81%

“…A family of chiral 3-and 4-substituted diarylamide derivatives were prepared using the following general procedure starting from either the acid chloride or carboxylic acid. This procedure is based on previously described literature reports [18,32] of closely related secondary amide compounds.…”

Section: Synthetic and Crystal Growth Proceduresmentioning

confidence: 99%

“…While the quasiracemic approach to material design has proven useful for various applications such as crystallization [21][22][23][24][25][26][27], asymmetric synthesis [28], and chemical detection/separation [28][29][30][31], only recently has the structural boundaries of quasiracemate formation been examined in detail [32]. Boundary identification was achieved by studying a homologous family of structurally simple chiral 2-substituted diarylamides where the pendant functional group incrementally varied from -H to −-C 6 H 5 ).…”

Section: Introductionmentioning

confidence: 99%

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Molecular Recognition and Shape Studies of 3- and 4-Substituted Diarylamide Quasiracemates

et al. 2021

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Families of quasiracemic materials constructed from 3- and 4-substituted chiral diarylamide molecular frameworks were prepared, where the imposed functional group differences systematically varied from H to CF3–9 unique components for each isomeric framework. Cocrystallization from the melt via hot stage thermomicroscopy using all possible racemic and quasiracemic combinations probed the structural boundaries of quasiracemate formation. The crystal structures and lattice energies (differential scanning calorimetry and lattice energy calculations) for many of these systems showed that quasienantiomeric components organize with near inversion symmetry and lattice energetics closely resembling those found in the racemic counterparts. This study also compared the shape space of pairs of quasienantiomers using an in silico alignment-based method to approximate the differences in molecular shape and provide a diagnostic tool for quasiracemate prediction. Comparing these results to our recent report on related 2-substituted diarylamide quasiracemates shows that functional group position can have a marked effect on quasiracemic behavior and provide critical insight to a more complete shape space, essential for defining molecular recognition processes.

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Section: Hot Stage Thermomicroscopycontrasting

confidence: 81%

Section: Synthetic and Crystal Growth Proceduresmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Molecular Recognition and Shape Studies of 3- and 4-Substituted Diarylamide Quasiracemates

et al. 2021

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“…From the previous description, it is clear that the conformational trimorphism for the title compound is a consequence of the rotation of the peripheral phenyl rings, which changes their environment, affecting the packing of the C(4) chains. This molecular flexibility is confirmed by the crystal-structure determination of the unique co-crystal reported to date including the title molecule (Tinsley et al, 2017): the conformation is far from that observed in the free amide we report, and one phenyl is even disordered by rotation. Polymorphism can then occur, although the hydrogenbonded pattern remains unaltered.…”

Section: Database Surveysupporting

confidence: 76%

One molecule, three crystal structures: conformational trimorphism of N-[(1S)-1-phenylethyl]benzamide

Manuel¹,

Sosa-Rivadeneyra²,

Bernès³

2020

Acta Cryst E

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The title compound, C15H15NO, is an enantiopure small molecule, which has been synthesized many times, although its crystal structure was never determined. By recrystallization from a variety of solvent mixtures (pure acetonitrile, ethanol–water, toluene–ethanol, THF–methanol), we obtained three unsolvated polymorphs, in space groups P21 and P212121. Form I is obtained from acetonitrile, without admixture of other forms, whereas forms II and III are obtained simultaneously by concomitant crystallizations from alcohol-based solvent mixtures. All forms share the same supramolecular structure, based on infinite C 1 1(4) chain motifs formed by N—H...O intermolecular hydrogen bonds, as usual for non-sterically hindered amides. However, a conformational modification of the molecular structure, related to the rotation of the phenyl rings, alters the packing of the chains in the crystal structures. The orientation of the chain axis is perpendicular and parallel to the crystallographic twofold screw axis of space group P21 in forms I and II, respectively. As for form III, the asymmetric unit contains two independent molecules forming parallel chains in space group P212121, and the crystal structure combines features of monoclinic forms I and II.

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“…Understandably, the makeup of chiral symmetry could be simply achieved by modulating the R / S ratio in pseudoracemate and R / S ′ constituent in quasiracemate. However, both of them have rarely been observed, − mainly due to the difficulty of controllable modification of one enantiomer in a racemic compound.…”

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confidence: 99%

Controlled Crystal Transformations of a Chiral Conglomerate with Heterotactic Helical Coordination Arrays

Zhou

Sun

et al. 2018

Crystal Growth & Design

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Helix represents the most essential molecular chiral symmetry at a supramolecular level. Here, a unique quasiracemate conglomerate {[Cd(L)I(H2O)3][Cd(HL)I2(H2O)2](H2O)4} n (1, HL = N-(3,5-di(pyridin-3-yl)-4H-1,2,4-triazol-4-yl)nicotinamide), which crystallizes in P21 space group and consists of two different sets of helical enantiomers, has been successfully constructed. Remarkably, crystal transformations from the chiral quasiracemate 1 to two different achiral racemates {[Cd(L)I(H2O)3]·(H2O)3} n (2) and {[Cd(HL)I2(H2O)2](H2O)} n (3) can be achieved controllably by introducing acid and base additives, via solvent-mediated crystal transformations.

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Mapping the structural boundaries of quasiracemate fractional crystallization using 2-substituted diarylamides

Abstract: Video-assisted hot stage polarized light microscopy of 55 quasienantiomeric pairs, constructed from 22 chiral diarylamides that systematically differ in topology, reveals the structural boundaries of molecular shape to supramolecular assembly.

Cited by 7 publications

References 20 publications

Molecular Recognition and Shape Studies of 3- and 4-Substituted Diarylamide Quasiracemates

Molecular Recognition and Shape Studies of 3- and 4-Substituted Diarylamide Quasiracemates

One molecule, three crystal structures: conformational trimorphism of N-[(1S)-1-phenylethyl]benzamide

Controlled Crystal Transformations of a Chiral Conglomerate with Heterotactic Helical Coordination Arrays

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