Non-equimolar discrete compounds in binary chiral systems of organic substances

Kotelnikova, E. N.; Isakov, Anton I.; Lorenz, Heike

doi:10.1039/c6ce02209j

Cited by 15 publications

(36 citation statements)

References 89 publications

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“…Racemate RSI is a stable modification (S.G. P2 1 /c), while racemate RSII is metastable (S.G. Cc). 32,35,36 The thermal behavior of both compounds is in accordance with this. Heating racemate RSI up to its melting point (124°C) only induces thermal deformations in the crystal structure.…”

Section: Equimolar Discrete Compoundssupporting

confidence: 67%

“…The binary (S)-and (R)-malic acid system (also known as LĲ−)-and DĲ+)-malic acid) has been repeatedly studied by various authors, [40][41][42][43][44][45][46] as well as by the present authors, 32,33,[35][36][37]47 using diverse chemical, spectroscopic, diffraction, and other techniques. At present, it is stated 33,35 that the phase diversity of this system includes the following discrete phases: enantiomers (S and R), equimolar racemic compounds of three modifications (RSI, RSII, and RSIII), and non-equimolar 1 : 3 and 3 : 1 stable (SR 3 and S 3 R) and metastable (1S3R and 3S1R) compounds.…”

Section: Experimental Techniquesmentioning

confidence: 99%

“…The crystal structures of the S-enantiomer, 41 racemates RSI 42 and RSII 43 and compound S 3 R are known. 35 Detailed specifications of all the phases are given in our highlight article published recently. 35 Structural peculiarities of the discrete compounds in this system are reflected in the particular character of their thermal deformations that will be described and discussed below.…”

Section: Experimental Techniquesmentioning

confidence: 99%

“…At present, it is stated 33,35 that the phase diversity of this system includes the following discrete phases: enantiomers (S and R), equimolar racemic compounds of three modifications (RSI, RSII, and RSIII), and non-equimolar 1 : 3 and 3 : 1 stable (SR 3 and S 3 R) and metastable (1S3R and 3S1R) compounds. The crystal structures of the S-enantiomer, 41 racemates RSI 42 and RSII 43 and compound S 3 R are known.…”

Section: Experimental Techniquesmentioning

confidence: 99%

“…The present work is a continuation of our previous research on these chiral systems. [32][33][34][35] 2. Materials and methods…”

Section: Introductionmentioning

confidence: 99%

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Thermal deformations of crystal structures formed in the systems of malic acid enantiomers and l-valine–l-isoleucine enantiomers

2018

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The thermal behavior of discrete phases formed in the respective systems of malic acid enantiomers and L-enantiomers of the amino acids valine and isoleucine was studied using the temperature-resolved PXRD method. In the (S)-malic acid-(R)-malic acid system, thermal deformations in crystal structures of stable compounds (enantiomer S, racemates RSI and RSII, and non-equimolar compound S 3 R) and polymorph transformations of metastable compounds (racemate RSIII and non-equimolar compound 3S1R) were examined. In the L-valine-L-isoleucine system, thermal deformations in crystal structures of stable compounds L-Val and L-Ile and non-equimolar compound V 2 I were investigated. Thermal deformation analysis included plotting the temperature dependence of the unit cell parameters and volume, calculating thermal deformation tensors, plotting figures of thermal expansion coefficients (CTE), and estimating the extent of thermal deformation anisotropy. In all the cases studied, the maximal thermal expansion was observed in the direction of the weakest hydrogen (malic acid) or van der Waals (valine and isoleucine) intermolecular bonds, i.e. in the directions closest to that perpendicular to the dimer molecule chains (malic acid) or to molecular layers (valine and isoleucine). The strongest anisotropy of thermal deformations in monoclinic crystals was observed in the ac plane, in which the symmetrically unfixed angle β can vary.

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Section: Equimolar Discrete Compoundssupporting

confidence: 67%