Chirality and chemical processes: A few afterthoughts

Cintas, Pedro

doi:10.1002/chir.20480

Cited by 13 publications

(9 citation statements)

References 16 publications

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“…Thus, only the ( R )‐PH 2 PHF system has been considered in the present article. Assuming a negligible effect of the parity violation principle, the energetic results for this system should be identical to those for ( S )‐PH 2 PHF 37. 69…”

Section: Resultsmentioning

confidence: 79%

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Chiral Discrimination in Dimers of Diphosphines PH₂PH₂and PH₂PHF

2014

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A theoretical study of the conformational profile of two diphosphines, PH2PH2 and PH2PHF, is carried using second‐order Møller–Plesset perturbation theory (MP2) computational methods. The chiral minima found are used to build homo‐ and heterochiral dimers. Six minima are found for the (PH2PH2)2 dimers and 27 for the (PH2PHF)2 dimers. Pnicogen and hydrogen bonds, the non‐covalent forces that stabilize the complexes, are characterized by Atoms in Molecules (AIM) and Natural Bond Orbital (NBO) methodologies. Those with several pnicogen bonds are more stable than those with hydrogen bonds. The chirodiastaltic energies amount to a total of 1.77 kJ mol−1 for the Ra:Ra versus Ra:Sa (PH2PH2)2 dimers, 0.81 kJ mol−1 for the RSa:RSa versus RSa:SRa (PH2PHF)2 dimers, and 2.93 kJ mol−1 for the RRa:RRa versus RRa:SSa (PH2PHF)2 dimers. In the first and second cases, the heterochiral complex is favored whereas in the third case, the homochiral complex is favored.

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Section: Resultsmentioning

confidence: 79%

“…Chiral recognition, also known as chiral distinction,37 is a topic of interest to both theorists and experimentalists. Of particular importance are the biological properties of chiral compounds, as optical isomers differ in their interactions with chiral receptors 38.…”

Section: Introductionmentioning

confidence: 99%

Chiral Discrimination in Dimers of Diphosphines PH₂PH₂and PH₂PHF

2014

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“…Importantly, examination of the language of stereochemistry has lately acquired renewed interest as a result of the considerable misuse and misunderstanding of this language evident in the literature today. Indeed, a number of articles lamenting such misuse and urging correct usage have appeared, [21][22][23][24][25][26] some authored by leading figures in stereochemistry.…”

Section: Introductionmentioning

confidence: 99%

Louis Pasteur, Chemical Linguist: Founding the Language of Stereochemistry

Gál

2019

Helvetica Chimica Acta

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Pasteur’s major discovery in chemistry was the recognition of molecular chirality, in 1848. He understood that his new science needed its own language, and introduced new terminology and nomenclature, thereby launching modern stereochemical language. He was eminently prepared for this task as a refined user of language, skills recognized by his election to the Académie française, the supreme institution for the protection and promotion of the French language. The terms chiral and chirality did not exist at the time and he adopted the French word dissymmétrie (dissymmetry) for the phenomenon of handedness. Although in his time almost nothing was known about molecular constitution and configuration, his insights allowed him to create useful language some of which is still used today in stereochemistry, e. g., racemic for the 1 : 1 mixture of the two enantiomers, and the use of the prefixes levo‐ and dextro‐ in the names of optically active substances. On the other hand, the limitations in the knowledge of organic chemistry at the time prevented him from creating some needed terms, e. g., for the phenomenon of diastereoisomerism. He also failed to adopt the enantio terminology introduced in the 1850s by German mineralogist Carl Friedrich Naumann. Analysis of Pasteur’s linguistic innovations is of interest from the point of view of the history of chemistry and is also useful in throwing light on the fundamental nature of the concepts of stereochemistry. Such understanding has acquired a new relevance due to the considerable misuse and misunderstanding of this language seen in the literature today.

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“…The misuse of scientific language provides additional motivation for its study. A great deal of discussion of problems associated with the use of stereochemical language has appeared6–14 and one can deduce from these discussions that two different types of problems exist. One encompasses problems arising from fundamental conceptual issues, e.g., perceived or real “incorrect” definitions of terms; changes in the meaning or connotation of terms arising from obsolescence or new technological developments; ignoring context in applying terminology; lack of appreciation of the intrinsic nature of chirality and its relationship to stereoisomerism; etc., and Mislow14 has given an incisive analysis of these matters.…”

Section: Introductionmentioning

confidence: 99%

Louis Pasteur, language, and molecular chirality. I. Background and Dissymmetry

Gál

2010

Chirality

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Louis Pasteur resolved sodium ammonium (±)-tartrate in 1848, thereby discovering molecular chirality. Although hindered by the primitive state of organic chemistry, he introduced new terminology and nomenclature for his new science of molecular and crystal chirality. He was well prepared for this task by his rigorous education and innate abilities, and his linguistic achievements eventually earned him membership in the supreme institution for the French language, the Académie française. Dissymmetry had been in use in French from the early 1820s for disruption or absence of symmetry or for dissimilarity or difference in appearance between two objects, and Pasteur initially used it in the latter connotation, without any reference to handedness or enantiomorphism. Soon, however, he adopted it in the meaning of chirality. Asymmetry had been in use in French since 1691 but Pasteur ignored it in favor of dissymmetry. The two terms are not synonymous but it is not clear whether Pasteur recognized this difference in choosing the former over the latter. However, much of the literature mistranslates his dissymmetry as asymmetry. Twenty years before Pasteur the British polymath John Herschel proposed that optical rotation in the noncrystalline state is due to the "unsymmetrical" [his term] nature of the molecules and later used dissymmetrical for handed. Chirality, coined by Lord Kelvin in 1894 and introduced into chemistry by Mislow in 1962, has nearly completely replaced dissymmetry in the meaning of handedness, but the use of dissymmetry continues today in other contexts for lack of symmetry, reduction of symmetry, or dissimilarity.

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Chirality and chemical processes: A few afterthoughts

Cited by 13 publications

References 16 publications

Chiral Discrimination in Dimers of Diphosphines PH₂PH₂and PH₂PHF

Chiral Discrimination in Dimers of Diphosphines PH₂PH₂and PH₂PHF

Louis Pasteur, Chemical Linguist: Founding the Language of Stereochemistry

Louis Pasteur, language, and molecular chirality. I. Background and Dissymmetry

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Chirality and chemical processes: A few afterthoughts

Cited by 13 publications

References 16 publications

Chiral Discrimination in Dimers of Diphosphines PH2PH2and PH2PHF

Chiral Discrimination in Dimers of Diphosphines PH2PH2and PH2PHF

Louis Pasteur, Chemical Linguist: Founding the Language of Stereochemistry

Louis Pasteur, language, and molecular chirality. I. Background and Dissymmetry

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Chiral Discrimination in Dimers of Diphosphines PH₂PH₂and PH₂PHF

Chiral Discrimination in Dimers of Diphosphines PH₂PH₂and PH₂PHF