Molecules, Crystals, and Chirality

Suh, Il-Hwan; Park, Koon Ha; Jensen, William P.; Lewis, David E.

doi:10.1021/ed074p800

Cited by 42 publications

(19 citation statements)

References 3 publications

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“…4) It is well known that chirality has attracted much attention in the field of organic chemistry because chirality plays a role in many important chemical reactions. 5,6) For instance, only one enantiomer of a molecule can participate in many biological reactions, and many drags are produced owing to the chiral reactions. However, only a few applications of chiral organic materials in electrical and optical devices have been proposed, although some chiral structures of organic materials may show interesting optical and electrical characteristics.…”

Section: Introductionmentioning

confidence: 99%

Induced Optical Chirality of Poly(diacetylene) Film by Circularly Polarized Light and Its Control by Changing Substrate Temperature

Kohn¹,

Ohshima²,

Manaka³

et al. 2008

jjap

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The strength of chirality of a blue-phase poly(diacetylene) (PDA) film polymerized from achiral monomers using circularly polarized light (CPL) was effectively controlled by changing substrate temperature (313 and 273 K). The obtained absorption spectra did not show a difference between PDA films polymerized using left-and right-CPL, whereas the chiral PDA films with opposite chirality were selectively produced by left-and right-CPL irradiations. The PDA film prepared at 313 K showed stronger chirality than that prepared at 273 K. Microscopy observation clearly indicates that the strength of chirality depends on the domain size.

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Section: Introductionmentioning

confidence: 99%

Induced Optical Chirality of Poly(diacetylene) Film by Circularly Polarized Light and Its Control by Changing Substrate Temperature

Kohn¹,

Ohshima²,

Manaka³

et al. 2008

jjap

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“…No caso do átomo de carbono, quando está ligado a 4 substituintes diferentes (carbono assimétrico; Figura 1), a molécula é dita quiral, e possui atividade ótica (SUH et al, 1997). Não tem plano de simetria, ou seja é assimétrica e a sua imagem especular não é idêntica, isso deve-se à distribuição espacial dos átomos.…”

Section: Sendo Que Vários Conceitos Devem Ser Apresentados Aos Alunosunclassified

Modelos Moleculares Confeccionados Em Papel Para Estudo Do Conteúdo De Estereoquímica / Molecular Models Made on Paper to Study of the Stereochemistry

Bitencourt

Bitencourt²,

Marinho

et al. 2020

BJD

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“…When considering rotation about the aryl-nitrogen bond, one sees that conformations with noncoplanar π systems such as (M)-2 are sterically less hindered than coplanar ones. (M)-2 shows neither an internal plane of symmetry nor a center of symmetry; thus two enantiomers must exist (6b, 8). These stereoisomers were experimentally separated and characterized (9).…”

Section: Two Elements Of Chiralitymentioning

confidence: 99%

The Metolachlor Herbicide: An Exercise in Today's Stereochemistry

Mannschreck

Angerer

2009

J. Chem. Educ.

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In the ClassroomMany plants such as cereals are cultivated for the nutrition of humans and animals. The output of these crops would be considerably diminished if they were not protected against a variety of detrimental weeds. The latter compete successfully with the cultivated plants for space, sunlight, water, and nutrients in the soil. Chemicals used to selectively inactivate or kill weeds are called herbicides (1a). One of the most used representatives, (particularly in the United States) is metolachlor (Figure 1), an anilide registered for the protection of many different types of plants worldwide (2). This molecule forms stereoisomers 1 that have been analyzed separately and as a mixture for their bioactivity in reference to weed extermination. Such experiments are required because of environmental aspects (2) and the necessity to optimize the agronomic use. The compositions of stereoisomeric mixtures must also be taken into account for the industrial preparation. The present article deals with the three-dimensional structures, the syntheses, and the bioactivities of metolachlor stereoisomers.An overview of the following topics is beneficial to the comprehension of this manuscript: racemic and chiral nonracemic (3a) samples; zigzag formulas (3b); the principle of NMR and chromatography with a nonracemic auxiliary or sorbent, respectively (4); crystallization of diastereomeric derivatives (5a, 6a); and the elements of enantioselective reactions (7a). The content of this article can be integrated into a lecture on advanced organic agrochemistry. The present manuscript describes facts related to metolachlor, such as its stereoisomers or its syntheses. These specific facts are proposed as examples to illustrate general stereochemical aspects, such as axial and central chirality or enantioselective hydrogenation of achiral substrates. These topics are often taught in the third (or a later) year of university chemistry curriculum. The general aspects will be summarized in the conclusion of the article. Several Metolachlor Stereoisomers Two Elements of ChiralityMetolachlor, 1, has a stereocenter in one of the N substituents but, in addition, it exhibits a second, less usual element of chirality, the axial one (3c, 7b). Before looking at metolachlor, we shall consider a similar molecule, the model anilide 2, showing this element exclusively. We focus for a moment on formulas (M)-and (P)-2 ( Figure 2) representing the enantio mers; the descriptors (M) and (P) will be explained later. (M)-2 contains two planar π systems: the arene ring and the O=C−N fragment 1 with O=C and C−N partial double bonds. When considering rotation about the aryl-nitrogen bond, one sees that conformations with noncoplanar π systems such as (M)-2 are sterically less hindered than coplanar ones. (M)-2 shows neither an internal plane of symmetry nor a center of symmetry; thus two enantiomers must exist (6b, 8). These stereoisomers were experimentally separated and characterized (9).The descriptors (M) and (P) will be briefly explained with the e...

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Molecules, Crystals, and Chirality

Cited by 42 publications

References 3 publications

Induced Optical Chirality of Poly(diacetylene) Film by Circularly Polarized Light and Its Control by Changing Substrate Temperature

Induced Optical Chirality of Poly(diacetylene) Film by Circularly Polarized Light and Its Control by Changing Substrate Temperature

Modelos Moleculares Confeccionados Em Papel Para Estudo Do Conteúdo De Estereoquímica / Molecular Models Made on Paper to Study of the Stereochemistry

The Metolachlor Herbicide: An Exercise in Today's Stereochemistry

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