Preferential Crystallization

Coquerel, Gérard

doi:10.1007/128_2006_077

Cited by 148 publications

(137 citation statements)

References 57 publications

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“…As the typical example of this latter category, well known is the "preferential crystallization" method to resolve a racemic conglomerate composed of a mixture of homochiral R and S crystals, in which by repeating crystallization from the supersaturated solution with the aid of its enantiopure seed crystals the enantiomerically enriched crystals are efficiently deposited in the alternating chirality sense [15][16][17][18]. However, the racemates existing as a racemic conglomerate occupy only less than 10% of the characterized crystalline racemates, and more than 90% of them are supposed to belong to racemic crystals [19], which are further classified into either a racemic compound consisting of a regular packing of a pair of R and S enantiomers or a racemic mixed crystal (in other words, a pseudoracemate or a solid solution) composed of a random alignment of the two enantiomers in the defined positions ( Figure 2) [9].…”

Section: Open Accessmentioning

confidence: 99%

Chiral Symmetry Breaking Phenomenon Caused by a Phase Transition

2010

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Abstract:We report the mechanism and scope of "preferential enrichment", which is an unusual symmetry-breaking enantiomeric resolution phenomenon that is initiated by the solvent-assisted solid-to-solid transformation of a metastable polymorphic form into a thermodynamically stable one during crystallization from the supersaturated solution of certain kinds of racemic mixed crystals (i.e., solid solutions or pseudoracemates) composed of two enantiomers. The mechanism can well be interpreted in terms of a symmetrybreaking complexity phenomenon involving multistage processes that affect each other.

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Section: Open Accessmentioning

confidence: 99%

Chiral Symmetry Breaking Phenomenon Caused by a Phase Transition

2010

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“…However, the specific behaviour of a particular chiral molecule is generally difficult to predict 13 and must be experimentally determined. Scanning tunnelling microscopy (STM) imaging at submolecular resolution has offered a great deal of information on the local structure, chiral organization, separation and recognition of both intrinsically chiral and prochiral molecules on surfaces [14][15][16][17][18][19] .…”

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confidence: 99%

Stereoselectivity and electrostatics in charge-transfer Mn- and Cs-TCNQ4 networks on Ag(100)

et al. 2012

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Controlling supramolecular self-assembly is a fundamental step towards molecular nanofabrication, which involves a formidable reverse engineering problem. It is known that a variety of structures are efficiently obtained by assembling appropriate organic molecules and transition metal atoms on well-defined substrates. Here we show that alkali atoms bring in new functionalities compared with transition metal atoms because of the interplay of local chemical bonding and long-range forces. using atomic-resolution microscopy and theoretical modelling, we investigate the assembly of alkali (Cs) and transition metals (mn) co-adsorbed with 7,7,8,8-tetracyanoquinodimethane (TCnQ) molecules, forming chiral superstructures on Ag(100). Whereas mn-TCnQ 4 domains are achiral, Cs-TCnQ 4 forms chiral islands. The specific behaviour is traced back to the different nature of the Cs-and mn-TCnQ bonding, opening a novel route for the chiral design of supramolecular architectures. moreover, alkali atoms provide a means to modify the adlayer electrostatic properties, which is important for the design of metal-organic interfaces.

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“…An option is the so-called preferential crystallization [71,72]; coupling it to chromatography is discussed in [73].…”

Section: E2 Smb Chromatography In Process Combinationsmentioning

confidence: 99%

New Developments in Simulated Moving Bed Chromatography

2008

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Chromatographic separation processes are widely used to isolate and purify value added products. Most frequently, such separation processes are performed exploiting the principles of injecting samples of the feed mixture in a repetitive periodic manner and collecting the target products batchwise. In the early 1960s, an alternative operation principle based on using several columns connected in series and exploiting a continuous countercurrent movement between the mobile and stationary phases initiated significant improvements in performing specific separation processes in the petrochemical and sugar industries. In the last decade, the so-called simulated moving bed (SMB) chromatography has rapidly entered the pharmaceutical industry. In particular enantioseparations using chiral stationary phases have become a strong driving force to develop more sophisticated concepts of continuous chromatography. Currently, the growing interest in efficient methods for the downstream processing of biomolecules enhances interest in SMB processes. This paper gives a brief overview of the new suggestions and trends. © 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim [accessed July 4, 2008

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Preferential Crystallization

Cited by 148 publications

References 57 publications

Chiral Symmetry Breaking Phenomenon Caused by a Phase Transition

Chiral Symmetry Breaking Phenomenon Caused by a Phase Transition

Stereoselectivity and electrostatics in charge-transfer Mn- and Cs-TCNQ4 networks on Ag(100)

New Developments in Simulated Moving Bed Chromatography

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