Asymmetric Dyes

Porter, C. W.; Ihrig, Harry K.

doi:10.1021/ja01661a020

Cited by 30 publications

(4 citation statements)

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“…The first unsuccessful attempt to resolve enantiomers based on their selective adsorption from the liquid phase onto chiral material was reported in 1904 by Willstätter in the course of his investigation to understand if coloring of wool is a chemical or physical process . Other attempts of enantiomer separation through the use of chiral nonracemic adsorbents date back to the 1920s, including the observation of induced optical rotation in racemic dye solutions used to dye wool. , In general, these early attempts were carried out by using natural chiral polymeric adsorbents such as wool and cellulose or other polysaccharides. In 1939, Henderson and Rule reported the first example of partial separation of enantiomers by using the disaccharide lactose as chiral adsorbent, and later Prelog and Wieland used the same lactose to separate Tröger’s base enantiomers .…”

Section: Chirality and Chiral Entitiesmentioning

confidence: 99%

Recognition in the Domain of Molecular Chirality: From Noncovalent Interactions to Separation of Enantiomers

2022

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It is not a coincidence that both chirality and noncovalent interactions are ubiquitous in nature and synthetic molecular systems. Noncovalent interactivity between chiral molecules underlies enantioselective recognition as a fundamental phenomenon regulating life and human activities. Thus, noncovalent interactions represent the narrative thread of a fascinating story which goes across several disciplines of medical, chemical, physical, biological, and other natural sciences. This review has been conceived with the awareness that a modern attitude toward molecular chirality and its consequences needs to be founded on multidisciplinary approaches to disclose the molecular basis of essential enantioselective phenomena in the domain of chemical, physical, and life sciences. With the primary aim of discussing this topic in an integrated way, a comprehensive pool of rational and systematic multidisciplinary information is provided, which concerns the fundamentals of chirality, a description of noncovalent interactions, and their implications in enantioselective processes occurring in different contexts. A specific focus is devoted to enantioselection in chromatography and electromigration techniques because of their unique feature as “multistep” processes. A second motivation for writing this review is to make a clear statement about the state of the art, the tools we have at our disposal, and what is still missing to fully understand the mechanisms underlying enantioselective recognition.

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Section: Chirality and Chiral Entitiesmentioning

confidence: 99%

Recognition in the Domain of Molecular Chirality: From Noncovalent Interactions to Separation of Enantiomers

2022

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“…Porter et al [8,79] discussed the relationship between miscibility and transesterification for a variety of polyester blends, including various polyesters with LCPs. Recent results on blends of LCPs with PC, PBT, and PET are summarised below.…”

Section: Liquid-crystalline Polymer (Lcp) Blendsmentioning

confidence: 99%

Effects of Transreactions on the Compatibility and Miscibility of Blends of Condensation Polymers

Xanthos¹,

Warth²

1999

Transreactions in Condensation Polymers

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Principles of blend compatibilisationFew polymers form truly miscible blends characterised by a single glass transition temperature (Tg) and homogeneity on a 5-10nm scale with domain sizes comparable to the dimension of a macromolecular statistical segment. The majority of blends are immiscible, i e . , possess a phase separated morphology. Blends of this type are often preferred over the miscible ones since they combine some of the important characteristics of both blend constituents. Blend composition, viscoelastic properties of the components, and interfacial adhesion are among the parameters known to control the size and morphology of the dispersed phase and its stability to coalescence. Heterogeneous blends of technological importance are termed "compatible" and they constitute the majority of the commercial blends introduced in the past 30 years. In such blends, often known also as alloys, satisfactory physical and mechanical properties are related to the presence of an interphase modified through compatibilisation and the formation of a fine dispersed morphology resistant to phase separation.Polymer compatibility, which may lead ultimately to complete thermodynamic miscibility, may be enhanced by various methods. In addition to cocrystallisation and cocrosslinking, strong interactions such as acidbase or ion-dipole, hydrogen bonding and transition metal complexation Transreactions in Condensation PolymersStoyho Fahirov copyright 0 WILEY-VCH Verlag GrnbH. 1999 412 M. Xanthos, H. Warth between suitably functionalised components, have been shown to improve compatibility. More commonly, compatibility is promoted through interfacially active copolymers (e.g., block, graft, random) with segments capable of specific interactions and/or chemical reactions with the blend components. The copolymers may be added separately, or formed in situ through chemical reactions, often catalysed by the addition of low molecular weight (MW) compounds. Reactive and non-reactive compatibilisation of polymer blends has been the subject of numerous reviews [l-71.During blending of a pair of suitably functionalised polymers A and B, interchain block, graft, or random copolymers may be formed at various concentrations through covalent or ionic bonding. According to Brown [3] , the following are five general types of chemical processes/reactions by which interchain copolymer formation has been achieved in extruder reactors: 1. Chain cleavage/recombination (main chain of A/main chain of B or 2. End-group of A/end-group of B; block. 3. End-group of A/pendant functionality of B; graft. 4. Covalent cross-linking: pendant functionality of Alpendant functionality of B or main chain of A/main chain of B; graft (crosslinked network). Ionic bond formation between A and B; usually graft (usually crosslinked).The compatibilisers formed in situ have segments that are chemically identical to those in the respective unreacted homopolymers and are thought to be located preferentially at the interface, thus lowering interfacial tension, and also promo...

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“…m-Azodimethylanilinemandelic Purple Neg. red rriatie amine; the products were bright colored azo derivatives of mandelic acid (1,9). Phenol, resorcinol, 2-naphthol, and two aromatic amines, dimethylaniline and m-aminomandelie acid, were used as coupling reagents.…”

Section: Synthesis Of Reagentsmentioning

confidence: 99%