Isolable Chiral Aggregates of Achiral π-Conjugated Carboxylic Acids.
Summary of "Isolable Chiral Aggregates of Achiral π-Conjugated Carboxylic Acids."
The induced aggregation of achiral building blocks by a chiral species to form chiral aggregates with memorized chirality has been observed for a number of systems. However, chiral memory in isolated aggregates of achiral building blocks remains rare. One possible reason for this discrepancy could be that not much is understood in terms of designing these chiral aggregates. Herein, we report a strategy for creating such isolable chiral aggregates from achiral building blocks that retain chiral memory after the facile physical removal of the chiral templates. This strategy was used for the isolation of chiral homoaggregates of neutral achiral π-conjugated carboxylic acids in pure aqueous solution. Under what we have termed an "interaction-substitution" mechanism, we generated chiral homoaggregates of a variety of π-conjugated carboxylic acids by using carboxymethyl cellulose (CMC) as a mediator in acidic aqueous solutions. These aggregates were subsequently isolated from the CMC templates whilst retaining their memorized supramolecular chirality. Circular dichroism (CD) spectra of the aggregates formed in the acidic CMC solution exhibited bisignated exciton-coupled signals of various signs and intensities that were maintained in the isolated pure homoaggregates of the achiral π-conjugated carboxylic acids. The memory of the supramolecular chirality in the isolated aggregates was ascribed to the substitution of COOH/COOH hydrogen-bonding interaction between the carboxylic acid groups within the aggregates for the hydrogen-bonding interactions between the COOH groups of the building blocks and the chiral templates. We expect that this "interaction-substitution" procedure will open up a new route to isolable pure chiral aggregates from achiral species.
Department of Chemistry, College of Chemistry and Chemical Engineering and the MOE Key Laboratory of Analytical Sciences, Xiamen University, Xiamen 361005 (P. R. China), Fax: (+86) 592-218-6401.
This article was published in the following journal.
Name: Chemistry (Weinheim an der Bergstrasse, Germany)
- PubMed Source: http://www.ncbi.nlm.nih.gov/pubmed/22328175
- DOI: http://dx.doi.org/10.1002/chem.201103651
Only the mixture works! Acrylic acid derivatives with CF3 substituents in α or β position were efficiently hydrogenated in the presence of a Rh(I) complex with a chiral secondary phosphine oxide (...
Four types of alkenyl organocopper(I) aggregates linked by 1,3-butadienyl and/or 1,3,5,7-octatetraenyl moieties were high selectively realized in good isolated yields. All these organocopper(I) aggreg...
An N-terminal L-α-methylvaline dimer induces complete conformational control over the screw sense of an otherwise achiral helical peptide foldamer formed from the achiral quaternary amino acids Aib a...
Three structurally related relay protecting groups for carboxylic acids that are based on chelating amines have been developed. These protecting groups can easily be introduced by coupling the carboxy...
Novel chiral 4,1-benzoxazepine-2,5-diones have been unusually synthesized in a single step by exploiting the chiral pool methodology. Substituted anthranilic acids afford N-acylanthranilic acids and (...
Conjugated linoleic acids (CLA) are naturally occurring free fatty acids derived from the tissues and milk of ruminant animals such as cows. CLA has multiple biological properties includin...
The purpose of the study is to see how a dietary oil called conjugated linoleic acid, or CLA, might be useful in combination with diabetes medication. Some studies show that CLA can modes...
The purpose of this research study is to evaluate the safety and effectiveness of this investigational drug for the treatment of menopausal symptoms while protecting the endometrium (uteri...
The primary purpose is to determine bioavailability of Bazedoxifene/conjugated estrogen formulations for future testing purposes.
The purpose of this study is to determine whether Bazedoxifine/conjugated estrogens are effective in the treatment of vaginal atrophy.
Medical and Biotech [MESH] Definitions
Organic compounds containing the carboxy group (-COOH). This group of compounds includes amino acids and fatty acids. Carboxylic acids can be saturated, unsaturated, or aromatic.
Enzymes which catalyze the hydrolysis of carboxylic acid esters with the formation of an alcohol and a carboxylic acid anion.
Compounds consisting of chains of AMINO ACIDS alternating with CARBOXYLIC ACIDS via ester and amide linkages. They are commonly cyclized.
Steroid acids and salts. The primary bile acids are derived from cholesterol in the liver and usually conjugated with glycine or taurine. The secondary bile acids are further modified by bacteria in the intestine. They play an important role in the digestion and absorption of fat. They have also been used pharmacologically, especially in the treatment of gallstones.
Carboxylic acids that have open-chain molecular structures as opposed to ring-shaped structures.