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Titolo:
MOLECULAR MECCANO, 38 - ENANTIOSELECTIVE DISCRIMINATION IN THE SELF-ASSEMBLY OF [2]PSEUDOROTAXANES
Autore:
ASAKAWA M; JANSSEN HM; MEIJER EW; PASINI D; STODDART JF;
Indirizzi:
UNIV CALIF LOS ANGELES,DEPT CHEM & BIOCHEM,405 HILGARD AVE LOS ANGELES CA 90095 UNIV BIRMINGHAM,SCH CHEM BIRMINGHAM B15 2TT W MIDLANDS ENGLAND EINDHOVEN UNIV TECHNOL,LAB MACROMOL & ORGAN CHEM NL-5600 MB EINDHOVENNETHERLANDS
Titolo Testata:
EUROPEAN JOURNAL OF ORGANIC CHEMISTRY
fascicolo: 6, , anno: 1998,
pagine: 983 - 986
SICI:
1434-193X(1998):6<983:MM3-ED>2.0.ZU;2-Z
Fonte:
ISI
Lingua:
ENG
Soggetto:
SYNTHETIC RECEPTORS; AQUEOUS-MEDIA; RECOGNITION; )N>PSEUDOROTAXANES; CHEMISTRY; BINDING;
Keywords:
CHIRALITY; HOST-GUEST CHEMISTRY; ENANTIOSELECTIVE RECEPTORS; CD SPECTROSCOPY; SELF-ASSEMBLY;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Citazioni:
33
Recensione:
Indirizzi per estratti:
Citazione:
M. Asakawa et al., "MOLECULAR MECCANO, 38 - ENANTIOSELECTIVE DISCRIMINATION IN THE SELF-ASSEMBLY OF [2]PSEUDOROTAXANES", EUROPEAN JOURNAL OF ORGANIC CHEMISTRY, (6), 1998, pp. 983-986

Abstract

The combination of (i) an optically active, axially chiral pi-electron-deficient tetracationic cyclophane derivative of cyclobis(paraquat-p-phenylene), in which both of the p-phenylene spacers have been replaced by axially-chiral 3,3'-disubstituted binaphthol spacers, and (ii) enantiomeric, pi-electron-rich substrates, in which a hydroquinone ringis inserted into the polyether backbone terminated by carboxyl groupsand substituted in a C-2-symmetric manner by two methyl groups, thus creating two equivalent chiral centers in the substrate, produces in solution 1:1 complexes in which the pi-electron-rich substrates are inserted into the pi-electron-deficient cavities of the cyclophanes in pseudorotaxane-like manner. The differences in the free energies of complexation for (RR) and (SS) enantiomers of the pi-electron-rich substrates span the range from 0.1 to 0.7 kcal mol(-1). Chiral recognition becomes more effective the closer the chiral centers are to the hydroquinone templating unit. CD spectroscopy reveals that the different modesof binding of the enantiomeric substrates by the axially chiral tetracationic cyclophane are not accompanied by drastically different core geometries for the [2]pseudorotaxanes. Thus, the chirality of the complex is governed primarily by the properties of the rigid receptor. Thecombination of the D-2, symmetry of the receptor with the C-2, symmetry of the substrates has been found to be particularly effective, considering that the chiral centers on the substrates are located on polyether chains which possess a high degree of conformational freedom.

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Documento generato il 27/01/20 alle ore 01:37:15