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Titolo:
CONSTITUTIONALLY ASYMMETRIC AND CHIRAL [2]PSEUDOROTAXANES
Autore:
ASAKAWA M; ASHTON PR; HAYES W; JANSSEN HM; MEIJER EW; MENZER S; PASINI D; STODDART JF; WHITE AJP; WILLIAMS DJ;
Indirizzi:
EINDHOVEN UNIV TECHNOL,ORGAN CHEM LAB,POB 513 NL-5600 MB EINDHOVEN NETHERLANDS EINDHOVEN UNIV TECHNOL,ORGAN CHEM LAB NL-5600 MB EINDHOVEN NETHERLANDS UNIV BIRMINGHAM,SCH CHEM BIRMINGHAM B15 2TT W MIDLANDS ENGLAND UNIV LONDON IMPERIAL COLL SCI TECHNOL & MED,DEPT CHEM LONDON SW7 2AY ENGLAND
Titolo Testata:
Journal of the American Chemical Society
fascicolo: 5, volume: 120, anno: 1998,
pagine: 920 - 931
SICI:
0002-7863(1998)120:5<920:CAAC[>2.0.ZU;2-R
Fonte:
ISI
Lingua:
ENG
Soggetto:
LIQUID-CRYSTALLINE POLYMERS; MOLECULAR DEVICES; MESOGENIC GROUPS; COMPLEXES; SUPERSTRUCTURES; DESIGN; PERSPECTIVES; BEHAVIOR; PARAQUAT; SYSTEMS;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Citazioni:
52
Recensione:
Indirizzi per estratti:
Citazione:
M. Asakawa et al., "CONSTITUTIONALLY ASYMMETRIC AND CHIRAL [2]PSEUDOROTAXANES", Journal of the American Chemical Society, 120(5), 1998, pp. 920-931

Abstract

The self-assembly and characterization of a range of chiral pseudorotaxanes has been explored using chiroptical methods. The syntheses of (i) constitutionally asymmetric acyclic hydroquinone-containing polyethers and (ii) optically active hydroquinone-containing acyclic polyethers, bearing pairs of methyl or isobutyl groups related to each other in a C-2-symmetric manner within the polyether backbone, are described. The combination of (i) the tetracationic cyclophane cyclobis(paraquat-p-phenylene) tetrakis(hexafluorophosphate), possessing a pi-electron deficient cavity, and (ii) the linear noncentrosymmetric acyclic polyethers produces [2]pseudorotaxanes that have been characterized by H-1 NMR, UV/vis and circular dichroism (CD) spectroscopies in solution andby X-ray crystallography in the solid state. The introduction of constitutional asymmetry or chirality gives rise to a number of different geometries for the [2]pseudorotaxanes in both the solution and solid states. in particular, CD-spectroscopic measurements on the optically active [2]pseudorotaxanes have shown that-depending on the positions ofthe C-2 symmetrically related chiral centers in the polyether chains with respect to the hydroquinone rings-the chirality present in the pi-electron rich threadrike guest can induce chirality that is associated with the supramolecular structure as a whole, resulting in a chiral charge-transfer transition involving not only the pi-donors in the chiral guests but also the pi-acceptors in the achiral host.

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Documento generato il 22/01/20 alle ore 09:32:52