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Titolo:
Synthesis and self-assembly of functionalized hexa-peri-hexabenzocoronenes
Autore:
Ito, S; Wehmeier, M; Brand, JD; Kubel, C; Epsch, R; Rabe, JP; Mullen, K;
Indirizzi:
Humboldt Univ, Dept Phys, D-10115 Berlin, Germany Humboldt Univ Berlin Germany D-10115 Dept Phys, D-10115 Berlin, Germany Max Planck Inst Polymer Res, D-55128 Mainz, Germany Max Planck Inst Polymer Res Mainz Germany D-55128 D-55128 Mainz, Germany
Titolo Testata:
CHEMISTRY-A EUROPEAN JOURNAL
fascicolo: 23, volume: 6, anno: 2000,
pagine: 4327 - 4342
SICI:
0947-6539(200012)6:23<4327:SASOFH>2.0.ZU;2-2
Fonte:
ISI
Lingua:
ENG
Soggetto:
DISCOTIC LIQUID-CRYSTALS; SCANNING-TUNNELING-MICROSCOPY; MOLECULAR-STRUCTURE; TRANSIENT PHOTOCONDUCTIVITY; COLUMNAR MESOPHASES; BOND FORMATION; GRAPHITE; TRIPHENYLENE; INTERFACE; CARBON;
Keywords:
aromatic hydrocarbons; liquid crystals; mesophases; scanning tunnelling spectroscopy; self-assembly;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Physical, Chemical & Earth Sciences
Citazioni:
77
Recensione:
Indirizzi per estratti:
Indirizzo: Rabe, JP Humboldt Univ, Dept Phys, Invalidenstr 110, D-10115 Berlin, Germany Humboldt Univ Invalidenstr 110 Berlin Germany D-10115 n, Germany
Citazione:
S. Ito et al., "Synthesis and self-assembly of functionalized hexa-peri-hexabenzocoronenes", CHEM-EUR J, 6(23), 2000, pp. 4327-4342

Abstract

Monolayers of hexa-alkyl substituted derivatives of hexa-peri-hexabenzocoronene (HBC) 1b have previously been investigated by scanning tunneling microscopy (STM) and scanning tunneling spectroscopy (STS). It is expected thatdifferent functional groups (electron donating or withdrawing) connected to the aromatic core will influence the packing pattern and possibly the current-voltage characteristics as well. In order to provide suitable model systems, a new synthetic approach to synthesize functionalized HBC derivatives has been developed. This was accomplished by [4+2]-cycloaddition of suitably bromo-substituted diphenylacetylenes and 2,3,4,5-tetraarylcyclopenta-2,4-dien-1-ones followed by an oxidative cyclodehydrogenation with iron(III) chloride/nitromethane. Using this strategy three different substitution patterns were synthesized: 2-bromo-5,8,11,14,17-pentadodecylhexa-peri-hexabenzocoronene (2a), 2,5-dibromo-8,11,14,17-pentadodecylhexa-peri-hexabenzocoronene (2b), and 2,11-dibromo-5,8,14,17-pentadodecylhexa-peri-hexabenzocoronene (2c). These bromo-substituted HBC derivatives were subjected to palladiumcatalyzed coupling reactions to give donor (alkoxy, amino) as well as acceptor (ester, cyano) substituted derivatives. The self-assembly of these newHBC derivatives was studied in the bulk as well as at an interface. DSC, optical microscopy, and X-ray diffraction revealed the existence of columnarmesophases. The bulk structure in the mesophase is largely insensitive to changes of the substitution pattern; however, in situ scanning tunneling microscopy at the solid-fluid interface between an organic solution of the HBC derivative and highly oriented pyrolytic graphite reveals different packing patterns of the first adsorbed monolayer.

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Documento generato il 27/11/20 alle ore 01:31:35