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Title: Conjugated double helices via self-dimerization of α,α′-dianilinotripyrrins
Authors: Umetani, Masataka
Tanaka, Takayuki  kyouindb  KAKEN_id  orcid (unconfirmed)
Osuka, Atsuhiro
Author's alias: 梅谷, 将隆
田中, 隆行
大須賀, 篤弘
Issue Date: 1-Jan-2018
Publisher: Royal Society of Chemistry
Journal title: Chemical Science
Volume: 9
Start page: 6853
End page: 6859
Abstract: A new motif for artificial double helices was developed on the basis of α, α′-disubstituted tripyrrin. α, α′-Dibromotripyrrin 3 was prepared by gentle bromination at the pyrrolic α-positions of 5, 10-diphenyltripyrrane followed by oxidation with DDQ. Nucleophilic substitution reactions of 3 with anilines proceeded efficiently to furnish a series of α, α′-dianilinotripyrrins 4–11, which displayed monomeric and dimeric forms depending upon the solvent used for crystallization and the structures of the substituted anilines. Dimeric forms show double helical structures with smooth π-conjugation as indicated by their absorption spectra. van't-Hoff plot analyses revealed that the dimerizations in CDCl3 are enthalpy-driven. Larger association constants of the dimerization are attained for 3, 5-di-t-butylanilino- and 3, 5-bis(trifluoromethyl)anilino-substituted tripyrrins (7 and 8) via additional multiple intermolecular interactions. In a nonpolar and aprotic solvent, tripyrrins (9 and 10) bearing bulkier 1-naphthylamino and mesitylamino groups do not dimerize but undergo unique tautomerization.
Rights: © The Royal Society of Chemistry 2018. This Open Access Article is licensed under a Creative Commons Attribution-Non Commercial 3.0 Unported Licence.
DOI(Published Version): 10.1039/c8sc02739k
PubMed ID: 30310618
Appears in Collections:Journal Articles

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