Self-Assembled Dimerization of Bis(crown ether)-2,2′-bibenzimidazoles

• Published in: Bulletin of the Chemical Society of Japan Vol. 87; no. 1; pp. 88 - 97
• Main Authors: Satake, Akiharu, Tanaka, Kazuo, Asakura, Hiroki, Okano, Masahiro, Hashimoto, Tsutsumu, Matsuura, You, Inaba, Yusuke, Oda, Tetsuhisa, Hirota, Shun, Koshino, Hiroyuki
• Format: Journal Article
• Language: English
• Published: TOKYO The Chemical Society of Japan 2014; Chemical Soc Japan; Chemical Society of Japan
• Subjects: Chemistry; Chemistry, Multidisciplinary; Curve fitting; Derivatives; Isomers; Methyl alcohol; Nuclear magnetic resonance; Physical Sciences; Potassium; Science & Technology; Stoichiometry; Titration; GUEST; COORDINATION; CRYSTAL; ROTAXANES; CYCLIC POLYETHERS; COMPLEXES
• ISSN: 0009-2673; 1348-0634
• DOI: 10.1246/bcsj.20130173

Bis(crown ether)-2,2′-bibenzimidazole 1 and its 1-substituted derivatives were synthesized as new self-assembled motifs. UV–vis and 1H NMR titration experiments of 1 with potassium ions in a mixture of chloroform and methanol (1:1) were carried out. The stoichiometries and curve fitting analysis showed that a 2:2 complex of 1 with potassium ions was formed in a face-to-face fashion. 1-Monosubstituted bis(crown ether)-2,2′-bibenzimidazole 6a having a (dodecylaminocarbonyl)methyl group also gave a 2:2 complex with potassium ions. Structural analysis of the 2:2 complex of 6a with potassium ions was performed using various two-dimensional NMR techniques. Results suggested that, of eight or more possible conformational isomers, the one having the two substituent groups diagonally opposite each other was predominantly formed. Reversible association and dissociation of the 2:2 complex was observed after adding potassium ions and then removing them with an 18-crown-6-ether.