Helicity Induction of Polyisocyanate with a Crown Cavity on the Main Chain Synthesized by Cyclopolymerization of α,ω-Diisocyanate

• Published in: Macromolecules Vol. 37; no. 11; pp. 3996 - 4003
• Main Authors: Sakai, Ryosuke, Satoh, Toshifumi, Kakuchi, Ryohei, Kaga, Harumi, Kakuchi, Toyoji
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 01.06.2004
• Subjects: Applied sciences; Exact sciences and technology; Organic polymers; Physicochemistry of polymers; Polymers with particular properties; Preparation, kinetics, thermodynamics, mechanism and catalysts; Liquid liquid extraction; Cyclopolymerization; Temperature effect; Chiral compound; Isocyanate polymer; Experimental study; Intermolecular interaction; Organic solution; Nitrogen heterocycle polymer; Cyclopolymer; Organic diisocyanate; Aminoacid; Ammonium compound; Preparation; Alkali metal ion; Anionic polymerization; Ion extraction; Helical structure; Acyclic crown compound; Crown compound polymer; Conformation
• ISSN: 0024-9297; 1520-5835
• DOI: 10.1021/ma0496448

Polymerization of a novel α,ω-diisocyanate monomer, 1,14-bis(4-isocyanatophenoxy)-3,6,9,12-tetraoxatetradecane (1), was carried out in DMF using MeLi to afford a gel-free linear polymer according to a cyclopolymerization mechanism. The resulting polymer was assignable to poly(phenyl isocyanate) with a C 2 symmetrical crown cavity on the main chain (2). The circular dichroism (CD) spectrum of 2 in the presence of the perchloric acid salt of l-phenylglycine (l-Pgly·HClO4) showed a negative Cotton effect with a high intensity of −3.2 × 104 deg cm2 dmol-1 in the range from 245 to 330 nm, corresponding to the absorption of the polymer backbone, while a positive Cotton effect was observed for d-Pgly·HClO4, and the CD spectrum pattern was a mirror image of that of 2 with l-Pgly·HClO4. Thus, this suggested that the novel type of poly(phenyl isocyanate) with the crown cavity on the main chain (2) formed a one-handed helical structure driven by the host−guest complexation with the chiral guest molecules. Although the solvent significantly influenced the CD intensities of 2, the CD intensities hardly changed at any temperature.