Cellulose derivatives bearing pyrene-based π-conjugated pendants with circularly polarized luminescence in molecularly dispersed state. (19th May 2017)

• Record Type: Journal Article
• Authors: Ikai, Tomoyuki; Kojima, Yutaka; Shinohara, Ken-ichi; Maeda, Katsuhiro; Kanoh, Shigeyoshi
• Is Part Of: Polymer. Volume 117(2017)
• Page Start: 220
• Page End: 224
• Publication Date: 2017-05-19
• Subjects: Circularly polarized luminescence -- Excimer formation -- Polysaccharides; Polymers -- Periodicals; Polymerization -- Periodicals; Polymères -- Périodiques; Polymérisation -- Périodiques; 547.7
• DOI: 10.1016/j.polymer.2017.04.032
• Languages: English
• ISSNs: 0032-3861

Abstract

Abstract: A series of novel cellulose derivatives bearing pyrene-based π-conjugated pendants as a fluorescent unit was synthesized from microcrystalline cellulose via carbamoylation followed by Sonogashira–Hagihara cross-coupling, and their photoluminescence and circularly polarized luminescence (CPL) properties were investigated in solution. The cellulose derivatives Ce-1 and Ce-2 carrying the pyrene units at the 2, 3, 6- and 2, 3-positions of the repeating glucose unit, respectively, exhibited greenish CPL with dissymmetry factors ( g lum ) greater than 3.0 × 10 −3 . In contrast, the analogous polymer (Ce-3 ), carrying the pyrene unit only at the 6-position, and the model molecules (Gl-1 and Gl-2 ) mainly emitted bluish monomer fluorescence with lower g lum values less than 0.5 × 10 −3 . Both the helical chirality derived from the cellulose backbone and the intramolecular excimer formation of the pyrene units were considered to play key roles in the efficient CPL. Graphical abstract: Highlights: Novel cellulose derivatives bearing pyrene-based π-conjugated pendants were synthesized. The substitution pattern of the pyrene pendants greatly impacted their fluorescence properties. The properly modified derivatives exhibited the apparent circularly polarized luminescence (CPL). Their CPL was mainly derived from the intramolecular excimer formed along the helical main-chain. This is the first example of cellulose materials exhibiting CPL in a molecularly dispersed state.