Cellulose derivatives bearing pyrene-based π-conjugated pendants with circularly polarized luminescence in molecularly dispersed state

Publication date: 19 May 2017
Source:Polymer, Volume 117
Author(s): Tomoyuki Ikai, Yutaka Kojima, Ken-ichi Shinohara, Katsuhiro Maeda, Shigeyoshi Kanoh
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 (glum) 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 glum 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.

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