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

A series of novel cellulose derivatives bearing pyrene-based pi-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 x 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 x 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. (C) 2017 Elsevier Ltd. All rights reserved.