1. Polyacetylenes Bearing Chiral-Substituted Fluorene and Terfluorene Pendant Groups: Synthesis and Properties
- Author
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Piero Mastrorilli, Pio Iannelli, Domenico Acierno, Gian Paolo Suranna, Cosimo Francesco Nobile, Antonino Rizzuti, Eugenio Amendola, Roberto Grisorio, Acierno, Domenico, Mastrorilli, P., Nobile, C. F., Grisorio, R., Rizzati, A., Scranna, G. P., Amendola, E., and Iannelli, P.
- Subjects
chemistry.chemical_classification ,Photoluminescence ,Polymers and Plastics ,Organic Chemistry ,Terfluorene ,Polymer ,Fluorene ,Inorganic Chemistry ,chemistry.chemical_compound ,Monomer ,chemistry ,Polymerization ,Acetylene ,polyacetylenes ,Polymer chemistry ,Materials Chemistry ,Thermal stability ,Alkyl - Abstract
The synthesis of the first polyacetylenes bearing chiral fluorene-based pendant groups is described. Poly{9,9-bis[(S)-3,7-dimethyloctyl]fluoren-2-ylacetylene} (PFA1), poly{9,9-bis[(S)-2-methylbutyl]fluoren-2-ylacetylene} (PFA2), and poly{9,9,9',9',9'',9''-hexakis[(S)-2-methylbutyl]-7,2';7',2''-terfluoren-2-ylacetylene} (PFA3) have been obtained by Rh(I)-catalyzed polymn. of the corresponding terminal acetylene monomers 2-ethynyl-9,9-bis[(S)-3,7-dimethyloctyl]fluorene , 2-ethynyl-9,9-bis[(S)-2-methylbutyl]fluorene, and 2-ethynyl-9,9,9',9',9'',9''-hexakis[(S)-2-methylbutyl]-7,2';7',2''-terfluorene. The effect of the alkyl chain length at the C-9 position of fluorene on the structural and conformational aspects of the polymers PFA1 and PFA2 as well as on their chiroptical properties was studied by XRD, DSC, TGA, GPC, UV-vis, and CD. A more planar conformation of the polyenic backbone of PFA1 with respect to PFA2 can be inferred by a red shift of the à-à* transition in the UV-vis spectra. Their photoluminescence properties are those typical of fluorene systems. CD measurements evidenced Cotton effects of opposite signs in correspondence of the backbone absorption region, ascribable to an excess of a screw sense of the helical conformations assumed by the two polymers. PFA3 revealed an amorphous structure and exhibited peculiar thermal stability features (as indicated by TGA and DSC). Its emission spectra interest the violet-blue region and do not show any substantial red shift passing from soln. to solid state, thus pointing out an aggregation prevention of terfluorene groups by means of the polyacetylene backbone.
- Published
- 2004