Detalhes bibliográficos
| Autor(a) principal: |
Prata, José Virgílio |
| Data de Publicação: |
2014 |
| Outros Autores: |
Costa, Alexandra,
Pescitelli, Gennaro,
Pinto, Hugo D. |
| Tipo de documento: |
Artigo
|
| Idioma: |
eng |
| Título da fonte: |
Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos) |
| Texto Completo: |
http://hdl.handle.net/10400.21/4926
|
Resumo: |
Supramolecular chirality was achieved in solutions and thin films of a calixarene-containing chiral aryleneethynylene copolymer. The observed chiroptical activity, which is primarily allied with the formation of aggregates of high molecular weight polymer chains, is the result of a combination of intrachain and interchain effects. The former arises by the adoption of an induced helix-sense by the polymer main-chain while the latter comes from the exciton coupling of aromatic backbone transitions. The co-existence of bulky bis-calixKlarene units and chiral side-chains on the polymer skeleton prevents efficient pi-stacking of neighbouring chains, keeping the chiral assembly highly emissive. In contrast, for a model polymer lacking calixarene moieties, the chiroptical activity is dominated by strong interchain exciton couplings as a result of more favourable packing of polymer chains, leading to a marked decrease of photoluminescence in the aggregate state. The enantiomeric recognition abilities of both polymers towards (R)- and (S)-alpha-methylbenzylamine were examined. It was found that a significant enantiodiscrimination is exhibited by the calixarene-based polymer in the aggregate state. |