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.
|Autori interni:||PESCITELLI, GENNARO|
|Autori:||José V. Prata; Alexandra I. Costa; Gennaro Pescitelli; Hugo D. Pinto|
|Titolo:||Chiroptical and emissive properties of a calixarene-containing chiral poly(p-phenylene ethynylene) with enantioselective recognition ability|
|Anno del prodotto:||2014|
|Digital Object Identifier (DOI):||10.1039/C4PY00729H|
|Appare nelle tipologie:||1.1 Articolo in rivista|