title: Predicting the switchable screw sense in fluorene-based polymers.
abstract: A chirality-switching free-energy landscape was reconstructed on a 43-mer of poly(9,9-dioctylfluoren-2,7-diyl) (PDOF). The simulations were conducted on amorphous silica surface as well as in the vacuum phase for a single chain or for a group of sixteen chains. The achiral-to-chiral transition occurs only on amorphous silica (activation free-energy 35 kcal mol(-1) ), where the enantiomeric (homochiral) basins are detected. This was supported by the experiments where effective chirality induction to PDOF using circularly polarized light (CPL) was attained only for a film deposited on a quartz glass and not for a solution or a suspension. These results indicate that interactions of PDOF with amorphous silica play a crucial role in chirality switching. Importance of chain assembling was also indicated. Theoretical ECD spectra of the enantiomeric basins containing a 51 helix reproduce the experimental spectra.
authors: Dipartimento di Scienze della Salute, Università di Catanzaro, Viale Europa, 88100 Catanzaro (Italy). apietropaolo@unicz.it.
authors: Adriana
authors: A
authors: Pietropaolo
authors: Yue
authors: Y
authors: Wang
authors: Tamaki
authors: T
authors: Nakano
keywords: chiral switches; chirality induction; helical structures; molecular dynamics; polymers