Molecular dynamics of coil-rod-coil molecules depending on their concentrations in polar or non-polar solvent: intra- and intermolecular interactionsand charge transfer emissions

Concentration-dependent molecular dynamics of long coil-rod-coil molecules at the concentrations of 1 x 10(-6) M similar to 1 x 10(-4) M in polar or n on-polar solvent were investigated by steady-state excitation, fluorescence , and picosecond time-resolved fluorescence spectroscopies. The fluorescenc e spectra of the molecules reveal both characteristics of local excited-sta te emission and strong intramolecular charge-transfer (ICT) emission. The s teady-state excitation spectra and the picosecond time-resolved fluorescenc e decay profiles in the concentrations of 5 x 10(-5) M and 1 x 10(-4) M asc ertain hydrophobic rod-to-rod interaction (J-aggregation) in methanol solut ion. The hydrophilic intermolecular interactions (amorphous aggregation) in n-hexane are also discussed. (C) 2000 Elsevier Science B.V. All rights res erved.