Bulletin des Sociétés Chimiques Belges vol:106 issue:9-10 pages:565-572
The influence of the rotational volume and redox properties of the N-substituents on the fluorescence spectra and decays of oxacarbocyanine dyes were investigated as function of the solvent polarity and/or polarisability. While alkyl and alkylbenzene side chains give rise to one-exponential fluorescence decay, the presence of a butylnaphthyl substituent induces a bi-exponential fluorescence decay in solvents with low polarisability and/or polarity. This was attributed to a conformation where the naphthyl moieties form a ground state dimer. With alkylpyrenyl substituents the fluorescence decay becomes bi-exponential due to the occurrence of a reversible intramolecular electron transfer.