Triple fluorescence of poly(methacrylates) with benzanilide side groups

The fluorescence behaviour of poly(methacrylates) with benzanilide side groups and that of related monomer model compounds are compared in solution, crystalline state and as spin-coated films. The fluorescence of benzanilide is characterized by three competitive radiative processes. In addition to the normal fluorescence F1 at 345 nm, a superposition of proton transfer (PT) fluorescence and intramolecular charge transfer (ICT) fluorescence is observed, characterized by a large Stokes shift. The emission of the crystalline monomers, solid polymers and spin-coated films is caused by intermolecular interactions between the benzanilide moieties in form of hydrogen bonds and by an intramolecular charge transfer process. Because of the high efficiency of these interactions, the fluorescence intensity of the normal fluorescence is strongly decreased in solid states and glassy films. The deactivation behaviour of the polymers is investigated in dependence on the matrix properties varied by the temperature. Moreover, it is demonstrated that the intermolecular interactions of the benzanilides are strongly influenced by changes in its intramolecular properties like the modification of the para-substitution of the benzanilide moieties. Photochemical deactivation processes affect neither the photophysical behaviour of the benzanilides in solution nor in the solid state.