Alternating copolymers containing an aromatic chromophore in every monomer unit. 2. Excimer formation and intramolecular energy migration in alternating copolymers of naphthylalkyl methacrylate and vinylnaphthalene

摘要

A series of alternating and random copolymers of 2-naphthylalkyl methacrylates (NpMMA and NpEMA) and 2-vinylnaphthalene (VNp) were synthesized, and their fluorescence properties in tetrahydrofuran (THF) were compared. All of the alternating copolymers containing NpMMA or NpEMA showed a weak excimer emission, indicating that excimer formation between naphthyl (Np) chromophores in the alternating methacrylate sequences cannot be perfectly inhibited. No distinct difference in the fluorescence from the NpMMA and VNp moieties in poly(NpMMA-alt-VNp) (a-NpVNp) suggests that practically the same chromophores are aligned along the whole polymer chain. This observation is sharp in contrast with the corresponding phenyl polymers exhibiting different spectral features. Fluorescence quenching studies, however, showed no enhancement of the quenching efficiencies for a-NpVNp among the present polymers. Therefore, energy migration between the nearest-neighboring Np chromophores would inefficiently occur, though this polymer has the highest density of chromophores. [References: 14]