Investigation of photophysical properties of 1,8-naphthalimides with an extended conjugation on naphthalene moiety via Suzuki coupling reaction.

Five 4-substituted 1,8-naphthalimides (-), with an extended conjugation on the naphthalene ring, have been synthesized via Suzuki coupling reaction. These derivatives showed a large Stokes shift (up to 200 nm) and longer emission due to the increase of conjugation. Besides strong solvation effect, the low quantum yield were observed in protic solvents compared to in aprotic solvents. The anion forms of - obtained from reacting with NaH gave a significant red-shift for both absorption and emission spectra. These results provided a new strategy for preparation of fluorescent dyes with a long emission on the basis of 1,8-naphthalimde structure by using Suzuki coupling reaction.