Synthesis and Cross-Linking of a Benzoxazine-Containing Anthracene Moiety: Thermally Stable Photoluminescent Benzoxazine Resin

A novel benzoxazine
derivative, 9,10-bis­(6-ethynyl-3-phenyl-3,4-dihydro-1,3-benzoxazine)­anthracene
(1a), was synthesized by the Sonogashira–Hagihara
coupling reaction of 9,10-dibromoanthracene and 6-ethynyl-3-phenyl-3,4-dihydro-1,3-benzoxazine.
A CH2Cl2 solution of 1a luminesced
with a high quantum yield (Φ = 81%). Compound 1a afforded solvent-insoluble cross-linked polybenzoxazine 1b by the bulk polymerization at 250 °C. Solution polymerization
of a dilute solution of 1a at 200 °C afforded solvent-soluble
samples, accompanied by a decrease of photoluminescence intensity.
The weight loss values of 1a and 1b were
81 and 87%, respectively, under nitrogen at 500 °C. We believe
that the present study will lead to thermally stable curing resins
whose degree of curing can be estimated with the naked eye by observing
the decrease of photoluminescence.