Poly(fluorene)s and poly(p-phenylene)s with pyrenyltriazine segments: synthesis and photophysics

A Friedel-Crafts reaction between cyanuric chloride and pyrene afforded 2,4-dichloro-6-(pynen-1-yl)-1,3,5-triazine (1). This reacted with 4-bromophenol to yield 2,4-bis(4-bromophenoxy)-6-(pyren-1-yl)-1,3,5-triazine (2). A series of random copolymers PF-Pyr with various compositions were prepared by Suzuki polycondensation from 2,7-dibromo-9,9-di-2-ethylhexylfluorene (3) and 2. In addition, a series of random copolymers PP-Pyr were similarly prepared from 1,4-dibromo-2,5-didodecyloxybenzene (5) and 2. Solutions of copolymers PF-Pyr emitted blue light with photoluminescence (PL) maximum at 414-444 nm. Thin films of these copolymers emitted intense green light with PL maximum near 520 nm. An efficient energy transfer took place in thin films from the fluorene to the pyrenyltriazine segment even the content of the latter in copolymer was 0.5 mol%. Copolymers PP-Pyr behaved as blue light-emitting materials both in solution and solid state. Their PL maximum was red shifted with increasing the pyrenyltriazine content in copolymer. The PL quantum yields in solution were 0.42-0.56 for PF-Pyr and 0.27-0.35 for PP-Pyr.