A NEW SOLUBLE POLY(P-PHENYLENE) WITH TETRAHYDROPYRENE REPEATING UNITS

The first poly(p-phenylene) (PPP) based on repeating 4,5,9,10-tetrahydropyrene units has been synthesized starting from 2,7-dibromo-4,9-di-n-octyl-4,5,9,10-tetrahydropyrene (3a) as the monomer in a polycondensation reaction. The new polymer is soluble in common organic solvents such as CHCl3, CH2Cl2, THF, and toluene. By contrast with other PPP's, the solubilizing alkyl substituents do not induce torsion about the aryl-aryl single bonds. GPC analysis indicates a monomodal molecular weight distribution, and the average degree of polymerization, based on tetrahydropyrene units, is 40 (polystyrene standards), corresponding to 80 phenylene rings. The NMR spectra reveal that the poly(tetrahydropyrene) (PTHPy, 4) obtained possesses a regular structure. The fluorescence spectrum measured in THF solution shows an emission maximum at 425 nm, while for the film, the maximum is shifted to 457 nm. The above characteristics qualify the new PPP as an attractive material for use in light-emitting diodes.