3,6,9,12-Tetrasubstituted Chrysenes: Synthesis, Photophysical Properties, and Application as Blue Fluorescent OLED

A short
synthesis of unsubstituted chrysene is described to provide
a cheap source of this compound. This chrysene was used to prepare
3,6,9,12-tetrabromochrysene, which was subsequently transformed into
various 3,6,9,12-tetrasubstituted chrysenes bearing four aryl, alkynyl,
or amino groups by means of the Suzuki, Sonogashira, or Buchwald–Hartwig
coupling reaction, respectively. These substituents result in large
bathochromic shifts in the chrysene absorption and emission spectra.
These new chrysene derivatives show blue fluorescent emission (401–471
nm) with high quantum yields (0.44–0.87). DFT calculations
on these chrysenes rationalize well the substituent effects on their
HOMO and LUMO energy levels. One representative chrysene (6g) was used as a blue fluorescent emitter in an OLED device that showed
an outstanding external quantum efficiency (η = 6.31%) with
blue emission [CIE (x, y) = (0.13,
0.20)] and a low turn-on voltage (3.0 V).