The synthesis, crystal structures and photophysical properties of a series of novel 4,6-diphenyl-1,9-anthrazolines

The synthesis and properties of a:series of nine new 4,6-diphenyl-1,9-anthrazolines molecules 1a-1i are reported. Compounds 1a-1i were synthesized by Friedlander condensation of 4,6-dibenzoyl-1,3-phenylenediamines and acetyl-functionalized compounds in the presence of polyphosphoric acid as catalyst, in yields ranging from 60% to 94%. The 4,6-diphenyl-1,9-anthrazolines are thermally robust with high decomposition temperatures (>371.0 degrees C) and high melt transitions (215.1-322.8 degrees C). Compounds la and if crystallized in the triclinic system with the space groups P-1. All of them show the lowest energy absorption bands (lambda(Abs)(max): 397-454 nm), revealing low optical band gaps (2.55-3.00 eV). The compounds emit blue fluorescence with lambda(Em)(max) ranging from 432 to 493 nm in dilute toluene solution. 4,6-Diphenyl-1,9-anthrazolines 1a-1i have a formal reduction potential in the range -1.02 to -1.19 V (versus SCE) and estimated electron affinities (LUMO levels) of 3.21-3.38 eV. These results demonstrate that the new 4,6-diphenyl-1,9-anthrazolines are promising thermally stable n-type semiconductors for organic electronics. (C) 2011 Elsevier Ltd. All rights reserved.