Fluorescent hexaaryl- and hexa-heteroaryl[3]-radialenes: Synthesis, structures, and properties

Abstract

The syntheses of three new [3]radialenes - hexakis(3, 5-dimethylpyrazolyl)- , hexakis(3-cyanophenyl)-, and hexakis(3, 4-dicyanophenyl)[3]radialene (1-3) - are reported. Compound 3 is obtained in five steps with an excellent yield of 76% in the key step. Compared to that, the respective steps of the syntheses of 1 and 2 result in lower yields. All compounds adopt a double bladed propeller conformation in solution. Compound 3 is considerably more electron deficient than previously reported hexaaryl[3]radi-alenes, with reduction potentials of -0.06 and -0.45 V in CH 2Cl 2. The compounds mostly display red fluorescence with large Stokes shifts. © 2012 Avellaneda et al; licensee Beilstein-Institut.