Journal of the American Chemical Society, Vol.129, No.43, 13193-13200, 2007
1,4,5,8,9,12-hexamethyltriphenylene. A molecule with a flipping twist
The synthesis and characterization of 1, 4,5,8,9,12-hexamethyltriphenylene (5) is described. In the solid state, X-ray crystallographic studies reveal that compound 5 presents a highly distorted C-2 geometry with a 53 degrees end-to-end twist. In solution, variable-temperature H-1 NM,R studies and molecular modeling present a story of rapid dynamic conformational interconversions between two C-2 enantiomers (with a low activation barrier) and a slower C-2-D-3 interconversion (with a relatively high barrier)-the first time clear evidence of conformational interchange for these hindered triphenylenes has been provided. Further studies have established that 5 is a fluorescent stable blue emitter, and that the compound undergoes an irreversible one-electron electrochemical oxidation. Calculations have predicted this to be a radical cation of C-2 geometry with 60 degrees end-to-end twist.