Intermolecularly hydrogen-bonded dimeric helices: tripyrrindiones

摘要: Abstract A rare and unusual class of tripyrrolic compounds, violet-colored tripyrrin-1,14-diones, can be prepared easily in moderately high yields from base (piperidine)-catalyzed condensation 3-pyrrolin-2-ones with 2,5-diformylpyrroles. Dipyrrinones adopt the all-syn-Z conformation leading to helical, lock-washer like structures, which form dimers that are held together by intermolecular hydrogen bonds nonpolar solvents crystal. Strong bathochromic spectral shifts tripyrrindione ∼480 nm long wavelength UV–visible absorption band seen added base: DBU, 615 nm; TFA, 573 nm; Zn(OAc)2, 586 nm.