1.
Angew Chem Int Ed Engl
; 39(6): 1101-1105, 2000 Mar.
Article
in English
| MEDLINE
| ID: mdl-10760933
2.
Angew Chem Int Ed Engl
; 38(19): 2919-2923, 1999 Oct 04.
Article
in English
| MEDLINE
| ID: mdl-10540393
ABSTRACT
Liberation of the ligand from the nickel complex 1 obtained by template synthesis yielded isoporphycene (as the octaethyl derivative 2), the first constitutional isomer of porphyrin with an N(4) core for which E/Z isomerism is involved: Compound 2 is present as the E isomer, which is in rapid, presumably acid-catalyzed equilibrium with a small amount (2 %) of the Z isomer. The remaining unknown constitutional isomers of porphyrin are considerably higher in energy than the already rather labile isoporphycene, so that the latter should mark the border of existence for this type of structural variant of porphyrin.