Synthesis and complexes of a constrained-cavity Schiff-base dipyrrin macrocycle

A new constrained-cavity [1 + 1] Schiff-base dipyrrin macrocycle comprising an N 4 donor-pocket has been synthesised by spontaneous oxidation and in situ crystallisation. Access to Fe( ii ) and Zn( ii ) complexes is achieved by salt elimination reactions of the lithium salt. All compounds have been characterised by NMR and UV-vis spectroscopy, X-ray crystallography, and DFT analysis. A one-pot cyclisation/oxidation process results in a new constrained-cavity Schiff-base dipyrrin macrocycle and allows access to Li, Fe, and Zn complexes of this unique chromophore.