The preparation of porphyrins functionalized with one or two carbazoles (or phenoxazines) is described. The electron donors were introduced into one or two porphyrin meso positions by using the inexpensive Ullmann coupling procedure. Very good yields were obtained, and for two new compounds, the X-ray structures were solved. Preliminary electrochemical data coupled with electronic spectroscopy are also reported.

The functionalization of porphyrins at the meso positions by azoles led, after subsequent alkylation, to several precursors of N-heterocyclic carbenes. Porphyrin dimers linked by palladium (or rhodium) bis-carbene spacers were prepared and characterized. Spectroscopic data and X-ray structures showed that the coordination geometry for the two carbenes around the palladium linker was trans-anti. Electrochemical studies revealed significant electronic communication between the two porphyrins, despite the absence of conjugation pathways.