Selective Intramolecular Dehydrocyclization of Co-Porphyrin on Au(111).

The on-surface C-H bond activation and coupling reaction is a powerful approach to constructing fine-tuned surface nanostructures. It is quite challenging to control its regioselectivity due to the inertness of the C-H bond involved. With scanning tunneling microscopy/spectroscopy and theoretical calculations, the C-H activation and sequential intramolecular dehydrocyclization of meso-tetra(p-methoxyphenyl)porphyrinatocobalt(II) was explored on Au(111), showing that the methoxy groups in the molecule could kinetically mediate the selectivity of the intramolecular reaction over its intermolecular coupling counterpart. The experimental results demonstrate that the introduced protecting group could help augment the selectivity of such on-surface reaction, which can be applied to the precise fabrication of functional surface nanostructures.