The formation of covalently-linked, functional organic surface structures through surface-catalyzed reactions and assembly is a potential route to next-generation sensors, catalysts, and electronics. As the complexity of molecular building blocks increases to direct ordering and function, thermal stability of the adsorbate often increases opening up new surface-catalyzed reaction pathways. We report dehydrocyclization of octaethylporphyrin (OEP) to tetrabenzoporphyrin (TBP) on the Cu(100) and Ag(111) surfaces at 500 K and 600 K, respectively. Dehydrocyclization of smaller species is not typically observed on these surfaces at low pressure due to short adsorption lifetimes. The surface species are characterized by high-resolution electron energy loss spectroscopy (HREELS), scanning tunneling microscopy (STM), and X-ray photoelectron spectroscopy (XPS). These results extend our understanding of reaction pathways that become possible as molecular building blocks increase in size. We have now applied this reaction scheme to the dehydrogenation of peripheral alkyl groups in 1,3,5-tris-(3,5-diethylphenyl)benzene (TDEPB) to create covalently linked structures on Cu(100) and Au(111). These results demonstrate strategies for applying principles of molecular building block design and the catalytic activity of a metal surface to develop new surface functionalization.

Surface catalyzed C-C bond formation through dehydrogenation and dehydrocyclization pathways

254th National Meeting (2017)

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