Dehydrocyclization of peripheral alkyl groups in porphyrins at Cu(100) and Ag(111) surfaces

SURFACE SCIENCE

卷:653

Article

Williams, Christopher G.¹  Wang, Miao²  Skomski, Daniel¹  Tempas, Christopher D.¹  Kesmodel, Larry L.²  Tait, Steven L.^1,2 

[1] Indiana Univ, Dept Chem, Bloomington, IN 47405 USA

[2] Indiana Univ, Dept Phys, Bloomington, IN 47405 USA

关键词: Dehydrocyclization;    Dehydrogenation catalysis;    Surface functionalization;    Organic adsorbates;    High-resolution electron energy loss spectroscopy;    Scanning tunneling microscopy;   

DOI  :  10.1016/j.susc.2016.06.013

来源: Elsevier

【 摘 要 】

The self-assembly of organic and metal-organic species at metal surfaces is a topic of high interest for applications that can benefit from tunable surface functionalization through, organic:building block design. 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 to tetrabenzoporphyrin on the Cu(100) and Ag(111) surfaces at 500-600 K. Dehydrocyclization of smaller species is not typically observed on these surfaces at low pressure due to short adsorption lifetimes. The dehydrocyclization of peripheral ethyl groups forms benzo groups which then undergo additional dehydrogenation. The reaction products 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 may be encountered as molecular building blocks increase in size and complexity on relatively inert surfaces. (C) 2016 Elsevier B.V. All rights reserved.

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