Discriminative response of surface-confined metalloporphyrin molecules to carbon and nitrogen monoxide.
The binding of small gas molecules to metalloporphyrins is of both fundamental scientific and technological interest. It plays a key role in the transport of respiratory gases, catalytic processes in biological systems, and artificial nanostructures for sensing. Here, we present a detailed molecular-level investigation regarding the interaction of nitrogen monoxide (NO) and carbon monoxide (CO) with metallo-tetraphenylporphyrin (M-TPP, M = Co, Fe) arrays, anchored on a noble metal Ag(111) surface, providing M-TPP species with a distinct saddle-shape conformation. Scanning tunneling microscopy and spectroscopy experiments reveal that the impact of CO and NO is strikingly different on both species. In the case of CO, the M-TPP core can be dressed by either one or two carbon monoxide ligands, whereby the porphyrin geometric and electronic structure remains nearly unaffected. In contrast, following NO exposure exclusively a mononitrosyl species evolves. The NO axial ligation induces a relaxation of the adsorption-induced molecular deformation and markedly modifies the electronic structure of the porphyrin.
Physik Department E20, Technische Universität München, D-85748 Garching, Germany. Knud.Seufert@ph.tum.de
Knud
K
Seufert
Willi
W
Auwärter
Johannes V
JV
Barth
D002248:Carbon Monoxide / Q000737:chemistry*; D004583:Electrons; D008665:Metalloporphyrins / Q000737:chemistry*; D016252:Microscopy, Scanning Tunneling; D049329:Nanostructures / Q000737:chemistry* / Q000648:ultrastructure; D009569:Nitric Oxide / Q000737:chemistry*
D008665:Metalloporphyrins; D009569:Nitric Oxide; D002248:Carbon Monoxide