Unidirectional Adsorption of Bifunctional 1,4-Phenylene Diisocyanide on the Ge(100)-2 × 1 Surface.
Adsorption of bifunctional organic molecules on semiconductor surfaces is important for surface modification; however, most bifunctional molecules previously studied have yielded mixtures of singly and dually tethered adsorbates. Here we report the adsorption of bifunctional 1,4-phenylene diisocyanide (PDI) on the Ge(100)-2 × 1 surface, in which singly bound adsorbates are selectively produced. As shown by polarized multiple internal reflection infrared spectroscopy experiments and density functional theory calculations, PDI adsorbates form a single C-dative bonding configuration through one of the isocyanide functionalities, retaining one unreacted isocyanide moiety per adsorbate. The angle of the molecular axis is ∼30° from the surface normal. The delocalized π* molecular orbital of the free molecule is also preserved upon adsorption. These results demonstrate the potential usefulness of isocyanide adsorbates as a means toward selective organic functionalization of semiconductor surfaces.
Department of Chemical Engineering, Stanford University, 443 Via Ortega, Stanford, California 94305, United States.
Bonggeun
B
Shong
Department of Chemical Engineering, Stanford University, 443 Via Ortega, Stanford, California 94305, United States.
Tania E
TE
Sandoval
Department of Chemical Engineering, Stanford University, 443 Via Ortega, Stanford, California 94305, United States.
Allison M
AM
Crow
Department of Chemical Engineering, Stanford University, 443 Via Ortega, Stanford, California 94305, United States.
Stacey F
SF
Bent
isocyanides; organic functionalization; selective adsorption; ultrahigh vacuum