title: Sticking with the Pointy End? Molecular Configuration of Chloro Boron-Subphthalocyanine on Cu(111).
abstract: In this combined low-temperature scanning tunneling microscopy (STM) and density functional theory (DFT) study, we investigate self-assembly of the dipolar nonplanar organic semiconductor chloro boron-subphthalocyanine (ClB-SubPc) on Cu(111). We observe multiple distinct adsorption configurations and demonstrate that these can only be understood by taking surface-catalyzed dechlorination into account. A detailed investigation of possible adsorption configurations and the comparison of experimental and computational STM images demonstrates that the configurations correspond to "Cl-up" molecules with the B-Cl moiety pointing toward the vacuum side of the interface, and dechlorinated molecules. In contrast to the standard interpretation of adsorption of nonplanar molecules in the phthalocyanine family, we find no evidence for "Cl-down" molecules where the B-Cl moiety would be pointing toward the Cu surface. We show computationally that such a configuration is unstable and thus is highly unlikely to occur for ClB-SubPc on Cu(111). Using these assignments, we discuss the different self-assembly motifs in the submonolayer coverage regime. The combination of DFT and STM is essential to gain a full atomistic understanding of the surface-molecule interactions, and our findings imply that phthalocyanines may undergo surface-catalyzed reactions hitherto not considered. Our results also indicate that care has to be taken when analyzing possible adsorption configurations of polar members of the phthalocyanine family, especially when they are adsorbed on comparably reactive surfaces like Cu(111).
authors.affiliation: Department of Chemistry and Biochemistry, University of Arizona, Tucson , 1306 E. University Boulevard, Tucson, Arizona 85721, United States.
authors.forename: Nahid
authors.initials: N
authors.lastname: Ilyas
authors.affiliation: Institute of Solid State Physics, NAWI Graz, Graz University of Technology , Petersgasse 16, 8010 Graz, Austria.
authors.forename: Shashank S
authors.initials: SS
authors.lastname: Harivyasi
authors.affiliation: Center for Functional Nanomaterials, Brookhaven National Laboratory , Upton, New York 11973, United States.
authors.forename: Percy
authors.initials: P
authors.lastname: Zahl
authors.affiliation: Center for Functional Nanomaterials, Brookhaven National Laboratory , Upton, New York 11973, United States.
authors.forename: Rocio
authors.initials: R
authors.lastname: Cortes
authors.affiliation: Institute of Solid State Physics, NAWI Graz, Graz University of Technology , Petersgasse 16, 8010 Graz, Austria.
authors.forename: Oliver T
authors.initials: OT
authors.lastname: Hofmann
authors.affiliation: Center for Functional Nanomaterials, Brookhaven National Laboratory, Upton, New York 11973, United States; Department of Electrical and Computer Engineering, University of Nebraska-Lincoln, Lincoln, Nebraska 68588, United States.
authors.forename: Peter
authors.initials: P
authors.lastname: Sutter
authors.affiliation: Institute of Solid State Physics, NAWI Graz, Graz University of Technology , Petersgasse 16, 8010 Graz, Austria.
authors.forename: Egbert
authors.initials: E
authors.lastname: Zojer
authors.affiliation: Department of Chemistry and Biochemistry, University of Arizona, Tucson, 1306 E. University Boulevard, Tucson, Arizona 85721, United States; Department of Physics, University of Arizona, Tucson, 1118 E 4th Street, Tucson, Arizona 85721, United States.
authors.forename: Oliver L A
authors.initials: OL
authors.lastname: Monti