title: Intermolecular Hybridization Creating Nanopore Orbital in a Supramolecular Hydrocarbon Sheet.
abstract: Molecular orbital engineering is a key ingredient for the design of organic devices. Intermolecular hybridization promises efficient charge carrier transport but usually requires dense packing for significant wave function overlap. Here we use scanning tunneling spectroscopy to spatially resolve the electronic structure of a surface-confined nanoporous supramolecular sheet of a prototypical hydrocarbon compound featuring terminal alkyne (-CCH) groups. Surprisingly, localized nanopore orbitals are observed, with their electron density centered in the cavities surrounded by the functional moieties. Density functional theory calculations reveal that these new electronic states originate from the intermolecular hybridization of six in-plane π-orbitals of the carbon-carbon triple bonds, exhibiting significant electronic splitting and an energy downshift of approximately 1 eV. Importantly, these nanopore states are distinct from previously reported interfacial states. We unravel the underlying connection between the formation of nanopore orbital and geometric arrangements of functional groups, thus demonstrating the generality of applying related orbital engineering concepts in various types of porous organic structures.
authors.affiliation: Physik-Department E20, Technische Universität München , 85748 Garching, Germany.
authors.forename: Yi-Qi
authors.initials: YQ
authors.lastname: Zhang
authors.affiliation: Department of Physics, Chemistry and Biology (IFM), Linköping University , 58183 Linköping, Sweden.
authors.forename: Jonas
authors.initials: J
authors.lastname: Björk
authors.affiliation: Physik-Department E20, Technische Universität München , 85748 Garching, Germany.
authors.forename: Johannes V
authors.initials: JV
authors.lastname: Barth
authors.affiliation: Physik-Department E20, Technische Universität München , 85748 Garching, Germany.
authors.forename: Florian
authors.initials: F
authors.lastname: Klappenberger
keywords: Electronic structure; intermolecular hybridization; orbital engineering; porous materials; scanning tunneling spectroscopy