C–H/π Mediated Assembly of a Chiral Nanoporous Network for Electron and Molecular Trapping on Au(111)

Abstract

Beyond traditional graphene, the emergence of graphyne and graphdiyne bestows sp-hybridization to push mechanical, catalytic, and electronic boundaries. One inspiring goal in the field of advanced two-dimensional (2D) materials is the introduction of chirality into these nanoporous frameworks, a shift that merges fundamentals of molecular biology with advanced material science to unlock new properties. In this work, through the self-assembly of 4,4″-diethynyl-1,1′:4′,1″-terphenyl (DETP) on Au(111), we have created a hydrogen-bonded surface chiral 2D rhombic nanoporous network. Low-temperature scanning tunneling microscopy/spectroscopy (LT-STM/STS) and non-contact atomic force microscopy (nc-AFM) reveal that the networks are stabilized by 4-fold surface chiral bonding motifs and C–H/π interactions. LT-STM/STS, nc-AFM, electron plane-wave expansion (EPWE) and density functional theory (DFT) simulations show that this molecular self-assembly has a ≈3.7 eV gap between highest occupied (HOMO) and lowest unoccupied (LUMO) molecular orbitals on Au(111), acts as a quantum well array for surface electron confinement, and weakly traps CO molecules within the nanopores. The resulting chiral structures not only enable the modulation of the electronic properties at the interface, but also reveal a variable electronic symmetry, becoming a chess-board-like landscape at high energies. These surface-stabilized nanoporous networks serve as suitable platforms to steer electronic textures in nanoscale materials.