Atomic-scale investigation on the electronic states in a one-dimensional π-d conjugated metal-organic framework

Enhanced electronic coupling gives rise to many intriguing properties in pi-d conjugated metal-organic frameworks (CMOFs). By low-temperature scanning tunneling microscopy and density functional theory calculation, we investigate the electronic coupling in one-dimensional (1D) pi-d conjugated FeQDI polymers. Our experiments have resolved the bulk and end states stemming from Fe atoms in different coordination environments and their spatial extension due to pi-d conjugation. By fitting the band structure by Wannier functions in an energy range of -0.5 eV to 0 eV, the Fe-Fe, QDI-QDI and Fe-QDI hopping integrals are determined to be 15 meV, 121 meV and 24 meV, respectively. Our work provides experimental and theoretical insights into the electronic coupling in 1D CMOFs. The electronic coupling was examined in 1D CMOF by investigating the electronic states in the FeQDI polymer at the atomic scale.