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 π-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) π-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 π-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.