2D coordination sheets based on tetranuclear cuprofullerene pentafluorobenzoate and their electronic properties

Abstract

Two 2D coordination sheets with pure Cu^I and mixed Cu^I/Cu^II centres based on tetranuclear cuprofullerene pentafluorobenzoate were realized under solvothermal conditions. They were constructed with linear (μ₂–η²:η²)₂-C₆₀ connecting Cu^I/Cu^II pentafluorobenzoate infinite chains. They exhibited optical absorptions covering the whole visible light and even the near-infrared region. Density functional theory (DFT) calculations revealed indirect characteristic with narrow bandgaps of 0.95 eV and 0.86 eV. The 3d-orbitals of Cu^I atoms and 2p-orbitals of C atoms from C₆₀ molecules contributed dominantly to the valence band maximum (VBM) and conduction band minimum (CBM), consistent with the calculated frontier orbitals with the tetranuclear cuperfullerene pentafluorobenzoate model and optical absorptions. This work provides the structural diversity of cuprofullerenes and an effective strategy for constructing polymeric materials based on exohedral metallofullerenes (ExMFs).