Linker Symmetry Lowering as a Strategy to Tune Electronic Properties in Two-Dimensional Conductive MOFs

Two-dimensional conductive metal-organic frameworks (2D cMOFs) have largely relied on highly symmetric linkers that give rise to symmetry-protected electronic degeneracies. Although such symmetry usually promotes extended conjugation and often leads to high electrical conductivity, it can also limit band structure tunability. Here, we demonstrate that deliberate lowering of the linker symmetry is an effective strategy for engineering electronic properties in 2D cMOFs. A reduced-symmetry C_2v catechol linker, hexahydroxylphenanthrene (HHP), was synthesized and incorporated into the 2D cMOF Cu₃(HHP)₂. Structural analysis reveals preserved long-range ordering alongside local symmetry descent relative to higher symmetry analogues. Density functional theory (DFT) calculations show that symmetry lowering lifts electronic degeneracies, leading to modified band dispersion and altered band gap characteristics. Together, these results establish linker symmetry as a fundamental parameter for band structure engineering in 2D cMOFs.