Semiconducting metal-organic frameworks (MOFs) show great potential to foster myriad advanced electronics and energy technologies, but they must possess adequate charge-carrier concentration and efficient charge-transport pathways in order to display useful electrical conductivity. A new intrinsically conducting 3D framework [Ag2(HATHCN)(CF3SO3)2]n was constructed by employing a highly π-acidic 1,4,5,8,9,12-hexaazatriphenylene-2,3,6,7,10,11-hexacarbonitrile (HATHCN) ligand, which assumed a paramagnetic HATHCN•- radical anion character by acquiring electron density from the TfO- anions involved in the anion-π interaction and facilitated charge movement along the staircase-like [-Ag+-HATHCN-]∞ chains having ample Ag4d+-N2p orbital overlap in the valence band region. As a result, the MOF displayed a narrow band gap (1.35 eV) and promising electrical conductivity (7.3 × 10-4 S/cm, 293 K) that ranked very high among those recorded for 3D MOFs. This work presents a new strategy to construct intrinsically conductive 3D frameworks by exploiting the dual metal coordination and anion-π interaction capabilities of a highly π-acidic HATHCN ligand.
Keywords: anion-induced electron transfer; anion−π interaction; electrical conductivity; metal−organic framework; π-acid.