Electrically Conductive 3D Metal–Organic Framework Featuring π-Acidic Hexaazatriphenylene Hexacarbonitrile Ligands with Anion−π Interaction and Efficient Charge-Transport Capabilities
Ashok Yadav, Dillip K. Panda, Shiyu Zhang, Wei Zhou, Sourav Saha
Abstract
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.