Superior charge transport in Ni-diamine conductive MOFs

Two-dimensional conductive metal–organic frameworks (2D cMOFs) are an emerging class of crystalline van der Waals layered materials with tunable porosity and high electrical conductivity. They have been used in a variety of applications, such as energy storage and conversion, chemiresistive sensing, and quantum information. Although de-signing new highly conductive 2D MOFs and studying their composition/structure-property relationships have at-tracted significant attention, there are still very few examples of 2D cMOFs that exhibit room-temperature electrical conductivity above 1 S cm–1. When such high conductivities are achieved, Ni-diamine linkages are often involved, yet Ni-diamine MOFs remain difficult to access. Here, we report two new 2D cMOFs M3(HITT)2 (M = Ni, Cu; HITT = 2,3,7,8,12,13-hexaiminotetraazanaphthotetraphene). Ni3(HITT)2 exhibits electrical conductivity of as high as 4.5 S cm–1 at 298 K, much higher than that of its copper analogue Cu3(HITT)2, 0.05 S cm–1. Spectroscopic analysis reveals that Ni3(HITT)2 exhibits significantly stronger in-plane π-d conjugation and higher density of charge carriers com-pared to Cu3(HITT)2, accounting for the higher electrical conductivity of Ni3(HITT)2. The present work provides a deeper understanding of the influence of metal nodes on the electrical conductivity of cMOFs.