High Electrical Conductivity in Ni3(2,3,6,7,10,11-hexaiminotriphenylene)2, a Semiconducting Metal–Organic Graphene Analogue

TLDR: Two-probe and van der Pauw electrical measurements reveal bulk and surface conductivity values of 2 and 40 S·cm(-1), respectively, both records for MOFs and among the best for any coordination polymer.

Abstract: Reaction of 2,3,6,7,10,11-hexaaminotriphenylene with Ni2+ in aqueous NH3 solution under aerobic conditions produces Ni3(HITP)2 (HITP = 2,3,6,7,10,11-hexaiminotriphenylene), a new two-dimensional metal–organic framework (MOF). The new material can be isolated as a highly conductive black powder or dark blue-violet films. Two-probe and van der Pauw electrical measurements reveal bulk (pellet) and surface (film) conductivity values of 2 and 40 S·cm–1, respectively, both records for MOFs and among the best for any coordination polymer.

Figures

Figure 1. Experimental and simulated PXRD patterns of Ni3(HITP)2. The inset shows the slipped-parallel structure with neighboring sheets displaced by 1/16 fractional coordinates in the a and b directions.

Figure 4. Variable temperature van der Pauw conductivity measurement on a ~500 nm thick film on quartz.

Figure 3. Top: SEMs for films of Ni3(HITP)2 at various magnifications. Bottom: AFM thickness profile and corresponding 3D AFM image of a representative Ni3(HITP)2 film.

Figure 2. A contour map of the potential energy surface generated by different translations between A and B layers. Black dots correspond to locations of single-point calculations performed using the PBE-D2 functional. Red lines indicate the borders of the ‘thermally accessible region’ (within kBT ≈ 0.026 eV of the minima). The surface was produced by interpolation with 2D Lagrange polynomials on a grid of Chebyshev points. The energy per unit cell has been normalized to zero at the minimum.