Conjugated Metal-Organic Macrocycles: Synthesis, Characterization, and Electrical Conductivity

The dimensional reduction of solids into smaller fragments provides a route to achieve new physical properties and gain deeper insight into the extended parent structures. Here, we report the synthesis of CuTOTP-OR (TOTPn- = 2,3,6,7-tetraoxidotriphenylene), a family of copper-based macrocycles that resemble truncated fragments of the conductive twodimensional (2D) metal-organic framework Cu3(HHTP) 2 (HHTP = 2,3,6,7,10,11-hexahydroxytriphenylene). The planar metal-organic macrocycles self-assemble into ordered nanotubes with internal diameters of similar to 2 nm and short interlayer distances of similar to 3.20 A. Strong p-p stacking interactions between macrocycles facilitate out-of-plane charge transport, and pressed pellet conductivities as high as 2(1) x 10(-3) S cm(-1) are observed. Peripheral alkyl functionalization enhances solution processability and enables the fabrication of thin-film field-effect transistor devices. Ambipolar charge transport is observed, suggesting that similar behavior may be operative in Cu-3(HHTP)(2). By coupling the attractive features of metal-organic frameworks with greater processability, these macrocycles enable facile device integration and a more nuanced understanding of out-of-plane charge transport in 2D conductive metal-organic frameworks.

Automated summary

We report the synthesis of copper-based macrocycles resembling truncated fragments of a two-dimensional metal-organic framework. These macrocycles self-assemble into ordered nanotubes and exhibit high conductivities and ambipolar charge transport. By enhancing solution processability, these macrocycles enable device integration and provide deeper insights into out-of-plane charge transport in two-dimensional metal-organic frameworks.