resumo
Electrically conductive Metal-Organic Frameworks (MOFs) have emerged as promising materials for applications in (opto)electronics, electrocatalysis or energy storage in the past few years.[1] Besides their inherent porosity, MOFs may also incorporate tunable electrical and optical properties that strongly depend on the selected building blocks, making them very attractive for their implementation as integral components in electronic devices. One of the most common strategies for designing conductive MOFs is based on using electroactive organic ligands and their partial oxidation/reduction to increase the number of charge carriers.[2] Although perylene salts were reported as the first molecular conductors, they have been scarcely explored as building blocks for constructing conductive MOFs. Herein, we report a detailed study on the electrical conductivity enhancement of a perylene-based MOF upon partial ligand oxidation by iodine doping using two-probe single-crystal devices (Fig 1a).[3] This conductivity is ascribed to the partial oxidation of the perylene ligands, as witnessed by EPR and emission spectroscopy and supported by theoretical calculations. The charge transport is described by means of a through-space hopping mechanism along the herringbone perylene packing, with the highest conductivities of the order of 10−5 S·cm−1. In addition, we have presented a new synthetic route to prepare a novel family of isostructural MOFs based on perylene-tetracarboxylic ligands and transition metals (TM = Co, Ni, and Zn) exhibiting high crystallinity and stability. The photophysical properties of perylene-Zn were thoroughly studied, revealing the presence of J-aggregation-based and monomer-like emission bands (Fig. 1b). These bands were experimentally identified, and their behavior was further understood using quantum-chemical calculations Solid-state cyclic voltammetry experiments on perylene-TMs showed that the perylene redox properties are maintained within the CP framework.[4] For these reasons, we highlight the versatility of perylene building blocks for the design of electroactive MOFs exhibiting tunable physical properties.
autores
G. Valente, J. Rocha, M. Souto
nossos autores
