Semiconductive Microporous Hydrogen-Bonded Organophosphonic Acid Frameworks

We report the first semiconductive, proton-conductive, microporous hydrogen-bonded organic framework (HOF) derived from phenylphosphonic acid and 5,10,15,20‐tetrakis[p‐phenylphosphonic acid] porphyrin (known as GTUB5). The structure of GTUB5 was characterized using single crystal X-ray diffraction (XRD). A narrow band gap of 1.56 eV was extracted from a UV-Vis spectrum of pure GTUB5 crystals, in excellent agreement with the 1.65 eV band gap obtained from density functional theory calculations. The same band gap was also measured for GTUB5 in DMSO. The proton conductivity of GTUB5 was measured to be 3.00 ´ 10-6 S cm-1 at 75 °C and 75 % relative humidity. The surface area of GTUB5’s hexagonal voids were estimated to be 422 m2 g-1 from grand canonical Monte Carlo simulations. XRD showed that GTUB5 is thermally stable under relative humidities of up to 90 % at 90 °C. These findings pave the way for a new family of microporous, organic, semiconducting materials with high surface areas and high thermal stabilities. Such materials could find applications in printed electronics, optoelectronics, and electrodes in supercapacitors.