Electrically Conductive Photoluminescent Porphyrin Phosphonate Metal–Organic Frameworks

Abstract

Herein, the design and synthesis of a highly photoluminescent and electrically conductive metal–organic framework [Zn{Cu-p-H6TPPA}]⋅2 [(CH3)2NH] (designated as GTUB3), which is constructed using the 5,10,15,20-tetrakis [p-phenylphosphonic acid] porphyrin (p-H8TPPA) organic linker, is reported. The bandgap of GTUB3 is measured to be 1.45 and 1.48 eV using diffuse reflectance spectroscopy and photoluminescence (PL) spectroscopy, respectively. The PL decay measurement yields a charge carrier lifetime of 40.6 ns. Impedance and DC measurements yield average electrical conductivities of 0.03 and 4 S m−1, respectively, making GTUB3 a rare example of an electrically conductive 3D metal–organic framework. Thermogravimetric analysis reveals that the organic components of GTUB3 are stable up to 400 °C. Finally, its specific surface area and pore volume are calculated to be 622 m2 g−1 and 0.43 cm3 g−1, respectively, using grand canonical Monte Carlo. Owing to its porosity and high electrical conductivity, GTUB3 may be used as a low-cost electrode material in next generation of supercapacitors, while its low bandgap and high photoluminescence make it a promising material for optoelectronic applications.