A Nanotubular Metal-Organic Framework with a Narrow Bandgap from Extended Conjugation

Abstract

A one-dimensional nanotubular metal-organic framework (MOF) [Ni(Cu-H(4)TPPA)].2 (CH3)(2)NH2+(H(8)TPPA=5,10,15,20-tetrakis[p-phenylphosphonic acid] porphyrin) constructed by using the arylphosphonic acid H(8)TPPA is reported. The structure of this MOF, known asGTUB-4, was solved by using single-crystal X-ray diffraction and its geometric accessible surface area was calculated to be 1102 m(2) g(-1), making it the phosphonate MOF with the highest reported surface area. Due to the extended conjugation of its porphyrin core,GTUB-4possesses narrow indirect and direct bandgaps (1.9 eV and 2.16 eV, respectively) in the semiconductor regime. Thermogravimetric analysis suggests thatGTUB-4is thermally stable up to 400 degrees C. Owing to its high surface area, low bandgap, and high thermal stability,GTUB-4could find applications as electrodes in supercapacitors.