High electrical conductivity and high porosity in a Guest@MOF material: evidence of TCNQ ordering within Cu3BTC2 micropores

• DOI: 10.1039/c8sc02471e
• Publication Date: 2018-08-08T07:05:03Z
• Authors: Christian Schneider; Dardan Ukaj; Raimund Koerver; A. Alec Talin; Gregor Kieslich; Sidharam P. Pujari; Han Zuilhof; Jürgen Janek; Mark D. Allendorf; Roland A. Fischer
• Keywords: Chemiresistor

The host-guest system TCNQ@Cu3BTC2 (TCNQ = 7,7,8,8-tetracyanoquinodimethane, BTC 1,3,5-benzenetricarboxylate) is a striking example of how semiconductivity can be introduced by guest incorporation in an otherwise insulating parent material. Exhibiting both microporosity and semiconducting behavior such materials offer exciting opportunities as next-generation sensor materials. Here, we apply solvent-free vapor phase loading under rigorous exclusion moisture, obtaining series the general formula xTCNQ@Cu3BTC2 (0 ≤ x 1.0). By using powder X-ray diffraction, infrared absorption spectroscopy together with scanning electron microscopy porosimetry, provide first structural evidence for systematic preferential arrangement TCNQ along (111) lattice plane bridging coordination motif to two neighbouring Cu-paddlewheels, was predicted theory. For 1.0TCNQ@Cu3BTC2 find specific electrical conductivity up 1.5 × 10-4 S cm-1 whilst maintaining high BET surface area 573.7 m2 g-1. These values are unmatched MOFs equally conductivity, making material attractive applications super capacitors chemiresistors. Our results represent crucial missing link needed firmly establish structure-property relationship revealed TCNQ@Cu3BTC2, thereby creating sound basis this design principle electrically conducting MOFs.