Topochemical conversion of a dense metal–organic framework from a crystalline insulator to an amorphous semiconductor†

Abstract

A dense, insulating metal–organic framework (MOF), is successfully converted into a semiconducting amorphous MOF via a topochemical route.

Abstract

The topochemical conversion of a dense, insulating metal–organic framework (MOF) into a semiconducting amorphous MOF is described. Treatment of single crystals of copper( i) chloride trithiocyanurate, Cu ^ICl(ttcH ₃) (ttcH ₃ = trithiocyanuric acid), 1, in aqueous ammonia solution yields monoliths of amorphous Cu ^I _1.8(ttc) _0.6(ttcH ₃) _0.4, 3. The treatment changes the transparent orange crystals of 1 into shiny black monoliths of 3 with retention of morphology, and moreover increases the electrical conductivity from insulating to semiconducting (conductivity of 3 ranges from 4.2 × 10 ^–11 S cm ^–1 at 20 °C to 7.6 × 10 ^–9 S cm ^–1 at 140 °C; activation energy = 0.59 eV; optical band gap = 0.6 eV). The structure and properties of the amorphous conductor are fully characterized by AC impedance spectroscopy, X-ray photoelectron spectroscopy, X-ray pair distribution function analysis, infrared spectroscopy, diffuse reflectance spectroscopy, electron spin resonance spectroscopy, elemental analysis, thermogravimetric analysis, and theoretical calculations.

Notes

†Electronic supplementary information (ESI) available: PXRD, impedance, TGA, IR, XPS, PDF, ESR, and CIF files. CCDC 1018776–1018778. For ESI and crystallographic data in CIF or other electronic format see DOI: 10.1039/c4sc03295k