Conductive Lanthanide\nMetal–Organic Frameworks\nwith Exceptionally High Stability

Abstract

Electrically conductive metal–organic frameworks\n(MOFs)\nhave been extensively studied for their potential uses in energy-related\ntechnologies and sensors. However, achieving that goal requires MOFs\nto be highly stable and maintain their conductivity under practical\noperating conditions with varying solution environments and temperatures.\nHerein, we have designed and synthesized a new series of {[Ln₄(μ₄-O)(μ₃-OH)₃(INA)₃(GA)₃]­(CF₃SO₃)(H₂O)₆}_<i>n</i> (denoted\nas <b>Ln</b>_<b>4</b><b>-MOFs</b>, Ln\n= Gd, Tm, and Lu, INA = isonicotinic acid, GA = glycolic acid) single\ncrystals, where electrons are found to transport along the π–π\nstacked aromatic carbon rings in the crystals. The <b>Ln</b>_<b>4</b><b>-MOFs</b> show remarkable stability,\nwith minimal changes in conductivity under varying solution pH (1–12),\ntemperature (373 K), and electric field as high as 800 000\nV/m. This stability is achieved through the formation of strong coordination\nbonds between high-valent Ln(III) ions and rigid carboxylic linkers\nas well as hydrogen bonds that enhance the robustness of the electron\ntransport path. The demonstrated lanthanide MOFs pave the way for\nthe design of stable and conductive MOFs.