Conductive Lanthanide Metal–Organic Frameworks with Exceptionally High Stability

Abstract

Electrically conductive metal–organic frameworks (MOFs) have been extensively studied for their potential uses in energy-related technologies and sensors. However, achieving that goal requires MOFs to be highly stable and maintain their conductivity under practical operating conditions with varying solution environments and temperatures. Herein, we have designed and synthesized a new series of {[Ln 4 (μ 4 -O)(μ 3 -OH) 3 (INA) 3 (GA) 3 ](CF 3 SO 3 )(H 2 O) 6 } n (denoted as Ln 4 -MOFs, Ln = Gd, Tm, and Lu, INA = isonicotinic acid, GA = glycolic acid) single crystals, where electrons are found to transport along the π–π stacked aromatic carbon rings in the crystals. The Ln 4 -MOFs show remarkable stability, with minimal changes in conductivity under varying solution pH (1–12), temperature (373 K), and electric field as high as 800 000 V/m. This stability is achieved through the formation of strong coordination bonds between high-valent Ln(III) ions and rigid carboxylic linkers as well as hydrogen bonds that enhance the robustness of the electron transport path. The demonstrated lanthanide MOFs pave the way for the design of stable and conductive MOFs.