Isoreticular Tuning of Conductive Metal-Organic Framework Nanocrystals for the Rapid Detection and Differentiation of Toxic Gases.

Shehayeb, Elissa O; Chan, Joseph Y M; Pennington, Doran L; Hendon, Christopher H; Mirica, Katherine A · ACS Nano · 2026

basic_science · Level V

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Abstract

Despite advances in gas sensing technologies, achieving rapid detection and differentiation of toxic gases remains a critical challenge. Herein, three conductive metal-organic frameworks (cMOFs) based on metallotetrapyrazinoporphyrazine (MTPz) ligands are utilized to enable distinct chemiresistive sensing toward hazardous gases within seconds of exposure. This study focuses on harnessing variations in material-analyte interactions upon tuning the central metal within MTPz ligand (M = Co, Ni, Cu), to achieve discrete sensing responses capable of identifying hydrogen sulfide (H<sub>2</sub>S), ammonia (NH<sub>3</sub>), sulfur dioxide (SO<sub>2</sub>), and nitric oxide (NO), with detection limits as low as 0.7, 0.6, 2.5, and 0.03 ppm, respectively, within 6 seconds of gas exposure. The sensor array differentiates these gases at concentrations exceeding their permissible exposure limits within seconds. Complementary <i>in situ</i> and <i>ex situ</i> spectroscopic analyses reveal distinct redox processes governing the varied sensing responses, underscoring the critical role of molecular design in optimizing performance. This work establishes a framework for tailoring molecular design strategies toward next-generation gas sensing materials.