Monomer

Nanotechnology

Organic chemistry

Metal-organic framework

Nitrogen dioxide

Porosity

Pollutant

Porous medium

Adsorption

Engineering

Inorganic chemistry

Chemistry

Materials science

Dimer

Molecule

Metal

Supramolecular chemistry

Chemical engineering

Nanoporous

Polymer

Nitrogen

Nature Materials

Nitrogen dioxide (NO2) is a major air pollutant causing significant environmental1,2 and health problems3,4. We report reversible adsorption of NO2 in a robust metal–organic framework. Under ambient conditions, MFM-300(Al) exhibits a reversible NO2 isotherm uptake of 14.1 mmol g−1, and, more importantly, exceptional selective removal of low-concentration NO2 (5,000 to &lt;1 ppm) from gas mixtures. Complementary experiments reveal five types of supramolecular interaction that cooperatively bind both NO2 and N2O4 molecules within MFM-300(Al). We find that the in situ equilibrium 2NO2 ↔ N2O4 within the pores is pressure-independent, whereas ex situ this equilibrium is an exemplary pressure-dependent first-order process. The coexistence of helical monomer–dimer chains of NO2 in MFM-300(Al) could provide a foundation for the fundamental understanding of the chemical properties of guest molecules within porous hosts. This work may pave the way for the development of future capture and conversion technologies. High and reversible nitrogen dioxide (NO2) uptake, and low-concentration NO2 removal from gas mixtures, is observed in a metal–organic framework. The NO2 is bound within the pores by cooperative supramolecular interactions.

Reversible adsorption of nitrogen dioxide within a robust porous metal–organic framework