Synergistic binding sites in a metal-organic framework for the optical sensing of nitrogen dioxide.

Luminescent metal-organic frameworks are an emerging class of optical sensors, able to capture and detect toxic gases. Herein, we report the incorporation of synergistic binding sites in MOF-808 through post-synthetic modification with copper for optical sensing of NO 2 at remarkably low concentrations. Computational modelling and advanced synchrotron characterization tools are applied to elucidate the atomic structure of the copper sites. The excellent performance of Cu-MOF-808 is explained by the synergistic effect between the hydroxo/aquo-terminated Zr 6 O 8 clusters and the copper-hydroxo single sites, where NO 2 is adsorbed through combined dispersive- and metal-bonding interactions.