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 NO2 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 Zr6O8 clusters and the copper-hydroxo single sites, where NO2 is adsorbed through combined dispersive- and metal-bonding interactions
We thank the Spanish Ministry of Science and Innovation MCIN/AEI/10.13039/501100011033 (grants No. PID2021-123839OB-I00, RYC2018-024328-I and CEX2018-000805-M for A.E.P.-P., grant No. RTI2018-101049-B-I00 for A.M., grants No. RTI2018-097508−BI00, CEX2020-001039-S and PID2021-128313OB-I00 for J.C.-G., grant No. PID2019-106315RB-I00 for V.A.d.I.P.O.), the “European Union NextGenerationEU/PRTR” (grant No. EUR2020-112294 for A.E.P.-P., grants No. PLEC2021-007906 and TED2021-130173B-C43 for V.A.d.I.P.O.), and the Regional Government of Madrid (TALENTO grants No. 2017-T1/AMB-5264 and 2021-5 A/AMB-20946 for A.M., grant No. S2018/NMT-4511 NMAT2D-CM for J.C.-G., Proyectos Sinérgicos de I + D grant No. Y2018/NMT-5028 FULMATEN-CM for J.C.-G., grant No. S2018/NMT-4367 FotoArt-CM for V.A.d.I.P.O.). V.A.d.I.P.O. acknowledges financial support from the European Research Council (ERC), through the HYMAP project (grant agreement No. 648319), under the European Union’s Horizon 2020 research and innovation programme. I.d.C.–V. and I.R.–M. acknowledge FPI-UAM fellowships from Universidad Autónoma de Madrid. C.C.-B. acknowledges the European Social Funds and the Regional Government of Madrid for a postdoctoral contract (PEJD-2018-POST/IND-7909). A.S. acknowledges financial support from the Margarita Salas programme (grant No. CA1/ RSUE/2021-00622). Part of this research was carried out at P02.1 beamline at DESY, a member of the Helmholtz Association (HGF), and utilising the computing facilities of CSUC. We acknowledge DESY (Hamburg, Germany), a member of the Helmholtz Association HGF, for the provision of experimental facilities. Parts of this research were carried out at PETRA III, and we would like to thank Dr. Welter for his assistance in using the P65 beamline. Beamtime was allocated for proposal I-20210304 EC