We used Ni K-edge resonant-valence-to-core X-ray emission spectroscopy (RVtC-XES, also referred to as direct RIXS), an element-selective bulk-sensitive synchrotron-based technique, to investigate the electronic structure of the CPO-27-Ni metal-organic framework (MOF) upon molecular adsorption of significant molecular probes: H2O, CO, H2S, and NO. We compare RVtC-XES with UV-vis spectroscopy, and we show that the element selectivity of RVtC-XES is of strategic significance to observe the full set of d-d excitations in Ni(2+), which are partially overshadowed by the low-energy π-π* transitions of the Ni ligands in standard diffuse-reflectance UV-vis experiments. Our combined RVtC-XES/UV-vis approach provides access to the whole set of d-d excitations, allowing us a complete discussion of the changes undergone by the electronic configuration of the Ni(2+) sites hosted within the MOF upon molecular adsorption. The experimental data have been interpreted by multiplet ligand-field theory calculations based on Wannier orbitals. This study represents a step further in understanding the ability of the CPO-27-Ni MOFs in molecular sorption and separation applications.
Titolo: | Effect of Molecular Guest Binding on the d-d Transitions of Ni(2+) of CPO-27-Ni: A Combined UV-Vis, Resonant-Valence-to-Core X-ray Emission Spectroscopy, and Theoretical Study | |
Autori Riconosciuti: | ||
Autori: | Gallo, Erik; Gorelov, Evgeny; Guda, Alexander A; Bugaev, Aram L; Bonino, Francesca; Borfecchia, Elisa; Ricchiardi, Gabriele; Gianolio, Diego; Chavan, Sachin; Lamberti, Carlo | |
Data di pubblicazione: | 2017 | |
Abstract: | We used Ni K-edge resonant-valence-to-core X-ray emission spectroscopy (RVtC-XES, also referred to as direct RIXS), an element-selective bulk-sensitive synchrotron-based technique, to investigate the electronic structure of the CPO-27-Ni metal-organic framework (MOF) upon molecular adsorption of significant molecular probes: H2O, CO, H2S, and NO. We compare RVtC-XES with UV-vis spectroscopy, and we show that the element selectivity of RVtC-XES is of strategic significance to observe the full set of d-d excitations in Ni(2+), which are partially overshadowed by the low-energy π-π* transitions of the Ni ligands in standard diffuse-reflectance UV-vis experiments. Our combined RVtC-XES/UV-vis approach provides access to the whole set of d-d excitations, allowing us a complete discussion of the changes undergone by the electronic configuration of the Ni(2+) sites hosted within the MOF upon molecular adsorption. The experimental data have been interpreted by multiplet ligand-field theory calculations based on Wannier orbitals. This study represents a step further in understanding the ability of the CPO-27-Ni MOFs in molecular sorption and separation applications. | |
Volume: | 56 | |
Fascicolo: | 23 | |
Pagina iniziale: | 14408 | |
Pagina finale: | 14425 | |
Digital Object Identifier (DOI): | 10.1021/acs.inorgchem.7b01471 | |
URL: | http://pubs.acs.org/doi/abs/10.1021/acs.inorgchem.7b01471 | |
Parole Chiave: | METAL-ORGANIC FRAMEWORKS; HYDROGEN STORAGE; GAS-ADSORPTION; MOFS; SITES | |
Rivista: | INORGANIC CHEMISTRY | |
Appare nelle tipologie: | 03A-Articolo su Rivista |
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