Heterogeneous Catalysis Unit

Summary

Since its installation in 2016, the use of EPR has increased year by year, and in 2018 it has been consolidated as a useful technique for ICIQ research. We have acquired a finger dewar to work with liquid nitrogen that allows to measure more samples in a short period of time and obtain the same quality signal when compared to the cryostat.

EPR Experiments

The EPR technique is highly used at ICIQ for the characterization of photochemical systems (radicals or complexes). The task of identifying and quantifying radical adducts from spin-trapping experiments is often difficult. With this in mind,  SpinFit and AnisoSpinFit fitting routines have been employed. The SpinFit and AnisoSpinFit modules are a standard part of the Xenon software platform. SpinFit is an isotropic CW-EPR spectrum simulation and fitting routine for liquid samples. SpinFit utilizes the g-value, the spin number, hyperfine coupling and width line distance to identify the paramagnetic species in the spectrum.

SpinFit is also an anisotropic-spectrum fitting routine to simulate and fit powder or cryogenic samples spectra (AnisoSpinFit). Utilizing perturbation theory, SpinFit  takes into account all desired EPR parameters to provide the best description of the measured spectrum. g- and A-matrices, their strains, zero-field parameters and populations can be fit with full flexibility as well as constrained to a specific part of the spectrum. Multiple EPR species in a spectrum can be rapidly fit to disentangle their individual components.

Until 2018, 3 papers have been already published using this quite new technique at ICIQ, and six other papers are being prepared:

P. Melchiorre: Angew. Chem. Int. Ed. 2017, 56, 15039.
J. Lloret: Inorg. Chem. 2018, 57 (7), 3529.
R. Martin: J. Am. Chem. Soc. 2018, 140 (38), 12200.

HC Unit (Number of Experiments per Instrument)