Electronic structures of blue copper centers of amicyanin and azurin in the solution state.

X-ray absorption near edge structure (XANES) spectra of blue copper proteins, amicyanin and azurin, in the solution state were measured in the copper L-edge energy region. The absorption peak energies were quite similar for both proteins, while the main edge region for azurin was broader than that for amicyanin, owing to more pronounced shoulder spectral features in the former. calculations at the whole protein level qualitatively reproduced the experimental spectra well.

The role of carboxylate ligand orbitals in the breathing dynamics of a metal-organic framework by resonant X-ray emission spectroscopy.

Metal-organic frameworks (MOFs) exhibit structural flexibility induced by temperature and guest adsorption, as demonstrated in the structural breathing transition in certain MOFs between narrow-pore and large-pore phases. Soft modes were suggested to entropically drive such pore breathing through enhanced vibrational dynamics at high temperatures. In this work, oxygen K-edge resonant X-ray emission spectroscopy of the MIL-53(Al) MOF was performed to selectively probe the electronic perturbation accompanying pore breathing dynamics at the ligand carboxylate site for metal-ligand interaction.