An EXAFS study of phenanthroline-holmium complex

A holmium complex, $$[\hbox {Ho}(\hbox {phen})_{\mathrm {2}}(\hbox {H}_{\mathrm {2}}$$ O) $$_{\mathrm {2}} (\hbox {Cl})_{\mathrm {2}}$$ ]Cl.H $$_{\mathrm {2}}$$ O, as a luminescent/bio probe has been made and characterized using extended X-ray absorption fine structure (EXAFS) as well as IR spectroscopy, UV-Vis spectroscopy, and elemental analysis. Structural data of the formed Ho(III)–phen species are determined from the Ho $$L_{\mathrm {III}}$$ -edge EXAFS spectra as well as its $$k^{\mathrm {2}}$$ -weighted and $$k^{\mathrm {3}}$$ -weighted spectra. The coordination numbers and distances between the holmium and the first shell atoms, i.e., O, N, and Cl, are measured. The EXAFS spectra are also analyzed by Fourier transform of the normalized absorption coefficient into the molecular distance coordinates to further verify the determined Ho(III) structural model.