title: In situ X-ray absorption spectroscopy studies of kinetic interaction between platinum(II) ions and UiO-66 series metal-organic frameworks.
abstract: The interaction of guest Pt(II) ions with UiO-66-X (X = NH2, H, NO2, OMe, F) series metal-organic frameworks (MOFs) in aqueous solution was investigated using in situ X-ray absorption spectroscopy. All of these MOFs were found to be able to coordinate with Pt(II) ions. The Pt(II) ions in UiO-66-X MOFs generally coordinate with 1.6-2.4 Cl and 1.4-2.4 N or O atoms. We also studied the time evolution of the coordination structure and found that Pt(II) maintained a coordination number of 4 throughout the whole process. Furthermore, the kinetic parameters of the interaction of Pt(II) ions with UiO-66-X series MOFs (X = NH2, H, NO2, OMe, F) were determined by combinational linear fitting of extended X-ray absorption fine structure (EXAFS) spectra of the samples. The Pt(II) adsorption rate constants were found to be 0.063 h(-1) for UiO-66-NH2 and 0.011-0.017 h(-1) for other UiO-66-X (X = H, NO2, OMe, F) MOFs, which means that Pt(II) adsorption in UiO-66-NH2 is 4-6 times faster than that in other UiO-66 series MOFs. FTIR studies suggested that the carboxyl groups could be the major host ligands binding with Pt(II) ions in UiO-66 series MOFs, except for UiO-66-NH2, in which amino groups coordinate with Pt(II) ions.
authors.affiliation: Department of Chemistry, Iowa State University , Ames, Iowa 50011, United States.
authors.forename: Chaoxian
authors.initials: C
authors.lastname: Xiao
authors.forename: Tian Wei
authors.initials: TW
authors.lastname: Goh
authors.forename: Kyle
authors.initials: K
authors.lastname: Brashler
authors.forename: Yuchen
authors.initials: Y
authors.lastname: Pei
authors.forename: Zhiyong
authors.initials: Z
authors.lastname: Guo
authors.forename: Wenyu
authors.initials: W
authors.lastname: Huang