title: X-ray Inducible Luminescence and Singlet Oxygen Sensitization by an Octahedral Molybdenum Cluster Compound: A New Class of Nanoscintillators.
abstract: Newly synthesized octahedral molybdenum cluster compound (n-Bu4N)2[Mo6I8(OOC-1-adamantane)6] revealed uncharted features applicable for the development of X-ray inducible luminescent materials and sensitizers of singlet oxygen, O2((1)Δg). The compound exhibits a red-NIR luminescence in the solid state and in solution (e.g., quantum yield of 0.76 in tetrahydrofuran) upon excitation by UV-vis light. The luminescence originating from the excited triplet states is quenched by molecular oxygen to produce O2((1)Δg) with a high quantum yield. Irradiation of the compound by X-rays generated a radioluminescence with the same emission spectrum as that obtained by UV-vis excitation. It proves the formation of the same excited triplet states regardless of the excitation source. By virtue of the described behavior, the compound is suggested as an efficient sensitizer of O2((1)Δg) upon X-ray excitation. The luminescence and radioluminescence properties were maintained upon embedding the compound in polystyrene films. In addition, polystyrene induced an enhancement of the radioluminescence intensity via energy transfer from the scintillating polymeric matrix. Sulfonated polystyrene nanofibers were used for the preparation of nanoparticles which form stable dispersions in water, while keeping intact the luminescence properties of the embedded compound over a long time period. Due to their small size and high oxygen diffusivity, these nanoparticles are suitable carriers of sensitizers of O2((1)Δg). The presented results define a new class of nanoscintillators with promising properties for X-ray inducible photodynamic therapy.
authors.affiliation: Institute of Inorganic Chemistry of the Czech Academy of Sciences , v.v.i, Husinec-Řež 1001, 250 68 Řež, Czech Republic.
authors.forename: Kaplan
authors.initials: K
authors.lastname: Kirakci
authors.affiliation: J. Heyrovský Institute of Physical Chemistry of the Czech Academy of Sciences , v.v.i., Dolejškova 3, 182 23 Praha 8, Czech Republic.
authors.forename: Pavel
authors.initials: P
authors.lastname: Kubát
authors.affiliation: Institute of Physics of the Czech Academy of Sciences , v.v.i., Cukrovarnická 10/112, 162 00 Praha 6, Czech Republic.
authors.forename: Karla
authors.initials: K
authors.lastname: Fejfarová
authors.affiliation: Institute of Physics of the Czech Academy of Sciences , v.v.i., Cukrovarnická 10/112, 162 00 Praha 6, Czech Republic.|Faculty of Nuclear Sciences and Physical Engineering, Czech Technical University in Prague , Břehová 7, 115 19 Praha 1, Czech Republic.
authors.forename: Jiří
authors.initials: J
authors.lastname: Martinčík
authors.affiliation: Institute of Physics of the Czech Academy of Sciences , v.v.i., Cukrovarnická 10/112, 162 00 Praha 6, Czech Republic.
authors.forename: Martin
authors.initials: M
authors.lastname: Nikl
authors.affiliation: Institute of Inorganic Chemistry of the Czech Academy of Sciences , v.v.i, Husinec-Řež 1001, 250 68 Řež, Czech Republic.
authors.forename: Kamil
authors.initials: K
authors.lastname: Lang
mesh_terms: D018360:Crystallography, X-Ray; D049449:Luminescence; D008982:Molybdenum / Q000737:chemistry*; D036103:Nanotechnology; D026082:Singlet Oxygen / Q000737:chemistry*
chemical_list: D026082:Singlet Oxygen; D008982:Molybdenum