title: DFT modeling, UV-Vis and IR spectroscopic study of acetylacetone-modified zirconia sol-gel materials.
abstract: Theoretical and spectroscopic studies of a series of monomeric and dimeric complexes formed through the modification of a zirconium butoxide precursor with acetylacetone and subsequent hydrolysis and/or condensation have been performed by applying DFT/B3LYP/6-31++G(d) and highly accurate RI-ADC(2) methods as well as IR and UV-Vis transmittance and diffuse reflectance spectroscopies. Based on DFT model calculations and simulated and experimental UV-Vis and IR spectra of all the studied structures, the most probable building units of the Zr(IV)-AcAc gel were predicted: the dimeric double hydroxo-bridged complex Zr(2)(AcAc)(2)(OH)(4)(OH)(2br) 9 and the monooxo-bridged complex Zr(2)(AcAc)(2)(OH)(4)O(br)·2H(2)O 12. In both structures, the two AcAc ligands are coordinated to one Zr atom. It was shown that building units 9 and 12 determine the photophysical and vibrational properties of the gel material. The observed UV-Vis and IR spectra of Zr(IV)-AcAc gel were interpreted and a relation between the spectroscopic and structural data was derived. The observed UV-Vis bands at 315 nm and 298/288 nm were assigned to partial ligand-metal transitions and to intra-/inter-AcAc ligand transitions, respectively.
authors: Institute of General and Inorganic Chemistry, Bulgarian Academy of Sciences, Sofia, Bulgaria. ivelina@svr.igic.bas.bg
authors: Ivelina
authors: I
authors: Georgieva
authors: Nina
authors: N
authors: Danchova
authors: Stoyan
authors: S
authors: Gutzov
authors: Natasha
authors: N
authors: Trendafilova
mesh_terms: D003198:Computer Simulation; D056831:Coordination Complexes / Q000737:chemistry*; D005782:Gels; D006860:Hydrogen Bonding; D006868:Hydrolysis; D008958:Models, Molecular; D008968:Molecular Conformation; D010422:Pentanones / Q000737:chemistry*; D011789:Quantum Theory; D013055:Spectrophotometry, Infrared; D013056:Spectrophotometry, Ultraviolet; D015040:Zirconium / Q000737:chemistry*
chemical_list: D056831:Coordination Complexes; D005782:Gels; D010422:Pentanones; C008790:acetylacetone; D015040:Zirconium; C028541:zirconium oxide