Search results for "Titanium"
showing 10 items of 878 documents
Photocatalytic Activity of TiO2 Coatings Obtained at Room Temperature on a Polymethyl Methacrylate Substrate
2022
Titanium dioxide (TiO2) coatings have a wide range of applications. Anatase exhibits hydrophilic, antimicrobial, and photocatalytic properties for the degradation of organic pollutants or water splitting. The main challenge is to obtain durable anatase nanoparticle coatings on plastic substrates by using straightforward approaches. In the present study, we revealed the preparation of a transparent TiO2 coating on polymethylmethacrylate (PMMA), widely used for organic optical fibres as well as other polymer substrates such as polypropylene (PP), polystyrene (PS), and polycarbonate (PC). The films were spin-coated at room temperature without annealing; therefore, our approach can be used for …
Mixed Titanium–Hafnium Chloridometallate Complexes
2007
The addition of either NEt 3 BzCl or [Ph 3 PNPPh 3 ]Cl (1 equiv. chloride per metal) to a 1:1 mixture of HfCl 4 and TiCl 3 in SOCl 2 results in Ti oxidation and leads to the corresponding salts of the [TiHfCl 10 ] 2- ion. A solution IR investigation in the v(M-Cl) region indicates that this ion is in equilibrium with the homodimetallic [Ti 2 Cl 10 ] 2- and [Hf 2 Cl 10 ] 2- ions. An X-ray study of the NEt 3 Bz + salt reveals an edge-sharing bioctahedral dianion sitting on a crystallographic inversion centre. The crystal is a solid solution of different species with compositional disorder at the metal site, each metal position having the occupancy Ti 0.685 Hf 0.315 . The M-M and M-Cl distance…
Influence of Adsorbed Water on the Activation Energy of Model Photocatalytic Reactions
2017
Two commercial (Merck and Sigma-Aldrich) and two home prepared (HP05 and HP05C) powdered TiO2 photocatalysts were investigated by fast field cycling nuclear magnetic resonance experiments in order to explore the nature of the interactions between water and the solid surfaces. The results were related to the activation energies determined at temperatures ranging from 303 to 353 K for the photocatalytic oxidation in water of three model molecules presenting different interactions with the solid surface (catechol, phenol, and metylbenzoate). The photoactivity results at different temperatures were comparable to each other because the runs were carried out while keeping constant the concentrati…
Reversible Colorimetric Probes for Mercury Sensing
2005
The selectivity and sensitivity of two colorimetric sensors based on the ruthenium complexes N719 [bis(2,2'-bipyridyl-4,4'-dicarboxylate)ruthenium(II) bis(tetrabutylammonium) bis(thiocyanate)] and N749 [(2,2':6',2' '-terpyridine-4,4',4' '-tricarboxylate)ruthenium(II) tris(tetrabutylammonium) tris(isothiocyanate)] are described. It was found that mercury ions coordinate reversibly to the sulfur atom of the dyes' NCS groups. This interaction induces a color change in the dyes at submicromolar concentrations of mercury. Furthermore, the color change of these dyes is selective for mercury(II) when compared with other ions such as lead(II), cadmium(II), zinc(II), or iron(II). The detection limit…
The efficacy of two rotary NiTi instruments and H-files to remove gutta-percha from root canals
2011
WOS: 000304343300026
Comparison of the photocatalytic degradation of 2-propanol in gas–solid and liquid–solid systems by using TiO2–LnPc2 hybrid powders
2009
Photocatalytic degradation of 2-propanol was carried out as a probe reaction both in gas–solid and in liquid–solid systems in the presence of TiO2 both bare and impregnated with lanthanide (Sm, Gd, Ho) bis-phthalocyanines (LnPc2) used as sensitizers. Continuous and batch photo-reactors, irradiated with an equal flux of photons, were used in gas–solid and in liquid–solid systems, respectively. Propanone and acetaldehyde were the main intermediates found in both systems during 2-propanol oxidation, whereas carbon dioxide and water were the final oxidation products exclusively in the gas–solid regime. The photocatalysts exhibited significantly higher activity in the liquid–solid system than in…
Surface modifications induced by nanosecond pulsed Nd:YAG laser irradiation of metallic substrates
2006
International audience; Substrate surface preparation is a key step in coating deposition process. In recent years, pulsed laser cleaning has emerged as a possible technique to challenge the traditional preparation methods (based on degreasing and eventually grit-blasting). The laser operated at short-pulse mode offers high cleaning efficiency and therefore has been largely used. In a specific process named PROTAL®, a nanosecond pulsed laser is introduced to prepare the surface simultaneously to thermal spraying, with the purpose of eliminating the contaminants and generating favorite surface conditions for coating deposition. This study aims at clarifying some fundamental aspects of nanose…
(Table 1) Geochemistry of ODP Site 160-963 sediments
2010
The Mediterranean Sea acts as a miniature ocean with the development of its own conveyor belt. It constitutes an ideal location to study and forecast how the marine environment responds to rapid climatic change. Here we present a palaeoenvironmental study carried out on the sediments of ODP Site 963, recovered in the Sicily Channel, the sill which divides the western from the eastern Mediterranean basin. We focused on the transition between the penultimate glacial (MIS 6) and the last interglacial (MIS 5), between approximately 130 and 115 kyr BP. A novel approach is proposed, taking into account centennial-scale geochemical data on major elements, selected trace elements, and yttrium and R…
Titanium Complexes of Chelating Bis(phenolato) Ligands with Long Titanium−Sulfur Bonds. A Novel Type of Ancillary Ligand for Olefin Polymerization Ca…
1996
The sulfide-linked bis(phenol) tbmpH2 (tbmp = 2,2‘-thiobis(6-tert-butyl-4-methylphenolato)) gives a series of titanium complexes of the formula [Ti(tbmp)X2]2 or [Ti(tbmp)(L)X2] (L = two-electron ligand, X = one-electron ligand). The molecular structures of [Ti(tbmp)(OiPr)2]2 and of [Ti(tbmp){C6H4(CH2NMe2)-2}Cl] were determined by single-crystal X-ray structural analyses. An unusually long titanium−sulfur bond of ∼270 pm is observed in both complexes which contain a six-coordinate titanium center. Variable-temperature NMR spectroscopy shows a fluxional coordination of the chelating aryl group in [Ti(tbmp){C6H4(CH2NMe2)-2}Cl].
Optically Active Titanium Complexes Containing Linked Amido‐cyclopentadienyl Ligands: Their Use as Asymmetric Hydrogenation Catalysts
1996
Optically active titanium complexes of the formula Ti(η5:η1−C5R4SiMe2NCHMePh)Cl2 (R = H, Me), containing the cyclopentadienyl ligand linked to a chiral 1-phenylethylamido moiety, were synthesized and characterized in both enantiomerically pure forms. A single-crystal X-ray structural analysis of (S)()Ti(η5:η1−C5H4SiMe2NCHMePh)Cl2 shows a conformation in which the phenyl group is turned away from the metal center. NOE measurements suggest that a related structure is retained in solution. Upon activation with n-butyllithium, these complexes show hydrogenation activity toward imines with slight enantioselectivity.