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Université de Fribourg

Photochemical investigation of a photochromic diarylethene compound that can be used as a wide range actinometer

Ribeiro Santos, André ; Ballardini, Roberto ; Belser, Peter ; Gandolfi, Maria Teresa ; Mahadevan Iyer, Vijay ; Moggi, Luca

In: Photochemical & Photobiological Sciences, 2009, vol. 8, p. 1734-1742

The photochromic diarylethene derivative 1,2-bis(5-(4-ethynylphenyl)-2-methylthiophen-3-yl)perfluorocyclopentene (1) was submitted to photochemical, thermal stability and fatigue resistance studies in acetonitrile, also to evaluate its possible application as a new actinometer. This photochromic system covers a wide spectral absorption range, with intense bands in the UV and visible regions for...

Université de Fribourg

Photophysical and redox properties of dinuclear ru and os polypyridyl complexes with incorporated photostable spiropyran bridge

Jukes, Ron T. F. ; Bozic, Biljana ; Belser, Peter ; Cola, Luisa De ; Hartl, František

In: Inorganic Chemistry, 2009, vol. 48, no. 4, p. 1711–1721

Aimed at creating a true photoswitchable energy transfer system, four dinuclear complexes containing ruthenium(II) and osmium(II) metal centers bridged by spiropyran-type linkers were designed and investigated. The bridge in its closed spiropyran form was shown to be a good insulator for energy transfer between the Ru-bpy donor and the Os-bpy acceptor (bpy = 2,2′-bipyridine). On the basis of...

Université de Fribourg

Photochemical, photophysical and redox properties of novel fulgimide derivatives with attached 2,2′-bipyridine (bpy) and [M(bpy)₃]²⁺ (M = Ru and Os) moieties

Jukes, Ron T. F. ; Kühni, Joël ; Salluce, Nunzio ; Belser, Peter ; Cola, Luisa De ; Hartl, František

In: Dalton Transactions, 2009, p. 3993-4002

Fulgimides monosubstituted with [M(bpy)₃]²⁺ (M = Ru, Os; bpy = 2,2′-bipyridine) chromophore units and with a single bpy group were synthesized and investigated as components of conceivable dinuclear photochromic switches of luminescence. The E-, Z- and closed-ring (C) photoisomer forms of the bpy-bound fulgimide were successfully separated by semi-preparative HPLC. The same...

Université de Fribourg

Synthesis, photophysical, photochemical, and redox properties of nitrospiropyrans substituted with Ru or Os tris(bipyridine) complexes

Jukes, Ron T. F. ; Bozic, Biljana ; Hartl, František ; Belser, Peter ; De Cola, Luisa

In: Inorganic Chemistry, 2006, vol. 45, no. 20, p. 8326 -8341

Photochromic nitrospiropyrans substituted with 2,2'-bipyridine (bpy), [Ru(bpy)₃]²⁺, and [Os(bpy)₃]²⁺ groups were synthesized, and their photophysical, photochemical, and redox properties investigated. Substitution of the spiropyran with the metal complex moiety results in strongly decreased efficiency of the ring-opening process as a result of energy transfer from the excited spiropyran...

Université de Fribourg

Gated photochromism of 1,2-diarylethenes

Kühni, Joël ; Belser, Peter

In: Organic Letters, 2007, vol. 9, no. 10, p. 1915 -1918

A dithienylethene derivative containing a cyclobutene-1,2-dione skeleton does not exhibit photochromic properties. However, when both ketone functions are protected with cyclic acetal groups, photochromic behavior is observed.

Université de Fribourg

Quantitative self-sensitized photooxidation of 1,2-diarylcyclobutene derivatives by singlet oxygen

Kühni, Joël ; Debieux, Jean-Luc ; Belser, Peter

In: Synthesis, 2007, p. 1421-1425

Ligands 1 and 2 underwent quantitative photooxidation when they were reacted with singlet oxygen sensitized by methylene blue. However, the quantitative reaction became self-sensitized for the compound Ru(1) wherein the ruthenium complex acted as a sensitizer.

Université de Fribourg

A perfluorocyclopentene dithienylethene based molecular switch: 1,2-bis[5-(4-ethynylphenyl)-2-methylthiophen-3-yl]-3,3,4,4,5,5-hexafluorocyclopentene

Iyer, Vijay Mahadevan ; Stoeckli-Evans, Helen ; Belser, Peter

In: Acta Crystallographica E, 2006, vol. 62, no. 9, p. o3942-o3943

The title compound, C₃₁H₁₈F₆S₂, is a molecular switch based on dithienylperfluorocyclopentene. The molecule possesses pseudo-C₂ symmetry and has the open form of the switch. There are a number of intramolecular C-H...F hydrogen bonds, but in the crystal structure there are no interactions between symmetry-related molecules.

Université de Fribourg

Synthesis of an unsymmetrically substituted, dithienylethene-containing 1,10-phenanthroline ligand and its ruthenium(ii) complex

Kühni, Joël ; Adamo, Vincent ; Belser, Peter

In: Synthesis, 2006, vol. 12, p. 1946-1948

The synthesis of an unsymmetrically substituted 1,10-phenanthroline ligand and its corresponding ruthenium(II) complex is reported. Suzuki coupling has been employed under different conditions to get the target ligand.

Université de Fribourg

Photochromic switches incorporated in bridging ligands: a new tool to modulate energy-transfer

Belser, Peter ; Cola, Luisa De ; Hartl, F. ; Adamo, Vincenzo ; Bozic, Biljana ; Chriqui, Yoel ; Iyer, Vijay Mahadevan ; Jukes, R. T. F. ; Kühni, Joel ; Querol, Manel ; Roma, Silvia ; Salluce, Nunzio

In: Advanced Functional Materials, 2006, vol. 16, no. 2, p. 195-208

The thoughful construction of molecular switches has led to a gamut of supramolecular systems that can be used in molecular electronics. These include molecules based on thienylethenes, spiropyrans, fulgides, dithienylphenanthrolines, and diazafluorenes. This article reviews the recent developments made in the synthesis and characterization of all these systems, thereby allowing a comparative...

Université de Fribourg

Assessment of theoretical prediction of the NMR shielding tensor of ¹⁹⁵PtClxBr6–x²⁻ complexes by DFT calculations: experimental and computational results

Penka Fowe, Emmanuel ; Belser, Peter ; Daul, Claude A. ; Chermette, Henry

In: Physical Chemistry Chemical Physics, 2005, vol. 7(8), p. 1732-1738

In the present work, the ZORA spin–orbit Hamiltonian, in conjunction with the gauge including orbital (GIAO) method based on DFT theory has been used to calculate ¹⁹⁵Pt chemical shift of ¹⁹⁵PtClxBr6–x²⁻ complexes. Excellent agreement with experiments has been obtained for calculations bearing on optimized geometries and all electrons triple zeta +...