Université de Fribourg

On the reversible photoisomerization of spiropyran-modified zeolite L single crystals

Albuquerque, R. Q. ; Kühni, Joël ; Belser, Peter ; Cola, Luisa De

In: ChemPhysChem, 2010, vol. 11, no. 3, p. 575-578

The reversible photoisomerization of a derivative of spiropyran at the level of a single crystal by using zeolite L is demonstrated. The synthesized spiropyran exhibits rare negative photochromism when dissolved in a 1:1 mixture of H₂O and EtOH The spiropyran is functionalized predominantly at the channel entrances in the case of 4 μm long crystals

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

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

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.