Université de Fribourg

Supramolecular organization of dye molecules in zeolite L channels: synthesis, properties, and composite materials

Cao, Pengpeng ; Khorev, Oleg ; Devaux, André ; Sägesser, Lucie ; Kunzmann, Andreas ; Ecker, Achim ; Häner, Robert ; Brühwiler, Dominik ; Calzaferri, Gion ; Belser, Peter

In: Chemistry - A European Journal, 2016, vol. 22, no. 12, p. 4046–4060

Sequential insertion of different dyes into the 1D channels of zeolite L (ZL) leads to supramolecular sandwich structures and allows the formation of sophisticated antenna composites for light harvesting, transport, and trapping. The synthesis and properties of dye molecules, host materials, composites, and composites embedded in polymer matrices, including two- and three-color antenna systems,...

Université de Fribourg

Efficient and robust host–guest antenna composite for light harvesting

Devaux, André ; Calzaferri, Gion ; Belser, Peter ; Cao, Pengpeng ; Brühwiler, Dominik ; Kunzmann, Andreas

In: Chemistry of Materials, 2014, vol. 26, no. 23, p. 6878–6885

We report discovery of a new efficient and robust antenna composite for light harvesting. The organic dye hostasol red (HR) is strongly luminescent in aprotic solvents but only weakly luminescent in potassium zeolite L (ZL) at ambient conditions. We observed a dramatic increase of the luminescence quantum yield of HR–ZL composites if some or all exchangeable potassium cations of ZL are...

Université de Fribourg

Self-absorption and luminescence quantum yields of dye-zeolite L composites

Devaux, André ; Calzaferri, Gion ; Miletto, Ivana ; Cao, Pengpeng ; Belser, Peter ; Brühwiler, Dominik ; Khorev, Oleg ; Häner, Robert ; Kunzmann, Andreas

In: The Journal of Physical Chemistry C, 2013, vol. 117, no. 44, p. 23034–23047

Electronic absorption and fluorescence spectra based on transmission measurements of thin layers obtained from new perylene–zeolite L composites and new dye1,dye2–zeolite L sandwich composites, the latter acting as antenna systems, have been investigated and analyzed. The influence of extra- and intraparticle self-absorption on the spectral shape and fluorescence quantum yield is discussed in...

Université de Fribourg

Host–guest interactions and orientation of dyes in the one-dimensional channels of zeolite L

Fois, Ettore ; Tabacchi, Gloria ; Devaux, André ; Belser, Peter ; Brühwiler, Dominik ; Calzaferri, Gion

In: Langmuir, 2013, vol. 29, no. 29, p. 9188–9198

A combined experimental and modeling study of methylacridine (MeAcr⁺) dye-zeolite L composites unravels the microscopic origin of their functional properties. The anisotropic orientation of the cationic dye inside the ZL channel is unambiguously determined and understood. The most stable orientation of MeAcr⁺, which features both its long and short molecular axes nearly perpendicular to the...

Université de Fribourg

The use of the triptycene framework for observing O⋯C=O molecular interactions

Lari, Alberth ; Pitak, Mateusz B. ; Coles, Simon J. ; Bresco, Emma ; Belser, Peter ; Beyeler, Andreas ; Pilkington, Melanie ; Wallis, John D.

In: CrystEngComm, 2011, vol. 13, p. 6978-6984

The triptycene skeleton has been used to measure (1,5) interactions between aldehyde groups, placed at both sp³ centres, and hydroxy or methoxy groups, placed at the respective ortho position on a benzene ring; HO⋯CHO interactions of 2.621–2.624 Å and MeO⋯CHO interactions of 2.528–2.584 Å were observed with the O⋯C vector making angles of 105.3–133.7° with the carbonyl bond. The...

Université de Fribourg

Tripodal osmium polypyridyl complexes for self-assembly on platinum nanoparticles

Contreras-Carballada, Pablo ; Edafe, Fabio ; Tichelaar, Frans D. ; Belser, Peter ; Cola, Luisa De ; Williams, René M.

In: The Journal of Physical Chemistry Letters, 2011, vol. 2, no. 12, p. 1460–1463

The combination of platinum nanoparticles with a tripodal osmium complex that anchors to the metal surface leads, under visible light irradiation, to the formation of solvated electrons. The formation kinetics is limited by the detachment of the electron from the platinum surface into the solution, the particle showing a type of capacitor behavior

Université de Fribourg

Luminescent acetylthiol derivative tripodal osmium(II) and iridium(III) complexes: Spectroscopy in solution and on surfaces

Ramachandra, Srinidhi ; Polo, Federico ; Edafe, Fabio ; Schuermann, Klaus C. ; Nijhuis, Christian A. ; Belser, Peter ; Reus, William F. ; Whitesides, George M. ; Cola, Luisa De

In: Pure and Applied Chemistry, 2011, vol. 4, no. 83, p. 779-799

Luminescent Os(II) and Ir(III) complexes containing a tripodal-type structure terminalized with three thiol derivatives are described. The tripod is introduced through derivatization, with a rigid spacer, of a phenanthroline ligand coordinated to the metal ion, and the entire structure possesses axial geometry. The geometry of the complexes combined with the three anchoring sites, the thiol...

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 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...