Université de Fribourg

Stereoselective synthesis of cyclometalated iridium(III) complexes: characterization and photophysical properties

Yang, Liangru ; Zelewsky, Alexander von ; Nguyen, Huong P. ; Muller, Gilles ; Labat, Gaël Charles ; Stoeckli-Evans, Helen

In: Inorganica Chimica Acta, 2009, vol. 36, no. 10, p. 3853-3856

The stereoselective synthesis of a highly luminescent neutral Ir(III) complex comprising two bidentate chiral, cyclometalating phenylpyridine derivatives, and one acetylacetonate as ligands is described. The final complex and some intermediates were characterized by X-ray structural analysis, NMR-, CD-, and CPL-spectroscopy.

Université de Fribourg

Diastereoselective preparation of Cu(I) and Ag(I) double helices by the use of chiral bis-bipyridine ligands

Perret-Aebi, Laure-Emmanuelle ; Zelewsky, Alexander von ; Neels, Antonia

In: New Journal of Chemistry, 2009, vol. 33, p. 462–465

Chiral bis-5,6-pinene bipyridine type ligands have been used to form, through self-assembly reaction, dinuclear coordination compounds which show a highly diastereoselective formation of double helices with copper(I) and silver(I) as coordination centers.

Université de Fribourg

New ruthenium(II) complexes with enantiomerically pure bis- and tris(pinene)-fused tridentate ligands: synthesis, characterization and stereoisomeric analysis

Sala, Xavier ; Poater, Albert ; Zelewsky, Alexander von ; Parella, Teodor ; Fontrodona, Xavier ; Romero, Isabel ; Solà, Miquel ; Rodríguez, Montserrat ; Llobet, Antoni

In: Inorganic Chemistry, 2008, vol. 47, no. 18, p. 8016–8024

A new set of Ru−Cl complexes containing either the pinene[5,6]bpea ligand (L1) or the C₃ symmetric pinene[4,5]tpmOMe (L2) tridentate ligand in combination with the bidentate (B) 2,2′-bipyridine (bpy) or 1,2-diphenylphosphinoethane (dppe) with general formula [RuCl(L1 or L2)(B)]⁺ have been prepared and thoroughly characterized. In the solid state, X-ray diffraction...

Université de Fribourg

New synthetic routes toward enantiopure nitrogen donor ligands

Sala, Xavier ; Rodríguez, Anna M. ; Rodríguez, Montserrat ; Romero, Isabel ; Parella, Teodor ; Zelewsky, Alexander von ; Llobet, Antoni ; Benet-Buchholz, Jordi

In: The Journal of Organic Chemistry, 2006, vol. 71, no. 25, p. 9283 -9290

New polypyridylic chiral ligands, having either C₃ or lower symmetry, have been prepared via a de novo construction of the pyridine nucleus by means of Kröhnke methodology in the key step. The chiral moieties of these ligands originate from the monoterpen chiral pool, namely (-)-α-pinene ((-)-14, (-)-15) and (-)-myrtenal ((-)-9, (-)-10). Extension of the...

Université de Fribourg

Stereoselectivity in the formation of tris-diimine complexes of Fe(II), Ru(II), and Os(II) with a C₂-symmetric chiral derivative of 2,2′-bipyridine

Drahoňovský, Dušan ; Knof, Ulrich ; Jungo, Laurence ; Belser, Thomas ; Neels, Antonia ; Labat, Gaël Charles ; Stoeckli-Evans, Helen ; Zelewsky, Alexander von

In: Dalton Transactions, 2006, p. 1444 - 1454

A C₂-symmetric enantiopure 4,5-bis(pinene)-2,2′-bipyridine ligand (–)-L was used to investigate the diastereoselectivity in the formation of [ML₃]²⁺ coordination species (M = Fe(II), Ru(II), Os(II), Zn(II), Cd(II), Cu(II), Ni(II)), and [ML₂Cl₂] (M = Ru(II), Os(II)). The X-ray structures of the [ML₃]²⁺ complexes were determined for Δ-[FeL₃](PF₆)₂,...

Université de Fribourg

Novel HEXOL-type cyclometallated iridium(III) complexes: stereoselective synthesis and structure elucidation

Yang, Liangru ; Zelewsky, Alexander von ; Stoeckli-Evans, Helen

In: Chemical Communications, 2005, vol. (33), p. 4155

Two diastereoisomers of tetranuclear cyclometallated iridium complexes, either having an inner core of HEXOL-type [Ir(IrCl₂)₃]⁶⁺ unit and a surface of six chiral, didentate, cyclometallated ligands, are stereoselectively synthesized from an enantiopure pinenopyridine derivative.

Université de Fribourg

Protonation behaviour of chiral tetradentate polypyridines derived from α-Pinene

Düggeli, Mathias ; Christen, Tobias ; Zelewsky, Alexander von

In: Chemistry - A European Journal, 2005, vol. 11, p. 185-194

Detailed protonation experiments of the [5,6]-pinenebipyridine molecule and the unsubstituted [4,5]- and [5,6]-CHIRAGEN[0] ligands in various solvents indicate a variety of structures of the protonated species. UV-visible and NMR measurements (including ¹⁵N chemical shifts) show the transition from trans to cis conformation of [5,6]-pinenebipyridine upon protonation. The...

Université de Fribourg

Diastereoselective synthesis of coordination compounds: a chiral tripodal ligand based on bipyridine units and its ruthenium(II) and iron(II) complexes

Hamann, Christine ; Zelewsky, Alexander von ; Neels, Antonia ; Stoeckli-Evans, Helen

In: Dalton Transactions, 2004, vol. 3, p. 402-406

The enantiomerically pure chiral tris-chelating ligand (+)-(7S,10R)-L(L) comprising three 4,5-pinenobipyridine subunits connected through a mesityl spacer has been synthesized. Complexes of L with RuII and FeII have been prepared and characterised. NMR spectroscopy indicates that...

Université de Fribourg

Asymmetric Synthesis of Coordination Compounds: Back to the Roots. Diastereoselective Synthesis of Simple Platinum(IV) Complexes

Drahoňovský, Dušan ; Zelewsky, Alexander von

In: Helvetica Chimica Acta, 2005, vol. 88(3), p. 496-506

A publication by Alexander P. Smirnoff in Helvetica Chimica Acta in 1920 [6] describes the first synthesis of a coordination species, i.e., of tris(propane-1,2-diamine-κN¹,κN²)platinum(4+) ([PtIV(pn)₃]⁴⁺), where it was shown that the configuration of a chiral center in the ligand can influence the configuration at the metal. The present investigation of...