2013-06-18 08:50:45 1228 Lilit Aboshyan-Sorgho, Céline Besnard, Phil Pattison, Kevin R. Kittilstved, Annina Aebischer, Jean-Claude G. Bünzli, Andreas Hauser, Claude Piguet Aboshyan-Sorgho, Lilit Besnard, Céline Pattison, Phil Kittilstved, Kevin R. Aebischer, Annina Bünzli, Jean-Claude G. Hauser, Andreas Piguet, Claude Angewandte Chemie International Edition Angew. Chem. Intl. Ed. 1433-7851 2011 50 4108 4112 H helical structures;lanthanides;photochemistry;self-assembly;upconversion helical structures lanthanides photochemistry self-assembly upconversion http://onlinelibrary.wiley.com/doi/10.1002/anie.201100095/abstract;jsessionid=C352764B1E9229A45C8C5FB9AEA7917B.d02t01 http://onlinelibrary.wiley.com/doi/10.1002/anie.201100095/pdf The connection of two Cr^III sensitizers around a central Er^III acceptor in a self-assembled cation provides high local metal concentrations that favor efficient nonlinear energy transfer upconversion luminescence (see picture). Upon selective low-energy near-infrared irradiation of Cr^III-centered transitions, 1 displays an unprecedented molecular two-photon upconverted green Er^III-centered emission.

]]> H210I421P653V 10.1002/anie.201100095 15714 http://www.unige.ch/sciences/chifi/publis/pics/double/ref01228.png http://www.unige.ch/sciences/chifi/publis/refs_pdf/ref01228.pdf 971 Soumaila Zebret, Nathalie Dupont, Gérald Bernardinelli, Josef Hamacek Zebret, Soumaila Dupont, Nathalie Bernardinelli, Gérald Hamacek, Josef Chemistry - A European Journal Chem. - Eur. J. 0947-6539 2009 15 14 3355 3358 H europium • luminescence • self-assembly • supramolecular chemistry • trinuclear complexes europium luminescence self-assembly supramolecular chemistry trinuclear complexes http://www3.interscience.wiley.com/journal/122210990/abstract http://www3.interscience.wiley.com/cgi-bin/fulltext/122210990/HTMLSTART http://www3.interscience.wiley.com/cgi-bin/fulltext/122210990/PDFSTART Triangular luminescent box: Self-assembly of a new multidentate receptor with europium cations results in the formation of trinuclear discrete complexes. X-ray crystallography shows that nine-coordinate cations are linked by ligands to provide a triangular complex in the solid state and in solution. Despite the coordinated solvent molecules, this topologically unusual complex exhibits remarkable luminescent properties.

]]> AH140I280P251 10.1002/chem.200802676 3543 http://www.unige.ch/sciences/chifi/publis/pics/double/ref00971.png http://www.unige.ch/sciences/chifi/publis/refs_pdf/ref00971.pdf 569 Stéphane Torelli, Sandra Delahaye, Andreas Hauser, Gérald Bernardinelli, Claude Piguet Torelli, Stéphane Delahaye, Sandra Hauser, Andreas Bernardinelli, Gérald Piguet, Claude Chemistry - A European Journal Chem. - Eur. J. 0947-6539 2004 10 14 3503 3516 H helical structures; isomerization; lanthanides; ruthenium; self-assembly helical structures isomerization lanthanides ruthenium self-assembly http://www3.interscience.wiley.com/cgi-bin/abstract/108567862/ABSTRACT http://www3.interscience.wiley.com/cgi-bin/fulltext/108567862/HTMLSTART http://www3.interscience.wiley.com/cgi-bin/fulltext/108567862/PDFSTART Unsymmetrical substituted bidentate benzimidazol-2-ylpyridine ligands L2 and L3 react with [Ru(dmso)₄Cl₂] in ethanol to give statistical 1:3 mixtures of fac-[Ru(Li)₃]²⁺ and mer-[Ru(Li)₃]²⁺ (i=2, 3; ΔGΘ_{isomerisation}=-2.7 kJ mol^-1). In more polar solvents (acetonitrile, methanol), the free energy of the facial ↔ meridional isomerisation process favours mer-[Ru(Li)₃]²⁺, which is the only isomer observed in solution at the equilibrium (ΔGΘ_{isomerisation}≤-11.4 kJ mol^-1). Since the latter process takes several days for [Ru(L2)₃]²⁺, fac-[Ru(L2)₃]²⁺ and mer-[Ru(L2)₃]²⁺ have been separated by chromatography, but the 28-fold increase in velocity observed for [Ru(L3)₃]²⁺ provides only mer-[Ru(L3)₃](ClO₄)₂ after chromatography (RuC₆₀H₅₁N₉O₈Cl₂, monoclinic, P2₁/n, Z=4). The facial isomer can be stabilised when an appended tridentate binding unit, connected at the 5-position of the benzimidazol-2-ylpyridine unit in ligand L1, interacts with nine-coordinate lanthanides(III). The free energy of the facial↔meridional isomerisation is reversed (ΔGΘ_{isomerisation}≥11.4 kJ mol^-1), and the Ru — N bonds are labile enough to allow the quantitative thermodynamic self-assembly of HHH-[RuLu(L1)₃]⁵⁺ within hours ([RuLu(L1)₃](CF₃SO₃)_4.5Cl_0.5(CH₃OH)_2.5: RuLuC₁₀₆H₁₀₉Cl_0.5N₂₁O₁₉S_4.5F_13.5, triclinic, P, Z=2). Electrochemical and photophysical studies show that the benzimidazol-2-ylpyridine units in L1-L3 display similar π-acceptor properties to, but stronger π-donor properties than, those found in 2,2'-bipyridine. This shifts the intraligand π→π^* and the MLCT transitions toward lower energies in the pseudo-octahedral [Ru(Li)₃]²⁺ (i=2, 3) chromophores. The concomitant short lifetime of the ³MLCT excited state points to efficient, thermally activated quenching via low-energy Ru-centred d-d states, a limitation which is partially overcome by mechanical coupling in HHH-[RuLu(L1)₃]⁵⁺.

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