118172-76-2Relevant academic research and scientific papers
Effective concentration as a tool for quantitatively addressing preorganization in multicomponent assemblies: Application to the selective complexation of lanthanide cations
Canard, Gabriel,Koeller, Sylvain,Bernardinelli, Gerald,Piguet, Claude
, p. 1025 - 1040 (2008)
The beneficial entropic effect, which may be expected from the connection of three tridentate binding units to a strain-free covalent tripod for complexing nine-coordinate cations (Mz+ = Ca2+, La 3+, Eu3+, Lusu
Allosteric effects in binuclear homo- and heterometallic triple-stranded lanthanide podates
Ryan, Patrick E.,Canard, Gabriel,Koeller, Sylvain,Bocquet, Bernard,Piguet, Claude
, p. 10012 - 10024 (2012/10/30)
This work illustrates a simple approach for deciphering and exploiting the various free energy contributions to the global complexation process leading to the binuclear triple-stranded podates [Ln2(L9)]6+ (Ln is a trivalent lanthanide). Despite the larger microscopic affinities exhibited by the binding sites for small Ln3+, the stability constants measured for [Ln2(L9)]6+ decrease along the lanthanide series; a phenomenon which can be ascribed to the severe enthalpic penalty accompanying the intramolecular cyclization around small Ln(III), combined with increasing anticooperative allosteric interligand interactions. Altogether, the microscopic thermodynamic characteristics predict β1,1,1 La,Lu,L9/β1,1,1Lu,La,L9 = 145 for the ratio of the formation constants of the target heterobimetallic [LaLu(L9)] 6+ and [LuLa(L9)]6+ microspecies, a value in line with the quantitative preparation (>90%) of [LaLu(L9)]6+ at millimolar concentrations. Preliminary NMR titrations indeed confirm the rare thermodynamic programming of a pure heterometallic f-f′ complex.
Bent tridentate receptors in calamitic mesophases with predetermined photophysical properties: New luminescent lanthanide-containing materials
Nozary, Homayoun,Piguet, Claude,Tissot, Paul,Bernardinelli, Gérald,Bünzli, Jean-Claude G.,Deschenaux, Robert,Guillon, Daniel
, p. 12274 - 12288 (2007/10/03)
A new synthetic strategy has been developed to introduce bent and rigid tridentate 2,6-bis(benzimidazol-2'-yl)pyridine cores into rodlike ligands L(11-17). The crystal structure of the nonmesogenic ligand L13 (C39H37N5O4, triclinic, P1, Z = 2) shows the expected trans-trans conformation of the tridentate binding unit, which provides a linear arrangement of the semirigid aromatic sidearms. The crystal structure of the related mesogenic ligand L16 (C61H81N5O4, triclinic, P1, Z = 2) demonstrates the fully extended conformation adopted by the lipophilic side chains, leading to a slightly helically twisted I-shaped molecule. A rich and varied mesomorphism results which can be combined with the simultaneous tuning of electronic and photophysical properties via a judicious choice of the spacers between the rigid central core and the semirigid lipophilic sidearms. Ligands L13,14 react with Ln(NO3)3·χH2O to give quantitatively and selectively the neutral 1:1 complexes [Ln(L')(NO3)3] (Ln = La to Lu), which are stable in the solid state at room temperature but partially dissociate in acetonitrile to give the cationic species [Ln(L')(NO3)2]+. The crystal structure of [Lu-(L13)(NO3)3]·3CH3CN (30, LUC45H46N11O13, monoclinic, C2/c, Z = 8) reveals a U-shaped arrangement of the ligand strand arising from the cis-cis conformation of the coordinated tridentate binding unit. This drastic geometric change strongly affects the thermal behavior and the photophysical and electronic properties of the lipophilic complexes [Ln(L14)(NO3)3]. Particular attention has been focused on structure-properties relationships, which can be modulated by the size of the lanthanide metal ions.
