101588-67-4Relevant articles and documents
Implementing liquid-crystalline properties in single-stranded dinuclear lanthanide helicates
Terazzi, Emmanuel,Zaim, Amir,Bocquet, Bernard,Varin, Johan,Guenee, Laure,Dutronc, Thibault,Lemonnier, Jean-Francois,Floquet, Sebastien,Cadot, Emmanuel,Heinrich, Benoit,Donnio, Bertrand,Piguet, Claude
, p. 3323 - 3333 (2013)
The connection of flexible protodendritic wedges to the bis-tridentate rigid polyaromatic ligand L1 provides amphiphilic receptors L5 and L6; their reduced affinities for complexing trivalent lanthanides (Ln = La, Y, Lu) in organic solvent (by fifteen orders of magnitude!) prevent the formation of the expected dinuclear triple-stranded helicates [Ln2(Lk) 3]6+. This limitation could be turned into an advantage because L1 or L6 can be treated with [Ln(hfac)3] (Hhfac = 1,1,1,5,5,5-hexafluoro-2,4-pentanedione) to give neutral single-stranded [Ln2(Lk)(hfac)6] complexes with no trace of higher-order helicates. Whereas ligands L1 and L5 are not liquid crystals, L6 can be melted above room temperature (41°C) to give a nematic mesophase, and its associated dinuclear helical complex [Y2(L6)(hfac)6] self-organises at the same temperature into a fluidic smectic mesophase. The lipophilic dendritic ligand L6 selectively reacts with trivalent yttrium hexafluoroacetylacetonate (hfac) to give the liquid-crystalline single-stranded dinuclear helicate [Y2(L6)(hfac)6], which self-organises into an SmA mesophase. Copyright
A simple chemical tuning of the effective concentration: Selection of single-, double-, and triple-stranded binuclear lanthanide helicates
Terazzi, Emmanuel,Guenee, Laure,Bocquet, Bernard,Lemonnier, Jean-Francois,Favera, Natalia Dalla,Piguet, Claude
scheme or table, p. 12719 - 12732 (2010/06/14)
The replacement of terminal 2-benzimidazol-6-carboxypyridine (two internal rotational degrees of freedom) with 2-benzimidazol-8-hydroxyquinoline (one internal rotational degree of freedom) into segmental bis-tridentate ligands in going from L2 and [L32H]2- to [L12D-2H]2- does not significantly affect the structures of the resulting binuclear lanthanide triplestranded helical complexes [Ln2(L2)3]6+, [Ln2(L3-2H)3], and [Ln2(L12b-2H)3] (palindromic helices, intermetallic contact distance 9 A, helical pitch 1.4 nm per turn). However, their thermodynamic assemblies are completely different in solution, as evidenced by the spectacular decrease of the effective concentrations by two orders of magnitude for [L12b-2H] 2-. This key parameter in the [Ln2(L12b-2H)n] (n = 2, 3) complexes is further abruptly modulated along the lanthanide series (Ln = La to Lu), which provides an unprecedented tool for 1) tuning the number of ligand strands in the final helicates, 2) selectively coordinating lanthanides in the various complexes, and 3) controlling the ratio of lanthanide-containing polymers over discrete assemblies.