title: Designing supramolecular liquid-crystalline hybrids from pyrenyl-containing dendrimers and arene ruthenium metallacycles.
abstract: The association of the arene ruthenium metallacycle [Ru4(p-cymene)4(bpe)2(donq)2][DOS]4 (bpe = 1,2-bis(4-pyridyl)ethylene, donq = 5,8-dioxydo-1,4-naphtoquinonato, DOS = dodecyl sulfate) with pyrenyl-functionalized poly(arylester) dendrimers bearing cyanobiphenyl end-groups is reported. The supramolecular dendritic systems display mesomorphic properties as revealed by polarized optical microscopy, differential scanning calorimetry and small-angle X-ray scattering measurements. The multicomponent nature of the dendrimers and of the corresponding host-guest supramolecules (i.e., end-group mesogens, dendritic core, pyrene unit, aliphatic spacers, and metallacycle) leads to the formation of highly segregated mesophases with a complex multilayered structure due to the tendency of the various constitutive building-blocks to separate in different organized zones. The pyrenyl dendrimers exhibit a multilayered smectic A-like phase, thereafter referred to as LamSmA phase to emphasize this unaccustomed morphology. As for the corresponding Ru4-metallacycle adducts, they self-organize into a multicontinuous thermotropic cubic phase with the Im3̅m space group symmetry. This represents a unique example of liquid-crystalline behavior observed for such large and complex supramolecular host-guest assemblies. Models of their supramolecular organizations within both mesophases are proposed.
authors.affiliation: Institut de Chimie, Université de Neuchâtel , Avenue de Bellevaux 51, 2000 Neuchâtel, Switzerland.
authors.forename: Anaïs
authors.initials: A
authors.lastname: Pitto-Barry
authors.forename: Nicolas P E
authors.initials: NP
authors.lastname: Barry
authors.forename: Virginie
authors.initials: V
authors.lastname: Russo
authors.forename: Benoît
authors.initials: B
authors.lastname: Heinrich
authors.forename: Bertrand
authors.initials: B
authors.lastname: Donnio
authors.forename: Bruno
authors.initials: B
authors.lastname: Therrien
authors.forename: Robert
authors.initials: R
authors.lastname: Deschenaux