title: Interplay between H-bonding and alkyl-chain ordering in self-assembly of monodendritic L-alanine derivatives.
abstract: This paper reports on the synthesis and self-organizing properties of monodendrons consisting of L-alanine at the focal point and alkyl chains with different length at the periphery. The structures of thin films and monolayers are studied by temperature-resolved grazing-incidence X-ray diffraction and scanning force microscopy. The interplay between H-bonding and ordering of the alkyl chains results in a rich temperature-dependent phase behavior. The monodendrons form H-bonded stabilized clusters with the number of molecules depending on the length of the aliphatic chains and temperature. The clusters play the role of constitutive units in the subsequent self-assembly. Short alkyl chains allow the material to form thermodynamically stable crystalline phases. The molecules with longer side groups exhibit additional transitions from the crystalline phase to thermotropic columnar hexagonal or columnar rectangular liquid-crystalline phases. In monolayers deposited on highly ordered pyrolytic graphite, the materials show ordering similar to thin films. However, for the compound bearing hexadecyl chains the affinity of the alkyl groups to graphite dominates the self-assembly and thereby allows epitaxial growth of a 2D lattice with flat-on oriented molecules.
authors.affiliation: Institut de Sciences des Matériaux de Mulhouse (CNRS IS2M), Mulhouse, France.
authors.forename: Denis V
authors.initials: DV
authors.lastname: Anokhin
authors.forename: Jānis
authors.initials: J
authors.lastname: Lejnieks
authors.forename: Ahmed
authors.initials: A
authors.lastname: Mourran
authors.forename: Xiaomin
authors.initials: X
authors.lastname: Zhu
authors.forename: Helmut
authors.initials: H
authors.lastname: Keul
authors.forename: Martin
authors.initials: M
authors.lastname: Möller
authors.forename: Oleg
authors.initials: O
authors.lastname: Konovalov
authors.forename: Natalia
authors.initials: N
authors.lastname: Erina
authors.forename: Dimitri A
authors.initials: DA
authors.lastname: Ivanov
mesh_terms: D000409:Alanine / Q000737:chemistry*; D000478:Alkylation; D002152:Calorimetry, Differential Scanning; D050091:Dendrimers / Q000138:chemical synthesis* / Q000737:chemistry; D006860:Hydrogen Bonding; D018625:Microscopy, Atomic Force; D008958:Models, Molecular; D015394:Molecular Structure
chemical_list: D050091:Dendrimers; D000409:Alanine