Chiral self-assembly of designed amphiphiles: Influences on aggregate morphology

Thomas Barclay, Kristina Constantopoulos, Wei Zhang, Michiya Fujiki, Nikolai Petrovsky, Janis Matisons

    Research output: Contribution to journalArticle

    14 Citations (Scopus)

    Abstract

    A series of novel amphiphiles were designed for self-assembly into chiral morphologies, the amphiphiles consisting of a glutamic acid (Glu) headgroup connected through an 11-carbon alkoxy chain to a diphenyldiazenyl (Azo) group and terminated with a variable length alkyl chain (R-Azo-11-Glu, where R denotes the number of carbons in the distal chain). TEM imaging of amphiphile aggregates self-assembled from heated, methanolic, aqueous solution showed that chiral order, expressed as twisted ribbons, helical ribbons, and helically based nanotubes, increased progressively up to a distal chain length containing eight carbons, and then decreased with further increases in distal chain length. TEM and CD showed that the chiral aggregations of single enantiomers were influenced by the molecular chirality of the headgroup. However, the assembly of d,l-10-Azo-11-Glu into nanotubes demonstrated that chiral symmetry breaking effected by the azo group was also relevant to the chiral organization of the amphiphiles. The chiral order of aggregate morphologies was additionally affected by the temperature and solvent composition of assembly in a manner correlated to the mechanism driving assembly; i.e., d,l-10-Azo-11-Glu was sensitive to the temperature of assembly but less so to solvent composition, while l-14-Azo-11-Glu was sensitive to solvent composition and not to temperature. FTIR and UV-vis spectroscopic investigations into the organization of the head and azo groups, in chiral and achiral structures, illustrated that a balance of the influences of the hydrophilic and hydrophobic components on self-assembly was required for the optimization of the chiral organization of the self-assembled structures.

    Original languageEnglish
    Pages (from-to)10001-10010
    Number of pages10
    JournalLangmuir
    Volume29
    Issue number32
    DOIs
    Publication statusPublished - 13 Aug 2013

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