Controllable hierarchical self-assembly: systematic study forming metallosupramolecular frameworks on the basis of helical beta-oligoamides

Norton G West; Sarah E Bamford; Paul J Pigram; Jisheng Pan; Dong-Chen Qi; Adam Mechler

doi:10.1039/d3mh01327h

Controllable hierarchical self-assembly: systematic study forming metallosupramolecular frameworks on the basis of helical beta-oligoamides

Mater Horiz. 2023 Nov 27;10(12):5584-5596. doi: 10.1039/d3mh01327h.

Authors

Norton G West^{1

2}, Sarah E Bamford³, Paul J Pigram³, Jisheng Pan², Dong-Chen Qi⁴, Adam Mechler¹

Affiliations

¹ Department of Biochemistry and Chemistry, La Trobe Institute for Molecular Science, La Trobe University, Melbourne, VIC, 3086, Australia. a.mechler@latrobe.edu.au.
² Institute of Materials Research and Engineering (IMRE), Agency for Science, Technology and Research (A*STAR), 2 Fusionopolis Way, Innovis #08-03, Singapore 138634, Republic of Singapore. js-pan@imre.a-star.edu.sg.
³ Center for Materials and Surface Science, and Department of Mathematical and Physical Sciences, La Trobe University, Melbourne, VIC, 3086, Australia.
⁴ School of Chemistry and Physics, Queensland University of Technology, Brisbane, Queensland, 4001, Australia.

PMID: 37815516
DOI: 10.1039/d3mh01327h

Abstract

Self-assembly is a key guiding principle for the design of complex nanostructures. Substituted beta oligoamides offer versatile building blocks that can have inherent folding characteristics, offering geometrically defined functionalities that can specifically bind and assemble with predefined morphological characteristics. In this work hierarchical self-assembly is implemented based on metal coordinating helical beta-oligoamides crosslinked with transition metals selected for their favourable coordination geometries, Fe²⁺, Cu²⁺, Ni²⁺, Co²⁺, Zn²⁺, and two metalates, MoO₄^2-, and WO₄^2-. The oligoamide Ac-β³Aβ³Vβ³S-αHαHαH-β³Aβ³Vβ³A (3H) was designed to allow crosslinking via three distinct faces of the helical unit, with a possibility of forming three dimensional framework structures. Atomic force microscopy (AFM) confirmed the formation of specific morphologies that differ characteristically with each metal. X-Ray photoelectron spectroscopy (XPS) results reveal that the metal centres can be reduced in the final structures, confirming strong chemical interaction. Time of flight secondary ion mass spectrometry (ToF-SIMS) confirmed the spatial distribution of metals within the self-assembled networks, also revealing molecular fragments that confirm coordination to histidine and carboxyl moieties. The metalates MoO₄^2- and WO₄^2- were also able to induce the formation of specific superstructure morphologies. It was observed that assembly with either of nickel, copper, and molybdate form thin films, while cobalt, zinc, and tungstate produced specific three dimensional networks of oligoamides. Iron was found to form both a thin film and a complex hierarchical assembly with the 3H simultaneously. The design of the 3H substituted beta oligoamide to readily form metallosupramolecular frameworks was demonstrated with a range of metals and metalates with a degree of control over layer thicknesses as a function of the metal/metalate. The results validate and broaden the metallosupramolecular framework concept and establish a platform technology for the design of functional thin layer materials.