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Steric Constraints Induced Frustrated Growth of Supramolecular Nanorods in Water
Author(s) -
Appel Ralph,
Fuchs Jonas,
Tyrrell Sara M.,
Korevaar Peter A.,
Stuart Marc C. A.,
Voets Ilja K.,
Schönhoff Monika,
Besenius Pol
Publication year - 2015
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201503616
Subject(s) - nanorod , isodesmic reaction , supramolecular chemistry , steric effects , materials science , monomer , supramolecular polymers , polymerization , dendrimer , dynamic light scattering , nanotechnology , polymer , chemical physics , chemical engineering , crystallography , chemistry , nanoparticle , polymer chemistry , density functional theory , organic chemistry , computational chemistry , crystal structure , engineering , composite material
A unique example of supramolecular polymerisation in water based on monomers with nanomolar affinities, which yield rod‐like materials with extraordinarily high thermodynamic stability, yet of finite length, is reported. A small library of charge‐neutral dendritic peptide amphiphiles was prepared, with a branched nonaphenylalanine‐based core that was conjugated to hydrophilic dendrons of variable steric demand. Below a critical size of the dendron, the monomers assemble into nanorod‐like polymers, whereas for larger dendritic side chains frustrated growth into near isotropic particles is observed. The supramolecular morphologies observed by electron microscopy, X‐ray scattering and diffusion NMR spectroscopy studies are in agreement with the mechanistic insights obtained from fitting polymerisation profiles: non‐cooperative isodesmic growth leads to degrees of polymerisation that match the experimentally determined nanorod contour lengths of close to 70 nm. The reported designs for aqueous self‐assembly into well‐defined anisotropic particles has promising potential for biomedical applications and the development of functional supramolecular biomaterials, with emerging evidence that anisotropic shapes in carrier design outperform conventional isotropic materials for targeted imaging and therapy.