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Folding versus Self‐Assembling
Author(s) -
Li Alexander D. Q.,
Wang Wei,
Wang LiQiong
Publication year - 2003
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.200305025
Subject(s) - chromophore , diimide , perylene , intermolecular force , folding (dsp implementation) , chemical physics , intramolecular force , molecular dynamics , ethylene glycol , self assembly , polymer , monomer , hydrophobic effect , protein folding , force field (fiction) , chemistry , molecule , materials science , crystallography , nanotechnology , computational chemistry , photochemistry , stereochemistry , physics , organic chemistry , biochemistry , quantum mechanics , electrical engineering , engineering
Model foldable polymers with sequences of rigid hydrophobic chromophores and flexible hydrophilic tetra(ethylene glycol) were synthesized and used as a paradigm for studying molecular‐folding and self‐assembly phenomena. Our results demonstrate that intramolecular association or folding prevails over intermolecular interaction or self‐assembling in the concentration region from 1 μ M to 0.1 M . Importantly, folded polymeric nanostructures have absorption and fluorescence properties that are distinct from those of unfolded polymers or free monomers. We hypothesize that the origins of folding and self‐assembly come from interactions between molecular units, and that the key parameter that regulates the on‐and‐off of such interactions is the distance R separating the two molecular units. Each molecular unit produces a characteristic force field, and when another molecular unit enters this field, the probability that the two units will interact increases significantly. A preliminary estimate of the radius of such a force field for the perylene tetracarboxylic diimide chromophore is about 90–120 Å. As a result, phenomena associated with folding or self‐assembly of molecular species are observed when these conditions are met in solution.