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Multi‐Stimuli‐Responsive Directional Assembly of an Amphiphilic Donor–Acceptor Alternating Supramolecular Copolymer
Author(s) -
Chakraborty Saptarshi,
Ray Debes,
Aswal Vinod K.,
Ghosh Suhrit
Publication year - 2018
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.201803170
Subject(s) - amphiphile , supramolecular chemistry , polymersome , chromophore , supramolecular assembly , copolymer , stacking , chemistry , polymer chemistry , amide , acceptor , photochemistry , materials science , crystallography , organic chemistry , polymer , crystal structure , physics , condensed matter physics
The stimuli‐responsive supramolecular co‐assembly of two π‐amphiphiles, NDI‐1 and Py‐1 , in which an acceptor (A) (naphthalene diimide) and a donor (D) (pyrene) chromophore, respectively, serve as the hydrophobic segment, is described. In addition, both contain an amide group in a designated location so that H‐bonding and D–A charge‐transfer (CT) interactions can operate simultaneously. H‐bonding among the amide groups not only enhanced the CT interaction promoted by the alternating D–A stacking propensity, but also fixed the lateral orientation of the two chromophores and thus compelled the anionic and nonionic hydrophilic head groups, appended with the D and A amphiphiles, respectively, to remain segregated on two opposite sides of the amphiphilic alternating supramolecular copolymer. This copolymer showed spontaneous polymersome assembly with the D‐appended anionic groups displayed at the outer surface, whereas the A‐appended hydrophilic wedge converged at the inner lacuna. In contrast, spherical or cylindrical micellar structures were produced by Py‐1 and NDI‐1 , respectively. Effective functional‐group display in the D–A supramolecular polymersome enabled protein‐surface recognition and inhibition of the enzymatic activity of Cht. Under a reducing environment, formation of NDI .− jeopardized the D–A interaction and thus the A chromophores were ejected out of the membrane of the polymersome causing its gradual contraction in size by >75 %. D–A supramolecular polymersomes also exhibited a lower critical solution temperature that could be tuned across a temperature window of 40 to 70 °C by varying the ratio of the A and D components in the alternating supramolecular copolymer.