Multi‐Stimuli‐Responsive Directional Assembly of an Amphiphilic Donor–Acceptor Alternating Supramolecular Copolymer

Abstract

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.

Hydrogen-bonding regulated assembly of molecular and macromolecular amphiphiles

“…6c). 40 Indeed 16 + 18 (1 : 1) produced a deep red color indicating CT interaction and in contrast to the fibrillar structure exhibited by 16, the mixture showed polymersome-like spherical assembly while 18 alone produced relatively small micellar aggregates. Zeta potential measurements showed highly negative surface charge indicating display of the carboxylate ions at the outer surface which was useful to inhibit the activity of an enzyme Chymotrypsin which has positive charges near its active site.…”

Light-Triggered Polymersome-Based Anticancer Therapeutics Delivery

“…The unilamellar vesicles were obtained through horn sonication [ 103 ]. Chakraborty and coworkers designed a multi-stimuli temperature- and redox-responsive polymersome based on co-assembly of two π-amphiphiles containing an acceptor (A) (naphthalene diimide) and a donor (D) (pyrene) chromophore [ 104 ]. Different authors, such as Li [ 105 ] and Lv [ 106 ], among others [ 102 ], also obtained self-assembled polymersomes from alternating amphiphilic copolymers.…”

Selenoamides modulate dipole–dipole interactions in hydrogen bonded supramolecular polymers of 1,3,5-substituted benzenes

“…Supramolecular chemistry has maturated up to a point where parallelisms between sophisticated multi-step covalent syntheses and the construction of increasingly complex, artificial supramolecular systems become more and more apparent. [1][2][3][4] Recent developments in living supramolecular polymerizations, [5][6][7][8] controlled supramolecular copolymerizations [9][10][11][12] and the design of unconventional thermal behaviour in supramolecular polymers [13][14][15] resulted in unprecedented control in length and microstructure of the formed polymers. Like in proteins, one of the central interactions underlying the stability and structure of many supramolecular systems is the formation of hydrogen bonds between amides.…”