Supramolecular Depolymerization in the Mixture of Two Poor Solvents: Mechanistic Insights and Modulation of Supramolecular Polymerization of Ionic π‐Systems

Abstract

Solvents are fundamentally essential for the synthesis and processing of soft materials.S upramolecular polymers (SPs), an emerging class of soft materials,are usually stable in single and mixtures of poor solvents.I nc ontrast to these preconceived notions,h ere we report the depolymerization of SPs in the mixture of two poor solvents.T his surprising behavior was observed for well-known cationic perylene diimides (cPDIs)i nt he mixtures of water and amphiphilic organic solvents such as isopropanol (IPA). cPDIs form stable SPs in water and IPAbut readily depolymerize into monomers in 50-70 vol% IPAcontaining water.This is due to the selective solvation of the p-surface of cPDIs by alkylchains of IPAand ionic side chains by water,asevidenced by molecular dynamic simulations.M oreover,b ys ystematically changing the ratio between water and amphiphilic organic solvent, we could achieve an unprecedented supramolecular polymerization both by increasing and decreasing the solvent polarity.

Heparin binding induced supramolecular chirality into the self-assembly of perylenediimide bolaamphiphile

“…A similar observation was recently reported by Rao and coworkers, and it was thought to be due to preferential solvation. 45 However, we could not extrapolate this reported explanation in this case because it was not consistent with all of our observations. Thus, we performed a detailed investigation to reveal that the inherent quantum yield of the monomers of 1 is much higher in 40% water (44% quantum yield) when compared to DMSO alone (7% quantum yield) as shown in Fig.…”

“…Concentration of 1 = 0.05 mM; solvent: 99% water in DMSO; concentration of heparin = 25.8 mg mL À1 . TEM samples were stained with 2% uranyl acetate solution.In the literature, self-assembly of 1 in water is shown to form nanofibres in water, but they were reported in a 2-10 times higher concentration than our working concentration 30,45.…”

“…48 These spectral features indicate the formation of a face-to-face H-aggregate of 1 in water. 45,49,50 Furthermore, the ratio of absorbance for the S 0–0 to S 0–1 bands (S 0–0 /S 0–1 ), which is known to be a signature of self-assembly in PDI derivatives, decreased from 1.5 in DMSO to 0.7 in 99% water, further confirming the self-assembly of 1 in water.…”

“…Such a monosignated CD signal could be due to the asymmetric In the literature, self-assembly of 1 in water is shown to form nanofibres in water, but they were reported in a 2-10 times higher concentration than our working concentration. 30,45 perturbation of the electronic transitions of 1 by neighbouring chiral centres in heparin, without producing a helical organization of 1. 41 This could be because in 99% water, there are stronger intermolecular interactions between the molecules of 1, and thus, they lack the conformational flexibility to rearrange into a helical organization upon heparin binding.…”

“…We demonstrate that the negatively charged, chiral heparin biopolymer binds to the positively charged 1 to facilitate self-assembly and induces supramolecular chirality into the self-assembly of an achiral PDI derivative. Previous reports on the self-assembly of 1 and similar PDI derivatives have been about demonstrating the role of solvents in self-assembly, charge transfer complexation, protein sensing, [45][46][47] including adenosine triphosphate responsive chiral assembly. 26,30 Here, for the first time, we demonstrate heparin binding assisted supramolecular ordering and induction of helicity into the self-assembly of 1 in aqueous as well as in a biological cell culture medium.…”