Supramolecularly Engineered π-Amphiphile

Abstract

This article describes self-assembly of supramolecularly engineered naphthalene-diimide (NDI)-derived amphiphiles NDI-1 and NDI-2. They have the same hydrophobic/hydrophilic balance but merely differ by a single functional group, amide or ester. They exhibit distinct self-assembly in water; NDI-1 forms hydrogel, which upon aging forms crystals, whereas NDI-2 forms micelles as revealed by in-depth structural analysis using cryo-TEM, dynamic light scattering, and small-angle X-ray scattering studies. These results suggest that the H-bonding among the amide groups fully regulates the self-assembly by overruling the packing parameters. Further, the present study elucidates sharp lower critical solution temperature exhibited by these π-amphiphiles, which has been extensively studied for many important applications of water-soluble polymers but hardly known in the literature of small-molecule surfactants. Control experiments with the same water-soluble hydrophilic wedge did not show such a property, confirming this to be a consequence of the supramolecular polymerization by extended amide-amide H-bonding and not inherent to the structure of the hydrophilic wedge containing oligo-oxyethylene chains.

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

“…Interestingly the morphology of the individual components was found to be distinctly different than that of the mixed D–A assembly. NDI‐1 showed (Figure b and Figure S1, Supporting Information) a 1D entangled fibrillar structure with the diameter of the individual fibers ranging between 50–100 nm and produced a hydrogel (Figure b, inset) as reported by us previously . In contrast, aggregation of Py‐1 generated (Figure c and Figure S1, Supporting Information) relatively smaller particles with a diameter in the range of 20–40 nm and remained as a colorless solution (Figure c, inset).…”

“…NDI-1 showed ( Figure 1b and Figure S1, Supporting Information) a1 De ntangled fibrillar structurew ith the diameter of the individual fibers ranging between 50-100 nm and produced a hydrogel (Figure 1b,i nset) as reported by us previously. [10] In contrast, aggregationo fPy-1 generated (Figure1ca nd Figure S1, Supporting Information) relativelys maller particles with ad iameter in the range of 20-40 nm and remained as ac olorless solution (Figure 1c,i nset). Dynamicl ight scattering studies ( Figure 1d)s howedasharp single peak for the 1:1m ixture with an average D h = 120 nm, which was distinctly different from the peaks for the individual components corresponding to D h = 530 and 50 nm, respectively,f or NDI-1 and Py-1.T he DLS results corroborated with the size obtained from TEM for the spherical assemblies of Py-1 or NDI-1 + Py-1,b ut in the case of the anisotropic structure of NDI-1,n oa ttemptw as made to correlate the size obtained from DLS and TEM as the DLS data was obtained by collecting the scattering at as ingle angle.…”

Thermodynamic insights into the entropically driven self-assembly of amphiphilic dyes in water

“…4,7 The desire to mimic and understand such naturally occurring self-assembled systems has prompted the investigation of various amphiphilic/bolaamphiphilic molecules consisting of non-polar hydrophobic cores attached with water solubilizing side chains. 8 Through these investigations, a wide variety of nanometric supramolecular aggregates of different morphologies (tubular, brillar, micellar, vesicular) has been prepared via exploring solvophobic effects, [9][10][11] H-bonding, [12][13][14][15] electrostatic screening, 16,17 metal-ion coordination, [18][19][20] variation of hydrophilic/hydrophobic balance, 21,22 and co-solvent modulation. [23][24][25] However, different from the very intensively conducted studies on the enthalpic and entropic contributions that govern supramolecular host-guest complex formation in water, [26][27][28] studies devoted to an in-depth understanding of the thermodynamic prole of self-assembly processes of p-amphiphiles in water remain scarce.…”

The influence of substituents on gelation and stacking order of oligoaramid – based supramolecular networks

“…S5), indicative of aromatic stacking. 19,20 All four compounds show signs of aggregation in 1 H-NMR and UV/vis spectroscopy. However, no gelation was observed for NH 2 COOMe-Y.…”

“…When 1 H-NMR experiments of the four branched tetramers (NO 2 COOMe-Y, NO 2 COOH-Y, NH 2 COOMe-Y and NH 2 COOH-Y) were conducted in D 2 O, we detected broadening and an up-field shift of the aromatic peaks indicative of aromatic stacking. 19 In DMSO-d 6 on the other hand well-defined sharp peaks were observed indicating a molecularly dissolved state ( 1 H-NMR spectra in D 2 O and DMSO see ESI, † Fig. S2).…”