Enantioselective Component Selection in Multicomponent Supramolecular Gels

Abstract

ABSTRACT:We investigate a two-component acid-amine gelation system in which chirality plays a vital role. A carboxylic acid based on a second generation L-lysine dendron interacts with chiral amines and subsequently assembles into supramolecular gel fibers. The chirality of the amine controls the assembly of the resulting diastereomeric complexes, even if this chirality is relatively 'poor quality'. Importantly, the selective incorporation of one enantiomer of an amine over the other into the gel network has been demonstrated, with the R amine that forms complexes which assemble into the most stable gel being primarily selected for incorporation. Thermodynamic control has been proven by forming a gel exclusively with an S amine, then allowing the R enantiomer to diffuse through the gel network, displacing it from the solid-like fibers, demonstrating these gels adapt and evolve in response to chemical stimuli to which they are exposed. Excess amine, which remains unincorporated within the 'solid-like' gel fiber network, can diffuse out and be reacted with an isocyanate, allowing us to quantify the enantioselectivity of component selection, but also demonstrating how gels can act as selective reservoirs of potential reagents, releasing them on demand to undergo further reactions -hence component-selective gel assembly can be coupled with controlled reactivity.

Supramolecular Chirality in Self-Assembled Systems

“…Moreover, when R amine enantiomers were added to the supramolecular gels formed by the L-lysine dendron and pure S amines, the diffusion of R amines and displacement of the original S amines from the "solid-like" fibers can be detected ( Figure 126B). 357 These results suggest that the two-component organogels are very sensitive to the molecular chirality of gelators and have great potential for chiral recognitions. In principle, if the chiral recognition can be triggered by a very small amount of chiral organic molecules, these assemblies with chiral recognition ability can be used as a chiral sensor.…”

Molecular, Local, and Network-Level Basis for the Enhanced Stiffness of Hydrogel Networks Formed from Coassembled Racemic Peptides: Predictions from Pauling and Corey

“…36−39 Heterochiral systems, containing both l - and d -isomers, offer unique material morphologies 40−43 as well as a control over hydrogel degradability 44 as peptides composed of d -amino acids are resistant to proteolysis. 45,46 As such, we initially sought to control the biodegradation of hydrogels formed by the peptide hydrogelator, MAX1, by preparing mixed gels of the parent peptide with its enantiomer.…”

Enantioselective Light Harvesting with Perylenediimide Guests on Self‐Assembled Chiral Naphthalenediimide Nanofibers

“…[2d, [8][9][10] Ther ecognition of chiral analytes by chiral molecular systems can be detected through changes in the optical spectra. [14][15][16][17][18][19] This amplified output makes the analyte detection possible at submicromolar to picomolar concentrations.Herein, we demonstrate the use of achiral nanofiber platform, obtained through the self-assembly of ac hiral bichromophoric naphthalenediimide (NDI) derivative,f or the absolute enantiomeric recognition of ap erylenediimide (PDI) based guest molecule.The chiral bichromophoric NDI derivatives self-assembled into nanofibers in am ethylcyclohexane (MCH) rich solution, exhibiting intense blue-green emission and acertain degree of CPL. [11] In contrast, the chiral response of supramolecular systems [3,[11][12][13] is often more sensitive owing to signal amplification.…”