Four‐Component Ugi Reaction for Optical Chirality Sensing and Surface Nanoengineering of Chiral Self‐Assemblies

Abstract

Using green chemistry to control chirality at hierarchical levels as well as chiroptical activities endows with new opportunities to the development of multiple functions. Here, the four‐component Ugi reaction is introduced for the general and precise optical chirality sensing of amines as well as the surface nanoengineering of chiral soft self‐assemblies. To overcome the relatively weak Cotton effects, direct synthesis of a folded peptide structure on a rotatable ferrocene core with axial chirality was accomplished from chiral amine, 1,1’‐ferrocenyl dicarboxylic acid, formaldehyde and isocyanide. Enhanced Cotton effects benefiting from the folded structure allow for the precise and quantitative sensing of natural and synthetic chiral amines covering alkyl, aromatic amines and amino acid derivatives. In addition, aqueous reaction enables the modification of amine‐bearing dye to microfibers self‐assembled from π‐conjugated amino acids. Surface dye‐modification via Ugi reaction barely changes the pristine morphology, showing non‐invasive properties in contrast to dye staining, which is applicable in soft nano/microarchitectures from self‐assembly. This work which combines the four‐component Ugi reaction to enable precise ee% detection and surface nanoengineering of soft chiral assemblies sheds light on the advanced application of green chemistry to chirality science.

Tunable Chirality of Self‐Assembled Dipeptides Mediated by Bipyridine Derivative

“…Then, molecular dynamics (MD) simulations were further performed to simulate the selfassembly of Fmoc-FY and co-assembly between Fmoc-FY and BPE at similar environmental conditions. [18] The preliminary optimum configuration of Fmoc-FY and BPE were carried out using Gaussian16 program with the B3LYP hybrid functional and the 6-311 + + G** basis set. After that, the building blocks were restrained in a box and placed randomly in DMSO and H 2 O medium.…”

Hydrogen Bonded Foldamers with Axial Chirality: Chiroptical Properties and Applications

“…have been widely used in optical chiral sensing because of their advantages in transfer and amplify chirality. [34,63,65] For optical chiral detection using foldamers, the formation of folding structure is the most important part. Ugi reaction, as a classical four-component reaction, is a reaction in which equal equivalents of amine, acid, aldehyde and isonitrile are condensed to obtain a dipeptide structure.…”

“…As shown in Figure 11a, 1,1'-Ferrocenyl dicarboxylic acids, paraformaldehyde, and tert-butyl isonitrile are used to react with chiral amines produced ferrocenyl chiral foldamers by one-pot method. [63] The formation of folding structures induced by intramolecular hydrogen bonds are observed in X-ray crystal structures. Compared to other chromophore, ferrocenyl foldamers can efficiently transfer and amplify the chirality, and exhibit a relatively large dissymmetry g-factor.…”