Aggregation‐Induced Emissive and Circularly Polarized Homogeneous Sulfono‐γ‐AApeptide Foldamers

Abstract

Through our continuous effort in developing a new class of foldamers, we have both designed and synthesized homogenous sulfono-γ-AApeptides using tetraphenylethylene (TPE) moieties attached to the backbone as luminogenic sidechains. Based on previous crystal structures, we have found that these foldamers adopted a left-handed 4 14 -helix. Due to the constraint of the helical scaffold, the rotation of the TPE moieties were restricted, leading to fluorescent emissive properties with high quantum yields not only at the aggregate state but also in solution. Investigation of the relationship between the structure and fluorescence behavior reveals that emission was induced by the combined effect of the aggregationinduced emission (AIE) and the rotated restriction from the backbone. Furthermore, as the packing mode of the luminogens could be precisely adjusted by the helical backbone, these foldamers were found to be circularly polarizable with relatively large luminescence dissymmetry factor (g lum ). Interestingly, possessing cationic amphipathic structures similar to that of host-defense peptides (HDPs), these sulfono-γ-AApeptides were able to inhibit the growth of Gram-positive bacteria methicillin-resistant S. aureus (MRSA) through membrane interactions.

Peptide-Based AIEgens: From Molecular Design, Stimuli Responsiveness to Biomedical Application

“…77 Cai and his colleagues designed a left-handed TPE-sulfono-γ-AApeptides. 78 It has a cationic amphiphilic structure similar to the host defense peptide, which can inhibit methicillin-resistant Staphylococcus aureus through membrane interaction with the Gram-positive bacteria.…”

Using Fluorescence to Enable Innovative Functions of Foldamers

“…Oligomers composed of 1 : 1 α/sulfono‐γ‐AApeptides with appended tetraphenylethylene (TPE) chromophores (representative example, 11 ) have been studied in aqueous solution to investigate the relationship between oligomer structural features and the aggregation‐induced emission (AIE) of this fluorophore [41,42] . γ‐AApeptides are γ‐substituted‐ N ‐acylated‐ N ‐aminoethyl amino acids, oligomers inspired by peptide nucleic acids (PNA).…”

Circularly Polarized Luminescence from Chiral p‐Terphenylene‐Based Supramolecular Aggregates

“…Generally, luminescence dissymmetry factor (g lum = 2(I L -I R )/(I L + I R ), I L and I R are the intensity of the left-and right-handed CPL emissions, respectively) and luminescence quantum yield (QY) are two important parameters to evaluate the level of CPL property. [1,5] So far, sustained efforts have been devoted to new structures and strategies towards CPL-active materials, e.g., chiral luminescent lanthanide and transition-metal complexes, [6] conjugated polymers, [7] small organic molecules, etc., [8] have been exploited. However, one of the greatest challenges on the path toward the practical applications of these CPL-active materials is the dilemma in possessing large g lum and high QY simultaneously.…”