Mechanochemical Encapsulation of Fullerenes in Peptidic Containers Prepared by Dynamic Chiral Self‐Sorting and Self‐Assembly

Abstract

Molecular capsules composed of amino acid or peptide derivatives connected to resorcin[4]arene scaffolds through acylhydrazone linkers have been synthesized using dynamic covalent chemistry (DCC) and hydrogen-bond-based self-assembly. The dynamic character of the linkers and the preference of the peptides towards self-assembly into β-barrel-type motifs lead to the spontaneous amplification of formation of homochiral capsules from mixtures of different substrates. The capsules have cavities of around 800 Å(3) and exhibit good kinetic stability. Although they retain their dynamic character, which allows processes such as chiral self-sorting and chiral self-assembly to operate with high fidelity, guest complexation is hindered in solution. However, the quantitative complexation of even very large guests, such as fullerene C60 or C70 , is possible through the utilization of reversible covalent bonds or the application of mechanochemical methods. The NMR spectra show the influence of the chiral environment on the symmetry of the fullerene molecules, which results in the differentiation of diastereotopic carbon atoms for C70 , and the X-ray structures provide unique information on the modes of peptide-fullerene interactions.

Porous Molecular Capsules as Non‐Polymeric Transducers of Mechanical Forces to Mechanophores

“…MS analysis and NMR spectra in [D 6 ]DMSO confirmt hat 1 is a D 4 -symmetric molecule composed of two covalently bridged hemispheres. Capsule 1,e xcept fort he presenceo fd isulfide bridges,i ss tructurally similar to the previously reportedn oncovalentc apsules, [39] fore xample, 7a 2 or 7b 2 -it has as imilar size and analogousi nner surface. The MS spectrum shows the presence of signals of [1À2H] 2À ions.…”

The templation effect as a driving force for the self-assembly of hydrogen-bonded peptidic capsules in competitive media

“…This conclusion is also supported by DOSY measurements that reveal a diffusion coefficient of 0.95 × 10 −10 m 2 s −1 for 3a and 0.95 × 10 −10 m 2 s −1 for 3b (in DMSO-d 6 at 298 K), corresponding to an average diameter of molecule of ∼2.2 nm ( predicted value for the cavitand is 2.3 nm, the model is based on the previously reported X-ray structure of the valine derivative). 17 This self-assembly behaviour and solubility characteristics of cavitands containing polar side chains are distinctly different from those of the previously reported hydrophobic derivatives that were soluble only in non-polar solvents and formed dimeric capsules in these media. 17 In subsequent experiments, we tested the possibility of templation of self-assembly by fullerene C 60 .…”

“…1). 17 In all these examples, hydrogen bonded shells are formed in non-polar media (chloroform, toluene, tetrachloroethane, carbon disulfide) and they are not able to survive in polar environments (even DMSO). In this work, we demonstrate that hydrophobic interactions together with β-sheet-like binding motifs are effective (a) in inducing the self-assembly of peptidic cavitands that otherwise do not self-assemble and (b) in ordering hydrogen bonded shells around hydrophobic cores even in competitive, polar environments ( Fig.…”

Solid-state inclusion of C60and C70in a co-polymer induced by metal–ligand coordination of a Zn–porphyrin cage with a bis-pyridyl perylene derivative

“…For example, the mechanochemical encapsulation of fullerenes in selfassembled peptidic containers has been reported. 38 Furthermore, alkyl and aryl functionalized copper(II) βdiketonate molecular squares has been used for the encapsulation of C 70 . 39 Scheme 1.…”