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The study of metal nanoparticles (NPs) and gold NPs (AuNPs), in particular, has been a subject of considerable interest in recent years. The present paper reports on the formation of the muoniated cyclohexadienyl radical in the Mu + C6H6→ MuĊ6H6addition reaction in the same 8 and 10 nm AuNP samples, encapsulated in SBA-15 mesoporous silica, where the spin-relaxation rates λMuwere recently reported on [FlemingJ. Phys. Chem. C, 2019, 123, 27628, paper “P1”], but the final state was not identified in that study. The formation of this MuĊ6H6radical and its interactions with the AuNP surfaces is investigated herein by the technique of avoided level crossing (ALC) resonance spectroscopy, for the same range of Bz loadings as studied earlier. The positions of the level crossings, giving the hyperfine coupling constants (hfcc) for the C-Mu and C-H bonds at the “ipso” position where Mu adds to the ring, are essentially the same as those seen in solid Bz and in bare silica, and hence these hfccdo notdistinguish site locations for the surface-adsorbed benzene. Theamplitudesof these resonances, which are a measure of the fraction of Mu forming the free-radical final state, do, however, provide such a distinction, being much less for Bz adsorbed in the AuNP/silica samples than in the bare silica. This loss in amplitude is attributed to competitive reaction channels, one forming the MuĊ6H6free radical interacting with the AuNPs and the other due to formation ofdiamagneticfinal states. An important signpost as to the nature of these competitive reaction channels is provided by the measuredwidthsof the ALC resonances seen. These are surprisingly narrower in the presence of the AuNPs than for the bare silica, implying that the MuĊ6H6radical isnotin direct contact with the AuNPs. These differing possibilities and contrasting mechanisms are discussed.

We report the reversible transformation between a singly stapled dynamic α‐helical peptide and a doubly stapled quasi‐static one through redox‐triggered dithiol/disulfide conversions of a stapling moiety. This process allows the rate of interconversion between the right‐handed (P) and left‐handed (M) α‐helices to be altered by a factor of approximately 103 before and after the transformation. An as‐obtained doubly stapled α‐helical peptide, which is composed of an achiral peptide having an l‐valine carboxylic acid residue at the C‐terminus, a disulfide‐based reversible staple, and a biphenyl‐based fixed staple, adopts an (M)‐rich form as a kinetically trapped state. The (M)‐rich helix was subsequently transformed into the thermodynamically stable (P)‐rich form in 1,1,2,2‐tetrachloroethane with the half‐life time (t1/2) of approximately 44 days at 25 °C. Reduction of the doubly stapled peptide with tri‐n‐butylphosphine in tetrahydrofuran/water (10/1, v/v) produced the corresponding singly stapled dynamic α‐helical peptide bearing two thiol groups at the side chains, which underwent solvent‐induced reversible helicity inversion. The resulting dithiol of the singly stapled peptide could be reoxidized to form the original doubly stapled form using 4,4'‐dithiodipyridine. Furthermore, the P/M interconversion of a doubly stapled peptide with two flexible hydrocarbon‐based staples is considerably more rapid than that with more rigid staples. [ABSTRACT FROM AUTHOR]

Multicomponent supramolecular self-assembled systems can potentially harness the properties of multiple systems simultaneously. However, creating multicomponent supramolecular nanostructures with narrow size distributions is challenging due to the dynamic nature of noncovalent interactions. In this article, we report the coassembly of a tris-Ni-(II)-salphen and a tris-Cu-(II)-salphen complex. Co-assembly of the complexes afforded nanofibers with low dispersity, with the metal complexes homogeneously distributed throughout the nanofibers. The length of the nanofibers could also be tuned by varying the ratio of the metal complexes. Density functional theory (DFT) calculations indicate that the dimerization of the copper-(II) complex is unfavorable, unlike the dimerization of the nickel-(II) complex. Co-assembly with the copper-(II) complex inhibits the self-assembly of the nickel-(II) complex, enabling length control of the bimetallic nanofibers. These results could pave the way for designing multicomponent supramolecular systems with applications in catalysis and magnetic devices. [ABSTRACT FROM AUTHOR]

A significant drawback of gels formed from low molecular weight gelators (LMWGs) is their typically poor mechanical stability due to the weak non-covalent interactions responsible for forming the gel. Here, we present a rare example of bicomponent gels prepared from LMWGs that show excellent mechanical stability even at <0.7 wt.% gelator loading. The gels can be moulded into any desired shape, without creep deformation. Dynamic diffusion of a guest, like β-carotene, from a spiked gel into its submerged solvent environment is explored through UV–vis spectrophotometry and NMR techniques, showing that the integrity of the gel network remains in the presence of the guest. [ABSTRACT FROM AUTHOR]

Metal‐metal bonds have rarely been explored as active elements in supramolecular assemblies despite their unique potential to introduce responsive behavior. In this report, a dynamic molecular container composed of two cyclometalated Pt units is constructed using Pt−Pt bonds. This molecule—the flytrap—has a flexible jaw composed of two [18]crown‐6 ethers that can adapt their shape to bind large inorganic cations with sub‐micromolar affinity. Along with the spectroscopic and crystallographic characterization of the flytrap, we report its photochemical assembly, which allows the capture of ions and their transport from solution to the solid state. In addition, we have been able to recycle the flytrap to regenerate its starting material due to the reversible nature of the Pt−Pt bond. We believe that other molecular containers and materials for harvesting valuable substrates from solution could be assembled using the advances presented here. [ABSTRACT FROM AUTHOR]

Films of cellulose nanocrystals (CNCs) with chiral nematic organization can show vivid iridescence that arises from their hierarchical structure. Unfortunately, the brittleness of the films limits their potential applications. In this paper, we investigate the incorporation of halloysite nanotubes (HNTs) into CNC films to prepare organic–inorganic composite films with enhanced mechanical properties, while preserving the chiral nematic structure and brilliant iridescence. The hybrid composite films containing 10 wt% HNTs are more elastic than pristine CNC films, with a 1.3-fold increase in tensile strength and a 1.6-fold increase in maximum strain. As well, the incorporation of HNTs slightly improves the thermal stability of the composite films. These materials mimic the hybrid composite structures of crab shells, leading to enhanced mechanical properties and thermal stability of CNC films while maintaining iridescence. [ABSTRACT FROM AUTHOR]