Quantitative Supramolecular Heterodimerization for Efficient Energy Transfer.

The challenge of quantitatively forming self-assembled heterodimers without other equilibrium by-products is overcome through self-sorting favored by the introduction of designed shape-complementary moieties. Such a supramolecular strategy based on cucurbit[8]uril-directed dimerization is further applied to generate hetero-chromophore dimers quantitatively, leading to efficient energy transfer (>85 %) upon photoexcitation.This work was supported by Leverhulme Trust (“Natural material innovation for sustainable living”, G.W., O.A.S.), ERC-2016 Consolidator Grant (CAM-RIG, 726470, G.W., O.A.S.), EPSRC Programme Grant (NOtCH, EP/L027151/1, Z.H., O.A.S.), and Marie Skłodowska-Curie Fellowship (H2020-MSCA-IF-2018, 845640, Z.H.)

Cucurbit[8]uril-mediated pseudo[2,3]rotaxanes.

Pseudo[2,3]rotaxanes have been successfully fabricated by the complexation of cucurbit[8]uril (CB[8]) macrocycles with extended viologen derivatives. Two design rules enable the incorporation of a third CB[8] onto a recently reported pseudo[2,2]rotaxane. Incorporation of a third macrocycle confines the dimeric stacking of chromophores into specific alignment, leading to effective electron-delocalisation along their long molecular axis.- Leverhulme Trust (project: “Natural material innovation for sustainable living”), - EPSRC Programme Grant (NOtCH, EP/L027151/1), - ERC-2016 Consolidator Grant (CAM-RIG, 726470,), - EPSRC (EP/R013012/1, EP/N020669/1), - BBSRC (BB/N007700/1), - ERC Starting Grant (BioNet,757850

Simple fluorinated moiety insertion on Aβ 16-23 peptide for stain-free TEM imaging.

Peptide aggregation and fibre formation are one of the major underlying causes of several neurodegenerative disorders such as Alzheimer's disease. During the past decades the characterisation of these fibres has been widely studied in an attempt to further understand the nature of the related diseases and in an effort to develop treatments. Transmission electron microscopy (TEM) is one of the most commonly used techniques to identify these fibres, but requires the use of a radioactive staining agent. The procedure we report overcomes this drawback through simple addition of a fluorinated moiety to a short Amyloid β sequence via solid phase peptide synthesis (SPPS). This method is synthetically straightforward, widely applicable to different aggregation-prone sequences and, above all, allows for stain-free TEM imaging with improved quality compared to standard imaging procedures. The presence of the fluorinated moiety does not cause major changes in the fibre structure or aggregation, but rather serves to dissipate the microscope's electron beam, thus allowing for high contrast and straightforward imaging by TEM.The authors are grateful for funding from the ERC Starting Investigator grant ASPiRe (no. 240629). The authors are also grateful to Dr Marco Di Antonio for assistance with HPLC purification.This is the final published version of the article. It was originally published in Analyst (Sonzini S, Jones ST, Walsh Z, Scherman OA, Analyst, 2015, 140, 2735, doi:10.1039/c4an02278e) http://dx.doi.org/10.1039/c4an02278

Oligopeptide-CB[8] complexation with switchable binding pathways.

Host-guest complexes exhibiting a 1 : 1 binding stoichiometry need not consist of a single host and guest. A series of oligopeptides, which were previously reported to have abnormally high binding enthalpies were investigated to deduce whether they exist as a 2 : 2 quaternary or a 1 : 1 binary complex with cucurbit[8]uril (CB[8]). Through a systematic study of the sequence-specific binding pathways of peptide-CB[8] association, a phenylalanine-leucine dipeptide was found to be capable of switching from a 1 : 1 stoichiometric complex to a 2 : 1 complex. By studying the differences in size-based diffusion properties of these two binding modes, the presence of a 1 : 1 pairwise inclusion complex was verified for the regime where CB[8] is in excess. Findings in this study can be utilised to 'customise' the precise CB[8]-oligopeptide self-assembly pathway, acting as a useful toolbox in the design of supramolecular systems.The Leverhulme Trust Marie Curie FP7 ERC EPSR

Stress dissipation in cucurbit[8]uril ternary complex small molecule adhesives.

The ability to control supramolecular and macroscopic self-assembly and disassembly holds great potential for responsive, reversible adhesives that can efficiently broker stresses accumulated between two surfaces. Here, cucurbit[8]uril is used to directly adhere two functionalized mica substrates creating surface-surface interactions that are held together through photo-reversible CB[8] heteroternary complexes. Comparison of single molecule, bulk and macroscopic adhesion behavior give insight into cooperativity and stress dissipation in dynamic adhesive systems

Cucurbit[8]uril-Regulated Colloidal Dispersions Exhibiting Photocontrolled Rheological Behavior.

In situ photocontrol over shear-thickening of condensed colloidal dispersions is of paramount importance in a wide range of applications including process technology and photorheological fluids. Its development and practicability, however, are hampered by the lack of well-designed photoresponsive systems. Here, a colloidal suspension whose rheological behavior is readily switchable between shear-thinning and shear-thickening using an external light stimulus is reported. This smart colloidal solution contains hybrid raspberry-like colloids prepared by employing cucurbit[8]uril as a supramolecular linker to assemble functional Fe3 O4 nanoparticles onto a silica core. The formed raspberry colloids are photoresponsive and can be reversibly disassembled under UV irradiation

Light-Regulated Molecular Trafficking in a Synthetic Water-Soluble Host.

Cucurbit[8]uril (CB[8])-mediated complexation of a dicationic azobenzene in water allows for the light-controlled encapsulation of a variety of second guest compounds, including amino acids, dyes, and fragrance molecules. Such controlled guest sequestration inside the cavity of CB[8] enables the regulation of the thermally induced phase transition of poly(N-isopropylacrylamide)-which is not photosensitive-thus demonstrating the robustness and relevancy of the light-regulated CB[8] complexation.J.D.B. thanks Marie Curie IEF (project no. 273807). S.T.J.R. acknowledges the Cambridge Home and European Scholarship Scheme and the Robert Gardiner memorial scholarship. This work was supported by the EPSRC (reference no. EP/G060649/ 1), an ERC Starting Investigator Grant (project no. 240629), and a Next Generation Fellowship from the Walters-Kundert Foundation. The authors thank HECBioSim (EPSRC grant no. EP/L000253/1) via ARCHER, and the Ada King’s HPC3 service.This is the author accepted manuscript. The final version is available from ACS Publications via http://dx.doi.org/10.1021/jacs.5b1164