Dynamic Covalent Synthesis of Donor–Acceptor Interlocked Architectures in Solution and at the Solution:Surface Interface

Wilson, Hannah; Byrne, Sean; Mullen, Kathleen M.

doi:10.1002/asia.201403288

Cited by 13 publications

(6 citation statements)

References 61 publications

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“…6 -step 3). However, as reported by Wilson et al, 42 the yield of the reaction was limited by concomitant decomposition of the nal product when longer reaction durations were performed (stacked 1 H NMR spectra are available in ESI - Fig. S4 †).…”

Section: 41mentioning

confidence: 82%

Regioselective chitosan end-group activation: the triskelion approach

et al. 2017

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Chitosan (CS) end-group conjugation methods are rarely reported in the literature, mainly since the CS terminal aldehyde moiety produced by nitrous acid depolymerization is only present in trace amounts in its reactive form. In a previous study, our group proposed an intermolecular thioacetylation process that allowed terminal conjugation of thiol-reactive species to chitosan with 50% efficiency. However, this reaction is incompatible with acid-labile substituents and the conversion efficiency of CS end-groups could be limited by the size of the thiol-reactive species engaged in the reaction, mainly by steric hindrance since two substituents are required to obtain the stabilized thioacetal derivative. In the present study, we developed a novel CS end-group thioacetylation approach relying on a new regioselective linker that bears three thiol moieties. This trivalent linker, referred to as triskelion here, was specifically designed for activation of the CS 2,5-anhydro-D-mannose (M-Unit) end-group and consists of a thiolhook for efficient aldehyde conjugation through an intramolecular reaction and a thiol-tail that remains available for subsequent end-group functionalization with any thiol-reactive species. The chemical synthesis of this linker provided the desired material with high yields over three steps. The in situ intramolecular thioacetylation process between the triskelion linker and 2,5-anhydro-D-mannose (MUnit, monomeric) was assessed by semi-quantitative LC-MS studies, revealing that the corresponding intramolecular thioacetal largely predominated ($90%). This regioselective derivatization was also performed onto M-Unit CS aldehydes and the desired CS-b-triskelion conjugates were obtained with functionalization degrees over 85%, as confirmed by NMR spectroscopy ( 1 H and DOSY). As a final assessment of the CS-b-triskelion thiol-tail reactivity, these conjugates were successfully engaged with thiol-reactive magnetic beads into disulfide bond displacement with 50% efficiency. The proposed CS terminal activation with the triskelion linker opens new perspectives for biomedical applications, especially brush-like surface modifications and other copolymer formation through disulfide linkages or Michael-type additions.

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Section: 41mentioning

confidence: 82%

Regioselective chitosan end-group activation: the triskelion approach

et al. 2017

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“…1e) binds to the DNP recognition sites of P STATION , and was designed in an analogous fashion to NDI-based macrocycles previously reported to form pseudorotaxanes with DNP recognition sites at the surface-liquid interface. 27,28 As the 3-NDI-ring functions as redox mediator in the envisioned p-DSSC, its redox properties are of key importance, and these compare favorable to those of the typically used I − /I 3 − (vide infra). Thus the proposed 3-NDI-ring:P STATION pseudorotaxane photosensitizer (Fig.…”

Section: Resultsmentioning

confidence: 99%

A Bioinspired Strategy for Directional Charge Propagation in Photoelectrochemical Devices Using Supramolecular Machinery

Bouwens¹,

Bakker²,

Hasenack³

et al. 2021

Preprint

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Molecular photoelectrochemical (PEC) devices are hampered by electron–hole recombination after photoinduced electron transfer (PET), causing losses in power conversion efficiency (PCE). Inspired by natural photosynthesis, we demonstrate the use of molecular machinery as a strategy to inhibit recombination, through organization of molecular components and unbinding of the final electron acceptor after reduction. We show that preorganization of the macrocyclic 3-NDI-ring electron acceptor to the PSTATION dye forming the PSTATION:3-NDI-ring pseudorotaxane, enables a “ring launching” event, upon PET from PSTATION to 3-NDI-ring releasing 3-NDI-ring•−. Implementing PSTATION:3-NDI-ring into p-type dye-sensitized solar cells (p-DSSCs) revealed a fivefold increase in PCE compared to benchmark dye P1, unable to facilitate pseudorotaxane formation. This active repulsion of anionic 3-NDI-ring•− with concomitant reformation PSTATION:3-NDI-ring circumvents recombination at semiconductor–dye interface, affording a twofold enhancement in hole lifetime. We envision this concept of supramolecular-directed charge-propagation will encourage further integration of molecular machinery into PEC devices.

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“…More recently, the use of dynamic covalent chemistry to assemble interlocked architectures at the solution–surface interface has been reported . In this study, disulfide exchange of a naphthoquinol bis‐thiol around either a stoppered naphthalene diimide thread in solution, or TentaGel resins functionalised with a stoppered naphthalene diimide thread, resulted in rotaxane formation.…”

Section: Surface‐attached Supramolecular Assembliesmentioning

confidence: 88%

“…However, attachment of interlocked architectures to swelling polymer supports (such as TentaGel polystyrene resins) allows the use of high‐resolution magic angle spinning (HR MAS) 1 H NMR spectroscopy to analyse the dynamic behaviour of molecules tethered to solid supports. This technique has been used more extensively to monitor biological protein or peptide synthesis and combinatorial chemistry, however spectra of more complex supramolecular systems tethered to solid supports have also been obtained …”

Section: Surface‐attached Supramolecular Assembliesmentioning

confidence: 99%

Surface‐Assembled Mechanically Interlocked Architectures

Rodrigues

Mullen

2017

ChemPlusChem

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Since the advent of supramolecular chemistry, there has been keen interest in the synthesis of interlocked molecules, given their unique potential to act as receptors, molecular machines and even motors. Despite advances in the complexity of molecular machines that can be synthesised and operated in solution, reports of the operation or even attachment of complex supramolecular systems on solid surfaces are less common. Synthetic challenges and a lack of adequate characterisation techniques to monitor the thermodynamic and kinetic influences governing assembly at the solution–surface interface has slowed progress in this area of research. This Review looks at the developments in the field of covalently assembled interlocked architectures on gold, silica and polymer surfaces, highlighting the differences observed between solution and surface assembly of these unique structures.

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Dynamic Covalent Synthesis of Donor–Acceptor Interlocked Architectures in Solution and at the Solution:Surface Interface

Cited by 13 publications

References 61 publications

Regioselective chitosan end-group activation: the triskelion approach

Regioselective chitosan end-group activation: the triskelion approach

A Bioinspired Strategy for Directional Charge Propagation in Photoelectrochemical Devices Using Supramolecular Machinery

Surface‐Assembled Mechanically Interlocked Architectures

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