The Role of Dethreading Process in Pseudorotaxanes and Rotaxanes towards Advanced Applications: Recent Examples

©2023 The Authors. European Journal of Organic Chemistry published by Wiley-VCH GmbH. This manuscript version is made available under the CC-BY-NC 4.0 license https://creativecommons.org/licenses/by-nc/4.0/ This document is the Published Manuscript version of a Published Work that appeared in final form in European Journal of Organic Chemistry. To access the final edited and published work see https://doi.org/10.1002/ejoc.202201512Rotaxanes are a type of mechanically interlocked molecules (MIMs), constituted by at least a thread surrounded by a wheel, which are widely employed in the research field of artificial molecular machines. Although applications retaining the integrity of the mechanical bond are usually reported, the dethreading of the components can be crucial to develop some advanced applications. Thus, different dethreading strategies have been reported, and advanced applications which require such a process have turned out to be suitable approaches towards machine-like operation. This review article covers recent examples of applications of pseudorotaxanes and rotaxanes in which dethreading processes have a key role to accomplish the desired function

Light-responsive rotaxane-based materials: inducing motion in the solid state

©2023 Saura-Sanmartin; licensee Beilstein-Institut. This manuscript version is made available under the CC-BY-4.0 license https://creativecommons.org/licenses/by/4.0/ This document is the Published Manuscript version of a Published Work that appeared in final form in Beilstein Journal of Organic Chemistry. To access the final edited and published work see https://doi.org/10.3762/bjoc.19.64Light-responsive rotaxane-based solid-state materials are ideal scaffolds in order to develop smart materials due to the properties provided by the mechanical bond, such as control over the dynamics of the components upon application of external stimuli. This perspective aims to highlight the relevance of these materials, by pointing out recent examples of photoresponsive materials prepared from a rotaxanated architecture in which motion of the counterparts and/or macroscopic motion of the interlocked materials are achieved. Although further development is needed, these materials are envisioned as privileged scaffolds which will be used for different advanced applications in the area of molecular machinery

Photoresponsive metal-organic frameworks as adjustable scaffolds in reticular chemistry

©2022. The Authors. This manuscript version is made available under the CC-BY 4.0 license https://creativecommons.org/licenses/by/4.0/ This document is the Published Manuscript version of a Published Work that appeared in final form in International Journal of Molecular Sciences. To access the final edited and published work see https://doi.org/10.3390/ijms23137121The easy and remote switching of light makes this stimulus an ideal candidate for a large number of applications, among which the preparation of photoresponsive materials stands out. The interest of several scientists in this area in order to achieve improved functionalities has increase parallel to the growth of the structural complexity of these materials. Thus, metal-organic frameworks (MOFs) turned out to be ideal scaffolds for light-responsive ligands. This review is focused on the integration of photoresponsive organic ligands inside MOF crystalline arrays to prepare enhanced functional materials. Besides the summary of the preparation, properties and applications of these materials, an overview of the future outlook of this research area is provided

Recent Advances in the Preparation of Delivery Systems for the Controlled Release of Scents

©2023.the Authors. This manuscript version is made available under the CC-BY-4.0 license https://creativecommons.org/licenses/by/4.0/ This document is the Published Manuscript version of a Published Work that appeared in final form in International Journal of Molecular Sciences. To access the final edited and published work see https://doi.org/10.3390/ijms24054685Scents are volatile compounds highly employed in a wide range of manufactured items, such as fine perfumery, household products, and functional foods. One of the main directions of the research in this area aims to enhance the longevity of scents by designing efficient delivery systems to control the release rate of these volatile molecules and also increase their stability. Several approaches to release scents in a controlled manner have been developed in recent years. Thus, different controlled release systems have been prepared, including polymers, metal–organic frameworks and mechanically interlocked systems, among others. This review is focused on the preparation of different scaffolds to accomplish a slow release of scents, by pointing out examples reported in the last five years. In addition to discuss selected examples, a critical perspective on the state of the art of this research field is provided, comparing the different types of scent delivery systems

The Mobility of Homomeric Lasso- and Daisy Chain-Like Rotaxanes in Solution and in the Gas Phase as a Means to Study Structure and Switching Behaviour

©2023 The Authors. This manuscript version is made available under the CC-BY-NC 4.0 license https://creativecommons.org/licenses/by-nc/4.0/ This document is the Published Manuscript version of a Published Work that appeared in final form in Israel Journal of Chemistry. To access the final edited and published work see https://doi.org/10.1002/ijch.202300022A precise structural determination of supramolecular architectures is a non-trivial challenge. This daunting task can be made even more difficult when interlocked species are to be analysed having macrocycles covalently equipped with a thread as repeating units, such as molecular lassos and daisy chains. When such functionalized macrocycles are included as scaffolds, different products having analogous NMR spectra as well as dynamic libraries can be obtained. Furthermore, if control over the motion of the parts relative to each other is to be achieved, a full understanding of the machinery's operation mechanism requires detailed insight into the structures involved. This understanding also helps designing improved synthetic molecular machines. Diffusion-ordered NMR spectroscopy and ion-mobility MS techniques are ideal tools to study such compounds in depth. This review covers recent examples on the use of the above-mentioned techniques to characterize these interlocked architectures

Stereoselective synthesis of β-lactams: recent examples

©2023 The Authors; published by The Royal Society of Chemistry. This manuscript version is made available under the CC-BY-NC 3.0 license https://creativecommons.org/licenses/by-nc/3.0/ This document is the Published Manuscript version of a Published Work that appeared in final form in Organic & Biomolecular Chemistry. To access the final edited and published work see https://doi.org/10.1039/D3OB00309DThe synthesis of β-lactam derivatives is a research topic of great interest due to the biological activity of these molecules. Indeed, there are several antibiotics which include a β-lactam core in their structures, such as penicilins, monobactams, carbacephems and cephamycins. The development of stereoselective approaches to access these molecular architectures turns out to be necessary in order to take advantage of the distinct properties provided by the different stereoisomers. This review covers recent advances towards the stereoselective synthesis of β-lactams, including Staudinger syntheses, cascade reactions, metal-catalyzed syntheses and base-promoted cyclizations. Within these methods, some particularly novel synthetic approaches are highlighted, such as the induction of chirality through bimetallic synergistic catalysis or the transfer of chirality between components in mechanically interlocked molecules. Additionally, a critical opinion on the state of the art of this research field is offered, remarking key points on which the future research should be focused on

Scratch-Resistant Hydrophobic Coating with Supramolecular-Polymer Co-Assembly

Está pagada la tasa. Se trata de un artículo de open access. La información que debe recogerse en Digitum es la siguiente: ©2023 The Authors. Advanced Functional Materials published by Wiley-VCH GmbH. This manuscript version is made available under the CC-BY-NC 4.0 license https://creativecommons.org/licenses/by-nc/4.0/ This document is the Published Manuscript version of a Published Work that appeared in final form in Advanced Functional Materials. To access the final edited and published work see https://doi.org/10.1002/adfm.202309140Supramolecular assembly for superhydrophobic coatings is known for its efficiency and efficacy. However, the mechanical fragility of the coatings limits their use as coating materials. Herein, the combination of (±)-N,N'-(trans-cyclohexane-1,2-diyl)-bis(perfluorooctanamide) CF7, a cyclohexyl diamide-based low molecular weight gelator, with acrylate polymers for the generation of semi-transparent omniphobic coatings with significantly enhanced scratch proofness is presented. CF7 has shown the ability to self-assemble in common solvents into highly entangled fibrous networks with extreme water repellency. The incorporation of covalent polymers, specifically poly(methyl methacrylate) (PMMA) and poly(trifluoroethyl methacrylate) (PTFEMA), helps to fixate the supramolecular CF7 fibers without interfering with the self-assembled structures. The resulting coatings, namely CF7/PMMA and CF7/PTFEMA, show significantly improved mechanical resistance as well as optical transparency while maintaining excellent water and oil repellency. Furthermore, the homogeneity of the coating in bulk is confirmed by depth profiling of the 3D distribution of the components using time-of-flight secondary ion mass spectrometry imaging, which turns out to be an essential technique in order to characterize such materials

Effects on Rotational Dynamics of Azo and Hydrazodicarboxamide-Based Rotaxanes

© 2017 by the authors. Licensee MDPI, Basel, Switzerland. This manuscript version is made available under the CC-BY 4.0 license https://creativecommons.org/licenses/by/4.0/ This document is the Published Manuscript version of a Published Work that appeared in final form in Molecules. To access the final edited and published work see https://doi.org/10.3390/molecules22071078The synthesis of novel hydrogen-bonded [2]rotaxanes having two pyridine rings in the macrocycle and azo- and hydrazodicarboxamide-based templates decorated with four cyclohexyl groups is described. The different affinity of the binding sites for the benzylic amide macrocycle and the formation of programmed non-covalent interactions between the interlocked components have an important effect on the dynamic behavior of these compounds. Having this in mind, the chemical interconversion between the azo and hydrazo forms of the [2]rotaxane was investigated to provide a chemically-driven interlocked system enable to switch its circumrotation rate as a function of the oxidation level of the binding site. Different structural modifications were carried out to further functionalize the nitrogen of the pyridine rings, including oxidation, alkylation or protonation reactions, affording interlocked azo-derivatives whose rotation dynamics were also analyzed

Exploring the Chemistry of the Mechanical Bond: Synthesis of a [2]Rotaxane through Multicomponent Reactions

© 2023 The Authors. Published by American Chemical Society and Division of Chemical Education, Inc. This manuscript version is made available under the CC-BY 4.0 license https://creativecommons.org/licenses/by/4.0/ This document is the Published Manuscript version of a Published Work that appeared in final form in Journal of Chemical Education. To access the final edited and published work see https://doi.org/10.1021/acs.jchemed.3c00163The synthesis of a [2]rotaxane through three- or five-component coupling reactions has been adapted to an organic chemistry experiment for upper-division students. The experimental procedure addresses the search for the most favorable reaction conditions for the synthesis of the interlocked compound, which is obtained in a yield of up to 71%. Moreover, the interlocked nature of the rotaxane is proven by NMR spectroscopy. The content of the sessions has been designed on the basis of a proactive methodology whereby upper-division undergraduate students have a dynamic role. The laboratory experience not only introduces students to the chemistry of the mechanical bond but also reinforces their previous knowledge of basic organic laboratory procedures and their skills with structural elucidation techniques such as NMR and FT-IR spectroscopies. The experiment has been designed in such a customizable way that both experimental procedures and laboratory material can be adapted to a wide range of undergraduate course curricula

Ring-to-Thread Chirality Transfer in [2]Rotaxanes for the Synthesis of Enantioenriched Lactams

© 2022 The Authors. Angewandte Chemie International Edition published by Wiley-VCH GmbH. This manuscript version is made available under the CC-BY-NC 4.0 license https://creativecommons.org/licenses/by-nc/4.0/ This document is the Published Manuscript version of a Published Work that appeared in final form in Angewandte Chemie International Edition. To access the final edited and published work see https://doi.org/10.1002/anie.202209904The synthesis of chiral mechanically interlocked molecules has attracted a lot of attention in the last few years, with applications in different fields, such as asymmetric catalysis or sensing. Herein we describe the synthesis of orientational mechanostereoisomers, which include a benzylic amide macrocycle with a stereogenic center, and nonsymmetric N-(arylmethyl)fumaramides as the axis. The base-promoted cyclization of the initial fumaramide thread allows enantioenriched value-added compounds, such as lactams of different ring sizes and amino acids, to be obtained. The chiral information is effectively transmitted across the mechanical bond from the encircling ring to the interlocked lactam. High levels of enantioselectivity and full control of the regioselectivity of the final cyclic compounds are attained