110 research outputs found

    Reactivity of Glutaconamides Within [2]Rotaxanes: Mechanical Bond Controlled Chemoselective Synthesis of Highly Reactive α-Ketoamides and their Light-Triggered Cyclization

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    Glutaconamide-based [2]rotaxanes are efficiently oxidized to the respective interlocked α-ketoamides, whereas their non-interlocked threads afford hydroxycyclohexene tetraamides under similar reaction conditions. These results showcase the mechanically interlocking of highly reactive substrates as a powerful tool for controlling their chemical behavior. Inside the macrocycle and under irradiation with light, the α-ketoamide threads convert, in a divergent manner, into the corresponding interlocked hydroxy-β-lactams or oxazolidinones by two modes of Norrish/Yang type-II intramolecular cyclizations, processes that are efficiently chemocontrolled by the mechanical bond

    Effects on Rotational Dynamics of Azo and Hydrazodicarboxamide-Based Rotaxanes

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    © 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

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

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    © 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

    Mechanically interlocked molecules in metal–organic frameworks

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    This document is the Accepted Manuscript version of a Published Work that appeared in final form in Chemical Society Reviews, copyright © Royal Society of Chemistry after peer review and technical editing by the publisher. To access the final edited and published work see: https://pubs.rsc.org/en/content/articlelanding/2022/CS/D2CS00167EMechanically interlocked molecules (MIMs) have great potential in the development of molecular machinery due to their intercomponent dynamics. The incorporation of these molecules in a condensed phase makes it possible to take advantage of the control of the motion of the components at the macroscopic level. Metal–organic frameworks (MOFs) are postulated as ideal supports for intertwined molecules. This review covers the chemistry of the mechanical bond incorporated into metal–organic frameworks from the seminal studies to the latest published advances. We first describe some fundamental concepts of MIMs and MOFs. Next, we summarize the advances in the incorporation of rotaxanes and catenanes inside MOF matrices. Finally, we conclude by showing the study of the rotaxane dynamics in MOFs and the operation of some stimuli-responsive MIMs within MOFs. In addition to emphasising some selected examples, we offer a critical opinion on the state of the art of this research field, remarking the key points on which the future of these systems should be focused

    Recent advances in the synthesis and application of hydrogen bond templated rotaxanes and catenanes

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    Alongside the use of metal cations and π–π stacking, hydrogen bonding is one of the major templating interactions used to prepare rotaxanes and catenanes. In this review, a brief summary of key historical milestones will be followed by discussion of developments from over the last decade in both synthetic methodology and application of hydrogen bond templated interlocked molecules. Hydrogen bond templation can allow for rapid access to interlocked molecules in high yields, with select examples having been put to useful purpose, in applications such as organocatalysis and cellular imaging

    Inflammatory biomarkers in Alzheimer's disease plasma.

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    INTRODUCTION: Plasma biomarkers for Alzheimer's disease (AD) diagnosis/stratification are a "Holy Grail" of AD research and intensively sought; however, there are no well-established plasma markers. METHODS: A hypothesis-led plasma biomarker search was conducted in the context of international multicenter studies. The discovery phase measured 53 inflammatory proteins in elderly control (CTL; 259), mild cognitive impairment (MCI; 199), and AD (262) subjects from AddNeuroMed. RESULTS: Ten analytes showed significant intergroup differences. Logistic regression identified five (FB, FH, sCR1, MCP-1, eotaxin-1) that, age/APOε4 adjusted, optimally differentiated AD and CTL (AUC: 0.79), and three (sCR1, MCP-1, eotaxin-1) that optimally differentiated AD and MCI (AUC: 0.74). These models replicated in an independent cohort (EMIF; AUC 0.81 and 0.67). Two analytes (FB, FH) plus age predicted MCI progression to AD (AUC: 0.71). DISCUSSION: Plasma markers of inflammation and complement dysregulation support diagnosis and outcome prediction in AD and MCI. Further replication is needed before clinical translation
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