[23]Crown-7-ether incorporated [2]rotaxanes, comprising an anthracene blocker and 4-isopropylphenyl/cyclohexyl end groups, exhibited varying degrees of metastability with a range of chemical (base, halide anions) and physical (solvent, heat) stimuli. Among halides, fluoride, chloride, and bromide anions affected the deslippage of 23-crown-7-ether in 4-isopropylphenyl stoppered [2]rotaxane. Surprisingly, only fluoride anions could selectively induce deslippage in cyclohexyl stoppered [2]rotaxane, whose fluorescence quenching provided an additional tool to selectively detect the fluoride anions down to 2.49 × 10 M.
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http://dx.doi.org/10.1021/acs.orglett.4c02544 | DOI Listing |
Angew Chem Int Ed Engl
January 2025
Institute of Organic Chemistry, Ulm University, Albert-Einstein-Allee 11, 89081, Ulm, Germany.
[2]Rotaxanes offer unique opportunities for studying and modulating charge separation and energy transfer, because the mechanical bond allows the robust, yet spatially dynamic tethering of photoactive groups. In this work, we synthesized [2]rotaxane triads comprising a central (aza)[10]CPP⊃C bis-adduct complex and two zinc porphyrin stoppers to address how the movable nanohoop affects light-induced charge separation and energy transfer between the rotaxane subcomponents. We found that neither the parent nanohoop [10]CPP nor its electron-deficient analogue aza[10]CPP actively participate in charge separation.
View Article and Find Full Text PDFChemistry
November 2024
Núcleo de Química de Heterociclos (NUQUIMHE), Departamento de Química, Universidade Federal de Santa Maria (UFSM), 97105-900, Santa Maria, Rio Grande do Sul, Brasil.
One of the most recent focuses in supramolecular chemistry is developing molecules designed to exhibit programmable properties at the molecular level. Rotaxanes, which function as molecular machines with movements controlled by external stimuli, are prime candidates for this purpose. However, the controlled synthesis of rotaxanes, especially amide-benzylic rotaxanes with more than two components, remains an area ripe for exploration.
View Article and Find Full Text PDFAngew Chem Int Ed Engl
January 2025
Department of Basic Science, Graduate School of Arts and Sciences, The University of Tokyo, 3-8-1, Komaba, Meguro-ku, Tokyo, 153-8902, Japan.
Artificial molecular motors have been presented as models for biological molecular motors. In contrast to the conventional artificial molecular motors that rely on covalent bond rotation, molecular motors with mechanically interlocked molecules (MIMs) have attracted considerable attention owing to their ability to generate significant rotational motion by dynamically shuttling macrocyclic components. The topology of MIM-type rotational molecular motors is currently limited to catenane structures, which require intricate synthetic procedures that typically produce a low synthetic yield.
View Article and Find Full Text PDFAngew Chem Int Ed Engl
January 2025
Faculty of Chemistry, University of Wrocław, 14 F. Joliot-Curie St., 50-387, Wrocław, Poland.
The synthesis of [2]rotaxanes stoppered with one or two dipyrromethane groups has opened a route for the construction of mechanically interlocked molecules incorporating various porphyrinoid stations. The exploitation of those precursors allowed the creation of [3]rotaxanes and [2]catenanes based on the calix[4]phyrin motif, presenting intriguing molecular dynamics. The intrinsic flexibility of the porphyrinoid allowed the introduction of a new type of molecular motion within the rotaxanes, termed fluttering.
View Article and Find Full Text PDFCommun Chem
August 2024
Departamento de Química Orgánica, Facultad de Química, Regional Campus of International Excellence "Campus Mare Nostrum", Universidad de Murcia, E-30100, Murcia, Spain.
The development of efficient methods for the synthesis of mechanically interlocked compounds is currently considered a major challenge in supramolecular chemistry. Twofold vinylogous fumaramides, a class of conjugated bis(enaminones), successfully achieve the assembly of hydrogen-bonded amide-based rotaxanes, with a templating ability comparable to that of their parent fumaramide-based systems, showcasing full conversions and impressive yields up to 92%. Computational calculations offer a compelling explanation for the remarkable efficiency of these bis(enaminones) in driving the synthesis of unprecedented rotaxanes.
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