Browsing by Subject "Hydrogen bonded rotaxanes"

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    A Thiourea-based Rotaxane Catalyst: Nucleophilic Fluorination Phase-Transfer Process Unlocked by the Mechanical Bond
    (American Chemical Society, 2025-03-18) Martínez Cuezva, Alberto; Berná Cánovas, José; Puigcerver Alarcón, Julio; Juan S. Santiago Dato; Alajarín Cerón, Mateo; Química Orgánica
    We report a five-component clipping approach using activated isophthaloyl-derived esters to synthesize an amide-based thiourea rotaxane. This method overcomes acyl chloride limitations with nucleophilic thiourea threads. The steric hindrance of the mechanical bond enables, for the first time, an interlocked thiourea as a hydrogen-bonding phase-transfer organocatalyst in nu-cleophilic fluorinations. This highlights how mechanical bonds expand thiourea catalysis to processes previously incompatible with conventional catalysts.
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    Effects on Rotational Dynamics of Azo and Hydrazodicarboxamide-Based Rotaxanes
    (Multidisciplinary Digital Publishing Institute, 2017-06-28) Saura Sanmartín, Adrián; Martinez-Espin, Juan S.; Martinez-Cuezva, Alberto; Alajarín, Mateo; Berna, José; Berna, José; Química Orgánica
    The 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.