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A capped bioinspired ligand built from a tris(2-pyridyl-methyl)amine (TPA) unit and surmounted by a triazole-based intramolecular H-bonding secondary sphere was prepared. The resulting cage provides a well-defined cavity combining the hydrophobic nature with H-bonding properties. Its coordinating properties were explored using Zn(II) and Cu(II) metal ions. [ABSTRACT FROM AUTHOR]

μ-Nitrido diiron tetrabutylphthalocyanine, (FePctBu4)2N, in combination with H2O2 can perform an efficient defluorination of heavily fluorinated aromatics via an oxidative pathway. To check whether hydroxyl radicals might be involved in this reaction we have compared catalytic activities of (FePctBu4)2N - H2O2 and FeSO4 - H2O2 systems in the transformation of five differently fluorinated benzenes, perfluoronaphthalene, pentafluoropyridine, and eight functionalized perfluorinated benzenes. In sharp contrast with (FePctBu4)2N - H2O2 system, all fluorinated benzene derivatives were completely stable in the presence of FeSO4 and H2O2 at 60 °C during 15 h. Perfluorinated aromatic compounds functionalized with electron-donating or electron-withdrawing groups as well as pentafluoropyridine exhibited very low conversions. These results unambiguously show that Fenton chemistry is not responsible for the oxidative defluorination of highly fluorinated aromatic compounds performed by the (FePctBu4)2N - H2O2 system. [ABSTRACT FROM AUTHOR]

Abstract: We demonstrate the benefits of using cofacial Zn–porphyrins as structural synthons in coordination‐driven self‐assembled prisms to produce cage‐like singlet oxygen (1O2) photosensitizers with tunable properties. In particular, we describe the photosensitizing and emission properties of palladium‐ and copper‐based supramolecular capsules, and demonstrate that the nature of the bridging metal nodes in these discrete self‐assembled prisms strongly influences 1O2 generation at the Zn–porphyrin centers. The PdII‐based prism is a particularly robust photosensitizer, whereas the CuII self‐assembled prism is a dormant photosensitizer that could be switched to a ON state upon disassembly of the suprastructure. Furthermore, the well‐defined cavity within the prisms allowed encapsulation of pyridine‐based ligands and fullerene derivatives, which led to a remarkable guest tuning of the 1O2 production. [ABSTRACT FROM AUTHOR]

The reversible encapsulation of a tetrapyridyl extended-tetrathiafulvalene (exTTF)-based ligand ( m-Py)exTTF by a tetragonal Zn-porphyrin-based prismatic nanocage ( 1) is described. The reversible uptake and release of the ( m-Py)exTTF guest proceeds through drastic electronic and conformational changes occurring upon oxidation of the latter. This reversible system has been explored in a guest-exchange process, by addition of ( m-Py)exTTF to the host-guest complex [C60⊂ 1], leading to fullerene C60 ejection from the host cavity. Remarkably, the subsequent redox-triggered ejection of ( m-Py)exTTF, leads to the recovery of the empty cage 1, which remains available for further C60 encapsulation. The C60 ejection is justified by the preferable coordination of the pyridine anchors of ( m-Py)exTTF to the two Zn-porphyrin units of 1. This approach, based on the use of a switchable competitive guest, offers a promising new strategy for guest-delivery control. [ABSTRACT FROM AUTHOR]

Using light to unveil unexplored reactivities of earth-abundant metal-oxygen intermediates is a formidable challenge, given the already remarkable oxidation ability of these species in the ground state. However, the light-induced reactivity of Cu-O 2 intermediates still remains unexplored, due to the photoejection of O 2 under irradiation. Herein, we describe a photoinduced reactivity switch of bioinspired O 2 -activating Cu I complexes, based on the archetypal tris(2-pyridyl-methyl)amine ( TPA ) ligand. This report represents a key precedent for light-induced reactivity switch in Cu-O 2 chemistry, obtained by positioning C-H substrates in close proximity of the active site. Open and caged Cu I complexes displaying an internal aryl ether substrate were evaluated. Under light, a Cu-O 2 mediated reaction takes place that induces a selective conversion of the internal aryl ether unit to a phenolate-CH 2 - moiety with excellent yields. This light-induced transformation displays high selectivity and allows easy postfunctionalization of TPA -based ligands for straightforward preparation of challenging heteroleptic structures. In the absence of light, O 2 activation results in the standard oxidative cleavage of the covalently attached substrate. A reaction mechanism that supports a monomeric cupric-superoxide-dependent reactivity promoted by light is proposed on the basis of reactivity studies combined with (TD-) DFT calculations., Competing Interests: The authors declare no competing financial interest., (© 2024 The Authors. Published by American Chemical Society.)

The dynamic adaptability of tetragonal prismatic nanocapsule 1 8+ in the selective separation of fullerenes and endohedral metallofullerenes (EMFs) remains unexplored. Therefore, the essential molecular details of the fullerene recognition and binding process into the coordination capsule and the origins of fullerene selectivity remain elusive. In this work, the key steps of fullerene recognition and binding processes have been deciphered by designing a protocol which combines 1 H- 1 H exchange spectroscopy (2D-EXSY) NMR experiments, long time-scale Molecular Dynamics (MD) and accelerated Molecular Dynamics (aMD) simulations, which are combined to completely reconstruct the spontaneous binding and unbinding pathways from nanosecond to second time-range. On one hand, binding ( k ' on ) and unbinding ( k off ) rate constants were extracted from 1 H- 1 H exchange spectroscopy (EXSY) NMR experiments for both C 60 and C 70 . On the other hand, MD and aMD allowed monitoring the molecular basis of the encapsulation and guest competition processes at a very early stage under nonequilibrium conditions. The receptor capsule displays dynamical adaptability features similar to those observed in the process of biomolecular recognition in proteins. In addition, the encapsulation of bis-aza[60]fullerene (C 59 N) 2 within a supramolecular coordination capsule has been studied for the first time, showcasing the pros and cons of the dumbbell-shaped guest in the dynamics of the encapsulation process and in the stability of the final bound adduct. The powerful combination of NMR, MD, and aMD methodologies allows to obtain a precise picture of the subtle events directing the encapsulation and is thus a predictive tool for understanding host-guest encapsulation and interactions in numerous supramolecular systems.