Self-assembled Containers based on Extended-Tetrathiafulvalene

International audienc

Self-assembled electron-rich receptors and guest release control

International audienc

RISK and SAFE signaling pathway interactions in remote limb ischemic perconditioning in combination with local ischemic postconditioning

Local ischemic postconditioning (IPost) and remote ischemic perconditioning (RIPer) are promising methods to decrease ischemia–reperfusion (I/R) injury. We tested whether the use of the two procedures in combination led to an improvement in cardioprotection through a higher activation of survival signaling pathways. Rats exposed to myocardial I/R were allocated to one of the following four groups: Control, no intervention at myocardial reperfusion; IPost, three cycles of 10-s coronary artery occlusion followed by 10-s reperfusion applied at the onset of myocardial reperfusion; RIPer, 10-min limb ischemia followed by 10-min reperfusion initiated 20 min after coronary artery occlusion; IPost+RIPer, IPost and RIPer in combination. Infarct size was significantly reduced in both IPost and RIPer (34.25 ± 3.36 and 24.69 ± 6.02%, respectively) groups compared to Control (54.93 ± 6.46%, both p < 0.05). IPost+RIPer (infarct size = 18.04 ± 4.86%) was significantly more cardioprotective than IPost alone (p < 0.05). RISK pathway (Akt, ERK1/2, and GSK-3β) activation was enhanced in IPost, RIPer, and IPost+RIPer groups compared to Control. IPost+RIPer did not enhance RISK pathway activation as compared to IPost alone, but instead increased phospho-STAT-3 levels, highlighting the crucial role of the SAFE pathway. In IPost+RIPer, a SAFE inhibitor (AG490) abolished cardioprotection and blocked both Akt and GSK-3β phosphorylations, whereas RISK inhibitors (wortmannin or U0126) abolished cardioprotection and blocked STAT-3 phosphorylation. In our experimental model, the combination of IPost and RIPer improved cardioprotection through the recruitment of the SAFE pathway. Our findings also indicate that cross talk exists between the RISK and SAFE pathways

Redox-Driven Transformation of a Discrete Molecular Cage into an Infinite 3D Coordination Polymer

Two M12L6 redox‐active self‐assembled cages constructed from an electron‐rich ligand based on the extended tetrathiafulvalene framework (exTTF) and metal complexes with a linear geometry (PdII and AgI) are depicted. Remarkably, based on a combination of specific structural and electronic features, the polycationic self‐assembled AgI coordination cage undergoes a supramolecular transformation upon oxidation into a three‐dimensional coordination polymer, that is characterized by X‐ray crystallography. This redox‐controlled change of the molecular organization results from the drastic conformational modifications accompanying oxidation of the exTTF moiety

Neutral versus polycationic coordination cages: a comparison regarding neutral guest inclusion

A neutral self-assembled container synthesized from a concave p-extended tetrathiafulvalene (exTTF) ligand and the cis-Pd(dctfb)2(cod) complex (dctfb = 3,5-dichloro-2,4,6-trifluorobenzene; cod = 1,5-cyclooctadiene) is described. This molecular host exhibits a good binding ability for fused polyaromatic substrates. The corresponding inclusion properties are compared with those of a previously described analogous octacationic cage, offering therefore the opportunity to address the effect of the cavity charge state over the binding of neutral molecules

Controlling the Host-Guest Interaction Mode through a Redox Stimulus

A proof-of-concept related to the redox-control of the binding/releasing process in a host-guest system is achieved by designing a neutral and robust Pt-based redox-active metallacage involving two extended-tetrathiafulvalene (exTTF) ligands. When neutral, the cage is able to bind a planar polyaromatic guest (coronene). Remarkably, the chemical or electrochemical oxidation of the host-guest complex leads to the reversible expulsion of the guest outside the cavity, which is assigned to a drastic change of the host-guest interaction mode, illustrating the key role of counteranions along the exchange process. The reversible process is supported by various experimental data (1 H NMR spectroscopy, ESI-FTICR, and spectroelectrochemistry) as well as by in-depth theoretical calculations performed at the density functional theory (DFT) level

Reversible Guest Uptake/Release by Redox-Controlled Assembly/Disassembly of a Coordination Cage

Controlling the guest expulsion process from a receptor is of critical importance in various fields. Several coordination-cages have been recently designed for this purpose, based on various types of stimuli to induce the guest release. Herein, we report the first example of a redox-triggered process from a coordination-cage. The latter integrates a cavity whose panels are based on the extended-tetrathiafulvalene unit. The unique combination of electronic and conformational features of this framework (i.e. high-p donating properties and drastic conformational changes upon oxidation) allows the reversible disassembling/reassembling of the redox-active cavity upon chemical oxidation/reduction respectively. This cage is able to bind the three-dimensional B12F122- anion in a 1:2 (host:guest) stoichiometry. The reversible redox-triggered disassembling of the cage could be also demonstrated in the case of the host-guest complex, offering a new option for guest delivering control