Hexayne Amphiphiles and Bolaamphiphiles.

Oligoynes with two or more conjugated carbon-carbon triple bonds are useful precursors for carbon-rich nanomaterials. However, their range of applications has so far been severely limited by the challenging syntheses, particularly in the case of oligoynes with functional groups. Here, we report a universal synthetic approach towards both symmetric and unsymmetric, functionalized hexaynes through the use of a modified Eglinton-Galbraith coupling and a sacrificial building block. We demonstrate the versatility of this approach by preparing hexaynes functionalized with phosphonic acid, carboxylic acid, ammonium, or thiol head groups, which serve as neutral, cationogenic, or anionogenic interfacially active groups. We show that these hexaynes are carbon-rich amphiphiles or bolaamphiphiles that self-assemble at liquid-liquid interfaces, on solid surfaces, as well as in aqueous media.

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

Two M12 L6 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.

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.

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

A neutral self-assembled container synthesized from a concave π-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.

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, the panels of which are based on the extended tetrathiafulvalene unit (exTTF). The unique combination of electronic and conformational features of this framework (i.e. high π-donating properties and drastic conformational changes upon oxidation) allows the reversible disassembly/reassembly of the redox-active cavity upon chemical oxidation/reduction, respectively. This cage is able to bind the three-dimensional B12 F12 (2-) anion in a 1:2 host/guest stoichiometry. The reversible redox-triggered disassembly of the cage could also be demonstrated in the case of the host-guest complex, offering a new option for guest-delivering control.

Tuning the size of a redox-active tetrathiafulvalene-based self-assembled ring.

The synthesis of a new Pd coordination-driven self-assembled ring M6L3 constructed from a concave tetrapyridyl π-extended tetrathiafulvalene ligand (exTTF) is described. The same ligand is also able to self-assemble in a M4L2 mode as previously described. Herein, we demonstrate that the bulkiness of the ancillary groups in the Pd complex allows for modulating the size and the shape of the resulting discrete self-assembly, which therefore incorporate two (M4L2) or three (M6L3) electroactive exTTF sidewalls.

A Self-Assembled Electro-Active M8L4 Cage Based on Tetrathiafulvalene Ligands.

Two self-assembled redox-active cages are presented. They are obtained by coordination-driven self-assembly of a tetra-pyridile tetrathiafulvalene ligand with cis-M(dppf)(OTf)2 (M = Pd or Pt; dppf = 1,1'-bis(diphenylphosphino)ferrocene; OTf = trifluoromethane-sulfonate) complexes. Both species are fully characterized and are constituted of 12 electro-active subunits that can be reversibly oxidized.

Self-assembled containers based on extended tetrathiafulvalene.

Two original self-assembled containers constituted each by six electroactive subunits are described. They are synthesized from a concave tetratopic π-extended tetrathiafulvalene ligand bearing four pyridyl units and cis-M(dppf)(OTf)2 (M = Pd or Pt; dppf = 1,1'-bis(diphenylphosphino)ferrocene; OTf = trifluoromethane-sulfonate) complexes. Both fully characterized assemblies present an oblate spheroidal cavity that can incorporate one perylene molecule.