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International audience; An unidirectional light-driven rotary motor was looped in a figure-of-eight molecule by linking two polymer chains between its stator and rotor parts. By properly tuning the size of these linkers, clockwise rotation of the motor under UV light was shown to create conformationally strained twists between the polymer chains and, in this tensed conformation, the energy stored in the molecular object was sufficient to trigger the reverse rotation of the motor back to its fully relaxed state. The functioning principle of this motorized molecular device appears very similar to the one of macroscopic whirligig crafts used by children for fun. In addition, we found that in its out-of-equilibrium tensed state, the fluorescence emission of the molecular motor increased by 500% due to the mechanical constraints imposed by the polymer chains on its conjugated core. Finally, by calculating the apparent thermal energies of activation for the backward rotations at different levels of twisting, we quantitatively determined a lower estimate of the work generated by this rotary motor, from which a torque and a force were extracted, thus answering a long-term open question in this field of research.

International audience; A S6-symmetric triarylamine-based macrocycle (i.e. hexaaza[16]para-cyclophane), decorated with six lateral amide functions, is synthesized by a convergent and modular strategy. This macrocycle is shown to undergo supramolecular polymerization in o-dichlorobenzene, and its nanotubular structure is elucidated by a combination of spectroscopy and microscopy techniques, together with X-ray scattering and molecular modelling. Upon sequential oxidation, a spectroelectrochemical analysis of the supramolecular polymer suggests an extended electronic delocalization of charge carriers both within the macrocycles (through bond) and between macrocycles along the stacking direction (through space).

International audience; The implementation of molecular machines in polymer science is of high interest to transfer mechanical motions from nanoscale to macroscale in order to access new kinds of active devices and materials. Toward this objective, thermodynamic and topological aspects need to be explored for reaching efficient systems capable of producing a useful work. In this paper we describe the branched polymerization of pH-sensitive bistable [c2] daisy chain rotaxanes by using copper(I)-catalyzed Huisgen 1,3-dipolar cycloaddition (“click chemistry”). With this cross-linked topology, the corresponding materials in the form of chemical gels can be contracted and expanded over a large variation of volume (∼50%) by changing the protonation state of the system. HR-MAS 1H NMR and neutron scattering experiments reveal that this macroscopic response of the gels results from the synchronized actuation of the mechanical bonds at the molecular level.

Triarylamine molecules appended with crown-ethers or carboxylic moieties form self-assembled supramolecular channels within lipid bilayers. Fluorescence assays and voltage clamp studies reveal that the self-assemblies incorporating the crown ethers work as single channels for the selective transport of K+ or Rb+. The X-ray crystallographic structures confirm the mutual columnar self-assembly of triarylamines and crown-ethers. The dimensional fit of K+ cations within the 18-crown-6 leads to a partial dehydration and to the formation of alternating K+ cation-water wires within the channel. This original type of organization may be regarded as a biomimetic alternative of columnar K+-water wires observed for the natural KcsA channel. Supramolecular columnar arrangement was also shown for the triarylamine-carboxylic acid conjugate. In this latter case, stopped-flow light scattering analysis reveals the transport of water across lipid bilayer membranes with a relative water permeability as high as 17 μm s–1.

International audience; The implementation of artificial molecular machines in polymer science is an important objective that challenges chemists and physicists in order to access an entirely new class of smart materials. To design such systems, the amplification of a mechanical actuation from the nanoscale up to a macroscopic response in the bulk material is a central issue. In this article we show that bistable [c2]daisy chain rotaxanes (i.e. molecular muscles) can be linked into mainchain Upy-based supramolecular polymers. We then reveal by an in depth quantitative study that the pH actuation of the mechanically active rotaxane at the nanoscale influences the physical reticulation of the polymer chains by changing the supramolecular behavior of the Upy units. This nano-actuation within the local structure of the main chain polymer results in a mechanically controlled sol-gel transition at the macroscopic level.

The study of supramolecular polymers in the bulk, in diluted solution, and at the solid–liquid interface has recently become a major topic of interest, going from fundamental aspects to applications in materials science. However, examples of supramolecular polymers at the liquid–liquid interface are mostly unexplored. Here, we describe the supramolecular polymerization of triarylamine molecules and their light-triggered organization at a chloroform–water interface. The resulting interfacial nematic layer of these 1D supramolecular polymers is further used as a template for the precise alignment of spherical gold nanoparticles coming from the water phase. These hybrid thin films are spontaneously formed in a single process, without chemical prefunctionalization of the metallic nanoparticles, and their ordering is improved by centrifugation. The resulting polymer chains and strings of nanoparticles can be co-aligned with high anisotropy over very large distances. By using a combination of experimental and theoretical investigations, we decipher the full sequence of this oriented self-assembly process. In such a highly anisotropic configuration, electron energy loss spectroscopy reveals that the self-assembled nanoparticles behave as plasmonic waveguides.

A concise and convergent total synthesis of the highly cytotoxic marine natural products iejimalide A-D (1-4) is reported, which relies on an effective ring-closing metathesis (RCM) reaction of a cyclization precursor containing no less than 10 double bonds. Because of the exceptional sensitivity of this polyunsaturated intermediate and its immediate precursors toward acid, base, and even gentle warming, the assembly process hinged upon the judicious choice of protecting groups and the careful optimization of all individual transformations. As a consequence, particularly mild protocols for Stille as well as Suzuki reactions of elaborate coupling partners have been developed that hold considerable promise for applications in other complex settings. Moreover, a series of non-natural "iejimalide-like" compounds has been prepared, differing from the natural lead in the polar head groups linked to the macrolide's N-terminus. With the aid of these compounds it was possible to uncover the hitherto unknown effect of iejimalide and analogues on the actin cytoskeleton. Their capacity to depolymerize this microfilament network rivals that of the latrunculins which constitute the standard in the field. Structural modifications of the peptidic terminus in 2 are thereby well accommodated, without compromising the biological effects. The iejimalides hence constitute an important new class of probe molecules for chemical biology in addition to their role as promising lead structures for the development of novel anticancer agents.

Organic materials exhibiting metallic behavior are promising for numerous applications ranging from printed nanocircuits to large area electronics. However, the optimization of electronic conduction in organic metals such as charge-transfer salts or doped conjugated polymers requires high crystallinity, which is detrimental to their processability. To overcome this problem, the combination of the electronic properties of metal-like materials with the mechanical properties of soft self-assembled systems is attractive but necessitates the absence of structural defects in a regular lattice. Here we describe a one-dimensional supramolecular polymer in which photoinduced through-space charge-transfer complexes lead to highly coherent domains with delocalized electronic states displaying metallic behavior. We also reveal that diffusion of supramolecular polarons in the nanowires repairs structural defects thereby improving their conduction. The ability to access metallic properties from mendable self-assemblies extends the current understanding of both fields and opens a wide range of processing techniques for applications in organic electronics.

The molecular chaperone HSP90 is an attractive target for chemotherapy because its activity is required for the functional maturation of a number of oncogenes. Among the known inhibitors, radicicol, a 14-member macrolide, stands out as the most potent. A molecular dynamics/minimization of radicicol showed that there were three low energy conformers of the macrocycle. The lowest of these is the bioactive conformation observed in the cocrystal structure of radicicol with HSP90. Corresponding conformational analyses of several known analogues gave a good correlation between the bioactivity and the energy of the bioactive conformer, relative to other conformers. Based on this observation, a number of proposed analogues were analyzed for their propensity to adopt the bioactive conformation prior to synthesis. This led to the identification of pochonin D, a recently isolated secondary metabolite of Pochonia chlamydosporia, as a potential inhibitor of HSP90. Pochonin D was synthesized using polymer-bound reagents and shown to be nearly as potent an HSP90 inhibitor as radicicol.