Hierarchical supramolecular Architectures – Supra-HierArchi

We will proceed in a bottom-up approach, starting from the synthesis of functionalized CDs. Followed by the study of their physico-chemical properties to understand and modulate their properties. Then we will construct and study the formation of supramolecular polymers or rods with our various systems and strategies. We will then study the hierarchy of association of designed rods into bundles.

Preliminary studies on weak interactions potentially interesting, and on the synthesis of monomers. We now showed that we could form supramolecular polymers in solution, and supramolecular hierarchical assemblies in the solid state.

Study of a potentially assembling monomer and other leads have to be sutdied. Biological applications of our systems is now studied.

4 papers have been published
Eur. J. Org. Chem. 2013, 3691–3699
Angew. Chem. Int. Ed. 2013, 52, 7213-7218
Angew. Chem. Int. Ed. 2014, 53, 7238-72421
Org. Chem. Frontiers 2014, 1, 703-706

Following the historical evolution of chemistry, which investigated first the preparation of small molecules, then of macromolecules, and more recently of supramolecules, it is clear that the next frontier will be the building of molecular systems with nanometer-sized dimensions, i.e., 10–1000 nm in size, with molecular weights between thousands and billions Daltons in a completely controlled fashion. Structures of this size, so-called "nanomolecules", are ubiquitous in nature where they help perform and control all the important functions and processes of life. Trying to understand the basis of this unique form of molecular matter and finding ways to synthesize these "nanomolecules" will require the input, knowledge, and experience of the fields of molecular, macromolecular, and supramolecular chemistry. However, despite tremendous interest in this challenge, there is at present no reliable system forming well-defined monodispersed and tunable fibrilar objects where the diameter of the cross-section is monodispersed and can be tuned with an atomic precision in the range 1-10nm. We wish to develop here such a system based on precisely functionalized cyclodextrins. Our project is based on various doubly-linked, hence rigid, cyclodextrin dimers called duplexes that will form a supramolecular polymer in water with rigid ditopic hydrophobic guests. This so far unexplored double rigidity is necessary to envisage interactions between polymer rods. In a first system, we will add two hydrophobic groups at a relative azimuthal angle of 120° on the duplex. Those groups will be too large to be included in a cyclodextrin but will tend to aggregate in water, and therefore force the polymer rods to assemble into bundles. Their relative and precise position as well as their size is the base for the control of the size and the helicity of the bundle. Further functionalization of the duplex will allow more complex assemblies. A second strategy will use negatively charged dendrimers to assemble rods with localized positive charges forming interpolyelectrolyte complexes. Due to the size of the dendrimer, several rods of supramolecular polymer will wrap around them, forming another type of bundles. A higher degree of complexity can be reached by combining both approaches: wrapping of twisted bundles assembled through hydrophobic interactions around dendrimers through electrostatic ones to form microfibrils. Similarly, DNA strands will be used as polyelectrolyte to form Tobacco Mosaic Virus analogues. Finally, 2D and 3D architectures will be reached using tritopic guests. At the end of the project we will be in possession of a tool-kit and we will have learned the basic rules to play around with. The modularity of the cyclodextrin duplex platform should then enable us to construct more and more complex assemblies.