Research project P6/27 (Research action P6)
This IAP-PAI network Supramolecular Functional Systems (acronym FS2) will evolve from the previous network, entitled Supramolecular Chemistry and Supramolecular Catalysis. Supramolecular chemistry describes the chemistry beyond the molecule and studies chemical species held together by non-covalent intermolecular interactions. The aim of the project is to develop novel systems, to understand driving forces that allow bi- and tridimensional organisation, to develop methods and tools to investigate, address, manipulate supramolecular structures and exploit their specific properties. In comparison with the previous project, selected new topics will be emphasized, while other promising areas will be further explored. A special emphasis will be placed on the functionality of four major supramolecular systems (cfr infra), and the specific research packages will be tackled at four different platform levels by several partners with complementary expertise and instrumental capabilities. The previous frame of the network, an organic, polymeric, inorganic and bio-approach to supramolecular phenomena, has been redesigned so as to maximize networking and intensify the degree of focus.
The following functional supramolecular systems will be studied:
1. Nanostructured systems: Typical nanostructured systems are zero-dimensional metal and semiconductor nanodots. They are studied as such, or in conjugated liquid crystals and polymers.
2. (Hierarchically) structured nanoporous materials: Via supramolecular templating, block copolymer templating and (repeated) nanocasting, nanoporous materials with pore size covering the whole micro-mesopore domain, different architecture and even multimodal distribution are accessible for use in separation, catalysis of large (bio)molecules. Among them are of particular interest mesoporous organogels, nanostructured carbon materials, (multi)porous oxides, metal-organic frameworks and (supported) nanoparticles.
3. (Hybrid) biomaterials: Artificial biomaterials are mimicking the natural components that function by a complexity of equilibria, intracellular and extracellular catalysis, and interface phenomena, the intra- and extracellular function being governed by supramolecular arrangements of various biopolymers, inorganic and organic molecules. Biomimetic material design requires tailored chemistry leading to characterized biomimetic surfaces and matrices, membranes, probes for cellular components, biomimetic catalysts, nanosized patterned surfaces, and hybrid systems.
4. Thin films (organic, inorganic and hybrid): Functional systems are most often organized in thin films; this applies, e.g., to conjugated polymers incorporated as the active element in semiconducting devices, functional polymer coatings or molecular layers on surfaces, and (bio)membranes.
To guarantee intensive networking, the partners for each of the system classes will contribute at the level of four different platforms:
PLATFORM 1: THEORY & MODELING
Multiscale modeling starts from simple structures (single molecules, molecular building blocks) and extends towards systems of growing complexity: polymer chains and supramolecular assemblies built by non-covalent interactions, molecular systems embedded in a solvent or polymer matrix, (macro)molecules adsorbed at surfaces or within pores, and finally interfaces in organic/inorganic, or organic/organic, or organic/bio hybrid systems.
The major goals of the activities of this platform will be:
(i) to determine the nature and intensity of the intermolecular interactions on the nanoscale;
(ii) to provide interpretation to the spectroscopic data and the photonic properties;
(iii) to understand the molecular dynamics in space and time, for (photo)physical and chemical processes.
Theoretical tools adapted to the scale of the problem will be implemented, from state-of-the-art quantum chemical methods to force-field-based molecular modeling techniques designed for accurate simulations of both organic and inorganic compounds, as well as biomolecules.
PLATFORM 2: SYNTHESIS & FABRICATION (MOLECULAR ENGINEERING)
2.1. Building block Synthesis: Supramolecular chemistry relies on the capability of designing/tailoring building blocks of various nature (organic/inorganic), size (molecules, oligomers, (co)polymers, particles…), shape (spherical, cylindrical, sponge-like, vesicular,…) and reactivity. A work-package will focus on efficient and selective processes for synthesis of these elementary (meccano or lego) pieces, with special emphasis on controlled/living polymerizations, sol-gel processes, and nanoparticle fabrication.
2.2. Self-assembly and nanomanipulation of building blocks (0D; 1D; 2D; 3D): Strategies are devised for (self)assembly of complementary building blocks, for their adsorption, grafting and manipulation at surfaces, their dispersion and nanostructuring within matrices (inorganic, polymeric) with the purpose to trigger novel behavior and specific properties in optoelectronics, catalysis, (bio)sensing, biomaterials, engineering polymers, etc.
2.3. Biomimetic chemical design: In active sites of enzymes and supramolecular systems alike, key issues are control over the access, steric and polarity factors, and targeted active site modification. Favored assembly methods are ‘ship-in-a-bottle’ synthesis of coordination compounds in the channels and cages of porous materials, and molecular imprinting of transition states or analytes. High-throughput design methods copy the genetic strategies of natural evolution.
2.4 Nanopatterning of adsorbed monolayers and their use as stamps and templates will be explored. (Chirally) ordered 2D-structures will serve as a template for 3D-nanostructures, using building blocks such as chiral conjugated molecules or conducting polymers. Patterning of the adsorbed molecules will also be investigated starting from a patterned substrate.
PLATFORM 3: STRUCTURE & FUNCTIONALITY
3.1. Interaction and Recognition between two building blocks is the elementary event for supra-molecular function. Chemical synthesis and theory aid in designing new interactions with increased specificity.
3.2. Adsorption, Motion, Diffusion: We will investigate the effect of the nature of the chemical adsorbate on the structures formed and on the kinetics of adsorption at model surfaces and at real surfaces. The adsorption and diffusion of small molecules in nanoporous materials will be simulated and the results related to experimental data. The translational and rotational motion of individual polymer chains and even of chain segments will be recorded using single molecule spectroscopy on probes dissolved in or covalently bound to a polymer. Fluorescent probes (small molecules, or labeled proteins) will also be used to image the motion (processivity) of enzymes, to follow transport of substrates and products to or from single enzymes and through membranes, and to follow formation of rafts in synthetic and natural bilayer membranes. The diffusion and drift of excitons and charge carriers will be monitored in nanostructured systems consisting of a conjugated polymer and nanodots or with a bulk heterojunction between a conjugated polymer and small molecules or between two types of small molecules.
3.3. Chemical stimulation: Upon reception of a chemical signal or reagent, the supramolecular response can vary from a subtle change of a weak bond, to complex breaking and formation of covalent bonds as in supramolecular catalytic processes. Focus will be on how supramolecular organization contributes to concerted or consecutive bond activation. Methodology concentrates on real-time imaging of chemical activation over large spatial ranges, with increasing spatial resolution.
3.4. Dynamics upon other stimulation: External stimuli such as T, E, pH, flow, static magnetic field, shear forces or hν will be used to induce changes of the supramolecular organisation. The reversibility, hysteresis, the time constants and the spatial homogeneity of the response will be studied with advanced physical techniques. Smart materials with memory behavior or reversible switching capability will be developed.
PLATFORM 4: DEVICES & RESPONSIVE SYSTEMS
Concepts will be designed and proven for specific applications such as drug delivery devices, sensors, opto-electronic devices and shape memory polymers.
