ERC FUNDED PROJECTS

We target a frontier in nanocrystal science of combining disparate materials into a single hybrid nanosystem. This offers an intriguing route to engineer nanomaterials with multiple functionalities in ways that are not accessible in bulk materials or in molecules. Such control of novel material combinations on a single nanoparticle or in a super-structure of assembled nanoparticles, presents alongside with the synthesis challenges, fundamental questions concerning the physical attributes of nanoscale systems. My goals are to create new highly controlled hybrid nanoparticle systems, focusing on combinations of semiconductors and metals, and to decipher the fundamental principles governing doping in nanoparticles and charge and energy transfer processes among components of the hybrid systems. The research addresses several key challenges: First, in synthesis, combining disparate material components into one hybrid nanoparticle system. Second, in self assembly, organizing a combination of semiconductor (SC) and metal nanoparticle building blocks into hybrid systems with controlled architecture. Third in fundamental physico-chemical questions pertaining to the unique attributes of the hybrid systems, constituting a key component of the research. A first aspect concerns doping of SC nanoparticles with metal atoms. A second aspect concerns light-induced charge transfer between the SC part and metal parts of the hybrid constructs. A third related aspect concerns energy transfer processes between the SC and metal components and the interplay between near-field enhancement and fluorescence quenching effects. Due to the new properties, significant impact on nanocrystal applications in solar energy harvesting, biological tagging, sensing, optics and electropotics is expected.

2 499 000 €

Start date: 2010-06-01, End date: 2015-05-31

Allostery is a fundamental concept Nature uses to regulate the affinity of a certain substrate to an active site of a protein by binding a ligand to a distant allosteric site. We will design experimental tools to gain an atomistic understanding of the conformational transitions that give rise to allostery. We will approach the problem from two distinctively different directions. First, we will initiate conformational transitions of proteins that per se are not photoswitchable, by cross-linking two sites of an allosteric protein with a photo-switchable azobenzene-moiety to initiate a conformational transition similar to ligand binding. We will use ultrafast infrared spectroscopy to time-resolve the conformational transition. Second, we will experimentally verify a frequently expressed hypothesis that allosteric and active site communicate by exchange of vibrational energy. To that end, we will design a versatile approach that allows us to locally deposit vibrational energy at essentially any site in a protein (e.g. through pumping of an optical chromophore that undergoes ultrafast internal conversion), and to detect its appearance at any other site by using vibrational transitions as local thermometers. Thereby, we will map out a network of connectivity in a given protein. Both approaches will applied both to one and the same protein family. One concrete example are PDZ domains, which are among the smallest allosteric proteins, and for which the connection between allostery and vibrational energy flow has been made explicit, based on computer simulations. We will eventually test this hypothesis experimentally, and provide the foundation for a description of allostery that is on an equal footing as our current understanding of protein folding.

2 400 000 €

Start date: 2010-02-01, End date: 2015-07-31

In recent years, as first established in some 6 papers in Science and Nature from the PI s group, a new paradigm has emerged. This reveals the remarkable and unsuspected - role of hydration layers in modulating frictional forces between sliding surfaces or molecular layers in aqueous media, termed hydration lubrication, in which the lubricating mode is completely different from the classic one of oils or surfactants. In this project we address the substantial challenges that have now arisen: what are the underlying mechanisms controlling this effect? what are the potential breakthroughs that it may lead to? We will answer these questions through several interrelated objectives designed to address both fundamental aspects, as well as limits of applicability. We will use surface force balance (SFB) experiments, for which we will develop new methodologies, to characterize normal and frictional forces between atomically smooth surfaces where the nature of the surfaces (hydrophilic, hydrophobic, metallic, polymeric), as well as their electric potential, may be independently varied. We will examine mono- and multivalent ions to establish the role of relaxation rates and hydration energies in controlling the hydration lubrication, will probe hydration interactions at both hydrophobic/hydrophilic surfaces and will monitor slip of hydrated ions past surfaces. We will also characterize the hydration lubrication properties of a wide range of novel surface systems, including surfactants, liposomes, polymer brushes and, importantly, liposomes, using also synchrotron X-ray reflectometry for structural information. Attainment of these objectives should lead to conceptual breakthroughs both in our understanding of this new paradigm, and for its practical implications.

2 304 180 €

Start date: 2010-05-01, End date: 2015-04-30

The design of an optimal catalyst for a given process is at the heart of what chemists do, but is in many times more an art than a science. The quest for molecular control of any, either existing or new, production process is one of the great challenges nowadays. The need for accurate rate constants is crucial to fulfil this task. Molecular modelling has become a ubiquitous tool in many fields of science and engineering, but still the calculation of reaction rates in nanoporous materials is hardly performed due to major methodological bottlenecks. The aim of this proposal is the accurate prediction of chemical kinetics of catalytic reactions taking place in nanoporous materials from first principles. Two types of industrially important nanoporous materials are considered: zeotype materials including the standard alumino-silicates but also related alumino-phosphates and the fairly new Metal-Organic Frameworks (MOFs). New physical models are proposed to determine: (i) accurate reaction barriers that account for long range host/guest interactions and (ii)the preexponential factor within a harmonic and anharmonic description, using cluster and periodic models and by means of static and dynamic approaches. The applications are carefully selected to benchmark the influence of each of the methodological issues on the final reaction rates. For the zeotype materials, reactions taking place during the Methanol-to-Olefin process (MTO) are chosen. A typical MTO catalyst is composed of an inorganic cage with essential organic compounds interacting as a supramolecular catalyst. For the hybrid materials, firstly accurate interaction energies between xylene based isomers and MOF framework, will be determined. The outcome serves as a step-stone for the study of oxidation reactions. This proposal creates perspectives for the design of tailor made catalyst from the molecular level.

1 150 000 €

Start date: 2010-01-01, End date: 2014-12-31