Circuits integrating molecular-scale components may ultimately allow the replacement of silicon-based electronics by high speed systems with low energy consumption. Because of the prominent use of magnetization-based information storage technologies in our daily life, Single-Molecule-Magnets (SMM), which are able to interconvert between two states with opposite magnetization directions receive a great deal of attention. In this proposal, we detail a new strategy to reversibly switch such molecular magnetic behavior with light. It relies on a ligand-centered light driven process within a metal complex containing photoswitchable ligands. Such strategy will be efficiently applied to the otherwise light insensitive 4f based SMM systems because their high sensitivity to minute changes in their coordination environment will maximize the impact of the photo-isomerization event on the resulting magnetic behavior.

Pyridines are key molecules in biology and materials science. Unfortunately, they are highly difficult to functionalize by means of transition metal (TM) catalysts as they displace the ligands of the metal active center via coordination of the nitrogen lone pair. This inhibits the catalysis or, at best, leads to very low reactivity. To overcome this issue, a unique set of supramolecular catalysts will be developed in this proposal. They are inspired by one of the most powerful action modes of enzymes: the highly selective molecular recognition via weak interactions occurring during the catalysis. The supramolecular catalysts incorporate (1) a substrate recognition site and (2) a catalytically active site with TM units. The substrate recognition site will fix the nitrogen lone pair of the pyridine substrate via weak interactions, leaving the catalytically active TM available for turnover. This approach will be applied to the directing-group-free C-H bond functionalization of pyridines.

In this 36 months material-modeling project, we aim at providing through a theoretical design a new generation of nano-objects able to convert sunlight into energy and store it in an efficient fashion. To this end we will make use of the so-called Molecular Solar Thermal (MOST) process, where the irradiation of an organic photochrome with solar light permits the switching to a second isomer, higher in energy (energy storage step), while the return to the most stable isomer with the help of a less energetic external stimulus induces the energy excess release as heat (energy release step). In the FALCON project, we propose to go beyond the current state of the art of MOST process in solution and use the functionalization of metallic NanoParticle (NP) has a mean of attaining optoelectronic nanomaterial with superior solar energy storage abilities. Coating NPs with organic photochromes will indeed permit a fine control of the molecules density, a critical parameter in the energy storage mechanism, and potentially enhance the switching process of the molecule due to the effect of the Localized Surface Plasmon Resonance (LSPR) of the NP. To reach this goal, the FALCON project is dedicated to the in-silico design of NP-photochromes solar thermal fuel devices with the help of atomistic modelling. The development of a theoretical approach is crucial as it will permit an in-depth understanding of the non-trivial interactions between the two parts of the device, that are today yet to be fully rationalized with quantum chemistry models. It will also save precious time, raw material and human resources prior to the experimental device fabrication. This computational design is however by definition a challenge for fundamental research, as one would need quantum mechanics model to describe the electronic interactions in the device up to a very large scale, much larger than the consideration of a sole molecule. So far, no computation method has been able to provide an atomic quantum description to contribute to the development of hybrid nanomaterial. The FALCON project aims at fulfilling this blank with the help of computations based on the Density Functional Tight Binding (DFTB) model, as it allows a quantum description of the electrons at a very low computational cost, once correctly parameterized. We thus propose to set up a specific DFTB protocol able to fully describe the ground state and excited states of these nano-objects, granting access to i) the description of the photochromic process of the molecules onto the NP, under the LSPR influence, ii) the quantity of energy stored during this process, and ultimately iii) the design of new devices with optimized properties. To achieve this goal a large part of the project is dedicated to the construction of a new DFTB parameterization able to describe accurately both the metallic NP and the organic photochromes properties. Once correctly set up, the second half of the project applies this theoretical tool to explore the photochromic and energy storage capabilities of various NP-photochromes hybrid systems, to establish general design rules and finally propose more efficient systems. The success of this fundamental project will permit to speed up the fabrication of complex functional nano-objects, in future large-scale experience/theory collaborations, in the critical field of renewable energy. Furthermore, DFTB computational schemes constructed during this project will be a real breakthrough for the material modeling community and will permit subsequent functionalized NP modeling for other applications.

The breakthrough discovery of ferrocene in 1951 has paved the way of metallocenes chemistry, a family of compounds in which two aromatics rings surround a metallic cation, here an iron ion. Prototypical compound of this family, ferrocene exhibits a high stability in various conditions and can even be stored at air without any notable decomposition. Cheapest of the metallocenes, ferrocene is therefore the most employed for various applications in sensing, catalysis, material and medicinal chemistry. A key parameter of this success lies in the planar chirality of ferrocene when two different substituents are on the same ring. However, these developments are limited to derivatives which are monosubstituted (one substituent on one cycle), 1,1’-disubstituted (one substituent on each cycle) and 1,2-disubstituted (two adjacent substituents on the same cycle). In sharp contrast, ferrocene featuring on original substitution pattern (1,3-disubstituted or 1,2,4-trisubstituted) or bearing 4 or 5 substituents on the same ring have been scarcely studied. However, they have specific properties resulting from the large angle between two substituents or from the fine tuning of steric and electronic properties for specific applications. The lack of general synthesis of such derivative, combined with purification troubles upon the successive introduction of substituents, explain why they do not benefit from more applications. Furthermore, the limited number of described examples combined with the absence of ferrocene-dedicated database does not allow properties predictions. The goal of the Ferrodance project is to fill that void with the development of a synthetic approach towards these compounds. Therefore, we will functionalize ferrocenic C-H bonds using strong bases for introducing a halogen atom on a remote position, especially in an enantioselective way. Post-functionalization reactions will afford polysubstituted ferrocene derivatives bearing up to five different substituents on the same ring. The electrochemical study of the various compounds made will allow the development of an easy amenable purification process able to solve the longstanding problem of ferrocene derivatives purification. Finally, we will benefit from the structural diversity accessible through Ferrodance to initiate the development of a ferrocene-dedicated database. In the future, its exploration will allow the establishment of structure-property relationships and will help the rational choice of a ferrocene compound for specific applications.

Magnetoelectrics, with their coupled electric and magnetic polarizations, are promising candidates for a number of applications. Specifically, such materials offer the possibility to control the magnetic properties by electric fields and vice versa. This property is extremely appealing regarding Today’s enormous global energy expenditure in our society. Despite the continuous development of magnetoelectric materials, notably in inorganic oxides, there remains tremendous demand for the development of a broader set of molecule-based magnetoelectrics. In particular, general molecular design principles and in-depth understanding of cross coupling for molecule-based magnetoelectrics are still lacking due in large part to a paucity of synthesized materials available to date. In this context, Magneto-e aims at harnessing innovative molecular building block approaches to rationally synthesize molecule-based magnetoelectric materials, and to carry out fundamental structure-function studies to guide the synthesis of future materials. To accomplish this objective, we will synthesize new designer magnetic molecule-based systems functionalized with tailored organic building blocks for electric polarization. In particular, the addressed challenge will be tackled by designing new coordination compounds comprising abundant 3d transition metal ions. Our bottom-up approach will allow molecular control over properties such as dipole moment, chirality, magnetic coupling and magnetic anisotropy. The efficient feedback between syntheses and analyses will guide us to establish general chemical design strategies towards molecule-based magnetoelectric materials. Moreover, the developed class of materials that feature tremendous collaborative potential will bridge multidisciplinary fields including synthetic chemistry, materials science and condensed matter physics.