Original organometallic switching nanomaterials combining optical, electrochemical, and magnetic properties for molecular electronics – PHOTOMAGCOM

This project prospects for molecular devices suitable for the next information processing technologies. This is a very challenging topic because the molecular devices are regarded as the most probable candidates to supersede the present semiconductor technology. Since practical applications require increasing data storage capacities, the future of molecular electronics is connected to the development of multifunctional materials in which distinct properties can be addressed separately, or in which a single property might be specifically altered by separate stimuli. The aim of the project is to develop in the laboratory a new topic that deals with novel issues for magneto-optical switching materials, including the full conception, realisation and analysis of devices. The challenge now is to design innovative multifunctional model compounds based on redox active carbon-rich organometallics associated with spin carriers and/or photochromic units. Through experimental and theoretical tools, their switching abilities will be explored via tuning of magnetic, optical or electrochemical properties with stimuli such as light or electron transfer. Further grafting of these systems on substrates will allow the building of experimental operating devices for molecular optoelectronics and spintronics. The originality of this project is related to the use of ruthenium carbon-rich complexes as redox active magnetic coupling units, as well as spin carriers. These compounds are particularly suitable as they promote exceptionally efficient intramolecular electronic communication and electrical conductivity. As a result, these systems must lead to highly enhanced magnetocommunication and switching behaviour, required for practical applications This area of interest will introduce researchers in chemistry (synthesis chemistry, theoretical chemistry, thin film chemistry) and physics to the newly developed field of magnetism. The project will be hold within an interdisciplinary frame. Three main targets with increasing complexity will be considered in this proposal: (1) The use of a combination of carbon-rich organometallics, i.e. metal acetylides [Cl2-n(dppe)2Ru(-C'C-R)n] (n = 1, 2) and metal bis-allenylidenes [(dppe)2Ru(=C=C=CR'2)2]2+, with organic/inorganic radicals R or R' (nitronyl nitroxide radical derivatives or M(hfac)2Bipirydine derivatives with M = CuII, MnII), directed to the search for strong through-bond magnetic interactions at the molecular scale. Their magnetic and optical properties will be tuned (i) by changing the oxidation state of the metal coupling unit upon electron-transfer processes, and (ii) through light irradiation in the charge transfer band of the molecules. (2) The insertion of a bistable diarylethene photochromic unit between two redox active organometallic species, in order to trigger radical formation. This will achieve a new nanometric switches, with up to three read out (optical, electrochemical, and magnetic), and two possible writing processes (light, electron transfer). The full understanding of the magnetic, optical, and switching properties, on the basis of the chemical structures, is a crucial point for further tailoring and improvement of the systems. To this end, theoretical calculations will be performed on the complexes targeted in these first two objectives. Of special interest will be the question of the relevant electronic states for the set up of magnetic interactions within these new molecular materials. (3) The design of prototype nanodevices with the achievement of self-assembled monolayers (SAMs) on metallic surfaces using modified complexes. The studies and evaluations of these new switching monolayers will help to understand and to predict the properties of grafted molecules with respect to those in solution. To this endeavour, theoretical calculations of the complexes immobilized on a surface will be of special interest to estimate the effects of the grafting on the properties. Beyond the operational aspect for nanodevices applications, this part deals strongly with fundamentals. Indeed, a crucial point for understanding and realizing any future molecular electronics, optics or magneto-optics will be the control of the connections between the molecular-scale components. To conclude, this project is aimed at developing a new topic to enhance the state of the art in the field of scientific innovation related to multifunctional molecular devices. In addition to the basic interest and with the help of an original approach using ruthenium organometallics, this research plan will improve the knowledge based development of new magnetic/optical nanoswitches directed towards the design of experimental operating devices with potential applications such as memories, quantum computing, and molecular spintronics.