CORDIS - EU research results

Theoretical insides in endohedral metallofullerene based Self-Assembled Monolayers: Statics and Dynamics.

Periodic Reporting for period 1 - SamSD (Theoretical insides in endohedral metallofullerene based Self-Assembled Monolayers: Statics and Dynamics.)

Reporting period: 2017-11-01 to 2019-10-31

Functional molecules are an essential building block of future materials as being cost-efficient and easy tunable systems. The fundamental properties and characteristics or states of such molecules define the scope of possible applications. Molecular sensors, transistors or magnets, in all cases path to a real-world application goes through the ordering of these systems on surfaces or otherwise. In such complex contractions, the molecules put in confined places where their properties can be controlled and manipulated. For example, an array of molecular magnets on a surface reassembles a feasible platform for high-density storages. This is an important platform to cope with the growing demand in data storing of a data-driven world, with an undoubtedly profound socio-economic impact.

The broad theoretical basis should exist capable to rationalize experimental observables and guide new strategies, to facilitate targeted research. In the field of functional molecular materials, the predictive computational schemes can narrow down the scope of promising candidates, with the significant cost efficiency in the research.

The SamSD project dealt with a new class of high-performance molecular magnets as individual units and they assemble on surfaces and in crystals. These molecular magnets have two important ingredients a fullerene – football like carbon cage and an atomic cluster inside. Fullerenes meant to protect clusters, clusters dictate the properties. In this study, the clusters included lanthanide atoms. These atoms in the right environment can maintain magnetic permeance. Our primary objectives were the theoretical investigation of magnetism in such molecular systems and understanding the stability and geometries of these systems in different molecular assemble. We have employed a full arsenal of quantum chemical models and methods from semiempirical to first principles to tackle these questions. In this attempt, we persuaded the development of theoretical protocols applicable not only for the system of interest in the project but for the border class of similar materials. We have developed such protocols and applied them with great successes to resolve the project objectives.
By design, all objectives in the project are persuadable independently. From the very start, we have performed massive first principle investigation of magnetism of isolated molecular systems with different clusters inside fullerene cages like dimmers of lanthanides, small lanthanides nitrides, oxides, sulfides and many more. Over time, it has mounted in a library of fundamental properties for the systems accessed by theoretical means and checked against experimental data if possible. Working in close collaboration with an outstanding research team, we have been able to report our theoretical findings in multiple joined scientific. Some of these systems, like lanthanides dimmers, have shown truly remarkable and even records breaking magnetic properties and single molecular magnetism stability. The theoretical investigations have helped better understand the systems and strategies further research.
As mentioned, the geometries of these clusters and special orientations are sensitive to the global environment. Importantly, in these systems, the magnetic order is strongly intertwined with these geometrical characteristics. Thus, the knowledge of structural order will provide great insight into magnetic arrangements. A small perturbation by surfaces by other molecules around may have a profound effect. These, in due turn, control the system's functionality and ability to use the desire properties in ensembles on surfaces in the form of self-assembled monolayers. Also, in the compact arrays on surfaces or crystals, the molecular magnets may be sensitive to the magnetic field generated by neighbor molecules. This facilitates unexpected system behaviors. SamSD dives deep in these issues through comprehensive research and modeling, using cutting-edge theoretical models. Having proposed a sophisticated way of sampling of the cluster conformational spaces, we were able to figure out the fundamental forces which control the clusters ordering and thus ordering of magnetic characteristics. These have improved a general knowledge about the sensitivities of the system and provided means to justify the experimental spectroscopy data, sensitive to the magnetic ordering of molecular arrays on surfaces.
Furthermore, we have considered the impact of valence electron on the formation of a magnetic state of the systems. The proposed theoretical strategy reviles a significant influence of valence shell compositions on magnetic properties and stability of molecular magnetism. Within this project, we have also entertained the idea of modeling the magnetic relaxation in these systems with the full complexity of atomic motions.
The dissemination of the SamSD results has been achieved through open access publication research that was presented at the research conference and general workshops. In multiple instances, the novelty and quality of the research were noted by editorials and awarded by the journal front covers.
When the project just started, in the literature, there was only a hand full of cases of similar complexity, which have been approached on the level of theory anticipated by SamSD. In our efforts we have formed a whole library including dozens of well-documented cases. Many of these systems have a high potential for future applications. In this quest, we have solidified a general theoretical pipeline with the capacity to handle such complex systems.
The effects of surfaces and non-covalent interactions on the magnetic ordering were little known, which limited the vision for strategic material design and applications. In this respect, SamSD findings provide a theoretical tool-box for an intelligent and cost-efficient design of future experiments. Finally, the effects of valence electrons or phonons have been discussed in models, but never have been approached in the true computation fashion. Thus, the reported results on this part do not only go beyond the state of the art, but they also provide an original and solid ground on which further research can and will evolve.
Systems complexity and theoretical pipeline, from optimized structures to predicted properties/
SamSD research highlights on the journal covers