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Magnetism and Magnetic Resonance of Molecules

Final Activity Report Summary - MOLMAG (Magnetism and magnetic resonance of molecules)

The goal of the "Magnetism and Magnetic Resonance of Molecules", MOLMAG Marie Curie Training Site was that of training young researchers in the use of magnetic techniques and magnetism to monitor the properties of molecular systems. The frame is that of Molecular Magnetism, which in the last years has produced dramatic breakthroughs in such diverse fields as nanomagnetism and biochemistry. The trainees were offered an a la carte choice of experimental and theoretical techniques. Among the former it was possible to measure the magnetisation and the susceptibility in a wide range of temperature and applied fields and to use electron spin resonance techniques in a wide range of frequencies. There were 14 trainees participating to the project, coming from seven countries. The stay in Florence had a positive result in terms of training in sophisticated experimental techniques as shown by the over 20 papers published in international journals.

The activities of the project can be resumed as shown below: 1) investigations of the electron structures of transition metal compounds, an old field which is revived by the now available experimental and theoretical techniques; 2) magnetic molecules, comprising for instance metal ions interacting with stable organic radicals, like nitroxides; 3) molecular nanomagnetism, which is currently under intense interdisciplinary investigation. As a typical example one can consider the so-called Single Molecule Magnets, SMM, highly anisotropic magnetic molecules which below a blocking temperature behave as tiny (of the order of 1 nm) magnets: several new systems, involving not only transition metal but also rare earth ions have been successfully investigated; 4) materials for novel information storage devices based on spin cross over compounds; 5) modified quantum dots for magnetic resonance imaging.

Being impossible to report all the results some highlights for the various above categories are given below:
1) Classic coordination chemistry produced brand new results in a dinuclear manganese(I) compound, whose unusual electronic structure was clarified through a concerted action using magnetic , EPR, and DFT calculations. The compound can shed light on fundamental catalytic processes.
A very detailed and accurate characterisation of oxamato complexes showed how deep insight can now be achieved by exploiting the modern techniques.
2) Compounds comprising semiquinones bound to transition metal and rare earth ions developing ferromagnetic exchange interactions were investigated.
3) The large majority of trainees was attracted by the properties of large magnetic molecules; one of them investigated new types of SMM based on manganese ions and the magnetic data were complemented with X-MCD spectra taken using synchrotron radiation in Berlin. It was shown how the magnetic properties can be tuned by chemically varying the oxidation state of some metal ion, while a new class of SMM based on dysprosium triangles was investigated by another fellow by means of a very refined technique, the torque magnetometry.
4) A systematic study of the spacer effects in dinuclear iron compounds showing spin cross over effects has been performed, using magnetic techniques coupled to photo-magnetisation measurements
5) Nanoparticles of CdSe covered by ZnS attached to gadolinium were investigated with the goal of exploiting the luminescence and magnetic properties to employ them in magnetic resonance imaging.

Another major success of the MOLMAG project was in the integration of the fellows. All of them established deep and friendly relations with the young and less young people of the laboratory and after the end of their stage we had several visits from one side and the other, continuation of the interactions and of the scientific collaboration. Moreover the work performed by the fellow in the frame of their stage was particularly appreciated in their home laboratory and their acquired knowledge was largely exploited.