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  • Magnetic interactions between metal ions are


    Magnetic interactions between metal ions are usually described by superexchange via intermediate ligands. Although the general principles of the superexchange mechanism are essentially the same for d and f ions, calculations of exchange parameters for lanthanides are more difficult than for transition metal compounds because of the complicated electronic structure of the ions. As a consequence little is still known about specific mechanism of exchange interactions in actual lanthanide or actinide compounds. For the explanation of the possible mechanism for the magnetic coupling in Ce2(COT)3 a Fmoc-Gly-OPfp of the active space it is necessary, and in order to describe the correct physics of the system the coupling is assumed as the interaction of the two local pseudospin in the same ground state that (See ESI). The states of one magnetic center were generated using the diamagnetic substitution technique, where one of the two Ce3+ atoms was replaced by a La3+. The generated wavefunctions were then introduced to POLY-ANISO program which computes the anisotropic exchange interaction between both magnetic centers within the Lines model and on this basis computes all static magnetic properties and parameters of the pseudospin Hamiltonian of the polynuclear complex [38], [39]. Different active spaces were evaluated in an attempt to describe properly the superexchange coupling constant (J), the first reduction included only the f orbitals with and , named in this work and , two electrons in six orbitals CAS(2,6) were considered. Different combinations including the orbitals of the central ring were also taken into account, and finally the configuration, which seems to be the most important one for the superexchange was considered. To describe the influence of the orbitals a new active space including two electrons in four orbitals CAS(2,4) two and two was employed. The magnetic coupling J is evaluated as the singlet-triplet gap . In the last part the precision in calculated magnetic coupling constant was improved using more sophisticated correlation methods like DDCIn (n = 2, 3) using ORCA 4.0 program.
    Results and discussion
    Conclusion In this work the spin-Hamiltonian for Ce2COT3 molecule was developed and the most important magnetic properties derived from it were determined with a good correspondence with the experimental parameters. The quality of the results is the consequence of a good selection of the level of theory employed and a careful and detailed study about the influence of different active spaces selected on these properties. A qualitative model to explain the small value of ZFS was proposed in terms of the orbital contributions to the ground and excited states concluding that, because of the symmetry, the contribution of the SOC to the ZFS value is zero or almost zero and the value is only due to the direct dipole-dipole interaction. On the other hand a satisfactory relationship between the monomer [Ce(COT)2]− and the bimetallic molecule magnetic parameters was obtained which can be summarized in a good determination of the magnetic susceptibility and g-factors for an even number of electrons. Finally an alternative to polarization model mechanism for the magnetic exchange interaction was proposed which involve the 4 and 5 metal orbitals. This mechanism explains satisfactorily the origin of the antiferromagnetic coupling inCe2(COT)3based on the interaction through orbitals supported by DDCI3 calculation that reveals that the involved “ionic” states have an important contribution to the wavefunction of the ground and excited states of the molecule reinforcing our hypothesis. The calculations including the orbitals of the central ring were less clear for all the active spaces used.
    Introduction Anaplastic large-cell (ALCL) lymphomas represent the 2% of the non-Hodgkin lymphomas. These types of lymphomas, as well as the Hodgkin/Reed-Sternberg (H-RS) lymphoma cells [1] overexpress CD30, a member of the TNF receptor family [2]. CD30 has been implicated in cell survival and proliferation and is an attractive target for therapeutic intervention [3]. CD30 overexpression leads to its self aggregation and signals independently of the CD30 ligand [4]. Activated CD30 induces, via Erk1/2 activation, JunB expression [5]. Indeed, H-RS and ALCL lymphoma cells present constitutively active Erk1/2 and enhanced expression of JunB that mediate the proliferation of these cells [6], [7]. Besides, in an autoactivatory loop, JunB mediates the induction of CD30 expression [5].