Hybrid Molecular Magnets with Lanthanide- and Countercation-Mediated Interfacial Electron Transfer between Phthalocyanine and Polyoxovanadate.

A series of {V 12 }-nuclearity polyoxovanadate cages covalently functionalized with one or sandwiched by two phthalocyaninato (Pc) lanthanide (Ln) moieties via V-O-Ln bonds were prepared and fully characterized for paramagnetic Ln = Sm III -Er III and diamagnetic Ln = Lu III , including Y III . The LnPc-functionalized {V 12 O 32 } cages with fully oxidized vanadium centers in the ground state were isolated as ( n Bu 4 N) 3 [HV 12 O 32 Cl(LnPc)] and ( n Bu 4 N) 2 [HV 12 O 32 Cl(LnPc) 2 ] compounds. As corroborated by a combined experimental (EPR, DC and AC SQUID, laser photolysis transient absorption spectroscopy, and electrochemistry) and computational (DFT, MD, and model Hamiltonian approach) methods, the compounds feature intra- and intermolecular electron transfer that is responsible for a partial reduction at V(3d) centers from V V to V IV in the solid state and at high sample concentrations. The effects are generally Ln dependent and are clearly demonstrated for the ( n Bu 4 N) 3 [HV 12 O 32 Cl(LnPc)] representative with Ln = Lu III or Dy III . Intramolecular charge transfer takes place for Ln = Lu III and occurs from a Pc ligand via the Ln center to the {V 12 O 32 } core of the same molecule, whereas for Ln = Dy III , only intermolecular charge transfer is allowed, which is realized from Pc in one molecule to the {V 12 O 32 } core of another molecule usually via the n Bu 4 N + countercation. For all Ln but Dy III , two of these phenomena may be present in different proportions. Besides, it is demonstrated that ( n Bu 4 N) 3 [HV 12 O 32 Cl(DyPc)] is a field-induced single molecule magnet with a maximal relaxation time of the order 10 -3 s. The obtained results open up the way to further exploration and fine-tuning of these three modular molecular nanocomposites regarding tailoring and control of their Ln-dependent charge-separated states (induced by intramolecular transfer) and relaxation dynamics as well as of electron hopping between molecules. This should enable us to realize ultra-sensitive polyoxometalate powered quasi-superconductors, sensors, and data storage/processing materials for quantum technologies and neuromorphic computing.