Tuning the magnetic properties of a new family of hybrid mixed metal oxalates having 1D magnetic chains and layers of J aggregates of [DAMS(+)] producing superior SHG

Hybrid mixed metal oxalates of general formula [M(2)(III)M(II)(C(2)O(4))(6)][DAMS](4)center dot 2DAMBA center dot 2H(2)O, where M(III) = Rh, Fe, Cr; M(II) = Mn, Zn; DAMBA = para-dimethylaminobenzaldehyde and [DAMS(+)] = trans-4-(4-dimethylaminostyryl)-1-methylpyridinium, belong to a new family of multifunctional materials displaying both very high second harmonic generation (SHG) efficiency and tunable magnetic properties. Here we report on the preparation and magnetic characterization of the new Ni(II) members of this family. Such new hybrid mixed metal oxalates are isostructural with the previously investigated containing Zn(II) and Mn(II), thus preserving the very high NLO efficiency but allowing further significant tuning of the magnetic properties. In particular the delocalization of Ni(II) magnetic orbitals along the inorganic "stripes" of the crystalline network produces strong next-nearest-neighbor magnetic interactions, otherwise absent in the chains of compounds containing the Mn(II) ions. Such interactions, when in the presence of magnetic M(III) ions such as Cr(III) or Fe(III), give rise to an interesting and complex magnetic behavior possibly due to an almost perfect compensation between nearest-neighbor and next-nearest-neighbor interactions along the chain.