Discrete polynuclear manganese nanorods: syntheses, crystal structures and magnetic properties†
Shape-anisotropic nanomaterials with uniform lengths and widths have attracted much interest but few of them are involved in self-assembled manganese complexes. The combination of two redox-active acylthiosemicarbazide ligands with Mn3+ cations leads to two discrete polynuclear Mn nanorods, pentanuclear [Mn5(L3)6][Mn0.7(DMF)1.4(H2O)2.8] (1a) and trinuclear Mn3(L4)3·2DMF (2), whose L3 and L4 represent N-(5-(2-hydroxyphenyl)-1,3,4-oxadiazol-2-yl)benzamide and N-(5-(2-hydroxyphenyl)-1,3,4-oxadiazol-2-yl)-propionamide, respectively, which are in situ synthesized from their acylthiosemicarbazide derivatives in the presence of Mn3+ cations, while the latter are reduced into divalent ones in rod-like moieties. For each pentanuclear anion in 1a, the charge is balanced by a solvated trivalent manganese cation, which can be replaced by two tetramethylammonium cations to yield pure valence compound 1b. Moreover, the magnetic studies reveal all of them possess antiferromagnetic properties.