Squaring the cube: a family of octametallic lanthanide complexes including a Dy8 single-molecule magnet

A series of isostructural octanuclear lanthanide complexes of general formula [Ln(8)(sao)(4)(mu(3)-OH)(4)( NO3)(12)(DMF)(12)] (Ln = Nd (1), Sm (2), Eu (3), Gd (4), Tb (5), Dy (6), Ho (7), Er (8); DMF = dimethylformamide) have been prepared via reactions of salicylaldoxime (saoH(2)), tetramethylammonium hydroxide (Me4NOH) with the appropriate lanthanide nitrate salt (Ln(NO3)(3)center dot 6H(2)O). The metallic skeletons of the complexes describe [Ln(4)] tetrahedra encapsulated inside a [Ln(4)] square with the inner core stabilised through mu(3)-OH-ions and the periphery by mu(4)-sao(2)-ligands. The magnetic properties of compounds 2-8 were investigated by dc and ac magnetometry. Temperature dependent ac magnetic susceptibility data reveal that the dysprosium analogue (6) displays an out-of-phase signal in the absence of an applied magnetic field indicative of slow relaxation of the magnetization typical of a Single-Molecule Magnet (SMM). Micro-SQUID measurements reveal temperature and sweep rate dependent hysteresis below 1.0 K.