A new family of 3d-4f polynuclear cocrystals [LnZn 2 L 2 (CH 3 CO 2 ) 4 ]•[Zn 2 Cl 4 L]•H 2 O [where Ln III = Gd(1), Tb(2), and Dy(3)] are synthesized by the sequential reaction of a tetradentate multisite coordinating compartmental ligand, i.e., (E)-2methoxy-6-(((pyridine-2-ylmethyl)imino)methyl)phenol, in the presence of LnCl 3 •6H 2 O and Zn(OAc) 2 •2H 2 O.The detailed studies involve mainly synthesis, structure, and magnetic properties of three isostructural cocrystals. The X-ray diffraction analysis reveals that complexes 1−3 crystallize in triclinic crystal system with the P1̅ space group. The dimeric [Zn 2 Cl 4 L] − complex appears as a cocrystal in the vicinity of the [LnZn 2 L 2 (CH 3 CO 2 ) 4 ] + crystal structure to counter balance the overall charge on the primary coordination sphere. Magnetic relaxation studies indicate that zero-field out-of-phase magnetic susceptibility signals are observed only for complex 3 (Dy III analogue) which gets well resolved in the presence of a H dc = 0.5 kOe magnetic field. The extracted effective energy barrier (U eff ) and pre-exponential factor (τ 0 ) for 3 is found to be 13.53 K and 1.78 × 10 −6 s, respectively. The appearance of single-ion magnet properties for 3 is rationalized with CASSCF/SO-RASSI/SINGLE_ANISO based ab initio calculations.

In this work, a tridentate N,N,O ligand [(E)-4-nitro-2-((pyridine-2ylmethylene)amino)phenol] (L NO2 H) is employed for the synthesis of neutral structurally similar complexes [Dy IIIBoth complexes are characterized by single-crystal X-ray diffraction studies. Ln III ion in complexes 1 and 2 is eight coordinated and possesses triangular dodecahedron geometry as confirmed by the SHAPE analysis. The Hirshfeld surface calculation emphasizes the importance of hydrogen bond interaction that controls the overall crystal packing. The magnetic studies reveal that complex 1 shows single ion magnet (SIM) behavior with an effective energy barrier of 34.16 K and pre-exponential parameter 6.51 × 10 −6 s. The CASSCF based ab initio calculations were performed on complexes 1 and 2 to extract SH parameters and the plausible magnetic relaxation dynamics.

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