Syntheses, Structures, and Magnetic Properties of Novel [3×1 + 2×1] Pentanuclear Zinc(II)-Lanthanide(III) Cocrystal Complexes: Slow Magnetic Relaxation Behavior of the Dy(III) Analogue

Abstract

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.

Tetranuclear CoII4O4 Cubane Complex: Effective Catalyst Toward Electrochemical Water Oxidation

“…Some major difficulty in synthetic chemistry is creating a ligand that is suitable to bind with multiple metal ions through their coordination sites to create a polynuclear entity . To meet this challenge, researchers have employed polydentate Schiff base ligands. , These ligands possess multiple coordination sites and flexible coordination arms, which allow them to coordinate with different metal ions. , Additionally, their oxygen donors can form short bridges between metal ions, providing a suitable structure for diverse topologies in polynuclear clusters. , …”

“…97,98 These ligands possess multiple coordination sites and flexible coordination arms, which allow them to coordinate with different metal ions. 99,100 Additionally, their oxygen donors can form short bridges between metal ions, providing a suitable structure for diverse topologies in polynuclear clusters. 101,102 Most of these molecules contain water-insoluble ligands, which typically makes them suitable for heterogeneous electrocatalysis since they can adsorb on the electrode surface for catalysis in aqueous media.…”

Effect of diamagnetic Zn(ii) ions on the SMM properties of a series of trinuclear ZnDy2 and tetranuclear Zn2Dy2 (LnIII = Dy, Tb, Gd) complexes: combined experimental and theoretical studies

“…To our understanding, the strategic manipulation of the electronic density distribution within specific directions of Dy III coordination geometries—specifically, enhancing or reducing axial/equatorial charge distributions around Dy III —is a pivotal challenge for advancing the SMM properties of Zn−Dy complexes. Additionally, while numerous Zn−Dy SMMs have been documented, only a select few demonstrate remarkable SMM behavior, characterized by an energy barrier surpassing 200 K. 56–59 Moreover, with an increase in the number of Dy III and/or Zn II within Zn−Dy complexes, there is a noticeable decline in U eff values. 58 In addition to the challenges associated with the deliberate adjustment of the electronic density distribution surrounding Dy III , we believe that the presence of weak magnetic couplings among Dy III ions within Zn−Dy complexes contributes to diminished SMM performance.…”