Constructing 3d-4f Molecular Magnetic Materials With Bis-tris Propane Ligands

3d-4f clusters have attracted continuous attention due to their fascinating aesthetic structures and potential applications in molecular magnetic materials,especially in the field of single-molecule magnets and magnetothermal effects.Organic ligands play a crucial role in the construction of 3d-4f clusters,they not only bridge 3d and 4f metal ions into nuclei,but also act as peripheral ligands to separate discrete species from each other.N,O-containing polydentate organic ligands can coordinate with different metal ions,which can lead to unexpected topologies.Therefore,in this paper,Bis-tris propane,which contains abundant active sites,is used as the ligand to design and synthesize 3d-4f molecular magnetic materials by a simple method,and their magnetic properties are studied.（1）By using Bis-tris propane as the ligand,we synthesized four isostructures tetranuclear clusters Na[Co₃Ln（H₃L）₂（OAc）₂（NO₃）₂]Cl₂·4H₂O（Ln=La,Ce,Pr,Nd）in aqueous solution by one-pot method,and the compounds were characterized by Fourier Transform Infrared Spectrometer,Thermogravimetric Analysis and UV-Vis absorption spectroscopy.The Bond Valence Sum（BVS）calculations revealed the presence of two diamagnetic Co ^Ⅲions,one paramagnetic Co ^Ⅱion and one uncoupled Ce ^Ⅲion in the compound.Magnetic studies revealed the presence of mainly weak antiferromagnetic interactions in the compounds{Co₃Ce}and{Co₃Nd}.（2）By using Bis-tris propane as the ligand,the light lanthanide and heavy lanthanide nitrates were added into the reaction system in the same ratio（1:1）under the same synthesis conditions as{Co₃Ln}.Elemental analysis and Powder X-ray Diffraction analysis of the collected crystals demonstrated the successful synthesis of three mixed-lanthanide clusters with the composition of{Co₃Ce_0.58Gd_0.42},{Co₃Ce_0.65Dy_0.35}and{Co₃Ce_0.79Yb_0.21}.An array of magnetic measurements was used to reveal the magnetocaloric effect and single-molecule magnet behaviors of{Co₃Ce_0.58Gd_0.42}and{Co₃Ce_0.65Dy_0.35}clusters,respectively.Thus,the synthesis of mixed-lanthanide clusters shows that the limitation of ionic radius can be broken,opening a new way for the design of molecular magnetic materials.（3）By using Bis-tris propane and tetramethylammonium hydroxide as mixed ligands,light lanthanide and heavy lanthanide nitrates were added simultaneously added to methanol solution.The elemental analysis and X-ray powder diffraction analysis of the obtained crystals proved that hat the heavy lanthanide Gd ^Ⅲ/Dy ^Ⅲions were successfully introduced into the compound{Mn ₄^ⅢNd₄},and three mixed-lanthanide clusters with the composition of{Mn ₄^ⅢNd_3.1Gd_0.9},{Mn ₄^ⅢNd_2.4Gd_1.6}and{Mn ₄^ⅢNd_2.9Dy_1.1}were synthesized.The magnetic studies revealed that the compound{Mn ₄^ⅢNd _2.4^ⅢGd_1.6}exhibits magnetothermal effect,with a maximum value of 14.42 J Kg^-1K^-1at T=8 K and?H=7 T.Thus,the synthesis of the mixed-lanthanide cluster Mn-Ln-Gd/Dy shows once again that the effect of ionic radius can be broken,providing a feasible strategy for expanding the family of molecular magnetic materials.