Controlling molecular magnetic anisotropy via structural engineering is delicate and fascinating, especially for single-molecule magnets (SMMs). Herein a family of dysprosium single-ion magnets (SIMs) sitting in pentagonal bipyramid geometry have been synthesized with the variable-size terminal ligands and counter anions, through which the subtle coordination geometry of Dy(III) can be finely tuned based on the size effect. The effective energy barrier (U_eff) successfully increases from 439 to 632 K and the magnetic hysteresis temperature (under a 200 Oe/s sweep rate) raises from 11 to 24 K. Based on the crystal-field theory, a semi-quantitative magneto-structural correlation deduced experimentally for the first time is revealed that the U_eff is linearly proportional to the structural-related value S⁰₂ corresponding to the axial coordination bond lengths and the bond angles. Through the evaluation of the remanent magnetization from hysteresis, quantum tunneling of magnetization (QTM) is found to exhibit negative correlation with the structural-related value S_tun corresponding to the axial coordination bond angles.

通过结构工程控制分子磁各向异性是微妙而令人着迷的，尤其是对于单分子磁体（SMM）。本文合成了五角双锥体几何形状的py单离子磁体（SIM），它们具有可变大小的末端配体和抗衡阴离子，通过它们，可以根据尺寸精细地调节Dy（III）的微妙配位几何形状影响。有效能垒（U _eff）从439成功提高到632 K，磁滞温度（在200 Oe / s的扫描速率下）从11 K升高到24K。基于晶体场理论，半定量磁首次通过实验推导的结构相关性揭示了U _eff与结构相关值S ⁰ ₂成线性比例，该结构相关值S ⁰ ₂对应于轴向配位键长和键角。通过评估磁滞的剩余磁化强度，发现量子隧穿磁化强度（QTM）与对应于轴向配位键角的结构相关值S _tun呈现负相关。