Key Laboratory of Functional Inorganic Material Chemistry Ministry of Education, School of Chemistry and Material Science , Heilongjiang University , 74 Xuefu Road , Harbin 150080 , P. R. China.
Jiangsu Key Laboratory for NSLSCS, School of Physical Science and Technology , Nanjing Normal University , Nanjing 210023 , China.
Inorg Chem. 2018 Jul 16;57(14):8065-8077. doi: 10.1021/acs.inorgchem.8b00056. Epub 2018 Jul 2.
A series of Salen-type Zn(II)-Dy(III) complexes [LZn(II)ClDy(III)(acac)]·HO (1), [LZn(II)BrDy(III)(acac)]·HO (2), [LZn(II)(HO)Dy(III)(acac)]·CHCl·PF (3), [LZn(II)(HO)Dy(III)(acac)]·PF (4), and Co(III)-Dy(III) complexes [LCo(III)BrDy(III)(acac)]·CHCl (5), [LCo(III)ClDy(III)(acac)Cl(MeO)] (6), [LCo(III)ClDy(III)(acac)Cl(HO)] (7), and [LCo(III)ClDy(III)(NO)(MeO)] (8) heterobinuclear single-molecule magnets (SMMs) were synthesized and magnetically characterized. These complexes were constructed by incorporating diamagnetic Zn(II) and Co(III) ions with acetylacetone (acac) and compartmental Schiff-base ligands (HL = N, N'-bis(2-oxy-3-methoxybenzylidene)-1,2-phenylenediamine; HL = N, N'-bis(2-oxy-3-methoxybenzylidene)-1,2-diaminocyclohexane). In the Zn(II)-Dy(III) (1-4) system, the coordination environments of the Dy(III) ions are nearly identical, but the apical coordination atom to the Zn(II) ion is different. Complexes 1, 2, and 4 displayed no magnetic relaxation in the absence of external magnetic field, but complex 3 displayed more pronounced SMM behavior with a relaxation energy barrier U/ k 38 K and magnetic hysteresis at 1.8 K. The SMM performances of 5, 6, and 7 were enhanced significantly by incorporating an octahedral Co(III) instead of square-pyramidal Zn(II) and replacing one of acac group around Dy(III) ion by a neutral O atom, displaying U of 167, 118, and 75 K as well as magnetic hysteresis up to 3.5 K. These studies indicated that the remote diamagnetic Zn(II) and Co(III) ions played a key role, and the SMM properties were very strongly related to the special coordination atoms configuration around Dy(III) ion. When this coordination configuration around was broken as 8 exhibited, however, it resulted in a dramatically decreased SMM performance. From this work, the key factors that significantly affect the SMM performance of these heteronuclear Zn(II)/Co(III)-Dy(III) SMMs are unambiguously presented.
一系列 Salen 型 Zn(II)-Dy(III) 配合物 [LZn(II)ClDy(III)(acac)]·HO（1）、[LZn(II)BrDy(III)(acac)]·HO（2）、[LZn(II)(HO)Dy(III)(acac)]·CHCl·PF（3）、[LZn(II)(HO)Dy(III)(acac)]·PF（4）和 Co(III)-Dy(III) 配合物 [LCo(III)BrDy(III)(acac)]·CHCl（5）、[LCo(III)ClDy(III)(acac)Cl(MeO)]（6）、[LCo(III)ClDy(III)(acac)Cl(HO)]（7）和 [LCo(III)ClDy(III)(NO)(MeO)]（8）被合成并进行了磁性表征。这些配合物由具有乙酰丙酮（acac）和间隔席夫碱配体（HL= N，N'-双（2-氧-3-甲氧基苄叉基）-1,2-苯二胺；HL= N，N'-双（2-氧-3-甲氧基苄叉基）-1,2-二氨基环己烷）的顺磁性 Zn(II)和 Co(III)离子构建而成。在 Zn(II)-Dy(III)（1-4）体系中，Dy(III)离子的配位环境几乎相同，但与 Zn(II)离子配位的顶端配位原子不同。配合物 1、2 和 4 在没有外磁场的情况下没有磁弛豫，但配合物 3 表现出更明显的 SMM 行为，具有弛豫能量壁垒 U/ k 38 K 和在 1.8 K 时的磁滞。通过用八面体 Co(III)取代正方形锥 Zn(II)，并将 Dy(III)离子周围的一个 acac 基团替换为中性 O 原子，5、6 和 7 的 SMM 性能显著增强，分别具有 167、118 和 75 K 的 U 值以及高达 3.5 K 的磁滞。这些研究表明，远程顺磁 Zn(II)和 Co(III)离子起着关键作用，SMM 性质与 Dy(III)离子周围特殊的配位原子构型密切相关。然而，当这种配位构型如 8 所示被破坏时，它导致 SMM 性能显著降低。从这项工作中，明确提出了这些异核 Zn(II)/Co(III)-Dy(III) SMM 的 SMM 性能的关键影响因素。
