Crystal Structures and Magnetic Properties of Ln2 Complexes Based on a Polydentate Schiff Base Ligand

Xiao-Li GAO Wen-Ting LEI Qing-Fang ZHANG Yu ZHOU Xiao-Min KANG

Citation:  Xiao-Li GAO, Wen-Ting LEI, Qing-Fang ZHANG, Yu ZHOU, Xiao-Min KANG. Crystal Structures and Magnetic Properties of Ln2 Complexes Based on a Polydentate Schiff Base Ligand[J]. Chinese Journal of Inorganic Chemistry, 2022, 38(1): 145-152. doi: 10.11862/CJIC.2022.002 shu

多齿席夫碱配体构筑的Ln2配合物的晶体结构及磁性

    通讯作者: 康晓敏, kangxm2020@163.com
  • 基金项目:

    国家自然科学基金 21671124

摘要: 使用多齿席夫碱配体,通过溶剂热法,设计与合成了3例新的稀土配合物[Ln2(L)2(acac)2(CH3OH)2]·2CH3OH(Ln=Sm(1)、Gd(2)、Ho(3),H2L=吡啶-2-羧酸-(1-甲基-3-氧代丁烯基)-酰肼),并对配合物1~3的结构与磁性质进行了系统的研究。单晶结构测试结果表明配合物1~3为同构,每个中心稀土Ln(Ⅲ)离子为八配位,其配位几何构型为扭曲的四方反棱柱;相邻的中心稀土Ln(Ⅲ)离子通过2个μ2-O连接形成了平行四边形的[Ln2O2]核心。磁性测试揭示配合物2具有磁制冷性质,其最大磁熵变(-ΔSmax)为31.9 J·K-1·kg-1T=2.0 K,ΔH=70 kOe);配合物3表现出了慢磁驰豫行为。

English

  • In recent years, the study of lanthanide - based complexes has attracted increasing attention of chemists and material scientists not only due to their beautiful and fascinating crystal structures but also because of the potential applications in functional materials, including interesting magnetic properties, luminescence, gas adsorption, and catalysis[1-4]. Among these potential applications of lanthanide - based complexes, the molecular - based magnetic material is one of the research hotspots for inorganic chemistry and material chemists[5], and magnetic refrigeration and singlemolecule magnets (SMMs) are particularly attractive[6-9]. Key to the potential magnetic refrigeration application of molecular-based magnetic materials is its large magnetocaloric effect (MCE) [10], and an excellent magnetic refrigeration material featuring large MCE should possess negligible magnetic anisotropy and a large magnetic density[11]. Hence, the isotropic Gd(Ⅲ) ion with a high spin state (S=7/2) is the best candidate for designing and constructing Ln (Ⅲ) - based complexes, which would be a promising magnetic refrigerant material to perform significant MCE[12]. Based on this, lots of polynuclear or high-nuclear Gd(Ⅲ)-based clusters with fascinating structures and larger MCE have been reported over the past decade[13-16]. It is worth mentioning that Zheng and Long's group has conducted outstanding work on the magnetic refrigeration materials of Gd(Ⅲ)-based clusters[17-18]. These studies promote the design and synthesis of lanthanide - based complexes with outstanding and excellent magnetic properties. On the other hand, lanthanide - based SMMs have caused public attention in recent years[19], and designing lanthanide-based SMMs with large energy barriers (Ueff) and high blocking temperatures (TB) is a great challenge[20]. Given this, lots of Ln(Ⅲ)- based SMMs exhibiting significant magnetic behavior have appeared since the first Ln(Ⅲ)-based SMM (Bu4N)[Tb(Pc)2] reported by Ishikawa et al. in 2003[21].

    To seek and study the magnetic behaviors of lanthanide - based complexes, an attractive polydentate ligand H2L (Scheme 1) has been selected to construct lanthanide complexes, and three Ln2 complexes [Ln2(L)2(acac)2(CH3OH)2]·2CH3OH (Ln(Ⅲ) =Sm (1), Gd (2), and Ho (3), H2L=pyridine - 2 - carboxylic acid (1 - methyl-3-oxo-butylidene)-hydrazide, Hacac=acetylacetone) have been synthesized. The magnetic refrigeration and slow magnetic relaxation behavior of 1-3 have been studied.

    Scheme 1

    Scheme 1.  Structure of ligand H2L

    Solvents (methanol, dichloromethane) and starting chemical reagent (Ln(NO3)3·6H2O, Ln=Sm, Gd, and Ho) were purchased commercially and used without further purification. Acetylacetone and 2 - pyridine carboxylic acid hydrazide were purchased from Aladdin Reagent (Shanghai) Co., Ltd. Ln(acac)3·2H2O (Ln=Sm, Gd, and Ho) was prepared using a reported method[22]. The elemental analyses (C, H, and N) of complexes 1-3 were measured on a PerkinElmer 240 CHN elemental analyzer. Powder X-ray diffraction (PXRD) of complexes 1-3 were performed using an Ultima Ⅳ (Rigaku) with Cu radiation in a 2θ range from 5° to 50°. The operating voltage and current were 40 kV and 25 mA, respectively. Thermogravimetric analyses (TGA) of complexes 1-3 were performed on a TG 209 apparatus (Netzsch) under an air atmosphere. Magnetic properties for complexes 1-3 were measured using a Quantum Design MPMS-XL7 and a PPMS-9 ACMS magnetometer. Diamagnetic corrections were estimated with Pascal's constants for all atoms[23].

    2-Pyridine carboxylic acid hydrazide (0.04 mmol), Ln(acac)3·2H2O (0.04 mmol, Ln=Sm (1), Gd (2), and Ho (3)), methanol (8 mL), and dichloromethane (2.0 mL) were enclosed in a 15 mL glass vial, and then the mixture was stirred at room temperature for about 2.0 h. Whereafter, the mixture was heated to 70 ℃ and kept for 48 h, and then the temperature was decreased to room temperature slowly. Yellow block crystals suitable for X-ray diffraction were obtained.

    [Sm2(L)2(acac)2(CH3OH)2]·2CH3OH (1): Yield based on Sm(acac)3·2H2O: 36%. Elemental analysis Calcd. for C36H52N6O12Sm2(%): C 40.66, H 4.89, N 7.91; Found (%): C 40.64, H 5.03, N 8.00.

    [Gd2(L)2(acac)2(CH3OH)2]·2CH3OH (2): Yield based on Gd(acac)3·2H2O: 32%. Elemental analysis Calcd. for C36H52N6O12Gd2(%): C 40.10, H 5.01, N 7.80; Found (%): C 40.21, H 4.97, N 7.75.

    [Ho2(L)2(acac)2(CH3OH)2]·2CH3OH (3): Yield based on Ho(acac)3·2H2O: 41%. Elemental analysis Calcd. for C36H52N6O12Ho2(%): C 39.57, H 4.76, N 7.69; Found (%): C 39.62, H 4.89, N 7.72.

    The X -ray diffraction measurements for complexes 1-3 were performed on a Bruker SMART APEX Ⅱ CCD diffractometer equipped with a graphite monochromatized Mo radiation (λ =0.071 073 nm) by using φ-ω scan mode. Multiscan absorption correction was applied to the intensity data using the SADABS program. The structures were solved by direct methods and refined by full - matrix least - squares on F2 using the SHELXTL -2018 program. All non - hydrogen atoms were refined anisotropically. All the other H atoms were positioned geometrically and refined using a riding model. Details of the crystal data and structure refinement parameters for 1-3 are summarized in Table 1, and selected bond lengths and angles of 1-3 are listed in Table S1-S3 (Supporting information).

    CCDC: 2052182, 1; 2052183, 2; 2052184, 3.

    Table 1

    Table 1.  Crystal data and structure refinement parameters for complexes 1-3
    下载: 导出CSV
    Parameter 1 2 3
    Empirical formula C36H52N6O12Sm2 C36H52N6O12Gd2 C36H52N6O12Ho2
    Formula weight 1 062.46 1 075.25 1 091.62
    T / K 150(2) 293(2) 153(2)
    Crystal system Monoclinic Monoclinic Monoclinic
    Space group P21/c P21/c P21/c
    a / nm 0.773 0(5) 0.777 6(6) 0.765 59(3)
    b / nm 2.118 3(3) 2.131 2(6) 2.117 2(3)
    c / nm 2.579 3(7) 2.594 7(1) 2.574 5(7)
    β/(°) 93.961(2) 92.993 0(15) 93.437 5(15)
    V / nm3 4.213 8(5) 4.294 6(2) 4.165 7(3)
    Z 4 4 4
    Cryst size / mm 0.25 × 0.21 × 0.14 0.25 × 0.17 × 0.11 0.27 × 0.21 × 0.14
    Dc / (g·cm-3) 1.574 1.582 1.639
    μ / mm-1 2.816 18.867 3.828
    Limiting indices -9 ≤ h ≤ 9, -8 ≤ h ≤ 9, -9 ≤ h ≤ 9,
    -26 ≤ k ≤ 26, -18 ≤ k ≤ 26, -26 ≤ k ≤ 26,
    Reflection collected -32 ≤ l ≤ 31 -27 ≤ l ≤ 32 -32 ≤ l ≤ 32
    67 691 17 142 52 003
    Unique 8 647 8 364 8 552
    Parameter 485 485 485
    Rint 0.091 5 0.042 2 0.066 8
    GOF on F2 1.006 1.084 1.085
    R1, wR2 [I > 2σ(I)] 0.045 2, 0.100 2 0.068 6, 0.182 5 0.042 7, 0.095 1
    R1, wR2 (all data) 0.073 6, 0.113 7 0.071 3, 0.184 5 0.060 2, 0.101 7

    Single - crystal X - ray diffraction analyses reveal that 1-3 are isostructural and crystallize in the monoclinic space group P21/c (Table 1). Hereon, we selected the structure of 2 as a representative for describing. As shown in Fig. 1, the structure of 2 comprises two Gd(Ⅲ) ions, two L2-, two acac-, and two coordinated CH3OH. Each central Gd(Ⅲ) ion is coordinated by six oxygen atoms and two nitrogen atoms formed a [N2O 6] coordination environment. As shown in Fig. S1, the Gd1 ion is coordinated by two nitrogen atoms (N3 and N4) and six oxygen atoms (O2, O3, O4, O7, O8, and O9) of two L2-, one CH3OH and one acac-. The eight-coordinated Gd1 ion possesses a square antiprism geometry which is confirmed by using SHAPE 2.0 software (Table 2). The coordination mode of L2- and acac- are shown in Fig. 2. The two central Gd(Ⅲ) ions are connected by two μ2-O atoms forming a parallelogram [Gd2 O2] core. In the [Gd2O2] core, the Gd1…Gd2 distance is 0.392 8(8) nm, O2—Gd1—O4 bond angle is 62.201 1(9)°, and the Gd1—O2 —Gd2 bond angle is 113.809 2(3)°. Furthermore, the bond distances of Gd—O in complex 2 are in a range of 0.225 0(6)-0.244 5(6) nm, and the Gd1—N3, Gd1—N4, Gd2—N1, and Gd2—N6 bond lengths are 0.255 5(8), 0.243 8(7), 0.242 6(7), and 0.254 1(8) nm, respectively. The O—Gd—O bond angles are in a range of 66.18(19)°-147.9(2)°. These bond lengths and angles of 2 are compared to those of reported Gd2 complexes[24-27].

    Figure 1

    Figure 1.  Molecular structure of complex 2 shown with 30% probability displacement ellipsoids

    H atoms are omitted for clarity

    Table 2

    Table 2.  Gd(Ⅲ) geometry analysis by SHAPE 2.0 for complex 2
    下载: 导出CSV
    Gd(Ⅲ) ion D4d SAPR D2d TDD C2v JBTPR C2v BTPR D2d JSD
    Gd1 2.193 2.379 3.673 2.582 5.883
    Gd2 2.185 2.211 3.656 2.511 5.749
    SAPR-8=square antiprism; TDD -8=triangular dodecahedron; JBTPR - 8=biaugmented trigonal prism J50; BTPR -8=biaugmented trigonal prism; JSD-8=snub diphenoid J84; The number 8 represents eight-coordinated geometrical configuration.

    Figure 2

    Figure 2.  (a) Coordination mode of L2- in 2; (b) Coordination mode of acac- in 2

    H atoms of C—H bonds are omitted for clarity

    To prove the phase purities of complexes 1-3, the crystalline products of these complexes were measured by PXRD. As shown in Fig. S2, the PXRD patterns of the crystalline samples of 1-3 were in good agreement with their simulated ones, which proves the high phase purity.

    To investigate the thermal stabilities of complexes 1-3, TGA was performed under an air atmosphere. As shown in Fig.S3, the TG curves of 1-3 showed a similar variation trend. Hereon, we selected the TG curve of complex 1 for a detailed description. The weight loss of 6.31% (Calcd. 6.02%) between 40 and 294 ℃ can be attributed to the loss of two free CH3OH. After that, complex 1 decomposed gradually.

    The magnetic susceptibility data for the Ln2 complexes (1-3) were measured with the polycrystalline samples during a temperature range of 2.0 to 300.0 K and under an external magnetic field of 1.0 kOe. The χΜT vs T plots for complexes 1-3 are shown in Fig. 3. At 300.0 K, the χΜT values of 1-3 were 2.40, 15.73, and 28. 20 cm3·mol-1·K, respectively. The expected values for two free Ln(Ⅲ) ions are shown as follows: two isolated Sm ions (6H5/2, g=2/7) gave 0.95 cm3·mol-1·K for 1; two isolated Gd(Ⅲ) ions (8S7/2, g=2) gave 15.76 cm3·mol-1·K for 2; two isolated Ho(Ⅲ) ions (5I8, g=4/5) gave 28.14 cm3·mol-1·K for 3. For 1, as the temperature decreased, the χΜT value slowly declined and reached the minor value of 0.26 cm3·mol-1·K at 2.0 K. For 2, during the temperature range of 20.0-300.0 K, the χΜT value almos remained constant; whereafter, the χΜT value dropped to a minimum of 10.83 cm3·mol-1·K at 2.0 K. The downtrend suggests that there is an antiferromagnetic interaction between adjacent Gd(Ⅲ) ions in complex 2[28]. For 3, the χΜT value decreased slowly from 300 to 50 K, then it decreased quickly to reach the minimum of 7.01 cm3·mol-1·K at 2.0 K. This behavior may be attributed to the thermal depopulation of the Ho(Ⅲ) Stark sublevels or/and the antiferromagnetic interactions between the adjacent Ho(Ⅲ) ions in complex 3[29].

    Figure 3

    Figure 3.  Temperature dependence of χMT at 1.0 kOe for 1-3

    Red solid line stands for the best fitting of complex 2 by using Eq.1

    The Curie - Weiss law was used for fitting the magnetic susceptibility of 2 (Fig.S4). Two parameters C (15.83 cm3·mol-1·K) and θ (-0.73 K) were obtained (R =0.999 78). The small and negative θ value of 2 further suggests that there is an antiferromagnetic interaction between adjacent Gd(Ⅲ) ions in 2[30]. For further exploring the magnetic interaction between the adjacent Gd(Ⅲ) ions in complex 2, we fitted the χMT vs T curve of 2 by using the Hamiltonian: ${\hat H_{{\rm{G}}{{\rm{d}}_2}}} = - J({\hat S_{{\rm{G}}{{\rm{d}}_1}}}{\hat S_{{\rm{G}}{{\rm{d}}_2}}}) - g{\mu _{\rm{B}}}\hat H({\hat S_{{\rm{G}}{{\rm{d}}_1}}} + {\hat S_{{\rm{G}}{{\rm{d}}_2}}})\;({\bf{1}})$[31], and the two significant parameters, J=-0.06 cm-1 and g=2.05, were obtained. The negative J value further proves that there is an antiferromagnetic coupling between the neighboring Gd(Ⅲ) ions in 2.

    The magnetization data for complex 2 were studied at 2.0 - 10.0 K in a 0-70 kOe field. As depicted in Fig. 4, the magnetization M for complex 2 rapidly increased blow 20 kOe and then steadily increased to 14.02 at 70 kOe, which is very close to the saturation value of 14 for two free Gd(Ⅲ) (S=7/2, g=2) ions.

    Figure 4

    Figure 4.  Plots of M vs H at 2.0-10.0 K for 2

    According to the previous literature[32-34], due to the presence of the isotropic Gd(Ⅲ) ion with a high -spin ground state, hereon, the magnetocaloric effect of complex 2 was investigated. The maximum magnetic entropy change (- ΔSmax) could be calculated by using the Maxwell equation: $\Delta {S_{\max }}(T){\rm{ }} = \int {{{[\partial M(T, H)/\partial T]}_H}{\rm{d}}H} $[35]. As shown in Fig. 5, at ΔH=70 kOe and T=2.0 K, the observed -ΔSmax was 31.9 J·K-1·kg-1, which was smaller than the theoretical value of 34.2 J·K-1·kg-1 based on the equation: ΔSmax=2Rln(2S+1) (SGd=7/2 and R= 8.314 J·mol-1·K-1). The difference between experimental and theoretical magnetic entropy change (- ΔSmax) may be due to the weak antiferromagnetic interactions between Gd(Ⅲ) ions in complex 2[36]. It is worth mentioning that the -ΔSmax of complex 2 was larger than those of mostly reported Gd2 complexes[37-39]. With the larger - ΔSmax value, complex 2 may be a good candidate for potential application in magnetocaloric materials.

    Figure 5

    Figure 5.  Plots of -ΔSmax vs T for 2

    Figure 6

    Figure 6.  Temperature dependence of in-phase (χ') and out-of-phase (χ″) components of ac magnetic susceptibility for 3 in 0 Oe field with an oscillation of 3.0 Oe

    In order to study the dynamic magnetic behavior of complex 3, the alternating current (ac) magnetic susceptibility measurements were performed during a temperature range of 2.0-15.0 K at various frequencies. Clear frequency dependence of out - of - phase (χ″) signals was observed which suggests that slow magnetic relaxation occurred in 3[40]. However, no χ″ peaks were observed until T=2.0 K, and χ″ values gradually increased in the lower temperature region, which can be ascribed to the quantum tunneling effect (QTE) [41]. This phenomenon commonly occurred in most Ln(Ⅲ) - based complexes[42].

    To check the quantum tunneling of magnetization (QTM) effect above 2.0 K in complex 3, under Hdc=2 500 Oe, the variable - temperature ac susceptibilities were determined. As shown in Fig. S5, remarkable and peak shapes were observed, which show that the QTE in complex 3 was pronounced, and the QTM effect was basically suppressed when it was under an external 2 500 Oe dc field. The ln τ vs T-1 plot is shown in Fig. 7. The relaxation time τ obeys the Arrhenius law: τ = τ0exp[ΔE/(kBT)]. Two key parameters, energy barrier ΔE/kB=17.99 K and pre - exponential factor τ0=9.55× 10-7 s, were obtained. The τ0 of complex 3 was consistent with the reported values of 10-6 -10-12 s for Ln(Ⅲ) - based SMMs[43-44].

    Figure 7

    Figure 7.  ln τ vs T-1 plot for complex 3

    Red solid lines represent the best fit of the experimental data to the Arrhenius law

    In summary, we have synthesized three new Ln2 complexes [Ln2(L)2(acac)2(CH3OH)2]·2CH3OH (Ln=Sm (1), Gd (2), Ho (3)). Complexes 1-3 are all isostructural and contain a parallelogram [Ln2O2] core. Magnetic measurements imply that Gd2 complex 2 displayed significant magnetic refrigeration property with a larger - ΔSmax of 31.9 J·K-1·kg-1H=70 kOe and T=2.0 K); while Ho2 complex 3 shows slow magnetic relaxation behavior.


    Supporting information is available at http://www.wjhxxb.cn
    1. [1]

      Liu J L, Chen Y C, Tong M L. Symmetry Strategies for High Performance Lanthanide-Based Single-Molecule Magnets[J]. Chem. Soc. Rev., 2018, 47:  2431-2453. doi: 10.1039/C7CS00266A

    2. [2]

      郑欢, 焦媛, 冯思思. 基于3, 4', 5-联苯三羧酸构筑的钕配合物的合成、结构、荧光、光催化及磁性质[J]. 无机化学学报, 2021,37,(9): 1691-1699. ZHENG H, JIAO Y, FENG S S. Synthesis, Structure, Luminescence, Photocatalytic and Magnetic Properties of a Neodymium Complex Constructed from Biphenyl-3, 4', 5-tricarboxylic Acid[J]. Chinese J. Inorg. Chem., 2021, 37(9):  1691-1699.

    3. [3]

      Mahata P, Mondal S K, Singha D K, Majee P. Luminescent Rare-Earth -Based MOFs as Optical Sensors[J]. Dalton Trans., 2017, 46:  301-328. doi: 10.1039/C6DT03419E

    4. [4]

      Li Y Z, Wang H H, Wang G D, Hou L, Wang Y Y, Zhu Z H. A Dy6-Cluster - Based fcu - MOF with Efficient Separation of C2H2/C2H4 and Selective Adsorption of Benzene[J]. Inorg. Chem. Front., 2021, 8:  376-382. doi: 10.1039/D0QI01182G

    5. [5]

      Zhou N, Ma Y, Wang C, Xu G F, Tang J K, Xu J X, Yan S P, Cheng P, Li L C, Liao D Z. A Monometallic Tri-spin Single-Molecule Magnet Based on Rare Earth Radicals[J]. Dalton Trans., 2009, 38:  8489-8492.

    6. [6]

      Bar A K, Kalita P, Singh M K, Rajaraman G, Chandrasekhar V. LowCoordinate Mononuclear Lanthanide Complexes as Molecular Nanomagnets[J]. Coord. Chem. Rev., 2018, 367:  163-216. doi: 10.1016/j.ccr.2018.03.022

    7. [7]

      Guo Y N, Xu G F, Guo Y, Tang J K. Relaxation Dynamics of Dysprosium(Ⅲ) Single Molecule Magnets[J]. Dalton Trans., 2011, 40:  9953-9963. doi: 10.1039/c1dt10474h

    8. [8]

      Zheng Y Z, Zhou G J, Zheng Z P, Winpenny R E P. Molecule-Based Magnetic Coolers[J]. Chem. Soc. Rev., 2014, 43:  1462-1475. doi: 10.1039/C3CS60337G

    9. [9]

      Dong J, Cui P, Shi P F, Cheng P, Zhao B. Ultrastrong Alkali-Resisting Lanthanide - Zeolites Assembled by [Ln60] Nanocages[J]. J. Am. Chem., Soc., 2015, 137:  15988-15991. doi: 10.1021/jacs.5b10000

    10. [10]

      Chen Y C, Prokleška J, Xu W J, Liu J L, Liu J, Zhang W X, Jia J H, Sechovský V, Tong M L. A Brilliant Cryogenic Magnetic Coolant: Magnetic and Magnetocaloric Study of the Ferromagnetically Coupled GdF3[J]. J. Mater. Chem. C, 2015, 3:  12206-12211. doi: 10.1039/C5TC02352A

    11. [11]

      Chen Y C, Qin L, Meng Z S, Meng Z S, Yang D F, Wu C, Fu Z D, Zheng Y Z, Liu J L, Tarasenko R, Orendac M, Sechovsky V, Tong M L. Study of a Magnetic - Cooling Material Gd(OH)CO3[J]. J. Mater. Chem. A, 2014, 2:  9851-9858. doi: 10.1039/C4TA01646G

    12. [12]

      Zhang Z M, Zangana K H, Kostopoulos A K, Tong M L, Winpenny R E P. A Pseudo-icosahedral Cage {Gd12} Based on Aminomethylphosphonate[J]. Dalton Trans., 2016, 45:  9041-9044. doi: 10.1039/C6DT00876C

    13. [13]

      Wang W M, He L Y, Wang X X, Shi Y, Wu Z L, Cui J Z. LinearShaped Ln4 and Ln6 Clusters Constructed by a Polydentate SchiffBase Ligand and a β-Diketone Co-ligand: Structures, Fluorescence Properties, Magnetic Refrigeration and Single - Molecule Magnet Behavior[J]. Dalton Trans., 2019, 48:  16744-16755. doi: 10.1039/C9DT03478A

    14. [14]

      Wang W M, Yue R X, Gao Y, Wang M J, Hao S S, Shi Y, Kang X M, Wu Z L. Large Magnetocaloric Effect and Remarkable Single-Molecule - Magnet Behavior in Triangle - Assembled Ln6 Clusters[J]. New J. Chem., 2019, 43:  16639-16646. doi: 10.1039/C9NJ03921J

    15. [15]

      Zheng X Y, Peng J B, Kong X J, Long L S, Zheng L S. Mixed-Anion Templated Cage - like Lanthanide Clusters: Gd27 and Dy27[J]. Inorg. Chem. Front., 2016, 3:  320-325. doi: 10.1039/C5QI00249D

    16. [16]

      Wang K, Chen Z L, Zou H H, Zhang S H, Li Y, Zhang X Q, Sun W Y, Liang F P. Diacylhydrazone Assembled {Ln11} Nanoclusters Featuring a "Double - Boats Conformation" Topology: Synthesis, Structures and Magnetism[J]. Dalton Trans., 2018, 47:  2337-2343. doi: 10.1039/C7DT03179C

    17. [17]

      Chen W P, Liao P Q, Jin P B, Zhang L, Ling B K, Wang S C, Chan Y T, Chen X M, Zheng Y Z. The Gigantic {NiGd} Hexagon: A Sulfate-Templated "Star - of - David" for Photocatalytic CO Reduction and Magnetic Cooling[J]. J. Am. Chem. Soc., 2020, 142:  4663-4670. doi: 10.1021/jacs.9b11543

    18. [18]

      Peng J B, Kong X J, Zhang Q C, Orendac M, Prokleska J, Ren Y P, Long L S, Zheng Z P, Zheng L S. Beauty, Symmetry, and Magnetocaloric Effect - Four - Shell Keplerates with 104 Lanthanide Atoms[J]. J. Am. Chem. Soc., 2014, 136:  17938-17941. doi: 10.1021/ja5107749

    19. [19]

      Yin D D, Chen Q, Meng Y S, Sun H L, Zhang Y Q, Gao S. Slow Magnetic Relaxation in A Novel Carboxylate/Oxalate/Hydroxyl Bridged Dysprosium Layer[J]. Chem. Sci., 2015, 6:  3095-3101. doi: 10.1039/C5SC00491H

    20. [20]

      Sun W B, Yan P F, Jiang S D, Wang B W, Zhang Y Q, Li H P, Chen P, Wang Z M, Gao S. High Symmetry or Low Symmetry, That is the Question-High Performance Dy(Ⅲ) Single-Ion Magnets by Electrostatic Potential Design[J]. Chem. Sci., 2016, 7:  684-691. doi: 10.1039/C5SC02986D

    21. [21]

      Ishikawa N, Sugita M, Ishikawa T, Koshihara S Y, Kaizu Y. Lanthanide Double-Decker Complexes Functioning as Magnets at the Single -Molecular Level[J]. J. Am. Chem. Soc., 2003, 125:  8694-8695. doi: 10.1021/ja029629n

    22. [22]

      Katagiri S, Tsukahara Y, Hasegawa Y, Wada Y. Energy - Transfer Mechanism in Photoluminescent Terbium (Ⅲ) Complexes Causing Their Temperature - Dependence[J]. Bull. Chem. Soc. Jpn., 2007, 80:  1492-1503. doi: 10.1246/bcsj.80.1492

    23. [23]

      Boudreaux E A, Mulay L N. Theory and Applications of Molecular Paramagnetism. New York: Wiley-Interscience, 1976.

    24. [24]

      Wang W M, Duan W W, Yue L C, Wang Y L, Ji W Y, Zhang C F, Fang M, Wu Z L. Magnetic Refrigeration and Single-Molecule Magnet Behaviour of Two Lanthanide Dinuclear Complexes (Ln=Gd, Tb) Based on 8 - Hydroxyquinolin Derivatives[J]. Inorg. Chim. Acta, 2017, 466:  145-150. doi: 10.1016/j.ica.2017.05.059

    25. [25]

      Zhang H T, Ma L, Han M R, Feng S S, Zhu M L. A One-Dimensional Chiral Gadolinium Complex Based on a Tartaric Acid Derivative: Crystal Structure, Thermal Behavior and Magnetic Properties[J]. Inorg. Nano-Met. Chem., 2021, 51(6):  761-765. doi: 10.1080/24701556.2020.1862211

    26. [26]

      靳平宁, 闫瑞芳, 胡鹏, 吴燕妮, 高媛媛, 黄玲珠, 朱怡璇, 苏妍, 汪应灵. 基于席夫碱配体的Gd(Ⅲ)/Dy(Ⅲ)配合物的结构和磁性[J]. 无机化学学报, 2018,34,(5): 951-956. JIN P N, YAN R F, HU P, WU Y N, GAO Y Y, HUANG L Z, ZHU Y X, SU Y, WANG Y L. Dinuclear Gd(Ⅲ)/Dy(Ⅲ) Complexes Based on Schiff base Ligands: Structures and Magnetic Properties[J]. Chinese J. Inorg. Chem., 2018, 34(5):  951-956.

    27. [27]

      Wang W M, Wang Q, Bai L, Qiao H, Zhao X Y, Xu M, Liu S Y, Shi Y, Fang M, Wu Z L. Lanthanide - Directed Fabrication of Fhree Phenoxo-O Bridged Dinuclear Complexes Showing Magnetic Refrigeration and Single - Molecule Magnet Behaviour[J]. Polyhedron, 2018, 142:  43-48. doi: 10.1016/j.poly.2017.12.017

    28. [28]

      Niu H J, Wang L H, Yang G E, Wang X X. Structures and Magnetic Refrigeration Properties of Three Gd2 Complexes[J]. Inorg. Chim. Acta, 2019, 489:  155-159. doi: 10.1016/j.ica.2019.02.018

    29. [29]

      Han M R, Zhang H T, Wang J N, Feng S S, Lu L P. Three Chiral One - Dimensional Lanthanide - Ditoluoyl - Tartrate Bifunctional Polymers Exhibiting Luminescence and Magnetic Behaviors[J]. RSC Adv., 2019, 9:  32288-32295. doi: 10.1039/C9RA06920H

    30. [30]

      Wang W M, Zhang H X, Wang S Y, Shen H Y, Gao H L, Cui J Z, Zhao B. Ligand Field Affected Single-Molecule Magnet Behavior of Lanthanide (Ⅲ) Dinuclear Complexes with an 8 - Hydroxyquinoline Schiff Base Derivative as Bridging Ligand[J]. Inorg. Chem., 2015, 54:  10610-10622. doi: 10.1021/acs.inorgchem.5b01404

    31. [31]

      Yu Z P, Liu J, Feng X, Zhou K, Wang W M, Shi Y. Structures and Magnetic Properties of Two Series of Phenoxo-O Bridged Ln2 Complexes: Two Gd2 Complexes Displaying Magnetic Refrigeration Properties[J]. Inorg. Chim. Acta, 2018, 469:  105-110. doi: 10.1016/j.ica.2017.09.008

    32. [32]

      Xu C Y, Wu Z L, Fan C J, Yan L L, Wang W M, Ji B M. Synthesis of Two Lanthanide Clusters Ln4 (Gd4 and Dy4) with [2×2] Square Grid Shape: Magnetocaloric Effect and Slow Magnetic Relaxation Behaviors[J]. J. Rare Earths, 2021, 39:  1082-1088. doi: 10.1016/j.jre.2020.08.015

    33. [33]

      Wang K, Chen Z L, Zou H H, Hu K, Li H Y, Zhang Z, Sun W Y, Liang F P. A Single - Stranded {Gd18} Nanowheel with Symmetric Polydentate Diacylhydrazone Ligand[J]. Chem. Commun., 2016, 52:  8297-8300. doi: 10.1039/C6CC02208A

    34. [34]

      Wang W M, Xue C L, Jing R Y, Ma X, Yang L N, Luo S C, Wu Z L. Two Hexanuclear Lanthanide Ln6 Clusters Featuring Remarkable Magnetocaloric Effect and Slow Magnetic Relaxation Behavior[J]. New J. Chem., 2020, 44:  18025-18030. doi: 10.1039/D0NJ03442H

    35. [35]

      Cui C H, Ju W W, Luo X M, Lin Q F, Cao J P, Xu Y. A Series of Lanthanide Complexes Constructed from Ln8 Rings Exhibiting Large Magnetocaloric Effect and Interesting Luminescence[J]. Inorg. Chem., 2018, 57:  8608-8614. doi: 10.1021/acs.inorgchem.8b01370

    36. [36]

      Chang L X, Xiong G, Wang L, Cheng P, Zhao B. A 24-Gd Nanocapsule with a Large Magnetocaloric Effect[J]. Chem. Commun., 2013, 49:  1055-1057. doi: 10.1039/C2CC35800J

    37. [37]

      Guan X F, Shen J X, Hu X Y, Yang Y, Han X, Zhao J Q, Wang J, Shi Y, Wang W M. Synthesis, Structures and Magnetic Refrigeration Properties of Four Dinuclear Gadolinium Complexes[J]. Polyhedron, 2019, 166:  17-22. doi: 10.1016/j.poly.2019.03.022

    38. [38]

      Xia Q Y, Feng M Y, Ma D X, Shi S M, Xie Y C, Tian W, Shi H J, Wang Q L, Wang W M. Structures, Luminescent Properties and Magnetic Refrigeration of Two Series of Ln2 Complexes[J]. Polyhedron, 2019, 166:  141-145. doi: 10.1016/j.poly.2019.03.040

    39. [39]

      Wang S Y, Wang W M, Zhang H X, Shen H Y, Jiang L, Cui J Z, Gao H L. Seven Phenoxido - Bridged Complexes Encapsulated by 8-Hydroxyquinoline Schiff Base Derivatives and β -Diketone Ligands: Single-Molecule Magnet, Magnetic Refrigeration and Luminescence Properties[J]. Dalton Trans., 2016, 45:  3362-3371. doi: 10.1039/C5DT04391C

    40. [40]

      Wang W M, Kang X M, Shen H Y, Wu Z L, Gao H L, Cui J Z. Modulating Single-Molecule Magnet Behavior Towards Multiple Magnetic Relaxation Processes through Structural Variation in Dy4 Clusters[J]. Inorg. Chem. Front., 2018, 5:  1876-1885. doi: 10.1039/C8QI00214B

    41. [41]

      Wang W M, Gao Y, Yue R X, Qiao N, Wang D T, Shi Y, Zhang H, Cui J Z. Construction of a Family of Ln3 Clusters Using Multidentate Schiff Base and β-Diketonate Ligands: Fluorescent Properties, Magnetocaloric Effect and Slow Magnetic Relaxation[J]. New J. Chem., 2020, 44:  9230-9237. doi: 10.1039/D0NJ01172J

    42. [42]

      Han L J, Chen J, Zhang Z Q, Zhang H H, Kang T T, Wang W M, Mu S L, Shi Y. Synthesis, Structure and Slow Magnetic Relaxation of a Linear Ho 4 Cluster[J]. Inorg. Chem. Commun., 2018, 96:  52-55. doi: 10.1016/j.inoche.2018.08.005

    43. [43]

      Xu C Y, Qiao X Y, Tan Y, Liu S S, Hou W Y, Cui Y Y, Wu W L, Hua Y P, Wang W M. Modulating Single-Molecule Magnet Behaviors of Dy4 Clusters through Utilizing Two Different β- Diketonate Coligands[J]. Polyhedron, 2019, 160:  272-278. doi: 10.1016/j.poly.2018.12.046

    44. [44]

      Tian H Q, Huang F P, Li Y F, Chen P Q, Chai K Y, Lu J, Liu H T, Zeng S Y, Li D C, Dou J M. Ring-Forming Transformation Associated with Hydrazone Changes of Hexadecanuclear Dysprosium Phosphonates[J]. Dalton Trans., 2021, 50:  1119-1125. doi: 10.1039/D0DT03536J

  • Scheme 1  Structure of ligand H2L

    Figure 1  Molecular structure of complex 2 shown with 30% probability displacement ellipsoids

    H atoms are omitted for clarity

    Figure 2  (a) Coordination mode of L2- in 2; (b) Coordination mode of acac- in 2

    H atoms of C—H bonds are omitted for clarity

    Figure 3  Temperature dependence of χMT at 1.0 kOe for 1-3

    Red solid line stands for the best fitting of complex 2 by using Eq.1

    Figure 4  Plots of M vs H at 2.0-10.0 K for 2

    Figure 5  Plots of -ΔSmax vs T for 2

    Figure 6  Temperature dependence of in-phase (χ') and out-of-phase (χ″) components of ac magnetic susceptibility for 3 in 0 Oe field with an oscillation of 3.0 Oe

    Figure 7  ln τ vs T-1 plot for complex 3

    Red solid lines represent the best fit of the experimental data to the Arrhenius law

    Table 1.  Crystal data and structure refinement parameters for complexes 1-3

    Parameter 1 2 3
    Empirical formula C36H52N6O12Sm2 C36H52N6O12Gd2 C36H52N6O12Ho2
    Formula weight 1 062.46 1 075.25 1 091.62
    T / K 150(2) 293(2) 153(2)
    Crystal system Monoclinic Monoclinic Monoclinic
    Space group P21/c P21/c P21/c
    a / nm 0.773 0(5) 0.777 6(6) 0.765 59(3)
    b / nm 2.118 3(3) 2.131 2(6) 2.117 2(3)
    c / nm 2.579 3(7) 2.594 7(1) 2.574 5(7)
    β/(°) 93.961(2) 92.993 0(15) 93.437 5(15)
    V / nm3 4.213 8(5) 4.294 6(2) 4.165 7(3)
    Z 4 4 4
    Cryst size / mm 0.25 × 0.21 × 0.14 0.25 × 0.17 × 0.11 0.27 × 0.21 × 0.14
    Dc / (g·cm-3) 1.574 1.582 1.639
    μ / mm-1 2.816 18.867 3.828
    Limiting indices -9 ≤ h ≤ 9, -8 ≤ h ≤ 9, -9 ≤ h ≤ 9,
    -26 ≤ k ≤ 26, -18 ≤ k ≤ 26, -26 ≤ k ≤ 26,
    Reflection collected -32 ≤ l ≤ 31 -27 ≤ l ≤ 32 -32 ≤ l ≤ 32
    67 691 17 142 52 003
    Unique 8 647 8 364 8 552
    Parameter 485 485 485
    Rint 0.091 5 0.042 2 0.066 8
    GOF on F2 1.006 1.084 1.085
    R1, wR2 [I > 2σ(I)] 0.045 2, 0.100 2 0.068 6, 0.182 5 0.042 7, 0.095 1
    R1, wR2 (all data) 0.073 6, 0.113 7 0.071 3, 0.184 5 0.060 2, 0.101 7
    下载: 导出CSV

    Table 2.  Gd(Ⅲ) geometry analysis by SHAPE 2.0 for complex 2

    Gd(Ⅲ) ion D4d SAPR D2d TDD C2v JBTPR C2v BTPR D2d JSD
    Gd1 2.193 2.379 3.673 2.582 5.883
    Gd2 2.185 2.211 3.656 2.511 5.749
    SAPR-8=square antiprism; TDD -8=triangular dodecahedron; JBTPR - 8=biaugmented trigonal prism J50; BTPR -8=biaugmented trigonal prism; JSD-8=snub diphenoid J84; The number 8 represents eight-coordinated geometrical configuration.
    下载: 导出CSV
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  • 发布日期:  2022-01-10
  • 收稿日期:  2021-06-04
  • 修回日期:  2021-10-23
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