Electronic supplementary information

Dinuclear Ln(III) complexes constructed by 8-hydroxyquinoline Schiff

base derivative with the different terminal groups feature different slow

magnetic relaxation

Yi-Xin Changa, Wen-Min Wanga, Ru-Xia Zhanga, Hai-Yun Shena, Xiao-Pu Zhoua, Ni-Ni Wanga, Jian-

Zhong Cuia,b and Hong-Ling Gaoa,b

Table S1 The important bond lengths (Å) and angles (°) for 1–10.

Complexes The range of Ln–O

bond lengths / Å

Average Ln–O bond

lengths / Å

The distance of

Ln---Ln / Å

The Ln–O–Ln

bond angles / °

1 2.3339(15)-2.4171(14) 2.3698(15) 3.8523(7) 108.35(5)

2 2.325(6)- 2.389(7) 2.355(6) 3.8473(16) 109.4(3)

3 2.3209(19)-2.376(2) 2.346(2) 3.8304(5) 109.26(8)

4 2.313(5)- 2.361(5) 2.336(5) 3.8091(15) 109.13(19)

5 2.336(2)- 2.421(2) 2.373(2) 3.8586(9) 108.40(8)

6 2.327(6)-2.402(6) 2.365(6) 3.8702(9) 108.8(2)

7 2.318(6)-2.387(7) 2.343(10) 3.8383(9) 108.5(3)

8 2.294(8)-2.370(9) 2.326(9) 3.8099(12) 108.8(3)

9 2.337(6)- 2.414(7) 2.369(7) 3.8811(18) 108.7(3)

10 2.287(4)-2.356(4) 2.314(7) 3.7946(6) 109.05(17)

Table S2. The continuous symmetry measurement value calculated by SHAPE 2.0 for complexes 3, 8.

a Department of Chemistry, Tianjin University, Tianjin, 300072, China.b State Key Laboratory of Medicinal Chemical Biology (NanKai University), Tianjin, 300071, China.*Corresponding author. E-mail: cuijianzhong@tju.edu.cn, ghl@tju.edu.cn.

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Electronic Supplementary Material (ESI) for New Journal of Chemistry.This journal is © The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2017

Dy3+ D4dSAPR D2dTDD C2vJBTPR C2vBTPR D2dJSD

Complex 3 2.929 0.973 3.199 2.265 3.675

Complex 8 1.902 1.771 2.798 1.737 4.391

Table S3. The important bond lengths (Å) and bond angles (°) for complexes 3, 8.

Dy–O(1) Dy–O(1a) Dy···Dy Dy–O–Dy

Complex 3 2.321(1) Å 2.376(1) Å 3.8303(5) Å 109.25(6)°

Complex 8 2.314(9) Å 2.369(1) Å 3.8095(1) Å 108.9(4)°

Powder X-ray diffraction (PXRD) and thermogravimetric analysis (TGA)

Fig.S1 PXRD patterns of complexes 1–5.

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Fig. S2 PXRD patterns of complexes 6−10

Fig. S3 TG curves of complexes 1−10.

UV-Vis Spectra and Photoluminescent Properties.

The UV-vis spectra of free ligand HL, HL′, Dy(tfa)3·2H2O and complexes 1−10 were

performed in methanol solutions of 10-5 mol L-1 in the wavelength range of 200−600 nm at

room temperature. As shown in Fig. S4 (ESI), the ligands display three broad bands at 205,

245, 273 nm for HL and 205, 243, 273 nm for HL′ in the UV region respectively. These

observed strong peaks may be attributed to n → π* and π → π* transition of the aromatic

rings. Dy(tfa)3·2H2O exhibits a strong characteristic absorption at 292 nm. The UV−vis

spectra of 1−5 (Fig. S4) display similar absorption profiles centered at 205 and 295 nm. The

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high-energy band at 205 nm results from the ligand L, and the absorption bands at 296 nm are

ascribed to the π → π* transition of tfa−. For 6−10 (Fig. S4), the absorption bands at 205 and

295 nm result from the ligand L′ and β-diketonate coligand, respectively. It is note that the

absorption band at 295nm in 1–10 have a slight red shift relative to that of the free ligand and

the absorption peak at 245 nm of the two ligands has disappeared when coordinated with LnIII

cations, which can be ascribed to the coordination effect between the ligand L− and LnIII

cations.

Fig. S4 UV-vis absorption spectra of the ligand HL, HL′, Dy(tfa)3·2H2O, 1–5(a) and 6–10(b) in MeOH solution at room temperature.

Considering the excellent luminescent properties of TbIII and DyIII, the photoluminescent

spectra of 2, 7, 3, and 8 were measured in a methanol solution at room temperature. The

emission spectra of compounds 2 and 7 exhibit characteristic bands of TbIII and a strong

luminescence upon excitation at 290 nm, designated as the 5D4 → 7FJ (J = 6, 5, 4, 3)

transitions.48 The first emission band of complex 2 and 7 at 491 nm can be assigned to the

transitions of 5D4 → 7F6, while the other bands at 545 and 620 nm can be attributed to the 5D4

→ 7F5 and 5D4→ 7F3 transitions, respectively . The peaks at 587 nm for 2 and 586 nm for 7

are assigned to the 5D4 → 7F4 transitions (Fig. S5). Among them, the 5D4 → 7F5 transition is

the strongest.49 The fluorescence spectra show the characteristic emission peaks of terbium

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ions.

The spectra of compounds 3 and 8 display the typical bands of DyIII and an intense

luminescence upon excitation at 290 nm with two main bands at 484, 577 nm and 482, 575

nm, respectively, ascribed to the 4F5/2 → 6H13/2 and 4F5/2 → 6H15/2 transitions (Fig. S5). The

fluorescence spectra present characteristic bands of the DyIII ion, indicating that the ligands

can transfer energy to DyIII effectively.

Fig. S5 The luminescence spectra of complexes 2, 3, 7 and 8 in methanol solution

Magnetic properties

Direct current (dc) magnetism

Fig. S6 Temperature dependence of the magnetic susceptibility in the form of χM

–1 vs T for

1(a) and 6(b).

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Fig. S7 Temperature dependence of the magnetic susceptibility in the form of χM –1 vs T for

2–5 (a) and 6–10 (b) at an applied field of 1000 Oe between 2 and 300 K. The solid

line was generated from the best fit by the Curie-Weiss expression.

Alternating current (ac) magnetism

The broad maximum in the 3-6 K range shows two underlying signals. In order to check

the phenomenon, the variable-temperature ac susceptibility at 2311Hz was measured with

application of dc fields ranging from 100 to 1500 Oe of 8. From Fig. S8, the well resolved

peak of 8 is observed around 6-8 K above 400Oe field, showing the typical shift in the peak

position resulted by the collective effect of quantum tunneling and direct process.

Fig. S8 The temperature dependency of the ac susceptibility was measured on powder samples 8 (a, b) in

the applied field from 100 to 1500 Oe at 2311 Hz.

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To better understanding the nature of two Dy2 clusters, the magnetization relaxation

time (τ) is derived from the χ″ peaks maxima of the frequency-dependent data, illustrating

that 3 and 8 has a relaxation process. As shown in Fig.S9, the plots of ln (τ) vs. T-1 reveal a

single dominant relaxation path (Orbach process) at high temperature, while other pathways

becoming competitive at low temperature.50 Therefore, the typical magnetic relaxation

pathways, namely QTM, direct, Raman, and Orbach processes are accounted for in equation

(5):

τ-1 =τQ-1 + ATm + CTn + τ0

-1exp( -Ueff/ kBT) (5)

Fig. S9 The ln (τ) versus T-1 plots for 3 (a) and 8 (b) under 0 Oe dc field; the red solid line is best

fitted with the eq 1.

The successful fitting (Fig. 7) was achieved using the sum of Orbach and direct processes

with the best-fit parameters as follows: for 3, A = 10750 s−1 K−1, the effective energy barrier

Ueff/kB = 34.48 K and the pre-exponential factor τ0 = 1.48×10-7 s; for 8 , A = 2700 s−1 K−1, the

effective energy barrier Ueff/kB = 35.04 K and the pre-exponential factor τ0 = 10-6 s, which lie

in the usual range of SMMs.

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Table 4. Parameters obtained from the ln (τ) vs. T-1 plots using the eq 1 for 3 and 8.

complex Ueff/ K τ0 /s τQTM /s A m C n

3 34.48 1.48×10-7 1.177×10-25 10750 8.4396 0 0.5663

8 35.04 10-6 0.01659 2700 2.1106 180.59 0

Fig. S10 Frequency dependence of the in-phase (χ′) and out-of-phase (χ″) ac susceptibility for

3 (a and b) and 8 (c and d) under zero dc field.

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