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: [email protected], [email protected].
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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.
References
48 C. Tedeschi, J. Azema, H. Gornitzka, P. Tisnes, C. Picard, Dalton Trans., 2003, 1738.
49 (a) S. Swavey, R. Swavey, Coord. Chem. Rev. 2009, 253, 2627−2638; (b) Z. Ahmed, K.
Iftikhar, Inorg. Chim. Acta., 2012, 392, 165.
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50 (a) K. R. Meihaus, S. G. Minasian, W. W. Lukens, S. A. Kozimor, D. K. Shuh, T.
Tyliszczak and J. R. Long, J. Am. Chem. Soc., 2014, 136, 6056; (b) K. S. Pedersen, L. Ungur,
M. Sigrist, A. Sundt, S. M. Magnus, V. Vieru, H. Mutka, S. Rols, H. Weihe, O. Waldmann, L.
F. Chibotaru, J. Bendix and J. Dreiser, Chem. Sci., 2014, 5, 1650; (c) H. Yersin and J.
Strasser, Coord. Chem. Rev., 2000, 208, 331.
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