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Cite This: Inorg. Chem. XXXX, XXX, XXX−XXX

A Series of Lanthanide Compounds Constructed from Ln8 Rings Exhibiting Large Magnetocaloric Effect and Interesting Luminescence Chenhui Cui,† WeiWei Ju,† XiMing Luo,† QingFang Lin,† JiaPeng Cao,† and Yan Xu*,†,‡ †

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College of Chemical Engineering, State Key Laboratory of Materials-Oriented Chemical Engineering, Nanjing Tech University, Nanjing 210009, P. R. China ‡ Coordination Chemistry Institute, State Key Laboratory of Coordination Chemistry, Nanjing University, Nanjing 210093, P. R. China S Supporting Information *

ABSTRACT: A series of lanthanide compounds, [Ln8(CH2OHCH2OH)8(SO4)12]·m(C2H7N)·nH2O (Ln = Gd (1), Sm (2), Tb (3), La (5), m = 2, n = 2; Ln = Eu (4), m = 0, n = 8), which contain Ln8 rings by sulfate and glycol as the ligand have been synthesized and characterized. Besides, small organic amine and L-tartaric acid act as dual templating roles during the synthetic process. Magnetic investigation of compound 1 reveals the existence of weak antiferromagnetic interactions between GdIII ions and the data of magnetic entropy change (−ΔSm) is 36.86 J K−1 kg−1 (108.55 mJ cm−3 K−1) for ΔH = 7 T at 2.0 K, which is comparatively large among GdIII based compounds. Additionally, because of the excellent luminescence properties of SmIII, TbIII, and EuIII, compounds 2−4 were investigated.

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INTRODUCTION One of the excellent properties of magnetic materials, magnetic refrigeration, has provoked ever-growing attentions1−6 due to not just their energy-efficient and environmental friendly but also their economic benefits for the substitution of the increasingly infrequent isotope He-3 in ultra-low-temperature refrigeration.7,8 To the best of our knowledge, magnetic refrigeration happens due to the phenomenon called magnetocaloric effect (MCE), which can be described as the change of isothermal magnetic entropy (ΔSm) as well as adiabatic temperature (ΔTad) with the variation of applied magnetic field (ΔH).9 Since the discovery of MCE in 1881 by Warburg,10 who opened the door to magnetic cryogenic materials, many chemists have been focused on the research of obtaining large MCE. Our efforts dedicated to modest magnetic fields found that one of the factors favoring MCE is the choice of synthetic materials. As substantiated by the literature,11,12 GdIII ions can be a logical candidate to the majorization of MCE, deriving from its large spin ground state (S), quenched orbital momentum (D = 0), as well as weak superexchange interactions. Subsequently, the research on MCE among GdIII based compounds has been flourishing in recent years.13,14 Nevertheless, previous works that concentrate on 3D compounds of MCE are rarely investigated.15−17 As transmitting from the literature,18,19 the advantage of 3D compounds lies in that the neighboring metal ions share © XXXX American Chemical Society

bridging ligands, which will boost magnetic density to gain large MCEs. In addition, they possess higher thermal and/or solvent stabilities which can offer a solid foundation in future applications. In addition to this, the proper theoretical description of the MCE is complicated and far from being comprehensive.17 In summary, MCE of GdIII based 3D compounds is worth studying. Another profitable factor to enhance MCE is the choice of ligand. As transmitted from the literature,20,21 small size ligands, in other words, high magnetic density (low Mw/NGd, Mw = molecular weight, NGd = number of Gd3+ ions) compounds, are preferable for enhancing MCE. Inspired by the above-mentioned, some ligands like phosphates, carbonates, and sulfates with small size intrinsic nature rightly satisfy the above requests undoubtedly.18,22 According to the literature,18 tetradentate sulfate possessing varying binding modes could rapidly link to lanthanide ions. In addition, weak magnetic couplings and comparatively high density may lie in GdIII compounds which are linked by sulfate. Hence, using sulfate as the linker to achieve the aforementioned effect is tactful, which was early documented in a molecular magnetic cooler [Gd2(SO4)3·8H2O]23,24 unequivocally. Furthermore, glycol also has small size, which coincides the aforesaid requirements, and theoretically can act as the supporting Received: May 18, 2018

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DOI: 10.1021/acs.inorgchem.8b01370 Inorg. Chem. XXXX, XXX, XXX−XXX

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Inorganic Chemistry Table 1. Crystallographic Data and Structure Refinements for 1−5 formula formula weight cryst syst space group a (Å) b (Å) c (Å) volume (Å3) Z Dc (mg·cm−3) R(int) data/restraints/parameters goodness-of-fit on F2 R1 [I > 2σ(I)]a wR2 [I > 2σ(I)]a R1 (all data) wR2 (all data)

1

2

3

4

5

C20H66Gd8N2O66S12 3012.30 tetragonal I41/a 19.8907(12) 19.8907(12) 17.173(2) 6794.4(12) 4 2.945 0.0623 3155/39/262 1.114 0.0265 0.0748 0.0361 0.0786

C20H66Sm8N2O66S12 2957.10 tetragonal I41/a 19.9623(10) 19.9623(10) 17.2397(19) 6869.9(10) 4 2.859 0.0879 3185/39/262 1.026 0.0333 0.0791 0.0526 0.0843

C20H66Tb8N2O66S12 3025.66 tetragonal I41/a 19.8410(11) 19.8410(11) 17.1482(19) 6750.7(11) 4 2.977 0.0554 3135/39/262 1.082 0.0273 0.0734 0.0336 0.0761

C16H64Eu8O72S12 3001.00 tetragonal I41/a 19.9164(19) 19.9164(19) 17.178(3) 6813.8(2) 4 2.925 0.0531 3013/12/244 1.052 0.0255 0.0646 0.0311 0.0670

C20H66La8N2O66S12 2865.58 tetragonal I41/a 20.292(3) 20.292(3) 17.503(4) 7207(3) 4 2.641 0.0827 3365/39/262 0.935 0.0400 0.1170 0.0629 0.1314

R1 = ∑||Fo| − |Fc||/∑|Fo|; wR2 = ∑[w(Fo2 − Fc2)2]/∑[w(Fo2)2]1/2.

a

ligand. Specially, as epitomized in the recent literature,25 the incorporation of light inorganic ligands and proper organic ligands will eventually contribute to MCE, inspiring us to use glycol to serve as the auxiliary ligand. Considering that a host of trivalent lanthanide ions can often be utilized as luminescence centers for their characteristic emissions from the visible to near-infrared region, luminescence investigation of lanthanide compounds cannot be ignored. Moreover, they also have lifetime from the microto the millisecond range. 26,27 As a consequence, the luminescence behavior of lanthanide compounds is also worth studying. Herein, several lanthanide compounds with the formula [Ln8(CH2OHCH2OH)8(SO4)12]·m(C2H7N)· nH2O (Ln = Gd (1), Sm (2), Tb (3), La (5), m = 2, n = 2; Ln = Eu (4), m = 0, n = 8) which contain Ln8 rings were synthesized by the bridge of sulfate anion and glycol. As we anticipated, magnetic study shows that compound 1 exhibits a comparatively large MCE (−ΔSm = 36.86 J K−1 kg−1, 108.55 mJ cm−3 K−1). As known to us that lanthanide ions, especially SmIII, TbIII, and EuIII, show intense photoluminescence behavior,28,29 the luminescence properties of 2−4 were also investigated. To sum up, it is meaningful to devise novel lanthanide compounds so as to study their magnetism, optical, as well as understanding the formation mechanism.30,31

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concentrated HCl (37.5 wt %, 0.2790 g, 2.84 mmol), concentrated H2SO4 (98 wt %, 0.2583 g, 2.53 mmol), and ethylene glycol (10 mL) were vigorously stirred for 1 h at room temperature; then dimethylamine hydrochloride (33 wt %, 0.5578 g, 2.26 mmol) was instilled into the prepared mixture and agitated for an additional 10 min. Finally, the product was transferred to the 25 mL Teflon-lined stainless steel reaction kettle, then reacted at 140 °C for 6 days. Subsequently, after cooling to ambient temperature, filtering with ethyl alcohol, drying at environmental temperature for 24 h, colorless crystals were collected (0.1062 g, yield 30% based on Gd). The elemental analysis calcd (%): C 7.97; H 2.19; N 0.93. (Found) (%): C 8.01; H 2.21; N 0.95. In addition, the synthesis of compounds 2−5 is found in the Supporting Information. X-ray Crystallography. By using a Bruker APEX II CCD, diffraction data were obtained under Mo-Kα radiation (λ = 0.71073 Å) at 296 K through the ω-2θ scan method. Five crystal structures were solved by direct methods, under full-matrix least-squares techniques by F2 and the SHELX-2014 crystallographic program package was utilized to refine crystal structures. The whole non-H atoms were refined anisotropically, while H atoms of organic amine templates were put on calculated positions and permitted to ride on their parent atoms (H atoms of OH as well as water are not located). All crystallographic data and structural determination of whole compounds are displayed in Table 1. Additionally, Table S1 as well as Table S2 contains selected bond lengths and angles.

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RESULTS AND DISCUSSION Synthesis. According to our experimental phenomenon, we can conclude that, among a specific solvothermal synthesis, a host of conditions may influence crystal growth of the target products, just like initial reactants, solvents, and reaction temperature. In this case, though L-tartaric acid did not appear in the final structure, it also plays a critical role in the structural orientation. The aforementioned compounds were not obtained without the introduction of L-tartaric acid and dimethylamine. It can be implied that the L-tartaric acid and dimethylamine act as dual templating roles during the obtaining of target products, which is not without precedent.32 Furthermore, the solvent glycol not only acts as the coligand in this system but also makes contributions to the stability of the structure. As confirmed by the literature,33,34 solvent molecules may enhance the interactions among organic amines and the framework, leading to the promotion of the thermodynamic

EXPERIMENTAL SECTION

Materials and Methods. All the purchased chemicals were in reagent pure grade. IR was gauged by a Nicolet Impact 410 Fourier transform infrared spectrometer through KBr pellets (400−4000 cm−1). C, H as well as N elemental analyses were measured in a PerkinElmer 2400 elemental analyzer. By using a Diamond thermogravimetric analyzer (298−1273 K, 283 K min −1, N2 atmosphere), TG measurement was finished. Solid-state luminescence properties were acquired by an F-4600 FL spectrophotometer. PXRD was accomplished by a Bruker D8X diffractometer which furnished monochromatized Cu-Kα (λ = 1.5418 Å) radiation under 5−50° at environmental temperature. Direct current (dc) magnetic values were measured at 1.8−300 K under an applied filed of 1000 Oe. In addition, magnetization measurements were made in fields of between 0 and 7 T at 2−7 K on an MPMS-XL7 SQUID magnetometer. Synthesis of Compound [Gd8(CH2OHCH2OH)8(SO4)12]·2(C2H7N)·2H2O (1). Taking compound 1 as an example, Gd2O3 (0.1713 g, 0.47 mmol), L-tartaric acid (0.3203 g, 2.14 mmol), B

DOI: 10.1021/acs.inorgchem.8b01370 Inorg. Chem. XXXX, XXX, XXX−XXX

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Figure 4. Dimethylamine molecules and free water molecules are full of the channels in compound 1 viewing along the c axis (for clarity, H atoms were omitted). Figure 1. (a) Asymmetric unit of 1 (all hydrogen atoms were omitted for clarity). (b) Coordination mode in Gd1 (left), Gd2 (right).

Figure 5. Temperature dependence of χMT data in compound 1 at 1000 Oe dc magnetic field. Figure 2. (a) Ln8 and Ln4 rings in compound 1; (b) four adjacent SBU-1s connected by sharing four sulfates to form a 16MR channel; (c) SBU-1; (d) two adjacent SBU-2s connected by sulfates to form an 8MR channel; (e) SBU-2.

three sulfate groups, half dimethylamine as well as half free water molecules. Gd1 and Gd2 atoms in compound 1 are all nine-coordinated with a {GdO9} unit to form a distorted tricapped triangular prism coordination geometry, which is accomplished by two O atoms from glycol as well as seven O atoms belonging to sulfate (Figure 1b). Overall, the structure of compound 1 can be built from structural building units Gd8 and Gd4 rings (Figure 2a), in which {SO4} units bridge the adjacent gadolinium centers to form the aforementioned rings along the a axis (Figure 2b,d). Compared with other reported Ln8 compounds,35 for example, [Gd8(O3PtBu)6(μ3-OH)2(H2O)2(HOiBu)(O2CtBu)12](NH3i Pr)2, which is a 4f-phosphonate with a distorted pyramid shape, is a completely different structure from the Ln8 compound we reported. For the purpose of better comprehending the structure, compound 1 is divided into two classes of secondary building units(SBUs). Two {GdO9} units connect with four sulfates by sharing oxygen atoms to form SBU-1: [Gd2(SO4)4]2− (Figure 2c). Four adjacent SBU1s join together with four common sulfate anions to yield an interesting serrated 16-membered inorganic−organic hybrid ring, consisting of 8 {GdO9} and 8 {SO4} units (Figure 2b), which can be viewed as a Ln8 ring. The SBU-2 [Gd2(SO4)2]2+ is constructed by two {GdO9} units linked by two sulfates (Figure 2e). Two neighboring SBU-2s tightly couple together by sharing bridging O atoms and yield an elliptical 8membered inorganic−organic hybrid ring (Figure 2d), which can also be considered as a Ln4 ring. Adjacent 16MR and 8MR are further connected via {SO4} units to generate an open

Figure 3. (a) 16MR and 8MR channel in compound 1 propagate along the a axis; (b) windmill-shaped 16MR-2 channel propagates along c axis; (c) one windmill-shaped 16MR-2 channel tube with 8MR side pockets along the b axis.

stability. In addition, it can be confirmed from experiment that this system is sensitive to the reaction temperature. We can only obtain the above compounds at 140 °C; otherwise, we cannot obtain them. Crystal Structure of Compound 1 [Gd8(CH2OHCH2OH)8(SO4)12]·2(C2H7N)·2H2O. Single-crystal X-ray structural analysis indicated that compounds 1−5 are in a tetragonal system, constructed from {LnO9} and {SO4} units with space group I41/a. For clarity, only compound 1 will be illustrated in detail as the representation. The asymmetric unit of 1 (Figure 1a) includes two gadolinium centers, two glycol molecules, C

DOI: 10.1021/acs.inorgchem.8b01370 Inorg. Chem. XXXX, XXX, XXX−XXX

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Figure 6. (a) Field-dependent magnetization of 1 from 2.0 to10.5 K. (b) Values of ΔSm calculated from one isolated GdIII atom at fields from 0 to7 T, temperatures between 2.5 and 10.0 K.

Table 2. : Comparison of −ΔSmmax Data among Selected GdIII Based Compounds compounds

−ΔSm (J K−1 kg−1)

ΔH (T)

T (K)

dimensionality

ref

[Gd(OH)CO3]n [Gd4]n [Gd6(OH)8(suc)5(H2O)2]n·4nH2O Gd104 Gd140 Gd8 Gd36Ni12 {[Gd2Cu(MSA)4(H2O)6]·2H2O}n Gd52Ni52 {[Gd(HPA)(NO3)(H2O)2]·H2O}n Gd12 [Gd2(MMA)2(INA)2(H2O)3]n [Gd(PAA)3(H2O)]n

66.4 51.29 48 46.9 38 36.86 36.3 36.05 35.6 35.58 35.3 34.32 26.73

7 7 7 7 7 7 7 7 7 7 7 7 7

1.8 2 1.8 2 2 2 3 2 4.2 2 3 2 3

3D 3D 3D 0D 0D 3D 0D 2D 0D 1D 0D 2D 1D

38 19 39 4 1 this work 6 41 2 42 40 43 44

the channels and play a crucial role in the stability of whole system (Figure S2, taking compound 1 as an example), which further contributes to the charming structure of these compounds. PXRD. Experimental and calculated PXRD patterns of the five compounds are depicted in Figures S7−S11. The fact that the compounds present similar PXRD patterns means that the five compounds have the same crystallinity. In addition, results show that there is almost no difference in diffraction peak positions between the measured and simulated XRD patterns in every compound, which indicates the phase purity of the five compounds. That conclusion corresponds to the consequences of X-ray crystallographic analysis. IR. FT-IR spectra of these five compounds are presented in Figures S12−S16. They are analogous except for slight shifts in some band positions, and thus, here we take compound 1 for a detailed analysis. The spectra can be described from the following four regions: (i) the characteristic peak at 3417 cm−1 is assigned to stretching vibrations of O-H in water and ethylene glycol; (ii) the absorption between 1573 and 1639 cm−1 is attributed to stretching vibrations in C-C and C-N; (iii) peaks ranging from 784 to 1039 cm−1 can be resulted from the stretching vibrations in C-O and S-O; (iv) the peaks around 696 cm−1 demonstrate the vibrations of Gd-O. TGA. Thermogravimetric analyses of the five compounds were conducted under a N2 atmosphere (25−1000 °C, Figures S17−S21). They have analogous weight loss curves, and we only illustrated the compound 1 according to the literature37 in

framework, which possesses a 3D channel system (Figure 3a), an emerging aesthetic structure of these compound. The above two kinds of channels are propagating along the crystallographic a axis. Albeit the 16- and 8-membered channels display different sizes, they displayed an ordered close packing arrays arrangement. Every 16MR channel is surrounded with four 8MR channels, and they are alternately encircled by three 8MR as well as three 16MR channels (Figure 3a). Interestingly, there exists another windmill-shaped 16MR-2 channel transmitting from the crystallographic c axis (Figure 3b). 16MR-2 channels mentioned above are also built from 8 {GdO9} and 8 {SO4} units (Figure S1c), which is linked by bridging oxygen atoms; the shape and the size of 16MR-1 and 16MR-2 channels are quite different. To best of our knowledge, the above phenomenon may be resulted from the appearance of disordered {SO4} units in the two types of 16-membered rings. As presented in Figure 4, the 16MR channels crowded out with dimethylamine molecules and free water molecules, which play a vital role in structure-directing and charge-balancing.34 It is worth mentioning that the guest molecules in the compound 4 are different from the other four compounds. The dimethylamine is not present in the compound 4, just free water molecules embedded in the channels. The structure of the five compounds exhibits comparability with previous work in our team, [(C2H8N)9][Eu5(SO4)12]·2H2O;36 they both have two types of extra-large channels and leading to a 3D channel system. However, the distinct point is that, except the dimethylamine, carbon ions from glycol molecules also exist in D

DOI: 10.1021/acs.inorgchem.8b01370 Inorg. Chem. XXXX, XXX, XXX−XXX

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of 29.54% (the calculated value is 31.87%) corresponds to the removal of SO3 molecules. Magnetic Properties. As depicted in Figure 5, χMT products of 7.893 cm3 K mol−1 at 300 K for 1 is close to the calculated 7.875 cm3 K mol−1, which accords with one GdIII ion. Upon cooling temperature, for 1, χMT decreases gradually to the minimum 7.078 cm3 K mol−1 at approximately 14 K, and rises slightly to 7.151 cm3 K mol−1 at 3 K before dropping weakly to 7.107 cm3 K mol−1 at 1.8 K. Susceptibility data obey Curie−Weiss law from 14 to 300 K (χM = C/(T − θ)), obtaining the parameters C = 7.856 cm3 K mol−1, θ = −2.912 K (Figure S3). The above negative value of θ and the monotonic drop of χMT values above jointly corroborated the presence of antiferromagnetic (AF) interactions among the adjacent metal atoms, while the enhancement of the χMT value at the low-temperature region may be the characteristic of short-range ordering. As shown in Figure 6a, M vs H chart presents a stabilized rise in magnetization, reaching maximum data of 6.308 NB under high magnetic field at 7 T. Magnetic entropy change (ΔSm) of 1 was investigated due to its importance in assessing the MCE. To the best of our knowledge, ΔSm can be acquired from magnetization change as a function of applied field as well as temperature by applying the Maxwell equation ΔSm(T) = ∫ [∂M(T, H)/∂T]H dH. We can observe from Figure 6b that, with an enhancing ΔH and declining temperature, the impressive resulting maximum −ΔSm is 36.86 J K−1 kg−1 (108.55 mJ cm−3 K−1, calculated from one uncoupled GdIII ion) for ΔH = 7 T at 2.0 K. It is worth noting that the obtained −ΔSmmax is comparable to those previously reported GdIII based compounds, and we display them in Table 2. Actually, full entropy change within a GdIII ion is 45.91 J K−1 kg−1, judged by an equation nR ln (2S + 1) with S = 7/2. The discrepancy between calculated and the experimental value is mainly because of the AF coupling in 1.1 The large MCE per unit of compound 1 is mainly due to the high magnetic density as well as small sulfate linker. There exists a long way in evaluating molecular magnetic coolers for practical applications because of their comparatively low volumetric isothermal entropy change.5 Luminescence Properties. Considering the remarkable luminescence properties of the SmIII, TbIII, and EuIII, compounds 2−4 were recorded under different excitation wavelengths, displaying their characteristic emissions of lanthanide ions. As illustrated in Figure 7a, the luminescence property of 2 was investigated at ambient temperature, exhibiting the characteristic of a SmIII cation under the maximum excitation wavelength at 402 nm.34,45 Three primary characteristic peaks are located at 561, 597, and 643 nm in the visible region, originating from the 4G5/2 → 6Hj (j = 5/2, 7/2, 9/2) with the 4 G5/2 → 6H7/2 emission as the dominant peak, which is corresponding to documented SmIII compounds.34 The luminescence property of 3 at ambient temperature was gauged at 369 nm34,45 (Figure 7b). The chart shows the characteristic transition of a TbIII ion. It presents four strong emission bands from 488 to 621 nm resulting from the 5D0 → 7 Fj (j = 6, 5, 4, 3) transition, displaying typical TbIII emission peaks. Two intense emission peaks at 488 and 544 nm are attributed to 5D0 → 7F6 magnetic dipolar transition and 5D0 → 7 F5 electric dipolar transition; nevertheless, weaker emission bands at 586 and 621 nm are due to 5D0 → 7F4 as well as 5D0

Figure 7. Solid-state emission spectra of compounds 2 (a), 3 (b), and 4 (c).

detail. The total percentage that compound 1 lost is 50.13, which is in accord with the theoretical value of 52.52%. The first mass loss percentage of 1.28 (25−300 °C) is due to the loss of water molecules (theoretical data 1.20%). Weight loss of 19.31% (calculated 19.45%) between 300−560 °C corresponds to the loss of dimethylamine and glycol. As is known to all that, once the organic template is wiped off from the whole structure, the framework will collapse. When temperature increases from 560 to 1000 °C, the weight loss E

DOI: 10.1021/acs.inorgchem.8b01370 Inorg. Chem. XXXX, XXX, XXX−XXX

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→ 7F3 transitions. This phenomenon is consistent with the luminescence properties of the TbIII compounds in the literature.45 The luminescent property of 4 was also measured (Figure 7c) with the characteristic f−f transition of an EuIII ion on excitation at 395 nm.34,45 Major emission peaks at 592, 615, 653, 696 nm are ascribed to characteristic emissions arising from the 5D0 → 7Fj (j = 1,2,3,4) transition. The strongest intensity at 615 nm corresponds to electric dipolar 5D0 → 7F2. Correspondingly, the medium intensity peak at 592 nm is due to magnetic dipolar 5D0 → 7F1, which hardly varies with the coordination environment. The remaining two peaks at 653 and 696 nm pertain to the 5D0 → 7F3 and 5D0 → 7F4 transitions, respectively.34 Luminescence decay curves of compounds 2−4 were obtained near ambient temperature as well (Figures S4−S6). Both curves were well fitted by the exponential function: I = I0 + A1 exp(−t/τ), in which I and I0 are defined as luminescence intensities at times t = t as well as t = 0, respectively, while τ is a parameter to describe luminescence lifetime. Thus, the results of the fitting are τ = 41.1 μs for 2, τ = 0.66 ms for 3, and τ = 0.81 ms for 4.

ACKNOWLEDGMENTS This work was supported by the National Natural Science Foundation of China (Grant 21571103), the Major Natural Science Projects of the Jiangsu Higher Education Institution (Grant 16KJA150005), and Topnotch Academic Programs Project of Jiangsu (TAPP).

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CONCLUSIONS In summary, a series of Ln8 rings lanthanide compounds, which are bridged by sulfate anion and glycol, have been successfully obtained. The luminescence spectra of compounds 2−4 indicate that these substances may become promising photoluminescence materials. The magnetic entropy value of compound 1 is 36.86 J K−1 kg−1 (108.55 mJ cm−3 K−1) for ΔH = 7 T at 2.0 K, which is a comparatively large value. The successful synthesis of 1 enriches the existing field of molecular magnetic coolers. Additionally, it confirms the potential of the synthesis of other outstanding Gd compounds with remarkable MCE such as condensing hydrogen, methane, and the substitution of isotope He-3. ASSOCIATED CONTENT

S Supporting Information *

The Supporting Information is available free of charge on the ACS Publications website at DOI: 10.1021/acs.inorgchem.8b01370. PXRD patterns, IR spectra, TG analysis, magnetic properties, luminescence properties, selected bond lengths and angles (PDF) Accession Codes

CCDC 1585358−1585360 and 1585363−1585364 contain the supplementary crystallographic data for this paper. These data can be obtained free of charge via www.ccdc.cam.ac.uk/ data_request/cif, or by emailing [email protected]. uk, or by contacting The Cambridge Crystallographic Data Centre, 12 Union Road, Cambridge CB2 1EZ, UK; fax: +44 1223 336033.

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AUTHOR INFORMATION

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*E-mail: [email protected]. ORCID

Yan Xu: 0000-0001-6059-075X Notes

The authors declare no competing financial interest. F

DOI: 10.1021/acs.inorgchem.8b01370 Inorg. Chem. XXXX, XXX, XXX−XXX

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DOI: 10.1021/acs.inorgchem.8b01370 Inorg. Chem. XXXX, XXX, XXX−XXX