Article pubs.acs.org/crystal
Cite This: Cryst. Growth Des. XXXX, XXX, XXX−XXX
Enantiopure Chiral Two-dimensional Sinusoidal Lanthanide(III) Coordination Polymers Based on R‑/S-2‑Methylglutarate: Luminescence, Magnetic Entropy Change, and Magnetic Relaxation Cai-Ming Liu,* Deqing Zhang, Xiang Hao, and Daoben Zhu Beijing National Laboratory for Molecular Sciences, Institute of Chemistry, CAS, Beijing 100190, China
Downloaded via UNIV OF SOUTHERN INDIANA on July 19, 2019 at 00:16:40 (UTC). See https://pubs.acs.org/sharingguidelines for options on how to legitimately share published articles.
S Supporting Information *
ABSTRACT: As a base for neutralizing homochiral dicarboxylic acids [R-/S-2-methylglutaric acid, abbreviated as (R/S)-2MG] rather than an N-donor ligand, 1,3-di(4-pyridyl)propane participates in the self-assembly of isostructural, homochiral lanthanide(III) coordination polymers derived from (R/S)-2MG at room temperature, which show 2D sinusoidal ruffling (4, 4) network structures with the formulas {[Eu2(R-2MG)3(H2O)4]·0.5H2O}n (Eu-R1), {[Gd2(R-2MG)3(H2O)4]·0.5H2O}n (Gd-R2), {[Tb2(R-2MG)3(H2O)4]·0.5H2O}n (Tb-R3), and {[Dy2(R-2-MG)3(H2O)4]·0.5H2O}n (Dy-R4) as well as {[Eu2(S-2-MG)3(H2O)4]· 0.5H2O}n (Eu-S1), {[Gd2(S-2-MG)3(H2O)4]·0.5H2O}n (Gd-S2), {[Tb2(S-2-MG)3(H2O)4]·0.5H2O}n (Tb-S3), and {[Dy2(S2-MG)3(H2O)4]·0.5H2O}n (Dy-S4). Among them, the europium(III) and terbium(III) compounds show solid fluorescent properties characteristic of lanthanide(III) ions, while the dysprosium(III) compound may exhibit magnetic relaxation. Furthermore, the magnetic entropy change or magnetocaloric effect of the gadolinium(III) complex is studied.
■
INTRODUCTION Lanthanide(III) coordination polymers (LnCP) or lanthanide(III) metal−organic frameworks (LnMOF) are unique in molecular materials due to not only their fascinating physical properties associated with 4f electrons but also their structural variability associated with high coordination numbers.1 For example, lanthanide(III) ions in LnCPs or LnMOFs may exhibit characteristic and narrow fluorescence emission by means of the “antenna effect” of ligands.2 In the field of molecule-based magnets, the lanthanide(III) ions in MOFs and CFs, especially the Dy3+ ion, can exhibit superparamagnetic properties thanks to not only significant magnetic anisotropy but also large magnetic moments,3,4 such as single-molecule magnet (SMM) properties that make LnCPs and LnMOFs potential applications in the fields of information storage and molecular device. However, owing to the characteristics of ferroelectricity5,6 and nonlinear optical activity,7 the chirality in molecular materials is highly valued, which is especially beneficial for multifunctional integration;8−11 moreover, homochiral MOFs may be used in not only heterogeneous asymmetric catalysis but also enantioselective separation.12−16 However, it remains a great challenge to obtain homochiral MOFs or homochiral CPs,17−21 especially homochiral LnCPs or homochiral LnMOFs.22−30 So far, most of the reported homochiral LnCPs or homochiral LnMOFs are obtained by solvothermal technology,22−30 which requires high energy consumption and often acquires racemates under high temperature and high pressure conditions. Therefore, it is necessary to investigate the room temperature synthesis of homochiral LnCPs or homochiral © XXXX American Chemical Society
LnMOFs under normal pressure. Since the solubility of LnCPs or LnMOFs is usually poor, slow diffusion technology is naturally the best choice for synthesizing such homochiral LnCPs or homochiral LnMOFs under normal temperature and pressure conditions. A significant advantage of the slow diffusion technology is that it can effectively avoid racemization of homochiral products; however, there are only few examples of successfully obtaining crystals of homochiral LnCPs or homochiral LnMOFs because this method often obtains amorphous products rather than crystalline products. Homochiral dicarboxylic acid is often used as the chiral source to construct homochiral LnCPs or homochiral LnMOFs. Recently, some homochiral LnCPs or homochiral LnMOFs based on (+)/(−)-camphoric acid have been explored.26−30 Nevertheless, another similar homochiral dicarboxylic acid, R-/S-2-methylglutaric acid, has never been successfully used for the assembly of homochiral LnCPs or homochiral LnMOFs, though it may be used to assemble homochiral NiCPs and homochiral CoCPs.31 We are also committed to the SMM and fluorescence studies of LnMOFs32−37 and hope to further expand the research to homochiral LnCPs or homochiral LnMOFs. We herein describe the room temperature preparation, crystal structures, luminescence, magnetic entropy change, and magnetic relaxation of a series of isostructural, homochiral 2D LnCPs based on R-/S-2-methylglutaric acid, {[Eu 2 (R-2Received: May 7, 2019 Revised: June 25, 2019
A
DOI: 10.1021/acs.cgd.9b00602 Cryst. Growth Des. XXXX, XXX, XXX−XXX
Crystal Growth & Design
■
RESULT AND DISCUSSION Synthesis. We found that the complexes using R-/S-2methylglutaric acid as a ligand are quite limited by searching CCDC data currently. Only several homochiral NiCPs and homochiral CoCPs derived from R-/S-2-methylglutaric acid have been reported, which are prepared by solvothermal technology.31 Solvothermal technology is a relatively mature synthesis method often used in the preparation of MOFs and/ or coordination polymers. Some homochiral LnCPs or homochiral LnMOFs derived from (+)/(−)-camphoric acid have also been prepared under solvothermal conditions recently.26−30 Differently, the homochiral LnCPs in this work were prepared using slow diffusion technology at room temperature. Equimolar amount of 1,3-bis(4-pyridyl)propane and R-/S-2-methylglutaric acid in water was slowly diffused by equimolar amount of LnCl3·6H2O (Ln = Gd, Eu, Tb, or Dy) in methanol at room temperature, yielding enantiopure chiral {[Ln 2 (R-2-MG) 3 (H 2 O) 4 ]·0.5H 2 O} n and {[Ln 2 (S-2MG)3(H2O)4]·0.5H2O}n, respectively. The peaks on the experimental powder XRD spectra of all eight compounds can be well matched to the simulated powder diffraction patterns calculated from crystal structures (Figures S1−S8). 1,3-Bis(4-pyridyl)propane, which is generally used as a bridging N-donor ligand in the transition metal coordination chemistry, does not appear in the composition of products, indicating that it only acts as a base for neutralizing homochiral R-/S-2-methylglutaric acid during the assembly process, probably because the Ln3+ ion is more easily coordinated by oxygen atoms with respect to nitrogen atoms.38 It is worth mentioning that when R-/S-methylsuccinic acid or (+)/(−)-camphoric acid is used instead of R-/S-2-methylglutaric acid or 4,4-bipyridine is used instead of 1,3-bis(4pyridyl)propane during the assembly process, no crystalline products can be obtained. These comparative experiments show that the crystallization conditions need to be carefully selected, and 1,3-bis(4-pyridyl)propane plays a key role in the self-assembly of crystalline enantiopure chiral {[Ln2(R-2MG) 3 (H 2 O) 4 ]·0.5H 2 O} n and {[Ln 2 (S-2-MG) 3 (H 2 O) 4 ]· 0.5H2O}n in this work. Crystal Structures. The analysis of X-ray crystal structures reveals that all R-/S-configuration crystal structures are isomorphous (Tables S1 and S2), so the structures of the Dy enantiomers (Dy-R4 and Dy-S4) are described by way of example only. Both Dy-R4 and Dy-S4 are crystallized in space group P212121, the Flack values of Dy-R4 and Dy-S4 are close to 0, which uncourtly indicates the enantiopurity of Dy-R4 and Dy-S4. As shown in Figure 1, Dy-R4 is a 2D layered network complex constructed from Dy2 junctions and R-2-methylglutarate spacers. Two crystallographically independent dysprosium atoms (Dy1 and Dy2) are observed in the crystal structure of Dy-R4 (Figure 1a). Either the Dy1 atom or the Dy2 atom is nine-coordinated, which is bonded by six carboxylate O atoms supplied by three R-2-methylglutarate ligands, one carboxylate O atom supplied by the fourth R-2methylglutarate ligand, and two O atoms supplied by two terminal hydrate molecules. According to the SHAPE software39 analysis, the coordination configurations of the Dy1 and Dy2 atoms are both closest to the spherical capped square antiprism, and the offset values for the standard C4v symmetry are 1.854 and 2.046 for the Dy1 and Dy2 atoms, respectively (Tables S3 and S4).
MG)3(H2O)4]·0.5H2O}n (Eu-R1), {[Gd2(R-2-MG)3(H2O)4]· 0.5H2O}n (Gd-R2), {[Tb2(R-2-MG)3(H2O)4]·0.5H2O}n (TbR3), and {[Dy2(R-2-MG)3(H2O)4]·0.5H2O}n (Dy-R4) as well as {[Eu2(S-2-MG)3(H2O)4]·0.5H2O}n (Eu-S1), {[Gd2(S-2MG)3(H2O)4]·0.5H2O}n (Gd-S2), {[Tb2(S-2-MG)3(H2O)4]· 0.5H2O}n (Tb-S3), and {[Dy2(S-2-MG)3(H2O)4]·0.5H2O}n (Dy-S4). These complexes represent the first enantiopure chiral LnCPs or LnMOFs constructed from R-/S-2-methylglutarate.
■
Article
EXPERIMENTAL PROCEDURES
Preparation of Enantiopure Chiral LnCPs. In order to obtain these compounds, the four solutions were gradually layered in a 25 mL test tube. The bottom layer consisted of a solution obtained by dissolving 0.25 mmol of R-/S-2-methylglutaric acid and 0.25 mmol of 1,3-di(4-pyridyl)propane in 5 mL of water; the second layer was composed of 5 mL of water; the third layer consisted of 5 mL of methanol; while the top layer was composed of LnCl3·6H2O (0.25 mmol, Ln = Gd, Eu, Tb, Dy) dissolved in 5 mL of methanol. Notably, the reactants come from the top and bottom layers; although the middle two layers are pure solvents, they can buffer the diffusion of the reactants. X-ray quality crystals appeared at the bottom of the bottle or the wall of the bottle via slow diffusion of the components at room temperature over 3 weeks, which were then filtered and sequentially washed with 5 mL of water and 5 mL of methanol. Yield: 45−55% based on Ln. Analysis calc. for C18H33Eu2O16.5 (Eu-R1) C, 26.45; H, 4.07. Found: C, 26.39; H, 4.09. IR(KBr, cm−1): 3337(br, s), 3250(br, s), 2976, 2941, 1647, 1550(vs), 1467(s), 1419(s), 1378, 1321, 1289, 1271, 1242, 1187, 1168, 1103, 1067, 1028, 956, 934, 914, 884, 808, 776, 765, 704(m), 678(m), 648, 613, 539, 474, 419. Analysis calc. for C18H33Eu2O16.5 (Eu-S1): C, 26.45; H, 4.07. Found: C, 26.47; H, 4.10. IR(KBr, cm−1): 3339(br, s), 3251(br, s), 2976, 2941, 1647, 1551(vs), 1467(s), 1420(s), 1378, 1321, 1290, 1242, 1168, 1103, 1067, 1029, 956, 934, 883, 815, 765, 703(m), 678(m), 648, 615, 539, 473, 419. Analysis calc. for C18H33Gd2O16.5 (Gd-R2) C, 26.11; H, 4.02. Found: C, 26.07; H, 4.05. IR(KBr, cm−1): 3333(br, s), 3248(br, s) 2976, 2941, 1648, 1553(vs), 1468(s), 1421(s), 1378, 1356,1322, 1290, 1271, 1242, 1168, 1103, 1067, 1028, 976, 957, 935, 885, 816, 767, 704(m), 678(m), 649, 616, 540, 473, 418. Analysis calc. for C18H33Gd2O16.5 (Gd-S2): C, 26.11; H, 4.02. Found: C, 26.13; H, 4.04. IR(KBr, cm−1): 3338(br, s), 3250(br, s), 2976, 2941, 1648, 1553(vs), 1468(s), 1421(s), 1378, 1322, 1290, 1271, 1242, 1168, 1103, 1067, 1026, 976, 957, 935, 915, 885, 816, 776, 705(m), 678(m), 649, 616, 540, 474, 421. Analysis calc. for C18H33Tb2O16.5 (Tb-R3) C, 26.01; H, 4.00. Found: C, 26.05; H, 4.03. IR(KBr, cm−1): 3338(br, s), 3249(br, s), 2975, 2941, 1649, 1552(vs), 1468(s), 1421(s), 1378, 1356, 1322, 1290, 1270, 1241, 1168, 1103, 1067, 1027, 977, 958, 936, 886, 809, 776, 705(m), 678(m), 649, 614, 539, 473, 426. Analysis calc. for C18H33Tb2O16.5 (Tb-S3): C, 26.01; H, 4.00. Found: C, 26.06; H, 4.02. IR(KBr, cm−1): 3337(br, s), 3252(br, s), 2975, 2941, 1648, 1552(vs), 1468(s), 1421(s), 1378, 1356, 1322, 1289, 1271, 1241, 1168, 1103, 1067, 1031, 977, 958, 936, 915, 886, 809, 775, 705(m), 679(m), 649, 614, 539, 474, 429. Analysis calc. for C18H33Dy2O16.5 (Dy-R4) C, 25.79; H, 3.97. Found: C, 25.71; H, 4.01. IR(KBr, cm−1): 3334(br, s), 3250(br, s), 2975, 2940, 1651, 1555(vs), 1469(s), 1422(s), 1378, 1355, 1322, 1290, 1270, 1242, 1168, 1103, 1067, 1020, 977, 958, 936, 915, 887, 817, 777, 706(m), 679(m), 650, 613, 539, 472, 419. Analysis calc. for C18H33Dy2O16.5 (Dy-S4): C, 25.79; H, 3.97. Found: C, 25.82; H, 4.02. IR(KBr, cm−1): 3337(br, s), 3249(br, s), 2975, 2940, 1650, 1553(vs), 1468(s), 1422(s), 1379, 1322, 1290, 1270, 1241, 1168, 1103, 1067, 1021, 978, 958, 936, 887, 817, 777, 705(m), 679(m), 649, 614, 539, 474, 434, 413. B
DOI: 10.1021/acs.cgd.9b00602 Cryst. Growth Des. XXXX, XXX, XXX−XXX
Crystal Growth & Design
Article
axis direction, such a layered network presents an S-shaped undulating fluctuation with the period of 20.759 Å (Figure 2), similar sinusoidal ruffling layered structures were also observed in some organic−inorganic hybrid vanadium oxide materials.40,41 As expected, the crystal structure of Dy-S4 is very similar to Dy-R4, but its configuration is mirror symmetrical with Dy-R4 (Figure 3). The reported homochiral LnCPs or homochiral LnMOFs derived from (+)/(−)-camphoric acid are focused on 3D compounds26,27,30 or 1D chain-like compounds,28 while our explored {[Ln2(R-/S-2-MG)3(H2O)4]·0.5H2O}n complexes in this work are characterized by a 2D sinusoidal layered structure, which is the first discovery of LnCPs or LnMOFs based on R-/S-2-methylglutaric acid. Comparably, the homochiral NiCPs and homochiral CoCPs derived from R-/S-2-methylglutarate are 3D transition metal−organic frameworks;31 and several of achiral lanthanide(III) glutarate complexes with three-dimensional (3D) framework structures have been prepared by hydrothermal method before.42 Luminescent Properties. Since the structures of the Rand S-configurations are very similar, we only report solid state luminescence of Eu-R1 and Tb-S3 as representatives. The excitation spectrum of Eu-R1 at room temperature was determined by detecting the luminescence of the 5D0 → 7F2 transition at 616 nm. As Figure 4a shows, five excitation peaks centered at 364, 384, 398, 419, and 468 nm can be clearly seen, which correspond to the 7F0 → 5D4 transition, the 7F0 → 5G2 transition, the 7F0 → 5L6 transition, the 7F0 → 5D3 transition, and the 7F0 → 5D2 transition,43 respectively. The reason why these five excitation peaks are clear is related to the fact that the ligand R-2-methylglutarate in Eu-R1 is fatty acid. Since there is no chromophoric group, the UV absorption of the ligand R-2-methylglutarate is inevitably weak, and the interference of the characteristic excitation peak of the lanthanide(III) ion can be ignored. Upon excitation at 398 nm, three classical europium(III) ion’s emission bands centered at 578, 616, and 695 nm appear for Eu-R1, which are assigned to the 5D0 → 7F1 transition, the 5D0 → 7F2 transition, and the 5D0 → 7F4 transition, respectively. The strongest luminescence comes from the 5D0 → 7F2 transition, which causes the solid sample to emit red light as a whole. By the way, owing to the Eu(III) ion’s asymmetrical coordination configuration, the luminous intensity of the electric dipole transition (5D0 → 7F2) is obviously stronger with respect to the magnetic dipole transition (5D0 → 7F1).44 For the terbium(III) complex Tb-S3, the excitation spectrum through monitoring the emission of the 5D4 → 7F5 transition at room temperature is shown in Figure 4b (λem = 545 nm), which displays four typical Tb(III) ion’s excitation bands, centered at 345, 356, 373, and 382 nm, corresponding to the 7F5 → 5L6, 7F5 → 5L9,
Figure 1. Independent Dy atoms in Dy-R4 (a); the 2D network structure of Dy-R4 looked from the top (b). For the sake of clarity, H atoms and lattice hydrate molecules are not shown.
The Dy2 junction is formed by bridging a pair of Dy3+ ions from two carboxyl groups of two R-2-methylglutarate anions, with the Dy1−Dy2# (# 1/2 − x, −y, −1/2 + z) distance or the Dy1#−Dy2 distance of 4.119 Å. These Dy2 nodes are connected to each other by a single R-2-methylglutarate bridge on the latitude (the Dy1−Dy2 distance is 9.097 Å) and by R-2-methylglutarate double bridges on the warp (along the a axis direction), forming a 2D network with a (4, 4) lattice parallel to the ac plane (Figures 1b and 2). Viewed along the a
Figure 2. Side-view of the 2D networks in Dy-R4.
Figure 3. Mirror symmetry of the 2D sinusoidal networks of Dy-R4 and Dy-S4. C
DOI: 10.1021/acs.cgd.9b00602 Cryst. Growth Des. XXXX, XXX, XXX−XXX
Crystal Growth & Design
Article
Figure 4. Solid state excitation and emission spectra for Eu-R1 (λem = 616 nm, λex = 398 nm) (a) and for Tb-S3 (λem = 545 nm, λex = 345 nm) (b).
F5 → 5L10, and 7F5 → 5G6 transitions,45 respectively. The fact that these excitation peaks in Tb-S3 are clearer than most reported in the literature is also due to the lack of chromophores in the ligand S-2-methylglutarate. Under excitation at 345 nm, four classical Tb(III) ion’s emission bands for Tb-S3 can be detected; they are centered at 491, 545, 584, and 620 nm, assigned to the 5D4 → 7F3 transition, the 5D4 → 7F4 transition, the 5D4 → 7F5 transition and the 5D4 → 7F6 transition, respectively. The most intense emission comes from the 5D4 → 7F5 transition, which makes the solid sample emit green light. These results suggest that the R-/S-2methylglutarate ligand may exhibit a good antenna effect on the suitable lanthanide(III) ions’ luminescence. In order to study the fluorescence lifetimes of Eu-R1 and Tb-S3, the fluorescence decay curves of Eu-R1 and Tb-S3 at room temperature were obtained using the maximum emissions (616 and 545 nm for Eu-R1 and Tb-S3, respectively) under excitation at 360 nm. From Figure S9a, the two decay curves obviously follow a different mechanism. A standard double-exponential function can well describe the decay curve of Eu-R1 (Figure S9a), and the related formula, τ = (B1τ12 + B2τ22)/(B1τ1 + B2τ2),46 was thus used to calculate the average fluorescence lifetime (τ), giving the τ value of 78.7 μs for Eu-R1, which is obviously shorter than that of [Eu(Rpba)3(phen)]2 (τ = 1.62 ms).44 Very differently, a singleexponential function can describe the decay curve of Tb-S3 (Figure S9b), giving the τ value of 1.01 ms, this value is obviously longer than that of Eu-R1, but comparable with that of [Tb(R-pba)3(phen)]2 (τ = 1.08 ms).44 The Tb(III) complex represents a much longer lifetime than the Eu(III) analogue, which can be attributed to the former having a more predominant charge transfer.47 The solid-state fluorescence quantum yields of Eu-R1 and Tb-S3 were measured using Edinburgh FLS980 to be 17.41% (λex = 398 nm) and 4.62% (λex = 360 nm), respectively. Magnetic Properties. The magnetic properties of Gd-S2 and Dy-R4 were measured as representatives. As shown in Figure 5, the room temperature χT values are 15.78 and 28.28 cm3·K·mol−1 for Gd-S2 and Dy-R4, respectively, which are in line with the values of 15.76 cm3·K·mol−1 calculated using two noncoupling gadolinium(III) ions (S = 7/2, g = 2) and 28.34 cm3·K·mol−1 calculated using two isolated dysprosium(III) ions (S = 5/2, g = 4/3). From room temperature into 2 K, the complex Gd-S2’s χT product drops very slowly as the temperature decreases, indicating that the antiferromagnetic 7
Figure 5. Plots of χT versus T of Dy-R4 and Gd-S2 (Hdc = 1000 Oe). The fitting curve is shown as the solid line.
exchange existing in the double gadolinium(III) ions of the Gd2 junction is weak. According to the Curie−Weiss law, the complex Gd-S2’s θ value was calculated to be −0.96 K at 2− 300 K (Figure S10), this small negative Weiss constant value undoubtedly verifies the weak antiferromagnetic interaction in Gd-S2. Furthermore, the MAGPACK package48 was also used to fit the χT−T plot of Gd-S2 with the Hamiltonian of H = −2JSGd1·SGd2, J in this equation represents the coupling parameter between double gadolinium(III) ions in the Gd2 junction. The best fitting results are the following: the J value is −0.009 cm−1; the g value is 2.00, while R = 3.7 × 10−4. The very small negative J value also indicates that the antiferromagnetic exchange in Gd-S2 is very weak. To evaluate the magnetic refrigeration potential of the gadolinium(III) complex Gd-S2, its magnetization as a function of magnetic field was measured at 2−9 K (Figure 6a). Based on these magnetic data, the magnetic entropy changes −ΔSm, an important parameter of the magnetocaloric effect, could be calculated using ΔSm(T)ΔH = ∫ [∂M(T,H)/ ∂T]HdH (this is the well-known Maxwell relation).49 The results show that the largest −ΔSm value (5.58 J·kg−1·K−1) appears at 2 K under the condition ΔH = 5 T (Figure 6b), this value is obviously smaller than the maximum entropy value expected for the ferromagnetic Gd(III) dinuclear system (S = 2 × 7/2 = 7), i.e., R ln(2S + 1) = 2.708R = 22.51 J·mol−1·K−1 = 27.36 J·kg−1·K−1, owing to the antiferromagnetic interaction in Gd-S2, Notably, the −ΔSm value of the complex Gd-S2 is clearly larger with respect to the 2D Gd(III) complex D
DOI: 10.1021/acs.cgd.9b00602 Cryst. Growth Des. XXXX, XXX, XXX−XXX
Crystal Growth & Design
Article
Figure 6. Magnetization versus field at 2−9 K of Gd-S2 (a). Plot of −ΔSm versus T of Gd-S2 (b).
{[Gd(NNO)(glu)]·0.25H2O}n (glu2− = glutate, NNO− = Noxidenicotinate),36 in which the very weak antiferromagnetic interaction also exits among gadolinium(III) ions; but smaller than that of the 3D Gd(III) complex, {[Gd(L)(Ox)(H2O)]· 3H2O}n (H2L = mucic acid; H2Ox = oxalic acid).50 This result suggests that the magnetocaloric effect of 3D gadolinium(III) complexes generally has obvious advantages over 2D gadolinium(III) complexes. For the dysprosium(III) complex Dy-R4, when the temperature is reduced from room temperature into about 50 K, the χT product also fell slowly, and then quickly became smaller and smaller, until reaching the value of 15.91 cm3·K·mol−1 at 2 K (Figure 5). Obviously, besides the very weak antiferromagnetic exchange existing in the double lanthanide(III) ions of the Ln2 junction mentioned before in Gd-S2, the depopulation of Mj levels of the dysprosium(III) ion in Dy-R4 is a major factor in the reduction of χT values.51−54 Moreover, the magnetization as a function of magnetic field of Dy-R4 at 2−6 K was also determined, which is presented as the form of M versus H/T curves (Figure S11); these curves are obviously not coincident to each other, which suggests the possible presence of magnetic anisotropy in Dy-R4. The alternating current (ac) magnetic susceptibility of DyR4 was studied to explore its magnetic dynamics. When the dc magnetic field was 0 Oe, we tried to measure the ac susceptibility of Dy-R4 at 997 Hz (Figure S12) and found that the imaginary part (χ″) has no response signal. However, when a suitable dc field is supplied, responsive signals may appear in the imaginary part (Figure S13), indicating the existence of the quantum tunneling effect (QTE).55,56 From variable field ac susceptibility curves recorded at 2 K and 997 Hz (Figure S13), the optimal magnetic field is 1400 Oe. Figure 7 shows plots of χ″ versus T from 10 to 1399 Hz under a 1400 Oe dc magnetic field of Dy-R4, and frequency dependence of χ″ can be observed, which belongs to SMM behavior; this experiment demonstrates that 1400 Oe dc field may effectively suppress the QTE of Dy-R4. Unfortunately, no peaks were detected even at 1399 Hz. Furthermore, a stronger dc magnetic field, such as 2000 Oe, cannot cause χ″ to show a peak (Figure S14), suggesting that the energy barrier of Dy-R4 is very small. This situation often happens on DyCPs or DyMOFs.
Figure 7. Plots of χ″ versus T for Dy-R4 (Hdc = 1400 Oe).
structures. The terbium(III) and europium(III) compounds display fluorescence of lanthanide(III) ion characteristics; the dysprosium(III) complex shows field-induced magnetic relaxation; and the gadolinium(III) species has a magnetocaloric effect. 1,3-Di(4-pyridyl)propane is used as a base to neutralize homochiral dicarboxylic acids rather than an Ndonor ligand during the self-assembly of these homochiral 2D lanthanide(III) coordination polymers, playing a critical role. This work demonstrates that homochiral crystalline lanthanide(III) coordination polymers or metal−organic frameworks with interesting optical and magnetic properties can be constructed at room temperature through the solution diffusion method under carefully selected conditions.
■
ASSOCIATED CONTENT
S Supporting Information *
The Supporting Information is available free of charge on the ACS Publications website at DOI: 10.1021/acs.cgd.9b00602. Figures S1−S14 and Tables S1−S4 (PDF) Accession Codes
CCDC 1911421−1911428 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], or by contacting The Cambridge Crystallographic Data Centre, 12 Union Road, Cambridge CB2 1EZ, UK; fax: +44 1223 336033.
■
■
CONCLUSIONS In summary, the enantiopure chiral lanthanide(III) complexes containing R-/S-2-methylglutarate have been prepared for the first time, which show beautiful sinusoidal layered network
AUTHOR INFORMATION
Corresponding Author
*E-mail:
[email protected]. E
DOI: 10.1021/acs.cgd.9b00602 Cryst. Growth Des. XXXX, XXX, XXX−XXX
Crystal Growth & Design
Article
ORCID
(16) Evans, O. R.; Ngo, H. L.; Lin, W. Chiral Porous Solids Based on Lamellar Lanthanide Phosphonates. J. Am. Chem. Soc. 2001, 123, 10395. (17) Cook, T. R.; Zheng, Y. - R.; Stang, P. J. Metal-Organic Frameworks and Self-Assembled Supramolecular Coordination Complexes: Comparing and Contrasting the Design, Synthesis, and Functionality of Metal-Organic Materials. Chem. Rev. 2013, 113, 734. (18) Li, J. R.; Sculley, J.; Zhou, H.-C. Metal-Organic Frameworks for Separations. Chem. Rev. 2012, 112, 869. (19) Zhang, W.; Xiong, R.-G. Ferroelectric Metal-Organic Frameworks. Chem. Rev. 2012, 112, 1163. (20) Xu, Z.-X.; Xiao, Y.; Kang, Y.; Zhang, L.; Zhang, J. Homochiral Cluster-Organic Frameworks Constructed from Enantiopure Lactate Derivatives. Cryst. Growth Des. 2015, 15, 4676. (21) Yue, Q.; Guo, W.-X.; Wang, Y.-Y.; Hu, X.-L.; Gao, E.-Q. Homochiral Porous Metal-Organic Frameworks Constructed from a V-Shaped Alanine Derivative Based on Pyridyl-Dicarboxylate. Cryst. Growth Des. 2019, 19, 2476. (22) Cui, Y.; Ngo, H. L.; White, P. S.; Lin, W. Homochiral 3D lanthanide coordination networks with an unprecedented 4966 topology. Chem. Commun. 2002, 38, 1666. (23) Thushari, S.; Cha, J. A. K.; Sung, H. H.-Y.; Chui, S. S.-Y.; Leung, A. L.-F.; Yen, Y.-F.; Williams, I. D. Microporous chiral metal coordination polymers: hydrothermal synthesis, channel engineering and stability of lanthanide tartrates. Chem. Commun. 2005, 41, 5515. (24) Wang, X.; Zhang, K.; Lv, L.; Chen, R.; Wang, W.; Wu, B. Homochiral Coordination Polymers Based on Amino Acid-Functionalized Isophthalic Acid: Synthesis, Structure Determination, and Optical Properties. Cryst. Growth Des. 2018, 18, 1799. (25) Xu, Y.; Bao, S.-S.; Huang, X.-D.; Zheng, L.-M. Homochiral Erbium Coordination Polymers: Salt-Assisted Conversion from Triple to Quadruple Helices. Cryst. Growth Des. 2018, 18, 4045. (26) Zhao, X.; Wong, M.; Mao, C.; Trieu, T. X.; Zhang, J.; Feng, P.; Bu, X. Size-Selective Crystallization of Homochiral Camphorate Metal-Organic Frameworks for Lanthanide Separation. J. Am. Chem. Soc. 2014, 136, 12572. (27) Sun, M.-L.; Zhang, J.; Lin, Q.-P.; Yin, P.-X.; Yao, Y.-G. Multifunctional Homochiral Lanthanide Camphorates with Mixed Achiral Terephthalate Ligands. Inorg. Chem. 2010, 49, 9257. (28) Song, Y.-m.; Huang, H.-x.; Sun, G.-m.; Liao, Z.-w.; Luo, M.-b.; Liu, S.-j.; Luo, F. Multi-functional magnetic, ferroelectric, and fluorescent homochiral lanthanide (Ln)-camphorate compounds built on helical {Ln−O}n inorganic substructures. CrystEngComm 2011, 13, 6827. (29) Jhu, Z.-R.; Yang, C.-I; Lee, G.-H. Two new series of rare-earth organic frameworks involving two structural architectures: syntheses, structures and magnetic properties. CrystEngComm 2013, 15, 2456. (30) Sun, M.-L.; Zhang, X.; Huang, Y.-Y.; Lin, Q.-P.; Qin, Y.-Y.; Yao, Y.-G. Homochiral 3D lanthanide camphorates with high thermal stability. New J. Chem. 2014, 38, 55. (31) Livage, C.; Guillou, N.; Rabu, P.; Pattison, P.; Marrot, J.; Férey, G. Bulk homochirality of a 3-D inorganic framework: ligand control of inorganic network chirality. Chem. Commun. 2009, 45, 4551. (32) Liu, C.-M.; Zhang, D.-Q.; Zhu, D.-B. A 3D MOF Constructed from Dysprosium(III) Oxalate and Capping Ligands: Ferromagnetic Coupling and Field-Induced Two-Step Magnetic Relaxation. Chem. Commun. 2016, 52, 4804. (33) Liu, C.-M.; Zhang, D.-Q.; Zhu, D.-B. Two-Step Warming Solvothermal Syntheses, Luminescence and Slow Magnetic Relaxation of Isostructural Dense LnMOFs Based on Nanoscale 3-Connected Linkers. Inorg. Chem. Front. 2016, 3, 1076. (34) Liu, C.-M.; Zhang, D.-Q.; Hao, X.; Zhu, D.-B. A Chinese PaneLike 2D Metal-Organic Framework Showing Magnetic Relaxation and Luminescence Dual-Functions. Sci. Rep. 2017, 7, 11156. (35) Liu, C.-M.; Zhang, D.-Q.; Zhu, D.-B. Slow magnetic relaxation of a three-dimensional metal-organic framework featuring a unique dysprosium(III) oxalate layer. RSC Adv. 2015, 5, 63186. (36) Liu, C.-M.; Zhang, D.-Q.; Hao, X.; Zhu, D.-B. Luminescence and slow magnetic relaxation of isostructural 2D lanthanide metal-
Cai-Ming Liu: 0000-0001-7184-6693 Deqing Zhang: 0000-0002-5709-6088 Daoben Zhu: 0000-0002-6354-940X Notes
The authors declare no competing financial interest.
■
ACKNOWLEDGMENTS
■
REFERENCES
This work is supported by the Strategic Priority Research Program of the Chinese Academy of Sciences (XDB12010103) and the National Natural Science Foundation of China (21471154 and 21871274).
(1) Rocha, J.; Carlos, L. D.; Paz, F. A. A.; Ananias, D. Luminescent multifunctional lanthanides-based metal-rganic frameworks. Chem. Soc. Rev. 2011, 40, 926. (2) Cui, Y.; Chen, B.; Qian, G. Lanthanide metal-organic frameworks for luminescent sensing and light-emitting applications. Coord. Chem. Rev. 2014, 273−274, 76. (3) Liu, K.; Zhang, X.; Meng, X.; Shi, W.; Cheng, P.; Powell, A. K. Constraining the coordination geometries of lanthanide centers and magnetic building blocks in frameworks: a new strategy for molecular nanomagnets. Chem. Soc. Rev. 2016, 45, 2423. (4) 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. Chem. Sci. 2015, 6, 3095. (5) Shi, P.-P.; Tang, Y.-Y.; Li, P.-F.; Liao, W.-Q.; Wang, Z.-X.; Ye, Q.; Xiong, R.-G. Symmetry breaking in molecular ferroelectrics. Chem. Soc. Rev. 2016, 45, 3811. (6) Liu, C.-M.; Xiong, R.-G.; Zhang, D.-Q.; Zhu, D.-B. Nanoscale Homochiral C3-Symmetric Mixed-Valence Manganese Cluster Complexes with Both Ferromagnetic and Ferroelectric Properties. J. Am. Chem. Soc. 2010, 132, 4044. (7) Wang, C.; Zhang, T.; Lin, W. Rational Synthesis of Noncentrosymmetric Metal-Organic Frameworks for Second-Order Nonlinear Optics. Chem. Rev. 2012, 112, 1084. (8) Train, C.; Nuida, T.; Gheorghe, R.; Gruselle, M.; Ohkoshi, S.-i. Large Magnetization-Induced Second Harmonic Generation in an Enantiopure Chiral Magnet. J. Am. Chem. Soc. 2009, 131, 16838. (9) Bogani, L.; Cavigli, L.; Bernot, K.; Sessoli, R.; Gurioli, M.; Gatteschi, D. Evidence of intermolecular π-stacking enhancement of second-harmonic generation in a family of single chain magnets. J. Mater. Chem. 2006, 16, 2587. (10) Liu, C.-M.; Zhang, D.-Q.; Xiong, R.-G.; Hao, X.; Zhu, D.-B. A homochiral Zn-Dy heterometallic left-handed helical chain complex without chiral ligands: anion-induced assembly and multifunctional integration. Chem. Commun. 2018, 54, 13379. (11) Hang, T.; Fu, D.-W.; Ye, Q.; Xiong, R.-G. Two Novel Noncentrosymmetric Zinc Coordination Compounds with Second Harmonic Generation Response, and Potential Piezoelectric and Ferroelectric Properties. Cryst. Growth Des. 2009, 9, 2026. (12) Seo, J. S.; Whang, D.; Lee, H.; Jun, S. I.; Oh, J.; Jeon, Y. J.; Kim, K. A homochiral metal-organic porous material for enantioselective separation and catalysis. Nature 2000, 404, 982. (13) Gu, Z.-G.; Zhan, C.; Zhang, J.; Bu, X. Chiral chemistry of metal−camphorate frameworks. Chem. Soc. Rev. 2016, 45, 3122. (14) Xu, Z.-X.; Tan, Y.-X.; Fu, H.-R.; Kang, Y.; Zhang, J. Integration of rigid and flexible organic parts for the construction of a homochiral metal−organic framework with high porosity. Chem. Commun. 2015, 51, 2565. (15) Xu, Z.-X.; Fu, H.-R.; Wu, X.; Kang, Y.; Zhang, J. SizeDependent Enantioselective Adsorption of Racemic Molecules through Homochiral Metal-Organic Frameworks Embedding Helicity. Chem. - Eur. J. 2015, 21, 10236. F
DOI: 10.1021/acs.cgd.9b00602 Cryst. Growth Des. XXXX, XXX, XXX−XXX
Crystal Growth & Design
Article
organic frameworks derived from both nicotinate N-oxide and glutarate. RSC Adv. 2015, 5, 92980. (37) Liu, C.-M.; Zhang, D.; Hao, X.; Zhu, D.-B. Field-Induced Relaxation of Magnetization in a Three-Dimensional LnMOF with the Second Bridging Ligand Squarate. ACS Omega 2016, 1, 286. (38) Cahill, C. L.; de Lill, D. T.; Frisch, M. Homo- and heterometallic coordination polymers from the f elements. CrystEngComm 2007, 9, 15. (39) Casanova, D.; Llunell, M.; Alemany, P.; Alvarez, S. The Rich Stereochemistry of Eight-Vertex Polyhedra: a Continuous Shape Measures Study. Chem. - Eur. J. 2005, 11, 1479. (40) Zhang, Y.; DeBord, J. R. D.; O’Connor, C. J.; Haushalter, R. C.; Clearfield, A.; Zubieta, J. Solid-State Coordination Chemistry: Hydrothermal Synthesis of Layered Vanadium Oxides with Interlayer Metal Coordination Complexes. Angew. Chem., Int. Ed. Engl. 1996, 35, 989. (41) Liu, C.-M.; Hou, Y.-L.; Zhang, J.; Gao, S. Hydrothermal Synthesis and Crystal Structure of a Novel Two-Dimensional Vanadium Oxide Complex with a 6,14-Net Sinusoidal Ruffling Anionic Layer: [Ni(phen)2V4O11] (phen = 1,10-Phenanthroline). Inorg. Chem. 2002, 41, 140. (42) Serpaggi, F.; Férey, G. Hybrid open frameworks (MIL-n). Part 4 Synthesis and crystal structure of MIL-8, a series of lanthanide glutarates with an open framework, [Ln(H2O)]2[O2C(CH2)3CO2]3· 4H2O. J. Mater. Chem. 1998, 8, 2737. (43) Zhang, J.-W.; Kan, X.-M.; Liu, B.-Q.; Liu, G.-C.; Tian, A.-X.; Wang, X.-L. Systematic Investigation of Reaction-Time Dependence of Three Series of Copper-Lanthanide/Lanthanide Coordination Polymers: Syntheses, Structures, Photoluminescence, and Magnetism. Chem. - Eur. J. 2015, 21, 16219. (44) Wen, H.-R.; Xie, X.-R.; Liu, S.-J.; Bao, J.; Wang, F.-F.; Liu, C.M.; Liao, J.-S. Homochiral luminescent lanthanide dinuclear complexes derived from a chiral carboxylate. RSC Adv. 2015, 5, 98097. (45) Raphael, S.; Reddy, M. L. P.; Cowley, A. H.; Findlater, M. 2Thiopheneacetato-Based One-Dimensional Coordination Polymer of Tb3+: Enhancement of Terbium-Centered Luminescence in the Presence of Bidentate Nitrogen Donor Ligands. Eur. J. Inorg. Chem. 2008, 2008, 4387. (46) Fujii, T.; Kodaira, K.; Kawauchi, O.; Tanaka, N.; Yamashita, H.; Anpo, M. Photochromic Behavior in the Fluorescence Spectra of 9Anthrol Encapsulated in Si-Al Glasses Prepared by the Sol-Gel Method. J. Phys. Chem. B 1997, 101, 10631. (47) Echenique-Errandonea, E.; Oyarzabal, I.; Cepeda, J.; San Sebastian, E.; Rodríguez-Diéguez, A.; Seco, J. M. Photoluminescence and magnetic analysis of a family of lanthanide(III) complexes based on diclofenac. New J. Chem. 2017, 41, 5467. (48) Borrás-Almenar, J. J.; Clemente-Juan, J. M.; Coronado, E.; Tsukerblat, B. S. MAGPACK 1 A package to calculate the energy levels, bulk magnetic properties, and inelastic neutron scattering spectra of high nuclearity spin clusters. J. Comput. Chem. 2001, 22, 985. (49) Pecharsky, V. K.; Gschneidner, K. A., Jr Magnetocaloric effect and magnetic refrigeration. J. Magn. Magn. Mater. 1999, 200, 44. (50) Biswas, S.; Chakraborty, J.; Parmar, V. S.; Bera, S. P.; Ganguli, N.; Konar, S. Channel-Assisted Proton Conduction Behavior in Hydroxyl-Rich Lanthanide-Based Magnetic Metal-Organic Frameworks. Inorg. Chem. 2017, 56, 4956. (51) Woodruff, D. N.; Winpenny, R. E. P.; Layfield, R. A. Lanthanide Single-Molecule Magnets. Chem. Rev. 2013, 113, 5110. (52) Liu, C.-M.; Zhang, D.-Q.; Zhu, D.-B. Field-Induced Single-Ion Magnets Based on Enantiopure Chiral β-Diketonate Ligands. Inorg. Chem. 2013, 52, 8933. (53) Lacelle, T.; Brunet, G.; Holmberg, R. J.; Gabidullin, B.; Murugesu, M. Unprecedented Octanuclear DyIII Cluster Exhibiting Single-Molecule Magnet Behavior. Cryst. Growth Des. 2017, 17, 5044. (54) Liu, C.-M.; Zhang, D.-Q.; Zhu, D.-B. A 2D→2D polyrotaxane lanthanide−organic framework showing field-induced single-molecule magnet behavior. RSC Adv. 2014, 4, 36053.
(55) Habib, F.; Long, J.; Lin, P.-H.; Korobkov, I.; Ungur, L.; Wernsdorfer, W.; Chibotaru, L. F.; Murugesu, M. Supramolecular architectures for controlling slow magnetic relaxation in field-induced single-molecule magnets. Chem. Sci. 2012, 3, 2158. (56) Liu, C.-M.; Zhang, D.-Q.; Su, J.-B.; Zhang, Y.-Q.; Zhu, D.-B. Single-Molecule Magnet Behavior of 1D Coordination Polymers Based on DyZn2(salen)2 Units and Pyridin-N-Oxide-4-Carboxylate: Structural Divergence and Magnetic Regulation. Inorg. Chem. 2018, 57, 11077.
G
DOI: 10.1021/acs.cgd.9b00602 Cryst. Growth Des. XXXX, XXX, XXX−XXX
