Syntheses, structures, and magnetic properties of cobalt(II) and nickel(II) coordination polymers based on a V-shaped ligand

Author’s Accepted Manuscript Syntheses, Structures, and Magnetic Properties of Cobalt(II) and Nickel(II) Coordination Polymers based on a V-shaped Ligand Shuang Yao, Fei-Yan Yi, Guanghua Li, Yang Yu, Jing-yuan Wang, Dan Liu, Shu-Yan Song www.elsevier.com/locate/yjssc

PII: DOI: Reference:

S0022-4596(17)30081-6 http://dx.doi.org/10.1016/j.jssc.2017.03.010 YJSSC19714

To appear in: Journal of Solid State Chemistry Received date: 19 October 2016 Revised date: 3 March 2017 Accepted date: 5 March 2017 Cite this article as: Shuang Yao, Fei-Yan Yi, Guanghua Li, Yang Yu, Jing-yuan Wang, Dan Liu and Shu-Yan Song, Syntheses, Structures, and Magnetic Properties of Cobalt(II) and Nickel(II) Coordination Polymers based on a Vshaped Ligand, Journal of Solid State Chemistry, http://dx.doi.org/10.1016/j.jssc.2017.03.010 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting galley proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

Syntheses, Structures, and Magnetic Properties of Cobalt(II) and Nickel(II) Coordination Polymers based on a V-shaped Ligand Shuang Yaoa,1, Fei-Yan Yic,1, Guanghua Lid, Yang Yu,a Jing-yuan Wangb,*, Dan Liua,*, Shu-Yan Song a a

State Key Laboratory of Rare Earth Resource Utilization, Changchun Institute of Applied

Chemistry, Chinese Academy of Sciences, 5625 Renmin Street, Changchun, 130022, P. R. China b

Technical Institute of Physics and Chemistry of the Chinese Academy of Sciences, 29

Zhongguancun East Road, Haidian District, Beijing, 100190, P. R. China c

The School of Materials Science and Chemical Engineering, Ningbo University, Ningbo,

315211, P. R. China d

State Key Laboratory of Inorganic Synthesis & Preparative Chemistry, College of Chemistry,

Jilin University, Changchun, 130012, P. R. China [email protected] [email protected] *

Corresponding author. Tel: +86-431-85262770; Fax: +86-431-85698041.

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These authors contributed equally.

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Abstract Two coordination polymers [Co2(TA)(4,4′-bipy)2(H2O)2]•H2O (1) and [Ni2(TA)(4,4′bipy)2(H2O)4]•3H2O (2) were prepared by hydrothermal reactions of MCl2•6H2O (M = Co, Ni) with a V-shaped ligand TDPA (3,3′,4,4′-thiodiphthalic anhydride) and a I-shaped N-donor coligand (4,4′-bipy). They were characterized by elemental analyses, thermogravinetric analyses, and magnetic behavior. As is expected, TDPA hydrolyzes into the corresponding tetracarboxylate acid H4TA (3,3′,4,4′-thiodiphthalic acid) during the reactions. Co2 dimer and Ni mononuclear center are connected into two-dimensional (2D) layers by H4TA and 4,4′-bipy bridge in 1 and 2, respectively. The most amazing feature is that 1 and 2 exhibit interesting spincanting metamagnetism and weak ferromagnetic behavior, respectively, with the critical Néel temperature of TN = 4 K for 1 and TN = 13 K for 2, based on variable temperature magnetic susceptibility measurements. In low mono- or dinuclear metal system, such magnetic behaviors have rare been observed. Furthermore, complex 1 will be a potential metamagnet material.

Graphical abstract Two Co(II) and Ni(II) coordination polymers were synthesized by hydrothermal reactions from a V-shape ligand (3,3′,4,4′-thiodiphthalic anhydride) and a I-shape ligand (4,4′-bipy), which were characterized by single crystal X-ray diffraction, elemental analyses, thermogravinetric

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analyses, and magnetic behavior, and exhibit interesting spin-canting metamagnetism and weak ferromagnetic behavior, respectively.

Keywords: Coordination polymer; Hydrothermal; Magnetic behavior; Metamagnetism; Ferromagnetic behavior

Introduction Coordination polymers (CPs) as functional materials have attracted considerable attention in recent years because of their potential applications in fields of catalysis, magnetism, luminescence, sensing and nonlinear optics,1-5 in which the molecular design of magnetic materials has especially attracting attention among researchers.6,7 But the rational design of magnetic CP-materials with specific structures has been proved to be a difficult task because the final products can be affected by various synthesis conditions, such as center metal ions, bridged ligands, reaction temperatures, metal-ligand ratio, solvent, etc.8-10 CPs as a class of crystalline materials are constructed by metal ions (or clusters) as nodes and multiple organic ligands as bridges. In most cases, the correlation between the detailed synthesis conditions and structural characters is very difficult to draw, but the metal ions selected play a crucial role in the determination of the properties of CPs. In addition, the designed organic ligands facilitate the successful prediction of target framework.11 Bearing those in our mind, Co/Ni-based CPs have

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been successfully synthesized based on an appropriate V-shaped ligand (TDPA). Firstly, our interest and expectation are that the V-shaped anhydride TDPA can form an X-shaped tetracarboxylate ligand with more flexible arms and coordinated sites during the coordination assembly. Such feature of ligand will be apt to extend three-dimensional directions, since flexible polycarboxylate ligands are particularly advantageous to construct new coordination polymers with diverse functions due to their diverse coordination modes, multiple coordination sites and flexible backbones. On the other hand, TDPA with a big ‘S’-atom linker are more easily delocalized for its big radius and lone pair of electrons, facilitating to coordinate more metal centers and transfer of magnetic interactions.12 So far, some transition metal CPs, such as Cd(II), Co(II), Ni (II), Cu(II) and Zn(II) CPs based on a similar V-shaped carboxylate ligands, including 3,3′,4,4′-oxidiphthalic acid, 3,3′,4,4′-diphenylsulfonetetracarboxylate acid and 4,4′(hexafluoro-isopropylidene)diphthalic acid, etc., have been constructed and exhibited appealing properties in photoluminescence and magnetism,13-16 but the CPs based on TA ligands have not been reported. Herein, we synthesized one cobalt(II) and one nickel(II) coordination polymers based on the TDPA ligand (Scheme 1). Bridged N-donors ligand of 4,4′-bipy was selected as co-linkers to construct new types of networks. Such dual-ligand way has been proved to be successful in the synthesis of new CPs,17 because the use of two complementary ligands with two different functions provides an additional level of control in the framework structure and charge density distribution. Hydrothermal reactions afforded compounds 1 and 2, namely, [Co2(TA)(4,4′bipy)2(H2O)2]•H2O (1) and [Ni2(TA)(4,4′-bipy)2(H2O)4]•3H2O (2). Their formulas were confirmed by elemental analyses, single-crystal X-ray diffraction studies and thermogravimetric

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analyses (TGA). We also describe their syntheses, crystal structures, and interesting magnetic behavior in detail. Experimental section Materials and methods 3,3′,4,4′-thiodiphthalicanhydride (TDPA) was prepared according to the literature reported previously.18 All other chemicals and solvents were commercial available and used without further purification. The C, H, and N elemental analyses were carried out on a Perkin-Elmer 2400 CHN elemental analyzer. Infrared (IR) spectra were preformed on a Bruker TENSOR 27 Fourier Transform Infrared Spectrometer in the range of 4000-400 cm-1 using the KBr pellet technique. The electronic absorption spectra were measured on a Hitachi U-4100 UV-visible spectrophotometer at room temperature. Powder X-ray diffraction (XRD) measurements were recorded on a Bruker D8 Focus diffractometer using Cu K radiation (λ = 0.15405 nm), in which the X-ray tube was operated at 40 kV and 40 mA at room temperature. Thermogravimetric and differential thermal analyses (TG-DTA) were carried out on a simultaneous SDT 2960 thermal analyzer under air atmosphere with a heating rate of 10°C/ min and a range of 40 °C to 800 °C. Preparation of [Co2(TA)(4,4′-bipy)2(H2O)2]•H2O (1) A mixture of CoCl2•6H2O (47.5 mg, 0.2 mmol), TDPA (32.6 mg, 0.1 mmol), 4,4′-bipy (38.4 mg, 0.2 mmol) and NaOH (12 mg, 0.3 mmol) was added into deionized water (10 mL). The mixture was stirred for about 10 minutes and sealed into a 15 mL Teflon-lined stainless steel vessel, then heated at 160 °C for three days. After being cooled to room temperature over a period of 27 h, red block crystals were collected by filtration and washed by deionized water and ethanol several times, and dried in air, with a yield of 47% based on TDPA. Anal. Calcd (%) for

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C36H28Co2N4O11S (Mr = 842.54): C, 51.32; H, 3.35; N, 6.65. Found: C, 52.01; H, 3.09; N, 6.62. Selected IR peaks (cm-1): 3407 (s), 3070 (w), 2928 (w), 1676 (w), 1610 (m), 1539 (w), 1381 (vs), 1245 (m), 1163 (m), 1104 (w), 1017 (w), 809 (w), 788 (m), 673 (w), 635 (w), 570 (w). (See Figure S1 of the supporting information). Preparation of [Ni2(TA)(4,4′-bipy)2(H2O)4]•3H2O (2) 2 was obtained by the similar procedure used for 1 except that NiCl2•6H2O (47.6 mg, 0.2 mmol) was used instead of CoCl2•6H2O. In addition, the different amount of NaOH (16 mg, 0.4 mmol) is used as starting material. Green block crystals of 2 were isolated in 54% yield. Anal. Calcd (%) for C36H36Ni2N4O15S (Mr = 914.17): C, 47.30; H, 3.97; N, 6.13. Found: C, 47.32; H, 3.88; N, 6.01. Selected IR peaks (cm-1): 3442 (s), 3215 (s), 2923 (w), 1610 (m), 1554 (m), 1496 (w), 1473 (w), 1385 (s), 1261 (w), 1229 (m), 1147 (w), 1114 (w), 1065 (m), 1011 (w), 816 (m), 738 (w), 636 (m), 575 (w) (See Figure S2 of the supporting information). X-ray crystal structure determination. Crystallographic data collections for 1 and 2 were carried out on a Bruker SMART Apex II CCD diffractometer with graphite monochromated Mo-K radiation (λ = 0.71073 Å) at 293 K. The diffraction data were integrated using the SAINT program, which was also used for the intensity corrections for the Lorentz and polarization effects. An empirical absorption correction was applied using multi-scan program SADABS.19 The structures were solved by direct methods and refined by the full-matrix least-squares methods based on F2 using the SHELXL-2014/7 and SHELXL-2016/6 crystallographic software package, except that some atoms have the ADP max/min ratios, therefore the ISOR instruction is used.20 All non-hydrogen atoms were refined with anisotropic temperature parameters. All hydrogen atoms except of free water molecules

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(O3W in 1, O1W and O2W in 2) were generated geometrically before the final cycle of refinement and were added to the structure factor calculation. The program SQUEEZE in PLATON20 was used to calculate the solvent area and remove their contribution to the overall intensity data in compound 1. See the CIF files for details. The crystallographic data and structural refinement results are summarized in Table 1. Selected bond lengths and angles are listed in Table 2. Results and Discussion Syntheses, XRD, absorption spectra and thermogravimetric analyses Hydrothermal method was used to assemble the target metal-organic coordination polymers based on two aims: (1) it is an effective and widely-used synthetic strategy;21 (2) it provides a hydrolytic condition of TDPA. The effects of more detailed synthetic conditions, such as, pH, reaction time and temperature, on the crystallinity of objective framework have been systematically investigated. Compared with low pH value (1~3.5) by adding HCl (0.1 M), high pH value (4~8) by adding NaOH is more favorable to form good crystals, but higher basic reaction condition is adverse. Those are in accordance with the hydrolytic process of TDPA: it is faster and more complete in basic condition than in acidic one, however, the hydrolysis product (TA) of TDPA is apt to coordinate with Na+ ions and not easy to release its coordinated sites in too high basic condition. At the same time, three days and 160 oC are also the most appropriate reaction conditions based on a lot of experimental results. As shown in Figure S3 and S4, the measured XRD patterns of 1 and 2 based on their powder samples are in good consistence with related simulated patterns based on the single-crystal structures, proving their phase purities of the as-synthesized products.

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The UV-visible electronic absorption spectra of the two compounds were measured in the region of 200-800 nm. As shown in Figures S5 and S6, the absorption peaks at 518, 317, 235 nm for compound 1 and 650, 357, 236 nm for compound 2 are observed in the spectra, respectively. The absorption bands observed at lower wavelengths in the spectra are assigned to π-π* transitions from the phenyl rings of the ligand. The absorption bands in the highest wavelengths are attributed to d-d transitions of metal ions, which have been reported previously.16e, f Further, their thermal stabilities of the complexes were investigated (Figure S7). TGA curve of compound 1 shows a minor weight loss of 5.5% in the temperature range of 50-90 °C, which can be attributed to adsorbed water molecules in the surface of sample 1. Two coordinated molecules (calcd. 4.27%, found 4.35%) were removed from 121 °C to 184 °C. Then its framework begins to decompose from 201 °C and ended at 504 °C. The total weight loss at 504 °C is 80.5%. In the case of compound 2, a weight loss of 6.2% is observed in the range of 56-136 °C due to the loss of three free water molecules (calcd. 6.14%). Then three steps of continuous losses were observed from 191 °C, corresponding to the pyrolysis of two coordinated water molecules and organic parts containing TA and 4,4′-bipy ligands. Finally, a plateau of 18.4% at 541 °C is observed. Structural descriptions [Co2(TA)(4,4′-bipy)2(H2O)2]•H2O (1) Single crystal X-ray analysis shows that complex 1 crystallizes in the triclinic space group P-1. As shown in Figure 1a, there are two crystallographically independent Co(II) ions, one TA4ligand, two 4,4′-bipy ligands, two aqua ligands and one free water molecule in the asymmetric unit of 1. Co1 and Co2 lie on general position and adopt slightly distorted octahedral geometries

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by four oxygen atoms and two N atoms. The base of octahedron is occupied by three carboxylate oxygen atoms from two different TA4- ligands and one coordinated water molecule; the apical positions are occupied by two N atoms from two 4,4′-bipy ligands. N1-Co1-N3 and N2-Co2N4C bond angles are 170.69(17)° and 172.86(18)°, respectively. The Co-O and Co-N bond distances are in the range of 2.052(4)–2.138(4) Å and 2.160(4)–2.199(4) Å, respectively. All the Co−O and Co−N bond distances are within the range reported for similar octahedral Co(II) complexes.22 The unique TA4- ligand is tetrahedral and connects four Co2+ ions by two μ2-η1η1 carboxylate groups and two μ1-η1η0 carboxylate groups. At the same time, Co(1) and Co(2) centers are bridged into two types of dimers (Co(1)2 and Co(2)2) by a pair of –O-C-Ocarboxylate bridges of two TA ligands with Co…Co distances of 4.8630(13) and 4.8559(14) Å, respectively (Figure 1b). Then the dimers of Co(1)2 and Co(2)2 are alternately connected into 1D wavy chain by TA4- ligands (Figure 1c). Furthermore, 4,4′-bipy ligands bridge adjacent Co2+ ions in 1D chains into a 2D layered structure as shown in Figure 1d, finally packing into a 3D supramolecular structure (Figure 1e). Intramolecular weak aromatic π…π interaction between phenyl ring of the TA4- ligand and aromatic ring of the 4,4′-bipy ligand exists in the supramolecular structure. The distance between the centers of these aromatic rings is 3.612 Å, and the corresponding dihedral angle is 10.9°. [Ni2(TA)(4,4′-bipy)2(H2O)4]•3H2O (2) While Ni2+ ions replace of Co2+, one new Ni-CP with fully different 2D layered structure from the one in 1 was obtained. Complex 2 crystallizes in tetragonal space group P43212 with the Flack parameter of 0.11(4).23 As illustrated in Figure 2a, its asymmetric unit consists of one Ni(II) ion, half a TA4- ligand, one 4,4′-bipy ligand, two coordinated water molecules (O5 and O6), as well as one and a half lattice water molecules (O1W and O2W). The unique Ni2+ center

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are coordinated by four oxygen atoms occupying basic plane from two carboxylate groups of one TA4- and two coordinated water molecules as well as two N atoms occupying two apical positions from two 4,4′-bipy ligands with N1-Ni1-N2A bond angle of 177.2(3)°, forming a distorted octahedral environment. The sum of bond angles (O1-Ni1-O5, O5-Ni1-O6, O6-Ni1-O3 and O3-Ni1-O1) is 360.0°, indicating the four O atoms exactly lie in a plane. The Ni-O distances vary from 2.045(5) to 2.062(5) Å, and the Ni-N bond lengths are 2.073(6) and 2.091(6) Å, which are close to those in reported literatures.24 Two uninuclear Ni centers are bridged into one dimer subunit [Ni(TA)Ni] by one bidentate TA4- ligand with four unidentate carboxylate groups (μ1η1η0). It should be point out that each Ni center are linked into 1D perpendicular chains along [100] and [010] directions, respectively, by bridging 4,4′-bipy ligands (Figure 2b). Finally, all dimer subunits [Ni(TA)Ni] are extended into 2D layers by Ni(4,4’-bipy) chains in two directions (Figure 2c). Further, a H-bonded 3D architecture are constructed, as shown in Figure 2d, among coordinated water molecules (O5, O6) and non-coordinated oxygen atoms (O1, O2, and O4) with bond lengths [O(5)-H...O(4)E: 2.662(7) Å (symmetry code: y-1/2,-x+3/2,z+1/4); O(5)H...O(2)D: 2.654(12) Å (symmetry code: -x+1/2,y-1/2,-z+3/4); O(6)-H...O(1)D: 2.676(7) Å (symmetry code: -x+1/2,y-1/2,-z+3/4)]. Weak aromatic π…π interactions between aromatic rings of the 4,4'-bipy ligand and TA4- ligand can be also found. The two compounds are firstly reported based on TA ligands with auxiliary ligands of 4,4’-bipy. The Co2 dinuclear unit was linked by carboxylate groups in compound 1, but only mononuclear Ni center was connected by TA ligands in compound 2. The other carboxylate ligands with similar structures, such as 3,3′,4,4′-oxidiphthalic acid (H4OA) and 3,3′,4,4′diphenylsulfonetetracarboxylic dianhydride (dpstc) have been adopted for the construction of Co and Ni compounds in the reported literatures.14b,25 Similar constructed unit can be also found.

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Magnetic Properties Compound 1 The temperature-dependent susceptibility of polycrystalline samples of 1 and 2 were measured at an applied magnetic field of 1000 Oe in the temperature range of 2–300 K. The magnetic susceptibility of 1 versus temperature is shown in Figure 3, its χMT value at 300 K is about 7.25 cm3 mol−1 K, which is much higher than expected spin-only value for two uncoupled Co2+ ions with g = 2 and S = 3/2 (3.74 cm3 mol-1 K), ascribing to the spin-orbit effect of Co(II) ions. Along with the lowering temperature, the χMT value decrease slowly and then more rapidly below 120 K to reach a minima of 4.31 cm3 mol−1 K at 12 K, then increase rapidly to peak value of 5.40 cm3 mol−1 K at 5.0 K, finally decrease more rapidly on further cooling. The reciprocal molar magnetic susceptibility versus temperature obeys the Curie-Weiss law above 30 K with a Weiss constant (θ) -12.54 K and the Curie constant, C = 7.43 cm3 mol-1 K. The negative Weiss constant indicates that the dominant interaction between spin carriers is antiferromagnetic, which can be demonstrated by the decrease value in χMT –T curve in the most temperature range. The steep increase in χMT at low temperature with its shallow minimum is indicative of ferrimagnetic behavior or spin canting. A long-range ordering was verified for a coexisting maximum. The sudden drops of χMT value below 5.0 K may be caused by the zero-field splitting (ZFS) effects in the ground state. Such ferromagnetic ordering was further verified by the field-dependence χMT vs. T measurements at low temperatures. As depicted in Figure 4a, the χMT value below 12 K is rather field-dependent, suggestive of a spin canting related weak ferromagnetism. Under 100 Oe the magnetization presents a maximum at 4 K, indicating the onset of antiferromagnetic ordering

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between the spin-canted Co2+ centers. This magnetic behavior implies that a frustrated nonzero spin ground state exist in the Co2 dimer, due to a noncanceled spin alignment, originating from spin-canted magnetism. It is antiferromagnetic interaction between Co2 dimers. The observed spin canting may be attributed to the magnetic anisotropy of Co2+ ions and to an absence of structural symmetry at low temperature, which has been reported for some spin-canting MOFs previously.26 The foregoing experimental results are in accordance with the structural information. 1 contains Co2 dimer units, in which magnetic interaction between Co centers are by the pathways of two carboxylate bridges –Co-O-C-O-Co- with Co⋯Co distance of 4.864(1) and 4.856(1) Å. To further investigate the possible phase transition, zero-field-cooled (ZFC) and field-cooled (FC) magnetization were measured from 2.0 to 50 K under 10 Oe. As can be seen from Figure 4b, the ZFC magnetization shows a narrow peak at 3 K and diverges from FC magnetization at about 4 K. This type of divergence reveals a possible transition from a paramagnetic state to either a long-range-ordered, spin-glass, or superparamagnetic state. The field dependent magnetization data for 1 was obtained at the different temperatures, respectively. As shown in Figure 5, the magnetizations values of 3.82, 3.80 and 3.49 Nβ tend to saturation at the highest field of 50 KOe and temperatures of 2 K, 3 K and 5 K, respectively. Moreover, the degree of saturations decreases with the increasing of the temperatures. The hysteresis loop at 2 K shows a very slightly sigmoid shape at low field, which indicates a weak metamagnetic behavior from antiferromagnetic state at low field to ferromagnetic state at high field. The metamagnetic critical field defined by dM/dH derivative curve (Figure S8) at 2 K is about 1.0 KOe. We attribute this behavior to the depression of the antiparallel configuration between spin-canting layers.26a,27,28 Furthermore, alternating-current (ac) susceptibilities under dc (Hdc= 0 Oe) and ac (Hac = 3.0Oe)

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fields were measuredfrom 2 to 20 K with a frequency at 10, 100, 500 and 1000 Hz. The results show sharp peaks at 4 K in both the in-phase (χM′) and out-of phase (χM′′) parts, as shown in Figure 6. The maxima in χM′ shift toward higher temperatures with the improvement of oscillating frequency, indicating the frequency dependent behavior. However, this phenomenon is not evident in the case of χM′′, in which two peaks indicates that TN is exactly 4.0 K, and small parts of the antiferromagnetic domains make acanting arrangement to produce a spontaneous magnetization. Compound 2 The temperature dependence of the magnetic susceptibility, χM and χMT, for 2 in a field of 1000 Oe is shown in Figure 7. The magnetic data in the whole temperature range of 2−300 K can be fitted by the Curie–Weiss Law with C =1.41 cm3 K mol-1 and θ = −1.87 K (Figure S9). The negative Weiss constant also displays the presence of overall antiferromagnetic coupling between mononuclear Ni2+ centers within the chain. The χMT value of 1.42 cm3 K mol-1 at 300 K, is significantly higher than the spin only value (1.0 cm3 K mol-1) that is expected for a magnetically isolated octahedral Ni2+ ion (S = 1, g = 2.00). Upon cooling, χMT smoothly decreases from room temperature to a broad minimum of 1.33 cm3 K mol-1 at ca. 22 K, confirming dominant antiferromagnetic interactions in the chain, then rapidly increases up to a sharp maximum of 1.43 cm3 K mol-1 at 14 K, last decreases rapidly till to 2.0 K. This type of magnetic behavior is characteristic of ferrimagnetism (or weak ferromagnetism) probably arising from spin canting, in which the predominantly antiferromagnetically coupled spins from different sub-lattices are not perfectly antiparallel, but canted to each other; the resulting net moments correlate in a weak ferromagnetic-like fashion. Furthermore, the field-cooled (FC) and zero field-cooled (ZFC) magnetization data measured at

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10 Oe down to 2 K do not show any deviation (Figure S10) and are rather field-dependent, indicative of the onset of a ferromagnetic phase transition. As shown in Figure 7, the field-cooled χMT versus T curve at different applied dc fields clearly shows the onset of spontaneous magnetization below∼20 K and shows the field-induced magnetizations up to 1000 Oe. This suggests that the moments of the lattices rotate proportionally to the applied field up to about 1000 Oe, where it starts to saturate to a value approaching the expected moment per nickel(II). The field dependent magnetizations at different temperatures are shown in Figure 8. The magnetization values approximately linearly increase with enhancing the applied magnetic field. With the increase of the temperature, the linear relationship is more evident. The test temperature is lower, the magnetization value increases faster. To acquire more information about the magnetic properties of compound 2, the alternative current susceptibility of 2 was measured under 3 Oe alternative fields with different frequencies, as shown in Figure 9. The peak maxima in both real component χM′ and imaginary component χM′′ are observed at TN = 13 K and this peak nearly does not shift with the change of the frequencies, suggesting a negligible contribution of spin-glass character. Conclusions In summary, we have successfully synthesized new Co(II) and Ni(II) coordination polymers based on a TA ligand and a auxiliary 4,4′-bipy ligand by hydrothermal reactions in the basic condition. Based on similar synthesized condition and ligands, different metal centers are assembled into two types of framework with Co2 dimer unit and mononuclear Ni center, respectively. One of the most fascinating outcomes of this work is that Co-CP (1) and Ni-CP (2) exhibit a spin canting metamagnetism and a spin canting weak ferromagnetic behavior in lownuclear building unit system, respectively. Magnetic properties also highlight the potential

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applications of 1 and 2 as magnetic materials. Future work will be focused on the explorative synthesis of more magnetic materials based on the designed ligands.

Supporting Information. X-ray crystallographic cif files, IR spectroscopy, simulated and measured XRD patterns, structural and magetization details. CCDC reference number 1015848-1015849. This material is available free of charge via the Internet at http://pubs.acs.org. ACKNOWLEDGMENT This work was supported by the financial aid from the National Natural Science Foundation of China (Grant No. 51372242, 21401205, 21401186 and 51402286), the National Key Basic Research Program of China (No. 2014CB643802), Jilin Province Youth Foundation (20140520077JH), and the K. C. Wong Magna Fund in Ningbo University. References [1] (a) H.-C. Zhou, J. R. Long, O. M. Yaghi, Chem. Rev. 112 (2012) 673. (b) H.-L. Jiang, Q. Xu, Chem. Commun. 47 (2011) 3351. (c) J. Lee, O. K. Farha, J. Roberts, K. A. Scheidt, S. T. Nguyen, J. T. Hupp, Chem. Soc. Rev. 38 (2009) 1450. (d) L. Ma, C. Abney, W. Lin, Chem. Soc.

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20

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Scheme 1. The formation of carboxylate ligand H4TA.

(a)

(b)

(c)

21

(d)

(e)

Figure 1. (a) Coordination environment of Co(II) atoms in 1 with the thermal ellipsoids drawn at the 30% probability level; hydrogen atoms, free water molecules and disorder of ligand were omitted for clarity. (b) Two dimmers centered at Co(1) and Co(2) with Co…Co distances (dashed lines). (c) 1D Co-TA chain. (d) View of 2D layer. Metal polyhedra are shaded in blue. 4,4′-bipy and TA4- are drawn in yellow and black sticks, respectively. (e) The stacking 3D supramolecular structure.

22

(a)

(b)

(c)

23

(d)

Figure 2. (a) ORTEP representation of the asymmetric unit of 2. Thermal ellipsoids are drawn at the 30% probability level. The hydrogen atoms, free water molecules and disorder of ligand are omitted for clarity. (b) The dimer subunit of [Ni(TA)Ni] and two vertical 1D chains of [Ni(4,4′bipy)] along a- and b- axes. (c) View of 2D network along [001] direction. (d) A H-bonded 3D network along the b axis. Hydrogen bonds are drawn into dash lines (black) showing the hydrogen bonds between the layers. TA4- and 4,4′-bipy ligands are shown as black and lavender sticks, respectively.

7.5

40

M

6.5

30

6.0 20

5.5 5.0

10

4.5 4.0

M-1 / cm-3 mol

 T / cm3 mol-1 K

7.0

0

3.5 0

50

100

150

200

250

300

T/K

Figure 3. χM T (black) and χM-1 (blue) vs. T plots for compound 1.

24

12 11

100 Oe 500 Oe 1000 Oe

MT / cm3 mol-1 K

10 9 8 7 6 5 4 0

10

20

30

40

50

T/K (a) 10

H = 10 Oe ZFC FC

M / cm3 mol-1

8 6

TN = 4 K 4 2 0 0

5

10

15

20

25

30

T/K (b)

Figure 4. (a) Plots of χM T vs. T at the indicated applied fields on 1. (b) Zero-field-cooled (ZFC) and field-cooled (FC) magnetization for 1.

4 3

2K 3K 5K

2

M / N

1 0 -1

0.34 0.33 0.32 0.31

-2 M/N 

0.30

-3

0.29 0.28 0.27 0.26 0.25 0.24 0.80

-4 -60

0.85

0.90

0.95

1.00

1.05

1.10

1.15

1.20

H / Koe

-40

-20

0

20

40

60

H / KOe

Figure 5. Plots of M / Nβ vs. H / T for 1 at the indicated low temperatures.

25

M'' / cm3 mol-1

M' / cm3 mol-1

3.5 3.0 2.5 2.0 1.5 1.0 0.5 0.0

10 Hz 100 Hz 500 Hz 1000 Hz

0.8

2

4

6

8

10

12

14

10 Hz 100 Hz 500 Hz 1000 Hz

0.6 0.4 0.2 0.0

-0.2 2

4

6

8

10

12

14

T/K

Figure 6. Real component (χM′) and imaginary component (χM′′) ac susceptibility signals of 1 in a 3 Oe field oscillating at the indicated frequencies. 4.5

0.40

1000 Oe 1000 Oe 500 Oe 100 Oe 10 Oe

3.5 3.0 2.5

0.35 0.30 0.25 0.20 0.15

2.0

0.10 0.05

1.0

-1

1.5

M / cm3 mol

MT / cm3 mol-1 K

4.0

0.00

0.5

-0.05 0

50

100

150

200

250

300

T/K

Figure 7. Plots of χM T vs. T and χM vs. T at indicated applied fields on 2.

8 6 4

M / N

2 0

5K 7K 10 K 13 K 15 K

-2 -4 -6 -8 -60

-40

-20

0

20

40

60

H / KOe

Figure 8. Plots of M / Nβ vs. H / T for 2 at the indicated low temperatures.

26

M' / cm3 mol-1 M'' / cm3mol-1

0.40 0.35 0.30 0.25 0.20 0.15 0.10 0.05 0.020

100 Hz 500 Hz 1000 Hz

0

2

4

6

8

10

12

14

16

18

20

22

100 Hz 500 Hz 1000 Hz

0.015 0.010 0.005 0.000 -0.005 -0.010 0

2

4

6

8

10

12

14

16

18

20

22

T/K

Figure 9. Real component (χM′) and imaginary component (χM′′) ac susceptibility signals of 2 in a 3 Oe field oscillating at the indicated frequencies.

O

O S

O

O

H2O

HOOC

S

HOOC

COOH COOH

O

O TDPA

H4TA

27

Table 1. Crystal data and structure refinements for 1 and 2.

Compounds

1

2

CCDC

1015848

1015849

Chemical formula

C36H28Co2N4O11S

C36H36Ni2N4O15S

Formula weight

842.54

914.17

Temperature (K)

293(2)

296(2)

Crystal system

triclinic

tetragonal

space group

P-1

P43212

a (Å)

10.099(2)

11.2036(5)

b (Å)

11.881(2)

11.2036(5)

c (Å)

16.868(3)

29.896(2)

α (°)

76.62(3)

90.00

β (°)

78.22(3)

90.00

γ (°)

86.49(3)

90.00

28

V (Å3)

1927.3(7)

3752.6(4)

Z

2

4

Dcalcd (g cm-3)

1.452

1.618

μ(Mo-Kα) mm-1

0.977

1.138

F(000)

860

1888

Reflections collected

10092

23414

R1a [I> 2σ(I)]

0.0595

0.0595

wR2b [I> 2σ(I)]

0.1396

0.1412

GOF

0.903

1.192

Largest diff peak/hole(e Å-3)

0.783/-0.586

0.483/-0.754

Flack a

0.11(4)

R1 = Fo -Fc/Fo, bwR2 = {w[(Fo)2 -(Fc)2]2/w[(Fo)2]2}1/2.

Table 2. Selected bond lengths (Å) and angles (deg) for 1 and 2.

[Co2(TA)(4,4′-bipy)2(H2O)2]•H2O (1) Co(1)−O(1)

2.079(3)

Co(1)−O(2A)

2.087(4)

Co(1)−O(3)

2.138(4)

Co(1)−O(2W)

2.061(4)

Co(1)−N(1)

2.166(4)

Co(1)−N(3)

2.199(4)

29

Co(2)−O(5)

2.116(4)

Co(2)−O(7)

2.055(4)

Co(2)−O(8B)

2.107(4)

Co(2)−O(1W)

2.052(4)

Co(2)−N(2)

2.160(4)

Co(2)−N(4C)

2.199(4)

O(1)−Co(1)−O(3)

81.56(14)

O(3)−Co(1)−O(2W)

95.72(16)

O(2A)−Co(1)−O(2W)

95.47(16)

O(1)−Co(1)−O(2A)

87.47(14)

N(1)−Co(1)−N(3)

170.69(17) O(5)−Co(2)−O(7)

83.48(16)

O(7)−Co(2)−O(8B)

88.35(14)

O(8B)−Co(2)−O(1W)

94.74(17)

O(1W)−Co(2)−O(5)

93.54(18)

N(2)−Co(2)−N(4C)

172.86(18)

[Ni2(TA)(4,4′-bipy)2(H2O)4]•3H2O (2) Ni(1)−O(1)

2.055(5)

Ni(1)−O(3)

2.046(5)

Ni(1)−O(5)

2.050(5)

Ni(1)−O(6)

2.062(5)

Ni(1)−N(1)

2.091(6)

Ni(1)−N(2A)

2.072(6)

O(1)−Ni(1)−O(5)

91.8(2)

O(5)−Ni(1)−O(6)

91.4(2)

O(6)−Ni(1)−O(3)

87.9 (2)

O(3)−Ni(1)−O(1)

88.8(2)

N(1)−Ni(1)−N(2A)

177.2(3)

Symmetry transformations used to generate equivalent atoms: For 1: A -x, -y+2, -z+1; B –x+1, y+1, -z; C x, y-1, z-1. For 2: A x+1, y, z.

30

GRAPHICAL ABSTRACT

Highlights Two Co(II) and Ni(II) coordination polymers were synthesized by hydrothermal reactions from a V-shape ligand (3,3′,4,4′-thiodiphthalic anhydride) and a I-shape ligand (4,4′-bipy), which were characterized by single crystal X-ray diffraction, elemental analyses, thermogravinetric analyses, and magnetic behavior, and exhibit interesting spin-canting metamagnetism and weak ferromagnetic behavior, respectively.

31