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Syntheses, Structures, Photochemical and Magnetic Properties of Novel Divalent Cd/Mn Coordination Polymers Based on Semi-rigid Tripodal Carboxylate Ligand jie hu cui, Qingxiang Yang, Yizhi Li, Zijian Guo, and Hegen Zheng Cryst. Growth Des., Just Accepted Manuscript • DOI: 10.1021/cg400015v • Publication Date (Web): 22 Feb 2013 Downloaded from http://pubs.acs.org on February 28, 2013

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Crystal Growth & Design

Syntheses, Structures, Photochemical and Magnetic Properties of Novel Divalent Cd/Mn Coordination Polymers Based on Semi-rigid Tripodal Carboxylate Ligand Jiehu Cui, Qingxiang Yang, Yizhi Li, Zijian Guo, and Hegen Zheng

State Key Laboratory of Coordination Chemistry, School of Chemistry and Chemical Engineering, Nanjing National Laboratory of Microstructures, Nanjing University, Nanjing 210093, P. R. China.

ABSTRACT:

The

reactions

of

a

semi-rigid

tripodal

carboxylic

ligand,

3,5-bi(4-carboxy-phenoxy)-benzoic acid (H3BCPBA) with Cd(NO3)2/ Mn(NO3)2 afford five novel complexes, {[Cd3(BCPBA)2·(DMA)2·(H2O)5]·7H2O·2DMA}n (1), {[Cd3(BCPBA)2 (L1) (H2O)6]·(L1)}n

(L1

=

(L2)·(H2O)3(DMF)2]·2DMF}n

4-[(E)-4-Pyridinylazo]pyridine) (L2

=

1,3-bis(4-pyridyl)propane)

(2), (3),

{[Cd3(BCPBA)2 {[Mn3(BCPBA)2

(H2O)4]·11H2O}n (4), {[Mn3(BCPBA)2(DMF)2(H2O)2]·2DMF·9H2O}n (5) in the presence or absence of auxiliary ligand. Compound 1 is a three-dimensional (3D) structure with 3, 4-connected net structure. Compound 2 possess 3D networks with 3D→3D two interpenetration frameworks. Compound 3 is a 3D sheet structure with the decorated tfz-d topology. Compound 4 is a 3D structure which consists of 2D Mn honeycomb net with infinite six Mn rings and BCPBA3- ligands. Compound 5 is also a 3D structure, while its 2D Mn honeycomb net with infinite eight Mn rings is difference from that of compound 4. The photochemical property of 1-3 is performed in the solid state at room temperature. Magnetic susceptibility measurements indicate that compounds 4 and 5 exhibit antiferromagnetic coupling between adjacent Mn(II) ions.

INTRODUCTION Metal-organic framework (MOF) have attracted considerable attention in recent years because of their potential applications as functional materials in the areas of magnetism, sensors, gas adsorption, ion exchange, catalysis as well as the intriguing nature of molecular connectivities and topologies.1-4 Multicarboxylate ligands are

ACS Paragon Plus Environment

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often selected as multifunctional organic linkers because of their abundant coordination modes to metal ions, allowing for various structural topologies.6 Recently, nonrigid ligands are usually the typical building elements in the multidimensional networks. The conformational freedom nature of the flexible ligand may provide more possibility for the construction of unusual topology structures and microporous coordination polymers. Now, a new trend in this field is to add functionalities other than porosity to these materials to achieve multifunctional materials.5 Therefore, 3,5-bi(4-carboxy-phenoxy)-benzoic acid (H3BCPBA) triangular flexible ligand7 can be considered to be an excellent candidate for the preparation of functional coordination polymers. This ligand has three obvious characteristics: first, H3BCPBA adopt various coordination modes when they coordinate to metals and thus may produce various structural topologies, owing to their tridentate carboxylate arms and their flexible structures; second, the carboxylic groups can change luminescent properties with Cd metal centers; third, the carboxylic groups can propagate magnetic super exchange between Mn metal centers. The creation of a porous magnet is a long-sought academic goal since magnetism and porosity are hostile to one another. 8 Past studies have shown three solutions to this antagonism: to use rigid open-shell organic radicals as polytopic ligands; to connect the polymetal units through rigid linkers; to link infinite M-O-M connectivies through flexible aliphatic dicarboxylate ligands.8b In addition, for attaining novel structure, mixed-ligands are also a good choice for the construction of new polymeric structures. 8-9 With the aim of understanding the coordination chemistry of this versatile ligand and preparing new materials with interesting structural topologies and physical properties, H3BCPBA is selected to react with the d-block metal ion Cd(II)/Mn(II), and

successfully

synthesized

compounds

1-5,

namely,

{[Cd3

(BCPBA)2·(DMA)2·(H2O)5]·7H2O·2DMA}n (1), {[Cd3(BCPBA)2(L1) (H2O)6]·(L1)}n (L1

=

4-[(E)-4-Pyridinylazo]pyridine)

(DMF)2]·2DMF}n

(L2

=

(2),

{[Cd3(BCPBA)2

1,3-bis(4-pyridyl)propane)

(3),

(L2)·(H2O)3

{[Mn3 (BCPBA)2

(H2O)4]·11H2O}n (4). {[Mn3(BCPBA)2(DMF)2(H2O)2]·2DMF·9H2O}n (5). Five new


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compounds have been characterized by elemental analysis, IR spectra, TG and X-ray crystallography. The crystal structures, topological analyses, magnetic properties, and thermal properties are studied in detail.

Scheme 1: The Pyridine and Carboxylic-substituted Tripodal Carboxylate Ligands

Scheme 2: Crystallographically Established Coordination Modes of Carboxylic Groups in Compounds 1-5. EXPERIMENTAL SECTION Materials and Methods. The reagents and solvents employed were commercially available and used as received. H3BCPBA was synthesized according to a similar reported method.10 IR absorption spectra of the complexes 1-5 were recorded in the range of 400–4000 cm-1 on a Nicolet (Impact 410) spectrometer with KBr pellets (5 mg of sample in 500 mg of KBr). C, H, and N analyses were carried out with a Perkin–Elmer 240C elemental analyzer. Powder X-ray diffraction (PXRD) measurements were performed on a Bruker D8 Advance X-ray diffractometer using Cu–Kα radiation (λ = 1.5418 Å), in which the X-ray tube was operated at 40 kV and 40 mA. Solid-state UV-vis diffuse reflectance spectra was obtained at room


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temperature using a Shimadzu UV-3600 double monochromator spectrophotometer, and BaSO4 was used as a 100% reflectance standard for all materials. Luminescent spectra

were

recorded

with

a

SHIMAZUVF-320

X-ray

fluorescence

spectrophotometer at room temperature. The as-synthesized samples were characterized

by

thermogravimetric

analysis

(TGA)

on

a

Perkin

Elmer

thermogravimetric analyzer Pyris 1 TGA up to 1023 K using a heating rate of 10 K min-1 under N2 atmosphere. The magnetic susceptibilities were measured on polycrystalline samples in 2-300 K temperature range for complexes 4 and 5 with a Quantum Design superconducting SQUID magnetometer. Pascal’s constants were used to determine the constituent atom diamagnetism. Syntheses of 1-5 {[Cd3(BCPBA)2·(DMA)2·(H2O)5]·7H2O·2DMA}n

(1).

A

mixture

of

Cd(NO3)2·6H2O (29.1 mg, 0.1 mmol), H3BCPBA (39.4 mg, 0.1 mmol) was added to in 8 mL of DMA/H2O (1:3, v/v). The final mixture was placed in a Parr Teflon-lined stainless steel vessel (15 mL) under autogenous pressure and heated at 95 °C for 3 d, colorless crystals were obtained. (Yield: 40% based on Cd). Anal. Calcd for C58H82 Cd3N4O32: C, 41.35, H, 4.91, N, 3.33; found C, 41.54, H, 4.82, N, 3.46. IR (KBr, cm-1): 3410(w), 1658(w), 1606(m), 1562(s), 1394(m), 1222(m), 1165(m), 988(m), 778(m). {[Cd3(BCPBA)2(L1)(H2O)6]·(L1)}n (2). Compound 2 was prepared by a procedure similar to that for the preparation of compound 1 by using Cd(NO3)2·6H2O (29.1 mg, 0.1 mmol), H3BCPBA (39.4 mg, 0.1 mmol), and L1 (15.6 mg, 0.1 mmol) in 8 mL DMF/H2O (1:1, v/v). Colorless crystals were obtained (Yield: 66% based on Co). Anal. Calcd for C62H50Cd3N8O22: C, 46.65, H, 3.16, N, 7.02; found C, 46.48, H, 3.25, N, 7.31. IR (KBr, cm-1): 3416(m), 1667(w), 1596(w), 1547(m), 1496(s), 1394(s), 1235(s), 1152(s), 1081(m), 1009(s), 869(w), 829(w), 785(m), 715(w), 632(s), 516(m). {[Cd3(BCPBA)2(L2)·(H2O)3(DMF)2]·2DMF}n (3). Compound 3 was prepared by a procedure similar to that for the preparation of compound 1 by using Cd(NO3)2·6H2O (29.1 mg, 0.1 mmol), H3BCPBA (39.4 mg, 0.1 mmol) and L2 (23.3


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mg, 0.1 mmol) in 8 mL DMF/H2O (1:3, v/v). A large quanitity of colorless crystals were obtained. (Yield: 53% based on Cd). Calcd for C67H70Cd3N6O23: C, 48.34, H, 4.24, N, 5.05; found C, 48.48, H, 4.36, N, 5.26. IR (KBr, cm-1): 3379(m), 3045(s), 2925(m), 1669(s), 1591(s), 1556(m), 1497(m), 1395(s), 1223(m), 1161(m), 1063(m), 1008(w), 858(m), 783(s), 673(m). {[Mn3(BCPBA)2(H2O)4]·11H2O}n (4). Compound 4 was prepared by using Mn(NO3)2·6H2O (29.1 mg, 0.1 mmol), H3BCPBA (39.4 mg, 0.1 mmol) in 8 mL H2O (pH=7). The final mixture was placed in a Parr Teflon-lined stainless steel vessel (15 mL) under autogenous pressure and heated at 120 °C for 3 d. Colorless crystals were obtained (Yield: 66% based on Mn). Anal. Calcd for C42H52Mn3O31: C, 41.42, H, 4.30; found C, 41.58, H, 4.45. IR (KBr, cm-1): 3416(m), 1671(w), 1596(w), 1551(m), 1506(s), 1402(s), 1285(s), 1225(w), 1165(s), 1119(m), 998(s), 858(w), 749(m), 705(w), 639(s), 516(m). {[Mn3(BCPBA)2(DMF)2(H2O)2]·2DMF·9H2O}n (5). Compound 5 was prepared by using Mn(NO3)2·6H2O (29.1 mg, 0.1 mmol), H3BCPBA (39.4 mg, 0.1 mmol) containing 4′,4-bipy (15.6 mg, 0.1 mmol) in 8 mL DMF/H2O (3:1, v/v). The final mixture was placed in a Parr Teflon-lined stainless steel vessel (15 mL) under autogenous pressure and heated at 95 °C for 3 d. Colorless crystals were obtained (Yield: 66% based on Mn). Anal. Calcd for C54H72Mn3N4O31: C, 45.10, H, 5.04, N, 3.89; found C, 45.28, H, 5.14, N, 3.85. IR (KBr, cm-1): 3446(m), 1686(w), 1603(w), 1547(m), 1506(s), 1402(s), 1295(s), 1225(w), 1165(s), 1119(m), 998(s), 858(w), 749(m), 705(w), 639(s), 516(m).

X-ray Data Collection and Structure Determinations. Single crystals of 1-5 were prepared in single crystal form. X-ray crystallographic data of 1-5 were collected at room temperature using epoxy-coated crystals mounted on glass fiber. All measurements were made on a Bruker Apex Smart CCD diffractometer with graphite-monochromated Mo-Kα radiation (λ = 0.71073 Å). The structures of complexes 1-5 were solved by direct methods, and the non-hydrogen atoms were located from the trial structure and then refined anisotropically with SHELXTL using


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a full-matrix least-squares procedures based on F2 values.11a The hydrogen atom positions were fixed geometrically at calculated distances and allowed to ride on the parent atoms. The distribution of peaks in the channels of 4 and 5 was chemically featureless to refine using conventional discrete-atom models. To resolve these issues, the contribution of the electron density by the remaining water molecule was removed by the SQUEEZE routine in PLATON.11b The relevant crystallographic data are presented in Table 1, while the selected bond lengths and angles are given in Supporting Information, Table S1.

RESULTS AND DISCUSSION Synthesis and Spectral Characterization. Compounds 1-5 are prepared in single crystalline through the hydrothermal reaction of Cadmium/Manganous nitrate, H3BCPBA, L1 and L2. It should be pointed out that compounds 1-5 are highly reproducible for repeated synthesis under the reaction conditions employed in this work. The infrared spectra of all of the compounds are consistent with their crystal structures (Figures S1–5). For all complexes, the absorption bands in the 1400-1600 cm-1 region and in 1454-1348 cm-1 show the skeletal vibrations of the aromatic ring for asymmetric vibration and for the symmetric vibration, respectively. The vibrations bands in the 3400 cm-1 and 1671-1660, and 1607-1602 cm-1 indicate the presence of H2O, DMF and -COO-, respectively. Phase purity is confirmed by elemental analysis and powder XRD (Figures S6-10). All compounds do not dissolve in water and common organic solvents. Crystal structures and Net works. X-ray analysis reveals that 1 crystallized in monoclinic space group C2/c. As shown in Figure 1a, 1 consists of one and a half crystallographically independent Cd(II) ions, one BCPBA3- ligand, one DMA and three coordinated water molecules. The deprotonated BCPBA3- anions adopt a bidentate chelating coordination mode to bridge three Cd centers (Scheme 2a). Cd1 is seven coordinated by four carboxylate oxygen atoms from two BCPBA3- ligand and three O atoms from three water molecules to form octahedral coordination geometry. The distances of O and Cd


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range from 2.260 to 2.470 Å, which falls in the usual range for similar Cd complexes.12 The angle of Cd1-µ2-O-Cd1# is 124.163° and the distance of Cd1 (Cd1#)-µ2-O is 2.4009 (2.4698) Å. Cd2 is also seven coordinated by four carboxylate oxygen atoms from two BCPBA3- ligand, one oxygen atom from water and two oxygen atoms from two DMA molecules. As shown in Figure 2b, compound 1 generates a 3D framework with one-dimensional (1D) channel through such coordination mode, and the void volume calculated by PLATON

13a

is 49.5%. A better insight into the nature of this intricate

framework can be achieved by the application of a topological approach, reducing multidimensional structures to simple node and connection nets. Cd1 can be regarded as one kind of linkers, with the BCPBA3- considered as the other linker. Thus, the BCPBA3- ligand acts as 3-connected node, Cd1 can be regarded as 4-connected node. So, the total topology of 1 can be considered to be a 2-nodal (3, 4)-connected net, and Schläfli symbol is (63)( 65.8), as displayed in Figure 1e, and the topological type is jeb. X-ray analysis reveals that 2 crystallize in monoclinic space group P21/n. The asymmetric unit of 2 contains one and a half independent Cd(II) cation, one BCPBA 3anion, two coordinated H2O, one µ2-O from H2O，a half bpe ligand and free a half bpe ligand. As shown in Figure 2a, Cd1 center is six coordinated by two carboxylic O atoms from two BCPBA3- ligands, one N atoms from one bpe ligand, one µ2-O from one water molecules and two water molecules to form a octahedron geometry. Cd2 center is six coordinated by four carboxylic O atoms from four BCPBA3- ligands and two µ2-O from two water molecules to form a octahedron geometry. The BCPBA3anions adopt two coordination modes: one carboxyl group adopts a bis(monodentate) coordination mode to bridge two Cd centers, the other two carboxylate group adopts a monodentate coordination mode (Scheme 2b). The Cd-O lengths are in the range of 2.187(3)-2.353(3) Å, and the Cd-N length is 2.294(4) Å. The angle of Cd1-µ2-O-Cd2 is 110.796°, and the distance between Cd1 and Cd2 is 3.8521 Å. Compound 2 reveals this structure possessing a two-fold interpenetrating 3D→3D network constructed with a unique building block, [Cd3(BCPBA3-)6], as shown in Figure 2f. Each of the three Cd(II) atoms were bridged by two water molecules to


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form an trinuclear cluster with Cd···Cd separation of 3.852(1) Å. The Cd3 unit, which acts as a node, is connected to six adjacent nodes through six H3BCPBA ligands to form a 2D layer parallel to the ab plane. The remaining coordination sites of the two Cd1 centers in each building block are occupied by nitrogen atoms of bpe ligands that act as pillars, and which bind the adjacent 2D layers to generate a pillared 3D framework. Such a pillared 3D structure composed of “double” metal-carboxylate layers is rare.14 Two of these pillared 3D motifs, identical in structure, interpenetrate to yield a new type of catenated network consisting of large, open, 1D channels. To fully appreciate the structure and its topology, it is necessary to consider that Cd2 atom can be regarded as one kind of linker because the Cd2 atom is located in a symmetrical position to link four Cd1 atoms, and the H3BCPBA and bpp ligands considered as another two kinds of linkers. Thus H3BCPBA ligands and two Cd1 atoms surrounding a Cd2 center constitute an eight-connected octahedral SBU. According to this simplification, the topology of this 3D network can be described as a (43)2(46.618.84), and the topological type is tfz-d (Figure 2e). When bpp was replaced by bpe, a structurally different complex 3 is obtained. X-ray analysis reveals that compound 3 is solved in orthorhombic space group Pna21. As shown in Figure 3a, 3 consists of three crystallographically independent Cd(II) ions, two BCPBA3- ligands, one L1 ligand, one µ2-H2O, two coordinated water molecules and two DMF molecules. The wholly deprotonated BCPBA3- anion adopts a bidentate chelating coordination mode to bridge three Cd centers (Scheme 2a). Cd1 is seven coordinated by four carboxylate oxygen atoms from two BCPBA3- ligand (2.240 to 2.353 Å), one N atom from L1 (2.308 Å) and two µ2-O atoms from two water molecules (2.441 and 2.450 Å) to form octahedral coordination geometry. Cd2 is also seven coordinated by four carboxylate oxygen atoms from two BCPBA3ligands, two oxygen atoms from water and one N atom from L1 molecule. In compound 3, there are two kinds bridge O (water): the angle of Cd1-µ2-O(2w)-Cd2 and Cd1-µ2-O(3w)-Cd2 is 127.216°, 123.123°, and the distances are 2.4271 (2.4467) and 2.4709 (2.4276) Å. Cd3 is also seven coordinated by four carboxylate oxygen atoms from two BCPBA3- ligands (2.320 to 2.431 Å), two oxygen atoms from DMF


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molecules (2.320 and 2.375 Å) and one O atom from one water molecule (2.276 Å) to form octahedral coordination geometry. As shown in Figure 3b, compound 3 generates a 3D framework with one-dimensional (1D) channel through such coordination mode. For avoiding overlapn in the compound 3, L2 ligand is omitted in order to make this structure clarity and simplify (Figure 3c). As shown in Figure 3c, complex 1 and 3 are similar and all posses a homogeneous channel with 3D structure when L2 ligand is omitted. In addition, it is interesting that L2 ligand as nog is connected with Cd atoms and divided quadrangle into two groups, so these cavities in 3 are smaller than that of 1. To fully appreciate the structure and its topology, it is necessary to consider that the H3BCPBA and L2 ligand can be regarded as two kinds of linker, Cd1 and Cd2 considered as another two kinds of linkers. Thus, the BCPBA3- ligand acts as 3-connected node, L2 ligand acts as 2-connected node, Cd1 and Cd2 can be regarded as 5-connected node. According to this simplification, the topology of this 3D network can be described as a (42.68)2(42.6) (Figure 3d). X-ray analysis reveals that compound 4 is solved in monoclinic space group C2/c. As shown in Figure 4a, 4 consists of one and a half crystallographically independent Mn(II) ions, two BCPBA3- ligand and three water molecules. The wholly deprotonated BCPBA3- anion adopts take different coordination modes to bridge Mn centers (Scheme 2c). Mn1 is six coordinated by five carboxylate oxygen atoms from five BCPBA3- ligands (2.133 to 2.226 Å) and one oxygen atom from water molecule (2.173 Å) to form octahedral coordination geometry. Mn2 is six coordinated by four carboxylate oxygen atoms from four BCPBA3- ligands and two oxygen atoms from two water molecules. The distance between Mn1 and Mn2 are 3.7827 and 5.8749 Å, respectively. From Figure b and c, it can be seen that compound 4 is a 3D structure which is consist of 2D Mn plane and BCPBA3- ligands. It is an interesting that two flexible carboxyl of BCPBA3- ligands are coordinated with Mn to form a 2D honeycomb layer but not a chain, and this 2D Mn plane consists of infinite six Mn rings. Although such 2D honeycomb layer exist in the metal oxalate layered compounds,8b,15 it should be noted that it is uncommon among the three-dimensional


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OCO bridged Mn atoms. As shown in Figure 4b, compound 4 generates a 3D framework with one-dimensional (1D) channel through such coordination mode, and the void volume calculated by PLATON is 10.7%. X-ray analysis reveals that compound 5 is solved in monoclinic space group C2/c. As shown in Figure 5a, 5 consists of one and a half crystallographically independent Mn(II) ions, two BCPBA3- ligand, two DMF molecules and two water molecules. The wholly deprotonated BCPBA3- anion adopts take different coordination modes to bridge Mn centers (Scheme 2d). Mn1 is six coordinated by five carboxylate oxygen atoms from four BCPBA3- ligands (2.020 to 2.451 Å) and one O atom from water molecule (2.281 Å) to form octahedral coordination geometry. Mn2 is six coordinated by four carboxylate oxygen atoms from four BCPBA3- ligands and two oxygen atoms from two DMF molecules. Compound 5 is a 3D structure which is same to compound 4, but there is a difference that 2D Mn honeycomb layer net consists of infinite eight Mn rings. As shown in Figure 5b, compound 5 generates a 3D framework with one-dimensional (1D) channel through such coordination mode, and the void volume calculated by PLATON is 17.2%. From the structural descriptions above, it can be seen that the neutral ligands have an influence on the final frameworks of the compounds 1-3. As shown in Scheme 2, the BCPBA3- with flexibilities in 1-3 display difference bridging coordination modes ( a and b in Scheme 2, respectively). When the Cd salt was replaced by Mn salt, it is surprising to find that 2D honeycomb layer is obtained in compounds 4 and 5, which shows that the cations also play an important role in the assembly process reaction process.

PXRD and TG Results. To confirm whether the crystal structures are truly representative of the bulk materials, PXRD experiments were carried out for 1-5. The PXRD experimental and computer-simulated patterns of the corresponding complexes are shown in Supporting Information (Figures S6-10). They show that the synthesized bulk materials and the measured single crystals are the same. To estimate the stability of the coordination architectures, 1-5 thermal behaviors


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were studied by TGA (Supporting Information, Figure S11). For complex 1, a weight loss of 25.08 % (calcd 25.10 %) are observed from 50 to 248 °C, which is attributed to the loss of the free and the coordinated water molecules (166-202 °C), and decomposed quickly after 363 °C, suggesting that the framework is thermally stable. For complex 2, a weight loss of 7.8 % are observed from 129 to 152 °C, which is attributed to the loss of the coordinated water and free ligand, and then it is decomposed quickly after 340 °C. For complex 3, a weight loss of 20.78 % (calcd 21.25 %) is observed from 128.1 to 182°C, which is attributed to the loss of the coordinated water, DMF and the free DMF molecules, next the structure is collapsed since 384 °C. For complex 4, a weight loss of 22.10 % (calcd 22.17 %) are observed from 30 to 350 °C, which is attributed to the loss of the coordinated water and free water, and then it is decomposed quickly after 480 °C. For complex 5, a weight loss of 21.8 % (calcd 21.45 %) are observed from 30 to 352 °C, which is attributed to the loss of the coordinated water, DMF and the free molecules, and then it is decomposed quickly after 480 °C.

Photochemical Properties. All UV-vis absorption spectra for both free ligands and complexes 1-3 were recorded in reflectance mode in solid state at room temperature as shown in Figure 6a. The absorption maxima of 1-3 are slight red-shifted as compared to those of the corresponding free ligands. This phenomenon is due to no d-d electron transitions of three complexes because of d10 structures, so the absorption maxima of 1-3 only show the electron absorption (π→π*) of ligands. Figure 6b and Figures S14-16 show the excitation and emission spectra for both the free ligands and compounds 1 and 3 in the solid state at room temperature. The excitation maxima for H3BCPBA and L2 are at λmax 364 and 371 nm, and the maxima emission spectra are at 410, 430 and 446 nm (shoulder peak), respectively, which are consistent with those of absorption in UV-vis spectra. While, compound 1 shows a blue-shift in emission at λem = 387 nm when λex =347 nm, the differences observed in the electronic spectra for 1 and H3BCPBA have their origins in a number of factor which mainly comes from the ILCT (intra ligand charge transfer) and at the same time


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exists L→M(4S) transfer. With tuning from single ligand to mixed ligand, the luminescent properties have corresponding changed. Comparing with H3BCPBA, compound 3 shows a red-shift in emission at λem = 443 nm when λex =328 nm, which may be probably caused by a change in the HOMO and LUMO energy levels of deprotonated H3BCPBA anions and neutral ligands coordinating to metal centers, a charge-transfer transition between ligands and metal centers, and a joint contribution of the intraligand transitions or charge-transfer transitions between the coordinated ligands and the metal centers16. It is noted that the excitation and emission spectra of compound 2 shows multiple peaks and is similar to that of ligand L1, which is connected with coordinated ligand and free ligand in this structure (Figure S17-18).

Magnetic properties. The frameworks of Mn(II) centers (4 and 5) provide a good opportunity for investigating an effective magnetic property through single O and carboxylate oxygen bridges, although organized into dramatically different supramolecular structures. The temperature dependence of magnetic susceptibility data for 4 is shown in Figure 7 in the form of χM and χMT versus T plots. At room temperature, χMT is 13.07 cm3 mol-1 K. Upon cooling, χMT rapidly decreases and is 0.4611 cm3 mol-1 K at T = 2 K. The χM slowly increases from 0.04356 at 300 K to 0.46109 cm3 mol-1 at 2 K. These features are characteristic of an overall antiferromagnetic behavior. From a magnetic viewpoint, it can be seen that the overall antiferromagnetic interaction should be mainly attributed to the single O and carboxylate oxygen bridges. According to the 2D Mn honeycomb layer molecular structures of 4, no appropriate model could be used for fitting the magnetic properties of such a system. While the magnetic properties of 4 obey the Curie-Weiss law and give C = 14.3(0) cm3 mol-1 K and θ = -26.9(2) K. The negative θ values indicates significant antiferromagnetic interactions exist between neighboring Mn(II) ions. Comparing with some honeycomb layer bimetallic oxalate-bridged compounds exhibiting spin-canted weak ferromagnetism under 5-10 K, 4 only exhibits antiferromagnetic interaction, which is probably due to the different dimensionality between some bimetallic compounds


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based on oxalate-bridged and compound 4 15,17. The χM and χMT vs. T plots for 5 are shown in Figure 8. Upon cooling, χMT decreases smoothly from 13.01 cm3 mol-1 K at 300 K to a minimum of 1.17 cm3 mol-1 K at 1.8 K. The χM slowly increases from 0.04333 at 300 K to 0.58823 cm3 mol-1 at 2 K, which suggests a dominant antiferromagnetic exchange interaction. Fitting the curves gives the parameters C = 13.7(2) cm3 mol-1 K and θ = -14.7(6) K. It should be noted that the magnetic properties of compound 5 is similar to that of compound 4. However, the parameters of C and θ have a difference because of their structures: first, there is a difference between this 2D Mn plane with infinite six Mn rings (compound 4) and 2D Mn honeycomb layer net with infinite eight Mn rings (compound 5); second, H3BCPBA ligand adopts a difference bridging modes (Scheme 2) which can change their magnetic super exchange pathway. Above causes led to similar magnetic properties with different parameters of C and θ values between compound 4 and 5.

CONCLUSION In conclusion, five novel coordination polymers with different structures have been synthesized by the self-assembly of Cd/Mn salt with H3BCPBA in the presence or absence of auxiliary ligands. These results show that the adjusting of the link’s shapes caused by different coordination modes is good for diversity of the produced structures. Compound 1 is a three-dimensional (3D) structure with 3, 4-connected net structure. Compound 2 possess three-dimensional (3D) networks with 3D→3D two interpenetration frameworks and the decorated tfz-d topology. Compound 3 is a 3D sheet structure with the decorated tfz-d topology. Compound 4 and 5 are 3D structures which are consists of 2D Mn honeycomb net and BCPBA3- ligands. In addition, magnetic susceptibility measurements indicate that compounds 4 and 5 exhibit antiferromagnetic coupling between adjacent Mn(II) ions. Next works will be focuses on the structures and properties of a series of coordination complexes constructed by H3BCPBA ligand with more auxiliary ligands and metal ions.

ASSOCIATED CONTENT


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Supporting Information. Five X-ray crystallographic files in CIF format, selected bond lengths, angles, UV absorbance, TGA, PXRD and IR in PDF format. This information is available free of charge via the Internet at http://pubs.acs.org.

AUTHOR INFORMATION *E-mail: [email protected]. Fax: 86-25-83314502.

ACKNOWLEDGMENT This work was financially supported by the Natural Science Foundation of China (Nos.91022011; 20971065; 21021062) and National Basic Research Program of China (2010CB923303).

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(5) (a) Rogez, G.; Massobrio, C.; Rabu, P.; Drillon, M. Chem. Soc. Rev., 2011, 40, 1031. (b) Wu, C. D.; Hu, A.; Zhang, L.; Lin, W. J. Am. Chem. Soc. 2005, 127, 8940. (c) Wang, Z.; Zhang, B.; Fujiwara, H.; Kobayashi, H.; Kurmoo, M. Chem. Commun. 2004, 416. (6) (a) Lu, Z. Z.; Zhang, R.; Li, Y. Z.; Guo, Z. J.; Zheng, H. G. J. Am. Chem. Soc. 2011, 133, 4172. (b) Ma, L. Q.; Jin, A.; Xie, Z. G.; Lin, W. B. Angew. Chem., Int. Ed., 2009, 48, 9905; (c) Zhang, Y. B.; Zhang, W. X.; Feng, F. Y.; Zhang, J. P.; Chen, X. M. Angew. Chem., Int. Ed., 2009, 48, 5287; (d) Thallapally, P. K.; Tian, J.; Kishan, M. R.; Fernandez, C. A.; Dalgarno, S. J.; McGrail, P. B.; Warren, J. E.; Atwood, J. L. J. Am. Chem. Soc., 2008, 130, 16842. (7) (a) Cui, J. H.; Li, Y. Z.; Guo, Z. J.; Zheng, H. G. Chem. Commun., 2013,49, 555; (b) Cui, J. H.; Li, Y. Z.; Guo, Z. J.; Zheng, H. G. Cryst.Growth Des. 2012, 12, 3610. (8) (a) Xiang, S. C.; Wu, X.; Zhang, J. J.; Fu, R. B.; Hu, S. M.; Zhang, X. D. J. Am. Chem. Soc., 2005, 127, 16352. (b) Sadakiyo, M.; Ōkawa, H.; Shigematsu, A.; Ohba, M.; Yamada, T.; Kitagawa, H. J. Am. Chem. Soc., 2012, 134, 5472. (9) (a) Dai, F. R.; Ye, H. Y.; Li, B.; Zhang, L. Y.; Chen, Z. N. Dalton Trans., 2009, 8697; (b) Constable, E. C.; Housecroft, C. E.; Neuburger, M.; Reymann, S.; Schaffner, S. CrystEngComm., 2008, 10, 991; (c) Schottel, B. Chifotides, H. T.; Shatruk, M.; Chouai, A.; Pérez, L. M.; Bacsa, J.; Dunbar, K. R. J. Am. Chem. Soc., 2006, 5895. (d) Fang, S. M. ; Zhang, Q. ; Hu, M. ; Saňudo, E. C. ; Du, M.; Liu, C. S. Inorg. Chem., 2010, 49, 9617 ; (e) Zhang, J. J.; Wojtas, L.; Larsen, R. W. ; Eddaoudi, M.; Zaworotko, M. J. J. Am. Chem. Soc., 2009, 131, 17040. (10) Matsumoto, K.; Higashihara, T.; Ueda, M. Macromolecules. 2008, 41, 7560. (11) (a) Bruker 2000, SMART (Version 5.0), SAINT-plus (Version 6), SHELXTL (Version 6.1), and SADABS (Version 2.03); Bruker AXS Inc.: Madison, WI. (b) Platon Program:Spek, A. L. Acta Crystallogr., Sect. A 1990, 46,194. (12) Dai, J. C.; Wu, X. T.; Fu, Z. Y.; Cui, C. P.; Hu, S. M.; Du, W. X.; Wu, L. M.; Zhang, H. H.; Sun, R. Q. Inorg. Chem. 2002, 41, 1391. (13) (a) Spek, A. L. J. Appl. Crystallogr. 2003, 36, 7. (b) Devic, T.; Serre, C.;


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Audebrand, N.; Marrot, J.; Férey, G. J. Am. Chem. Soc. 2005, 127, 12788. (c) Zhang, J. P.; Lin, Y. Y.; Zhang, W. X.; Chen, X. M. J. Am. Chem. Soc. 2005, 127, 14162. (14) Omar M. Yaghi, Michael O’Keeffe, Nathan W. Ockwig, Hee K. Chae, Mohamed Eddaoudi, Jaheon Kim. Nature., 2003, 423, 705. (15) Okawa, H.; Shigematsu, A.; Sadakiyo, M.; Miyagawa, T.; Yoneda, K.; Ohba, M.; Kitagawa, Hiroshi. J. Am. Chem. Soc., 2009, 131, 13516. (16) (a) Allendorf, M. D.; Bauer, C. A.; Bhakta, R. K.; Houk, R. J. T. Chem. Soc. Rev. 2009, 38, 1330. (b) Guo, H. D.; Guo, X. M.; Batten, S. R.; Song, J. F.; Song, S. Y. Dang, S.; Zheng, G. L.; Tang, J. K.; Zhang, H. J. Cryst. Growth Des. 2009, 9, 1394. (c) Cui, J. H., Lu, Z. Z., Li, Y. Z., Guo, Z. J., Zheng, H. G. Cryst. Growth Des. 2012, 12, 1022. (17) (a) Wang, X. T.; Wang, Z. M.; Gao, S. Inorg. Chem. 2007, 46, 10452. (b) Xiang, S. C.; Wu, X. T.; Zhang, J. J.; Fu, R. B.; Hu, S. M.; Zhang, X. D. J. Am. Chem. Soc., 2005, 127, 16352.

Table 1．．Crystallographic Data and Structure Refinement Details for Compounds 1-5.

compounds

1

2

3

4

5

C50H50Cd3N2O23

C64H52Cd3N6O22

C67H70Cd3N6O23

C42H30Mn3O20

C48H40Mn3N2O20

1384.15

1596.33

1664.52

1019.48

1129.64

crystal system

Monoclinic

Monoclinic

Orthorhombic

Monoclinic

Monoclinic

space group

C2/c

P21/n

Pna21

C 2/c

C 2/c

a (Å)

46.414(16)

17.278(3)

36.680(15)

16.488(3)

27.430(4)

b (Å)

5.908(2)

11.0227(18)

5.819(2)

9.4509(15)

21.601(3)

c (Å)

33.320(9)

18.580(3)

33.079(14)

27.363(4)

9.3796(12)

α (deg)

90

90.00

90

90

90

β (deg)

128.581(16)

116.817(2)

90

102.758(3)

106.412(2)

γ (deg)

90

90.00

90

90

90

Z

4

2

4

4

4

empirical formula formula weight


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V (Å3)

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7143(4)

3158.0(9)

7060(5)

4158.6(12)

5331.1(13)

Dcalcd(g cm )

1.287

1.679

1.566

1.628

1.408

µ(Mo Ka)(mm-1)

0.948

1.087

0.976

0.982

0.775

F(000)

2768.0

1596.0

3368.0

2068.0

2308.0

R(int)

0.0784

0.0774

0.0240

0.0786

0.0505

6984

6118

13566

3660

6236

0.0553/0.1011

0.0348/0.896

0.0429/0.1066

0.0448/ 0.1051

0.0496/ 0.1250

1.083

1.059

1.017

1.051

1.032

-3

observed data [I > 2σ(I)] R1,wR2 ( I > 2σ(I)) S

Figure 1. (a) Coordination environment of the Cd(II) ions in 1. The hydrogen atoms are omitted for clarity. (b) Views of 1 D framework by water molecules and Cd ions. (c) The connect modes


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of two Cd(II). (d) Schematic representation of the 3D framework. (e) Schematic representation of the (3, 4) topological net.

Figure 2. (a) Coordination environment of the Cd(II) ions in 2. The hydrogen atoms are omitted for clarity. (b) Views of 3 D framework by BCPBA3- and Cd ions. (c) and (d) Schematic representation of the 3D→3D framework by two identical sheets. (e) Schematic representation of the (3, 8) topological net. (f) Trinuclear Cd cluster formed in compound 2.


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Figure 3. (a) Coordination environment of the Cd(II) ions in 3. The hydrogen atoms are omitted for clarity. (b) Views of 3 D framework by BCPBA3-, bpe and Cd ions. (c) Views of 3 D framework by BCPBA3- and Cd ions. (d) The topology network of this 3D structure.


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Figure 4. (a) Coordination environment of the Mn(II) ions in 4. The hydrogen atoms are omitted for clarity. (b) Views of 3 D framework by BCPBA3- and Mn ions. (c) The honeycomb layer 2D structure.


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Figure 5. (a) Coordination environment of the Mn(II) ions in 5. The hydrogen atoms are omitted for clarity. (b) Views of 3 D framework by BCPBA3- and Mn ions. (c) The honeycomb layer 2D structure.

1.5

(b)

1 H3PBCBA

(a)

1

3

Intensity

3 2

1.0 A 0.5

250 300 350 400 450 500 550 600

200 300 400 500 600 700 800 900

Wavelength/nm

Wavelength/nm

Figure 6. The diffuse reflect solid-state UV/Vis spectra of free ligands and compounds 1-3 (a) and the photoemission spectra of 1 and 3 (b). 14

0.5 0.4

25

χ m-1/emu -1 mol

10

20

8

0.3

15

6

10

4

0.2

5 50

2

100

150

200

250

300

0.1

T/K

0 0

50

100 150 200 250 300

χ M / cm3 mol-1

χ MT / cm3 K mol-1

12

0.0

T/K

Figure 7. Temperature dependence of magnetic susceptibility in the form χmT, χm and 1/χmT (inset) for compound 4. The red line shows the best-fit curve to the Curie-Weiss fit law.

14

0.6

12 χ m-1 /emu -1 mol

20

8

0.4

15

6

0.3

10

4

0.2

5 50

2 0

100

150

200

250

300

T/K

0

50

100 150 200 250 300 T/K


0.1 0.0

χ M / cm3 mol-1

0.5

25

10 χ MT / cm3 K mol-1

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


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Figure 8. Temperature dependence of magnetic susceptibility in the form χmT, χm and 1/χmT (inset) for compound 5. The red line shows the best-fit curve to the Curie-Weiss fit law.


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For Table of Contents Use Only

Syntheses, Structures, Photochemical and Magnetic Properties of Novel Divalent Cd/Mn Coordination Polymers Based on Semi-rigid Tripodal Carboxylate Ligand Jiehu Cui, Qingxiang Yang, Yizhi Li, Zijian Guo and Hegen Zheng

Five new coordination polymers based on a tripodal carboxylate ligand have been synthesized. They possess different structures and topology types. Their photochemical and magnetic properties have been studied.


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Syntheses, Structures, Photochemical and Magnetic Properties of

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