OrganicâInorganic Hybrid Coordination Polymers Based on 6

CRYSTAL GROWTH & DESIGN

Organic–Inorganic Hybrid Coordination Polymers Based on 6-Methylpyridine-2,4-dicarboxylic Acid N-Oxide (MPDCO) Ligand: Preparations, Interpenetrating Structures, and Magnetic and Luminescent Properties

2007 VOL. 7, NO. 12 2526–2534

Jian-Guo Lin,† Yang Su,† Zheng-Fang Tian,† Ling Qiu,‡ Li-Li Wen,† Zhen-Da Lu,† Yi-Zhi Li,† and Qing-Jin Meng*,† Coordination Chemistry Institute, State Key Laboratory of Coordination Chemistry, School of Chemistry and Chemical Engineering, Nanjing UniVersity, 210093 Nanjing, P. R. China, and School of Chemical Engineering, Nanjing UniVersity of Science and Technology, 210094 Nanjing, P. R. China ReceiVed April 14, 2007; ReVised Manuscript ReceiVed October 8, 2007

ABSTRACT: Eight novel coordination polymers based on the 6-methylpyridine-2,4-dicarboxylic acid N-oxide (MPDCO) ligand, [M(MPDCO)(H2O)x]n (M ) Mn2+, x ) 1 (1); M ) Cu2+, x ) 2 (2)), [M(MPDCO)(bpy)(H2O) · (H2O)]n (M ) Co2+ (3), Ni2+ (4)), [M(MPDCO)(TPB)0.5(H2O) · (H2O)x]n (M ) Co2+(5), Ni2+ (6), Zn2+ (7), Cd2+ (8)) (bpy ) 4,4′-bipyridine, TPB ) 1,2,3,4-tetra(4-pyridyl)-butane) have been prepared and structurally characterized. Compounds 1 and 2 are both two-dimensional (2-D) layers, which are further stacked via strong interlayer hydrogen-bond interactions to form three-dimensional (3-D) supramolecular structures. Compounds 3 and 4, which contain 3-fold interpenetrating nets, are isostructural and feature 3-D (10,3)-d open frameworks. In isomorphous compounds 5–8, 2-D sheets with nonequivalent nodes of (42 · 62 · 82)(4 · 62)2 topology were constructed from metal cations, MPDCO, and the four-connecting ligand 1,2,3,4-tetra-(4-pyridyl)-butane (TPB). Then the inclined interpenetration of these 2-D sheets leads to 3-D porous architectures with rhombic channels that embody some disordered water molecules. Dominant antiferromagnetic coupling was observed in compounds 1, 3, and 4. The compounds 7 and 8 both exhibit strong fluorescent emissions in the solid state and may be suitable as candidates of blue-fluorescent materials. Introduction Over the few past decades, the chemistry of metal-organic frameworks (MOFs) has become an increasingly popular field of research.1 Metal-directed self-assembly to construct rigid and robust MOFs has provided an extensive class of solid materials with high stability and desired physical properties.2 Within this context, interpenetrating networks with optimal porous functionalities have attracted particular attention. The structures of interpenetrated arrays not only provide interesting topological types but also exhibit promising applications as superhard materials for their peculiar magnetic, optical, and catalytic properties, etc.3 As they are well-known, pyridine-dicarboxylic acids (PDCs) are good ligands for the preparation of high dimensional metal coordination polymers with exceptional physical properties.4–11 However, designing and controlling high-dimensional MOFs by employing their N-oxides as the ligands remains largely unexplored.12,13 A new ligand similar to PDCs, 6-methylpyridine-2,4-dicarboxylic acid N-oxide (MPDCO) (Chart 1), not only has a rigid planar structure containing two carboxylic acid groups arranged discretely around the pyridine ring like PDCs, but also has an O atom of the N-oxide group, which is a much better electron donor than the N atom of the PDCs.13 For the purpose of preparing novel materials with beautiful architectures and excellent physical properties, we start to elaborate novel coordination polymers constructed from MPDCO. Furthermore, pyridyl-based ligands of 4,4′bipyridine (bpy), 1,2,3,4-tetra-(4-pyridyl)-butane (TPB), and tetra-(4-pyridyl)-thiophene (TPT) (Chart 1) were introduced as auxiliary ligands in the syntheses. These long spacers of * To whom correspondence should be addressed. E-mail: [email protected]. † Nanjing University. ‡ Nanjing University of Science and Technology.

Chart 1

auxiliary ligands can often favor the formation of interpenetrating networks. The results of this present investigation provide eight interesting coordination polymeric complexes, namely, [M(MPDCO)(H2O)x]n (M ) Mn2+, x ) 1 (1); M ) Cu2+, x ) 2 (2)), [M(MPDCO)(bpy)(H2O) · (H2O)]n (M ) Co2+ (3), Ni2+ (4)), [M(MPDCO)(TPB)0.5(H2O) · (H2O)x]n (M ) Co2+ (5), Ni2+ (6), Zn2+ (7), Cd2+ (8)). Six complicated interpenetrating structures of them were successfully obtained when a long spacer of bpy or TPB was involved. To the best of our knowledge, complexes containing the MPDCO or TPB ligand have not been reported before. The magnetic and fluorescent properties have been investigated. To understand the origin of luminescence, density functional theory (DFT) calculations were also carried out on the experimental geometries of 7 and 8. Experimental Section Materials and Apparatus. All analytical reagents employed were purchased from commercial sources and used without further purification. Water used in the reactions is distilled water. The ligand, 6-methylpyridine-2,4-dicarboxylic acid, was synthesized by oxidizing 2,4,6-trimethylpyridine with the aqueous KMnO4 solution similar to the reported methods14 and was further N-oxidated according to the previous work.15 Tetra-(4-pyridyl)-thiophene was synthesized as reported previously16 and then was reductively desulfurated to get TPB.17

10.1021/cg070363b CCC: $37.00  2007 American Chemical Society Published on Web 11/15/2007

Organic–Inorganic Hybrid Coordination Polymers C, H, and N elemental analyses were performed on a Perkin-Elmer 240C elemental analyzer. The IR spectra were recorded on KBr pellets on a Bruker VECTOR 22 spectrophotometer in the region of 4000–400 cm-1. Magnetic susceptibility data on the powder-sample were collected over the temperature range of 1.8–300 K by using a Quantum Design MPMS7 superconducting quantum interference device magnetometer. Luminescence spectra for the solid samples were recorded with a Hitachi 850 fluorescence spectrophotometer. Thermogravimetric analyses (TGA) were performed on a simultaneous SDT 2960 thermal analyzer under flowing N2 with a heating rate of 10 °C/min between ambient temperature and 750 °C. Powder X-ray diffraction (XRD) patterns were recorded on a Rigaku D/max-RA rotating anode X-ray diffractometer with graphite monochromatic Cu KR (λ ) 1.542 Å) radiation at room temperature. Preparations. [M(MPDCO)(H2O)x]n (M ) Mn2+, x ) 1 (1); M ) Cu2+, x ) 2 (2)). A mixture of Mn(OAc)2 (17.3 mg, 0.1 mmol), MPDCO (19.7 mg, 0.1 mmol), TPT (19.6 mg, 0.05 mmol), NaOH (8.0 mg, 0.2 mmol), and H2O (6 mL) was heated at 120 °C for 3 days. After the mixture was slowly cooled to room temperature, colorless crystals of 1 were obtained (yield: 68% based on Mn). Anal. Calcd for C8H7MnNO6(268.09): C 35.84, H 2.63, N 5.22. Found: C 36.01, H 2.57, N 5.35%. IR (cm–1, KBr): 3396 (s), 3058 (m), 1671 (m), 1625 (s), 1598 (s), 1430 (m), 1414 (m), 1385 (s), 1369 (s), 1263 (w), 1231(w), 1204 (m), 1119 (m). An identical procedure with 1 was followed to prepare 2 except Mn(OAc)2 was replaced by Cu(NO3)2 · 3H2O (23.6 mg, 0.1 mmol) (yield: 75% based on Cu). Anal. Calcd for C8H9CuNO7(294.70): C 32.60, H 3.08, N 4.75. Found: C 32.49, H 3.31, N 4.62%. IR (cm-1, KBr): 3568 (s), 3423 (s), 1647 (s), 1601 (s), 1412 (m), 1356(s), 1261 (w), 1236 (w), 1210 (m), 1200 (m). [M(MPDCO)(bpy)(H2O) · (H2O)]n (M ) Co2+ (3), Ni2+ (4)). A mixture of Co(NO3)2 · 3H2O (23.7 mg, 0.1 mmol), MPDCO (19.7 mg, 0.1 mmol), 4,4′-bpy (15.6 mg, 0.1 mmol), NaOH (8.0 mg, 0.2 mmol), and H2O (8 mL) was heated at 120 °C for 3 days. After the mixture was slowly cooled to room temperature, pink crystals of 3 were obtained (yield: 57% based on Co). Anal. Calcd for C18H17CoN3O7(446.28): C 48.44, H 3.84, N 9.42. Found: C 48.19, H 3.97, N 9.36%. IR (cm–1, KBr): 3442 (s), 1635 (s), 1606 (s), 1558 (w), 1541 (w), 1491 (w), 1413 (w), 1360 (s), 1226 (w), 1200 (m). A procedure identical to that for 3 was followed to prepare 4 except Co(NO3)2 · 3H2O was replaced by Ni(NO3)2 · 3H2O (23.7 mg, 0.1 mmol) (yield: 61% based on Ni). Anal. Calcd for C18H17N3NiO7 (446.06): C 48.46, H 3.84, N 9.42. Found: C 48.62, H 4.03, N 9.27%. IR (cm–1, KBr): 3419 (s), 1625 (s), 1605 (s), 1559 (w), 1520 (s), 1436 (w), 1422 (w), 1357 (s), 1285 (w), 1235 (w), 1195 (m), 1108 (s). [M(MPDCO)(TPB)0.5(H2O) · (H2O)x]n (M )Co2+, x ) 1 (5); M ) 2+ Ni , x ) 1.375 (6); M ) Zn2+, x ) 2 (7) and M ) Cd2+, x ) 1 (8)). A mixture of Co(NO3)2 · 3H2O (23.7 mg, 0.1 mmol), MPDCO (19.7 mg, 0.1 mmol), TPB (18.3 mg, 0.05 mmol), NaOH (8.0 mg, 0.2 mmol), and H2O (8 mL) was heated at 120 °C for 3 days. After the mixture was slowly cooled to room temperature, red crystals of 5 were obtained (yield: 48% based on Co). Anal. Calcd for C20H20CoN3O7 (473.32): C 50.75, H 4.26, N 8.88. Found: C 50.98, H 3.95, N 8.94%. IR (cm-1, KBr): 3242 (s), 3050 (m), 1649 (s), 1610 (s), 1590 (s), 1556 (m), 1421 (m), 1387 (m), 1362 (s), 1259 (w), 1208 (m). The complexes 6, 7, and 8 were synthesized according to the method for preparing 5 and obtained in 43, 55, and 49% yield based on Ni, Zn, and Cd, respectively, except replacing Co(NO3)2 · 3H2O by Ni(NO3)2 · 3H2O (23.7 mg, 0.1 mmol), Zn(NO3)2 · 3H2O (24.3 mg, 0.1 mmol), and Cd(NO3)2 · 3H2O (29.0 mg, 0.1 mmol), respectively. Anal. Calcd for C20H20.75N3NiO7.375 (479.86) (6): C 51.50, H 4.01, N 15.02. Found: C 51.39, H 4.33, N 15.20%. IR (cm-1, KBr): 3419 (s), 1625 (s), 1605 (s), 1559 (w), 1520 (s), 1436 (w), 1422 (w), 1357 (s), 1285 (w), 1235 (w), 1195 (m), 1108 (s). Anal. Calcd for C20H22N3O8Zn (497.8) (7): C 48.28, H 4.45, N 8.44. Found: C 47.95, H 4.71, N 8.39%. IR (cm-1, KBr): 3423 (s), 1649 (s), 1611 (s), 1590 (s), 1555 (m), 1422 (m), 1387 (m), 1363 (s), 1260 (w), 1214 (m). Anal. Calcd for C20H20CdN3O7 (526.80) (8): C 45.60, H 3.80, N 7.98. Found: C 45.39, H 3.97, N 7.85%. IR (cm-1, KBr): 3421 (s), 1643 (s), 1609 (s), 1590 (s), 1557 (m), 1425 (m), 1410 (m), 1386 (m), 1361 (s), 1258 (w), 1210 (m). X-ray Crystallographic Studies. Single crystals of compounds 1–8 in appropriate dimensions were used for structural determinations on a Bruker SMART APEX CCD diffractometer using graphite-monochromatized Mo KR radiation (λ ) 0.71073 Å) at room temperature using the ω-scan technique. Data reductions and absorption corrections were performed with the SAINT and SADABS software packages,

Crystal Growth & Design, Vol. 7, No. 12, 2007 2527 Table 1. Crystal Data and Structure Refinement Information for Compounds 1–4 1 formula fw crystal system space group T/K a/Å b/Å c/Å β/° V/Å3 Z µ/mm-1 reflns collected unique reflns obs reflns [I > 2σ(I)] Rint R1 [I > 2σ(I)] wR2 [I > 2 σ(I)] goodness-of-fit

2

3

4

C8H7MnNO6 C8H9CuNO7 C18H17CoN3O7 C18H17N3NiO7 268.09 294.70 446.28 446.06 monoclinic monoclinic monoclinic monoclinic P21/c

P21/c

C2/c

C2/c

293(2) 6.763(2) 9.211(3) 13.729(4) 94.652(6) 852.5(4) 4 1.563 4767

293(2) 6.9389(14) 18.353(4) 7.7976(16) 98.445(4) 982.2(3) 4 2.250 5641

293(2) 18.758(4) 10.859(2) 20.596(4) 114.928(4) 3804.5(12) 8 0.949 10053

293(2) 18.656(5) 10.847(3) 20.452(5) 115.032(5) 3750.0(16) 8 1.082 9847

1864 1501

2130 1327

3748 2271

3686 2784

0.035 0.0371 0.0821

0.035 0.0505 0.0911

0.023 0.0520 0.0997

0.046 0.0430 0.0850

0.94

1.026

0.855

1.018

respectively. The structures were solved by direct methods using the SHELXS-97 program and were further refined by the full-matrix leastsquares technique using the SHELXL-97 program.18 All non-hydrogen atoms were refined with anisotropic displacement parameters, except in disordered water oxygen atoms. Hydrogen atoms attached to carbon atoms were calculated and refined with isotropic displacement parameters 1.2 or 1.5 times higher than the value of their carbon atoms. Different solvent–water molecules located in the cavities of 5–8 are disordered. The disordered oxygen atoms were assigned with partial site occupancy factors. Analytical expressions of neutral-atom scattering factors were employed, and anomalous dispersion corrections were incorporated. The crystallographic data and other pertinent information for 1–8 are summarized in Tables 1 and 2. Selected bond lengths and bond angles are listed in Table S1, Supporting Information. More details on the crystallographic studies presented in this paper as well as the atom displacement parameters are contained in the CCDC 620380620387, which can be obtained free of charge via http://www.ccdc. can.ac.uk/conts/retrieving.html or from the Cambridge Crystallographic Centre (12 Union Road, Cambridge CB21EZ, UK; fax: (+44) 1223336033; e-mail: [email protected]). The pore volumes of the frameworks were calculated by using the program PLATON; the guest water molecules were omitted in these calculations.19 Computational Methods. Two related mononuclear species [M(MPDCO)2(mp)2(H2O)]2- (M ) Zn2+ (7), Cd2+ (8); mp ) γ-methylpyridine) with the experimental geometries were used to calculate and evaluate their electronic structures and ground-state properties. The ab initio calculations on the electronic ground states were carried out by the Gaussian 03 program20 with the B3LYP hybrid density functional theory.21 The “Double-ξ” quality basis set LANL2DZ, which uses the Duning D95V basis set on first row atoms and Los Alamos ECP plus DZ on Na-Bi, was employed as the basis set. This has been proven to be useful and satisfactory for other metal polypyridyl complexes.22 The calculated results were compared with the available experimental data. All calculations were performed on a Pentium-IV personal computer using the default convergence criteria given in the program.

Results and Discussion Preparations. The preparations of compounds 1–8 were achieved in 25 mL Teflon-lined autoclaves under autogenous pressure, which followed by slow cooling yielded crystalline products directly. In the syntheses of 1 and 2, the presence of the TPT molecule is of great significance. When the ligand MPDCO reacted with the metal ions Mn(II) and Cu(II), respectively, in the presence of TPT, two compounds (1 and 2)

2528 Crystal Growth & Design, Vol. 7, No. 12, 2007

Lin et al.

Table 2. Crystal Data and Structure Refinement Information for Compounds 5–8

formula fw crystal system space group T/K a/Å b/Å c/Å β/° V/Å3 Z µ/mm-1 reflns collected unique reflns obs reflns [I > 2σ(I)] Rint R1 [I > 2σ(I)] wR2 [I > 2σ(I)] goodness-of-fit

5

6

7

8

C20H20CoN3O7 473.32 monoclinic C2/c 293(2) 18.867(3) 13.511(2) 16.415(3) 106.892(4) 4003.8(11) 8 0.907 10672 3915 2892 0.035 0.0534 0.1168 1.098

C20H20.75N3NiO7.375 479.86 monoclinic C2/c 293(2) 19.073(4) 13.329(3) 16.272(4) 107.395(5) 3947.5(16) 8 1.036 10464 3871 3021 0.035 0.0390 0.0884 1.014

C20H22N3O8Zn 497.80 monoclinic C2/c 293(2) 19.437(2) 13.4396(15) 16.7213(19) 106.056(2) 4197.7(8) 8 1.224 11118 4133 3034 0.023 0.0500 0.1092 1.041

C20H20CdN3O7 526.80 monoclinic C2/c 293(2) 19.429(3) 13.436(2) 16.728(3) 106.133(3) 4194.5(11) 8 1.089 11212 4118 3441 0.035 0.0495 0.1313 1.074

with different topological structures were formed even under the same reaction conditions. However, without TPT, MPDCO reacts straight with the M(II) salts, and the products cannot be obtained as expected in any cases (at different reaction temperatures and with different portions of NaOH or triethylamine). Thus, the TPT molecule may act as template to direct the crystal growth of compounds 1 and 2, although the detailed mechanism still remains unclear.23 Description of Crystal Structures. [Mn(MPDCO)(H2O)]n (1). The single crystal X-ray diffraction study reveals that 1 crystallizes in the centrosymmetric P21/c space group and features a 2-D layer network. As depicted in Figure 1a, Mn1 exhibits a slightly distorted octahedral coordination sphere, which is defined by two oxygen atoms (O5C from the carboxylate group of the MPDCO ligand and O6 of the coordinated water molecule) occupying the apical positions, while the basal plane is completed by four oxygen atoms (O1, O2, O3A, and O4B) from three carboxylate groups and one N-oxide group of three individual MPDCO ligands, respectively. The central metal ion Mn1 deviates from the basal plane by -0.1057 Å. The distances between the metal atom and different types of oxygen atoms in the MnO6 range from 2.094(2) to 2.252(2) Å and decrease in the order of Mn-Omean (aqua) > Mn-Omean (N-oxide) > Mn-Omean (carboxylate), while the bond angles O-Mn-O vary from 78.61(7) to 174.24(7)°. As can be seen from Figure 1b, every six Mn(II) atoms are coordinated by two antiparallel MPDCO anions to generate a hexagon that propagates infinitely to form a 2-D layered structure in the bc plane. Two carboxylate groups of the MPDCO ligand are coordinated to the metal centers in bidentate bridging fashion with syn-syn and syn-anti conformations, respectively. Therefore, two different Mn · · · Mn separations are observed in the hexagon, 4.72 Å for Mn1#1 · · · Mn1#2 and 5.80 Å for Mn1#2 · · · Mn1#3, respectively. Additionally, it is interesting to note that the individual 2-D layers are stacked by weaker noncovalent interactions. As shown in Figure 1c, adjacent layers are stacked in a slipped AAAA fashion by the O-H · · · O hydrogen bonding interactions (The D · · · A separations are 3.096 and 2.885 Å, D-H · · · A angles are 152.3 and 165.3° for two kinds of hydrogen bonding (Table 3), respectively), which hence leads to the construction of a 3-D supramolecular network. [Cu(MPDCO)(H2O)2]n (2). When we investigated the coordination chemistry of the same ligands with Cu(NO3)2 · 3H2O, compound 2 was isolated which comprises a 2-D (4,4) sheet.1a

As shown in Figure 2a, the copper atom is positioned in a highly distorted octahedron where the angles subtended at the copper atom vary from 86.69 to 176.01°, and the distances between Cu1 and the oxygen atoms range from 1.926(3) to 2.561(3) Å. Because of the Jahn–Teller effect for the d9 configuration of Cu2+, weaker interactions exist between Cu1 and the remaining N-oxide group of the ligand and the coordinated water molecule at the axial sites, which can also be validated from the slightly longer distances of Cu1-O5A (2.561(3) Å) and Cu1-O6 (2.367(4) Å). Different from the conformations in the compound 1 (see Figure 2b), both carboxylate groups of the same MPDCO ligand in 2 are coordinated to the copper atoms in a monodentate fashion. The N-oxide group from the ligand exhibits a rare bridging coordination mode, and it connects to a binuclear copper unit. The whole MPDCO molecule establishes a physical bridge between the bicopper clusters, imposing an identical separation of 9.97 Å for two adjacent clusters. Progression of the bimetallic clusters through the MPDCO spacer yields a 2-D four-connected (4,4) infinite sheet in the bc plane (Figure 2b). Similar to 1, a 3-D supramolecular network has also been formed by cross-linking the individual 2-D layers through the strong hydrogen-bonding interactions (see Table 3 and Figure S1, Supporting Information). M(MPDCO)(bpy)(H2O) · (H2O)]n (M ) Co2+ (3), Ni2+ (4)). The X-ray structural analysis reveals that 3 crystallizes in the centrosymmetric space group C2/c and features 3-fold interpenetrating networks of 3-D MOFs. As illustrated in Figure 3, the coordination geometry around the Co(II) center is a slightly distorted octahedron, where the equatorial plane comprises two oxygen atoms from the carboxylate group and N-oxide moiety of two individual MPDCO anions and two N atoms of two different bpy molecules. One coordinated water molecule and one oxygen atom from the carboxylate group occupy the remaining apical coordination sites. The O-Co-O bond angles vary from 74.11(10) to 176.85(12)°, and the Co-O distances range between 2.065(3) and 2.111(2) Å, which are comparable to those of other Co(II) complex systems.24 By closer inspection of the structure 3, two antiparallel MPDCO ligands bridge two Co(II) atoms to form a small irregular ring. These Co(II) atoms contained in the rings are further linked by the bpy molecules to give a infinite cylindrical 21 helix through spontaneous resolution (Figure 4). The helical pitch, given by one full rotation around the 21 helical axis, is 10.859 Å (the unit cell length along the crystallographic b axis),

Organic–Inorganic Hybrid Coordination Polymers

Crystal Growth & Design, Vol. 7, No. 12, 2007 2529

Figure 2. (a) Coordination arrangement of the Cu(II) atom in 2. Hydrogen atoms are omitted for clarity (A: 1 - x, -y, 1 - z; B: 1 x, –0.5 + y, 1.5 - x). (b) 2-D network and schematic illustration of (4,4) topology of 2.

Figure 1. (a) Coordination arrangement of the Mn(II) atom in 1. Hydrogen atoms are omitted for clarity (A: 0.5 - x, –0.5 + y, 1.5 z; B: -x, –1 + y, z; C: -x, 1 - y, 2 - z). (b) 2-D network of 1. One hexagon is highlighted. Hydrogen atoms and water molecules are omitted for clarity. (c) AAAA stacking fashion for 1 with the hydrogenbonding interactions.

Figure 3. Coordination arrangement of the Co(II) atom in 3. Hydrogen atoms are omitted for clarity (A: 1 - x, 2 - y, 2 - z).

Table 3. Selected Distances (Å) and Angles (deg) of Hydrogen Bonding for Compounds 1 and 2a D-H

d(D-H)

d(H · · · A)

DHA

d(D · · · A)

A

3.096 2.885

O(5)#1 O(1)#2

2.916 2.741 2.550

O(2)#3 O(2)#3 O(3)#4

Compound 1 O(6)-H(6B) O(6)-H(6C)

0.85 0.85

O(6)-H(6C) O(7)-H(7B) O(7)-H(7C)

0.85 0.85 0.85

2.40 2.09

139.4 154.6

Compound 2 2.41 2.16 2.06

118.4 125.3 116.3

a Symmetry codes: #1 -x + 3/2, y + 3/2, -z + 5/2; #2 -x + 3/2, y + 1/2, -z + 5/2; #3 x + 1, y, z; #4 -x + 1, y - 1/2, -z + 3/2.

and the axis of the helix is at (1/4, y, 3/4) with the Co · · · Co separations also of 10.859 Å. The bridging ligand bpy further binds to the unsaturated sites of the Co centers in the infinite helical chain, resulting in the final 3-D architecture by sharing the common nodes (Figure 5a). Accordingly, the network

Figure 4. The helical structure of complex 3 and the smallest repeated unit of the helix.

contains one type of three-connected node and two types of edges (One is the connectivity defined by the MPDCO bridging ligand, the other is bpy linear ligand). The whole structure can


Lin et al.

Figure 6. Coordination arrangement of the Co(II) atom in 5. Hydrogen atoms and solvent–water molecules are omitted for clarity (A: 0.5 x, 1.5 - y, 1 - z; B: -x, 1 - y, -z.).

Figure 5. (a) Space-filling model for 3-D MOF of 3. Water molecules and hydrogen atoms are omitted for clarity. (b) (10,3)-d network topology of 3, 4,4′-bipyridine molecules are denoted by blue color (M ) left handed; P ) right handed). (c) Schematic view of the 3-fold interpenetrating (10,3)-d nets.

be extended to an unusual (10,3)-d net,25,26 as illustrated in Figure 5b. The extended Schläfli symbol of this net is 102 · 104 · 104, which is assigned to the utp net. A characteristic feature of the single (10,3)-d net is the 4-fold helices, which are arranged left- and right-handed alternately making the whole net racemic. However, all the helices are of the same handedness in a single (10,3)-b net.26,27 As shown in Figures 4 and 5a, parallel single helices exist running through the structure. Then, this net is constructed by hexagonal helices along the b axis, and each hexagonal helix connects to six adjacent helices by sharing common edges (Figure 5a,b). Another interesting characteristic is that three adjacent independent and topologically identical nets interpenetrate each other to form a complicated structure of 3 with 3-fold interpenetrating 3-D (10,3)-d nets (Figure 5c). Furthermore, when changing Co(NO3)2 · 3H2O to Ni(NO3)2 · 3H2O in the synthesis, compound 4 was obtained in the same reaction condition as 3. Structural analysis of 4 showed it is an isomorphous and isostructural complex of 3 (Table 1). Therefore, for clarity, detailed structural characteristics of 4 are not repeatedly discussed herein, and the structural characteristics

of compound 4 are illustrated in Figures S2-S4, Supporting Information. The corresponding distances between M(II) center and O or N atoms in 4 are slightly shorter than those in 3 (see Table S1, Supporting Information), which may originate from the fact that the central ion of Ni(II) has an extra proton in the nucleus compared to Co(II). [M(MPDCO)(TPB)0.5(H2O) · (H2O)x]n (M )Co2+ x ) 1 (5), Ni2+ x ) 1.375 (6), Zn2+ x ) 2 (7), Cd2+ x ) 1 (8)). To evaluate the role of metal ions with different geometrical requirements in the self-assembly of organic–inorganic hybrid frameworks, the reactions of MPDCO and TPB ligands with Co(II), Ni(II), Zn(II), and Cd(II) metal ions were carried out to afford four compounds 5-8, respectively, which have the general formula of [M(MPDCO)(TPB)0.5(H2O) · (H2O)x]n. X-ray crystallography reveals that the four compounds are isomorphous and isostructural, and similar cell parameters of them have been summarized in Table 2. The most prominent characteristic of these compounds is that they all possess a quasi-3-D framework formed by 2-fold inclined interpenetration of 2-D sheets with topologically nonequivalent nodes. In this series, the coordination environments of the central metal ions are almost consistent with each other except for different uncoordinated disordered water molecules located at the cavities of the interlayers. Therefore, we choose compound 5 as a representative to characterize the detailed structure and coordination mode in this text. As shown in Figure 6, each Co(II) atom in compound 5 is coordinated in a very similar way as in compound 3. The subtle difference from 3 is that two coordinated N atoms in 5 come from half of one TPB ligand instead of the 4,4′-bipyridine. The corresponding bond lengths are almost identical with the largest deviation of 0.028 Å in Co-O distances and 0.009 Å in Co-N distances relative to those of compound 3. Here, it should be pointed out that the TPB is an interesting ligand since it contains four equivalent discrete metal-binding sites with approximate bond angles of 62.4 and 116.7° between two adjacent γ-methylpyridine and four N-donor atoms in a plane (see Figure S5, Supporting Information). In present study, we develop a strategy that employs this tetradentate ligand in the self-assembly to act as a four-connecting framework node. As expected, each TPB binds with four Co cations in compound 5 and forms a onedimensional (1D) linear chain in the [1 1j 0] direction, as illustrated in Figure 7a. These adjacent 1-D chains are further connected by every two MPDCO ligands in antiparallel directions, thus leading to a 2-D sheet. The most intriguing structural


Figure 7. (a) 1-D linear chain bridged by a TPB ligand. (b) 2-D MOF of 5. Water molecules and hydrogen atoms are omitted for clarity. (c) Schematic illustration of 2-D network with (42 · 62 · 82)(4 · 62)2 topology of 5.

feature of the sheet is that it contains two topologically nonequivalent nodes with the rare Schläfli symbol (42 · 62 · 82)(4 · 62)2 (Figure 7b,c). The void space in the sixmembered ring is so large that it can accommodate the relatively small four-membered ring. Any particular 2-D network layer then has an infinite number of inclined layers (almost perpendicularly) passing through it, which is an interesting example of the inclined catenation 2-D + 2-D f 3-D framework (see Figure 8a). In the 2-D inclined polycatenation system, to our knowledge, the research based on the 2-D layer with topologically nonequivalent nodes has rarely been explored.28 In the 3-D supramolecular architecture, the windows of the channels along the [1 0 1] direction were about 13.6 × 13.6 Å. The solvated water molecules filled up the whole void space of the cavities in compounds 5-8, as illustrated in Figure 8b. The void volumes occupied by these water molecules in 5–8, as calculated by PLATON from the crystal structures, are 8.7, 8.7, 10.4, and 8.8%, respectively. Different solvated water molecules per formula unit are found (most of them with partial occupancies) with the occupancies of 0.30, 0.40, and 0.30 in 5, 0.38 and 1 in 6, 1, 0.50 and 0.50 in 7, 0.55 and 0.45 in 8, respectively. Overall analysis of the syntheses of these isostructural coordination polymers indicates that the network prototypes present in the Co(II) compound can be further modified by changing the central metal ions of different groups or periods. In this series, the distances between the d10 metal ions (i.e., Zn(II) and Cd(II)) and the coordinated N or O donors are much longer than the corresponding bond distances in Co(II) or Ni(II) compounds with the average discrepancy of 0.2 Å, whereas the bond angles in Zn(II) and Cd(II) compounds or Co(II) and Ni(II) compounds are almost equal (Detailed geometrical parameters


Figure 8. (a) Schematic illustration of the interlocked 3-D porous framework formed by 2-fold inclined interpenetration of 2-D sheets. (b) View of the interpenetrating frameworks of 5-8 with solvated water molecules located at the cavities of the interlayers.

are summarized in Table S1, Supporting Information). These discrepancies may be attributed to the different ion radii of the different metal centers in these compounds. Exclusion of Water Molecules. As described above, 5–8 have one to two disordered solvated water molecules per formula unit located at the cavities of the frameworks. To verify whether the frameworks can be sustained after the removal of the guest molecules, two typical compounds 7 and 8 were used to perform TGA and powder XRD. As shown in Figure S6, Supporting Information, weight loss of 11.0% (calcd 10.8%) occurred in the temperature range of 60–174 °C, corresponding to the removal of one coordinated and two solvated water molecules per formula unit in 7. For 8, the first weight loss takes place in the range of 57–160 °C, which is attributed to the departure of one solvated and one coordinated water molecules (obsd 6.71%, calcd 6.84%). Subsequently, the plateau regions are observed for 7 and 8 below 240 °C, and consecutive decompositions over 240 °C suggest the total destruction of both frameworks. As a whole, the TGA curves indicate that the coordinated and solvated water molecules can be removed after heating, and the frameworks are stable below 240 °C. To verify the above speculations, the as-synthesized samples of 7 and 8 were calcined at 200 °C for 3 h. Powder XRD patterns of assynthesized 7 and 8 and dehydrated samples show only minor changes (Figures S7 and S8, Supporting Information), which indicates that these compounds can maintain their structural integrity even at the loss of both the coordinated and the solvated water molecules. Magnetic Properties. The magnetic properties of compounds 1, 3, and 4 were investigated in the temperature range of


Lin et al.

Figure 10. Emission spectra of compounds 7 and 8 at room temperature.

Figure 9. Temperature dependence of χMT and 1/χM (inset) for compounds 1 (a), 3 (b), and 4 (c). The red line shows the best-fit curve to the Curie–Weiss fit law.

1.8–300.0 K, and results are shown in Figure 9. As for 1, the χMT value at room temperature (300 K) is 4.14 cm3 K mol-1, which is close to the predicted value 4.375 cm3 K mol-1 for an isolated spin-only Mn(II) ion (S ) 5/2, g ) 2.0). Upon cooling of the sample, the χMT value decreases gradually to 0.26 cm3 K mol-1 at 1.8 K (see Figure 9a). This behavior indicates a dominant antiferromagnetic interaction between the Mn(II) centers in the structure. The plot of 1/χM versus T for the compound 1 in the range of 32–300 K is consistent with the Curie–Weiss law, which gives a Curie constant C ) 4.33 cm3 K mol-1 and a negative Weiss constant θ ) -12.99 K. Considering the short distances (4.72 and 5.80 Å) between two Mn(II) centers bridged through the 4- and 2-carboxylate groups, respectively, it is deduced that the observed occurrence of strong antiferromagnatic coupling between the spin carriers may arise from the magnetic superexchange through the carboxylate bridges.29 The phenomenon we have found for the intramolecular magnetic interactions of 1 is in agreement with that found in other similar carboxylate bridged structures of Mn(II) systems.30 Comparative investigations on the isostructural compounds 3 and 4 have also been performed, which may be helpful to learn about the contributions of different metal centers with the same coordination mode to the magnetic properties. As illustrated in Figure 9b,c, the χMT value of both polymers

decreases as the temperature decreases. However, it should be noted that the χmT vs T values of 4 decreases slightly in the temperature range of 300–14 K, which shows the compound is nearly paramagnetic in the higher temperature region. Upon cooling of 4 below 14 K, the χmT values decrease dramatically to 0.52 cm3 K mol-1 at 1.8 K. In addition, the plots of 1/χM versus T for compounds 3 and 4 give two straight lines over the entire temperature range, respectively. Fitting the curves to the Curie–Weiss law gives the parameters C ) 2.82 cm3 K mol-1 and θ ) -9.08 K for 3 and C ) 0.83 cm3 K mol-1 and θ ) -0.66 K for 4, respectively. The small negative θ value of 4 indicates extremely weak antiferromagnetic interactions exist between neighboring Ni(II) ions. In these two compounds, the M(II) · · · M(II) separations were bridged through the long spacer bridging ligands bpy and MPDCO, which exclude an efficient direct exchange between the Co(II) and Ni(II) centers.31 Therefore, with respect to the compound 3, the overall antiferromagnetic interaction should be mainly attributed to the significant spin–orbit coupling, which is remarkable for the 4T1g ground term of Co(II) in an octahedral ligand field. While in regard to compound 4, the very weak antiferromagnetic interaction in the higher temperature region (such as from 300 to 14 K) may be primarily ascribed to the magnetic superexchange through the long OOC · · · COO bridges. Whereas in the lower temperature region (from 14 to 1.8 K), the characteristic of the weak antiferromagnetic coupling effect may be correlated with the zero-field splitting of the 3A2g state.32 Luminescent Properties. Luminescent properties of compounds 7 and 8 in the solid state were investigated under the same situation. Excitation of the solid samples at λ ) 362 nm and room temperature leads to strong blue-fluorescent emission bands with the maximum intensity at 427 nm for 7 and 408 nm for 8, which can be seen in Figure 10. The free MPDCO ligand exhibits emission bands at 432 nm upon excitation at λ ) 343 nm, while no clear photoluminescence emission can be observed for the ligand TPB at room temperature. It is clear that in comparisonwithothercompoundssuchas[Cd2(bptc)(bpy)(H2O)2 · (H2O)]n,33 a hypsochromic shift of emissions occurs in the compounds 7 and 8 (especially obvious in 8).This is probably due to the differences of the central metal ions, because the photoluminescence behavior is closely associated with the metal ions and the ligands coordinated around them.34 The enhancement of the emissions for 7 and 8 compared with those of the free ligands may be ascribed to the increase of the ligand conformational rigidity due to their coordination to d10 ions.35 Furthermore, π-π interactions existing between the adjacent aromatic rings may be favorable for reduction of the energy of the π-π* transition to some extent and thus help the lumines-



(10,3)-d nets (3 and 4), and 2-D to 3-D inclined interpenetration (42 · 62 · 82)(4 · 62)2 networks (5–8). The effect of different auxiliary ligands on the structures and properties of these products is obvious. MPDCO adopts the same coordination mode in 3-8, which may provide useful information for the crystal prediction and design. Compounds 1, 3, and 4 display dominant antiferromagnetic interactions between the metal centers, which is correlated with the magnetic pathways of the corresponding structures. Compounds 7 and 8 exhibit efficient luminescence at room temperature, and the frameworks are stable below 240 °C. DFT calculations compare well with the experiments and demonstrate that the fluorescent emissions of 7 and 8 are assigned to the LLCT character.

Figure 11. Contour plots and energy gaps between frontier orbitals of 7 (a) and 8 (b).

cence.36 In the crystal lattice, two MPDCO ligands in 7 and 8 are packed into a slightly off-set head-to-tail pair by the π-π stacking interactions (centroid-to-centroid distance of 3.759 and 3.762 Å, respectively). As a result, it is inferred that both 7 and 8 may be suitable as candidates of blue-fluorescent materials. On the other hand, it is well-known that the emission bands in d10 metal compounds usually originate from the nd f (n+1)s or nd f (n+1)p electronic transitions, which are often mixed in the metal-to-ligand charge transfer (MLCT), ligand-to-metal charge transfer (LMCT), and ligand-to-ligand charge transfer (LLCT) characteristics.37 To better understand the nature of the fluorescence emissions of these two compounds, we carried out theoretical computations on 7 and 8. DFT calculations using the hybrid B3LYP functional were performed on the two compounds with their ground-state geometries adapted from the truncated X-ray data. Figure 11a shows the frontier molecular orbitals of 7, that is, the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO), with an energy gap between the frontier orbitals of 3.18 eV. This compares well with the corresponding experimental observation 2.91 eV (427 nm). Obviously, as observed from Figure 11a the electron densities of the singlet state in the HOMO of 7 are mainly located on one whole MPDCO2- ligand, while those in the LUMO are distributed on the γ-methylpyridine moiety of the TPB ligand. This suggests that the emission band of compound 7 is attributed to the LLCT.38 Similarly, Figure 11b shows that the electron densities of the HOMO and LUMO+1 in compound 8 are located on one whole MPDCO2ligand and the moiety of TPB molecule, respectively, with a larger energy gap of 3.85 eV. This also agrees reasonably with the corresponding experimental value 3.02 eV (408 nm). At the same time, it also supports the conclusion that the emission of compound 8 results from the LLCT. The deviations between calculations and experiments are probably due to only the ground states taken in the molecular orbital (MO) calculations. Furthermore, the existence of hydrogen bonds and π-π stacking in the experimental complexes also play an important role in decreasing the HOMO–LUMO gap.39 Conclusion This work focuses on the systematic investigation on the overall molecular architectures constructed from a new ligand MPDCO. Several different attractive topological types were obtained: 2-D (4,4) sheets (2), 3-fold interpenetrating 3-D

Acknowledgment. We appreciate the financial support from the National Nature Science Foundation of China (No. 20490218), the National Basic Research Program of China (2007CB925102), Jiangsu Science & Technology Department, and the Center of Analysis and Determining of Nanjing University. Supporting Information Available: Crystallographic information files, figures, and tables mentioned in the text are available free of charge via the Internet at http://pubs.acs.org.

References (1) (a) Hill, R. J.; Long, D. L.; Champness, N. R.; Hubberstey, P.; Schroder, M. Acc. Chem. Res. 2005, 38, 337. (b) Albrecht, M. Chem. ReV. 2001, 101, 3457. (c) Swiegers, G. F.; Malefetse, T. J. Chem. ReV. 2000, 100, 3483. (d) Blake, A. J.; Champness, N. R.; Hubberstey, P.; Li, W. S.; Withersby, M. A.; Schroder, M. Coord. Chem. ReV. 1999, 183, 117. (e) Leininger, S.; Olenyuk, B.; Stang, P. J. Chem. ReV. 2000, 100, 853. (2) (a) Sato, O.; Iyoda, T.; Fujishima, A.; Hashimoto, K. Science 1996, 271, 49. (b) Robin, A. Y.; Fromm, K. M. Coord. Chem. ReV. 2006, 250, 2127. (c) Kesanli, B.; Lin, W. B. Coord. Chem. ReV. 2003, 246, 305. (3) (a) Proserpio, D. M.; Hoffman, R.; Preuss, P. J. Am. Chem. Soc. 1994, 116, 9634. (b) Ermer, O. AdV. Mater. 1991, 3, 608. (c) Miller, J. S. AdV. Mater. 2001, 13, 525. (d) Batten, S. R.; Robson, R. Angew. Chem., Int. Ed. 1998, 37, 1460. (4) (a) Maji, T. K.; Mostafa, G.; Matsuda, R.; Kitagawa, S. J. Am. Chem. Soc. 2005, 127, 17152. (b) Yue, Q.; Yang, J.; Li, G. H.; Li, G. D.; Xu, W.; Chen, J. S.; Wang, S. N. Inorg. Chem. 2005, 44, 5241. (c) Gutschke, S. O. H.; Slawin, A. M. Z.; Wood, P. T. Chem. Commun. 1995, 2197. (d) Yu, Z. T.; Liao, Z. L.; Jiang, Y. S.; Li, G. H.; Li, G. D.; Chen, J. S. Chem. Commun. 2004, 1814. (e) Tao, J.; Zhang, Y.; Tong, M. L.; Chen, X. M.; Yuen, T.; Lin, C. L.; Huang, X. Y.; Li, J. Chem. Commun. 2002, 1342. (5) (a) Gerrard, L. A.; Wood, P. T. Chem. Commun. 2000, 2107. (b) Noro, S.; Miyasaka, H.; Kitagawa, S.; Wada, T.; Okubo, T.; Yamashita, M.; Mitani, T. Inorg. Chem. 2005, 44, 133. (c) Noro, S.; Kitagawa, S.; Yamashita, M.; Wada, T. Chem. Commun. 2002, 222. (d) Humphrey, S. M.; Chang, J. S.; Jhung, S. H.; Yoon, J. W.; Wood, P. T. Angew. Chem., Int. Ed. 2007, 46, 272. (6) (a) Garcia-Zarracino, R.; Hopfl, H. J. Am. Chem. Soc. 2005, 127, 3120. (b) Garcia-Zarracino, R.; Hopfl, H. Angew., Chem. Int. Ed. 2004, 43, 1507. (c) Humphrey, S. M.; Wood, P. T. J. Am. Chem. Soc. 2004, 126, 13236. (d) Liang, Y. C.; Cao, R.; Su, W. P.; Hong, M. C.; Zhang, W. J. Angew. Chem., Int. Ed. 2000, 39, 3304. (7) (a) Tian, G.; Zhu, G. S.; Yang, X. Y.; Fang, Q. R.; Xue, M.; Sun, J. Y.; Wei, Y.; Qiu, S. L. Chem. Comm. 2005, 1396. (b) Liu, Y. L.; Kravtsov, V. C.; Beauchamp, D. A.; Eubank, J. F.; Eddaoudi, M. J. Am. Chem. Soc. 2005, 127, 7266. (c) Qin, C.; Wang, X. L.; Wang, E. B.; Su, Z. M. Inorg. Chem. 2005, 44, 7122. (8) (a) Smith, T. S.; Root, C. A.; Kampf, J. W.; Rasmussen, P. G.; Pecoraro, V. L. J. Am. Chem. Soc. 2000, 122, 767. (b) Zhao, B.; Cheng, P.; Dai, Y.; Cheng, C.; Liao, D. Z.; Yan, S. P.; Jiang, Z. H.; Wang, G. L. Angew. Chem., Int. Ed. 2003, 42, 934. (c) Tancrez, N.; Feuvrie, C.; Ledoux, I.; Zyss, J.; Toupet, L.; Bozec, H. L.; Maury, O. J. Am. Chem. Soc. 2005, 127, 13474. (9) (a) MacDonald, J. C.; Dorrestein, P. C.; Pilley, M. M.; Foote, M. M.; Lundburg, J. L.; Henning, R. W.; Schultz, A. J.; Manson, J. L. J. Am. Chem. Soc. 2000, 122, 11692. (b) Zhao, B.; Chen, X. Y.; Cheng, P.;


(10) (11)

(12) (13) (14) (15) (16) (17) (18) (19) (20)

(21) (22)

Liao, D. Z.; Yan, S. P.; Jiang, Z. H. J. Am. Chem. Soc. 2004, 126, 15394. (c) Zhao, B.; Gao, H. L.; Chen, X. Y.; Cheng, P.; Shi, W.; Liao, D. Z.; Yan, S. P.; Jiang, Z. H. Chem. Eur. J. 2006, 12, 149. Wang, X. L.; Qin, C.; Wang, E. B.; Li, Y. G.; Hao, N.; Hu, C. W.; Xu, L. Inorg. Chem. 2004, 43, 1850. (a) Piepers, O.; Kellogg, R. M. Chem. Commum. 1978, 383. (b) Lu, Y. L.; Wu, J. Y.; Chan, M. C.; Huang, S. M.; Lin, C. S.; Chiu, T. W.; Liu, Y. H.; Wen, Y. S.; Ueng, C. H.; Chin, T. M.; Hung, C. H.; Lu, K. L. Inorg. Chem. 2006, 45, 2430. Nathan, L. C.; Doyle, C. A.; Mooring, A. M.; Zapien, D. C.; Larsen, S. K.; Pierpont, C. G. Inorg. Chem. 1985, 24, 2763. Wen, L. L.; Dang, D. B.; Duan, C. Y.; Li, Y. Z.; Tian, Z. F.; Meng, Q. J. Inorg. Chem. 2005, 44, 7161. Syper, L.; Kloc, K.; Mlochowski, J. Tetrahedron 1980, 36, 123. Heywood, D. L.; Dunn, J. T. J. Org. Chem. 1959, 24, 1569. Hunig, S.; Langels, A.; Schmittel, M.; Wenner, H.; Perepichka, I. F.; Peters, K. Eur. J. Org. Chem. 2001, 1393. Thayer, H. I.; Corson, B. B. J. Am. Chem. Soc. 1948, 70, 2333. Sheldrick, G. M. SHELXS-97 and SHELXL-97, Program for X-ray Crystal Structure Solution;University of Göttingen: Göttingen, Germany, 1997. Spek, A. L. PLATON, A Multipurpose Crystallographic Tool;Utrecht University: Utrecht, The Netherlands, 2003. Frisch, M. J.; Trucks, G. W.; Schlegel, H. B.; Scuseria, G. E.; Robb, M. A.; Cheeseman, J. R.; Montgomery, J. A.; Vreven, T.; Kudin, K. N.; Burant, J. C.; Millam, J. M.; Iyengar, S. S.; Tomasi, J.; Barone, V.; Mennucci, B.; Cossi, M.; Scalmani, G.; Rega, N.; Petersson, G. A.; Nakatsuji, H.; Hada, M.; Ehara, M.; Toyota, K.; Fukuda, R.; Hasegawa, J.; Ishida, M.; Nakajima, T.; Honda, Y.; Kitao, O.; Nakai, H.; Klene, M.; Li, X.; Knox, J. E.; Hratchian, H. P.; Cross, J. B.; Bakken, V.; Adamo, C.; Jaramillo, J.; Gomperts, R.; Stratmann, R. E.; Yazyev, O.; Austin, A. J.; Cammi, R.; Pomelli, C.; Ochterski, J. W.; Ayala, P. Y.; Morokuma, K.; Voth, G. A.; Salvador, P.; Dannenberg, J. J.; Zakrzewski, V. G.; Dapprich, S.; Daniels, A. D.; Strain, M. C.; Farkas, O.; Malick, D. K.; Rabuck, A. D.; Raghavachari, K.; Foresman, J. B.; Ortiz, J. V.; Cui, Q.; Baboul, A. G.; Clifford, S.; Cioslowski, J.; Stefanov, B. B.; Liu, G.; Liashenko, A.; Piskorz, P.; Komaromi, I.; Martin, R. L.; Fox, D. J.; Keith, T.; Al-Laham, M. A.; Peng, C. Y.; Nanayakkara, A.; Challacombe, M.; Gill, P. M. W.; Johnson, B.; Chen, W.; Wong, M. W.; Gonzalez, C.; Pople, J. A. Gaussian 03; Gaussian, Inc.: Wallingford, CT, 2004. (a) Becke, A. D. J. Chem. Phys. 1993, 98, 5648. (b) Lee, C.; Yang, W.; Parr, R. G. Phys. ReV. B 1988, 37, 785. Polson, M.; Ravaglia, M.; Fracasso, S.; Garavelli, M.; Scandola, F. Inorg. Chem. 2005, 44, 1282.

Lin et al. (23) Cao, R.; Shi, Q.; Sun, D. F.; Hong, M. C.; Bi, W. H.; Zhao, Y. J. Inorg. Chem. 2002, 41, 6161. (24) (a) Yang, L.; Crans, D. C.; Miller, S. M.; Cour, A.; Anderson, O. P.; Kaszynski, P. M.; Godzala, M. E.; Austin, L. D.; Willsky, G. R. Inorg. Chem. 2002, 41, 4859. (b) Noro, S.; Miyasaka, H.; Kitagawa, S.; Wada, T.; Okubo, T.; Yamashita, M.; Mitani, T. Inorg. Chem. 2005, 44, 133. (25) (a) Wells, A. F. Structural Inorganic Chemistry, Clarendon Press, Oxford, 1984. (b) Wells, A. F. Three-dimensional nets, polyhedra, John Wiley & Sons, New York, 1977. (26) Zhang, J.; Chen, Y. B.; Li, Z. J.; Cheng, J. K.; Kang, Y.; Yao, Y. G. Inorg. Chem. 2006, 45, 3161. (27) Bai, Y.; Duan, C. Y.; Cai, P.; Dang, D. B.; Meng, Q. J. Dalton Trans. 2005, 2678. (28) (a) Batten, S. R.; Robson, R. Angew. Chem., Int. Ed. 1998, 37, 1460. (b) Carlucci, L.; Ciani, G.; Proserpio, D. Coord. Chem. ReV. 2003, 246, 247. (c) Chen, S. M.; Zhang, J.; Lu, C. Z. CrystEngComm 2007, 9, 390. (29) Durot, S.; Policar, C.; Pelosi, G.; Bisceglie, F.; Mallah, T.; Mahy, J. P. Inorg. Chem. 2003, 42, 8072. (30) (a) Ghosh, S. K.; Ribas, J.; Salah El Fallah, M.; Bharadwaj, P. K. Inorg. Chem. 2005, 44, 3856. (b) Zheng, Y. Q.; Lin, J. L.; Kong, Z. P. Inorg. Chem. 2004, 43, 2590. (c) Gutschke, S. O. H.; Price, D. J.; Powell, A. K.; Wood, P. T. Inorg. Chem. 2000, 39, 3705. (31) Zheng, L. M.; Wang, X. Q.; Wang, Y. S.; Jacobson, A. J. J. Mater. Chem. 2001, 11, 1100. (32) Calatayud, M. L.; Castro, I.; Sletten, J.; Cano, J.; Lloret, F.; Faus, J.; Julve, M.; Seitz, G.; Mann, K. Inorg. Chem. 1996, 35, 2858. (33) Xiao, D. R.; Wang, E. B.; An, H. Y.; Li, Y. G.; Su, Z. M.; Sun, C. Y. Chem. Eur. J. 2006, 12, 6528. (34) (a) Dai, J. C.; Wu, X. T.; Fu, Z. Y.; Cui, C. P.; Wu, S. M.; Du, W. X.; Wu, L. M.; Zhang, H. H.; Sun, Q. Inorg. Chem. 2002, 41, 1391. (b) Wang, X. L.; Qin, C.; Li, Y. G.; Hao, N.; Hu, C. W.; Xu, L. Inorg. Chem. 2004, 43, 1850. (35) Yersin, H.; Vogler, A. Photochemistry and Photophysics of Coordination Compounds; Eds.; Springer-Verlag: Berlin, 1987. (36) Wang, S. N.; Bai, J. S.; Xing, H.; Li, Y. Z.; Song, Y.; Pan, Y.; Scheer, M.; You, X. X. Cryst. Growth Des. 2007, 7, 747. (37) (a) Ford, P. C.; Vogler, A. Acc. Chem. Res. 1993, 26, 220. (b) Casadonte, D. J.; McMillin, D. R. J. Am. Chem. Soc. 1987, 109, 331. (38) (a) Yang, L.; Ren, A. M.; Feng, J. K.; Liu, X. D.; Ma, Y. G.; Zhang, H. X. Inorg. Chem. 2004, 43, 5961. (b) Ikeda, S.; Kimachi, S.; Azumi, T. J. Phys. Chem. 1996, 100, 10528. (39) Zheng, S. L.; Zhang, J. P.; Wong, W. T.; Chen, X. M. J. Am. Chem. Soc. 2003, 125, 6882.

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