Tuning Different Kinds of Entangled Networks by Varying N-Donor

Article pubs.acs.org/crystal

Tuning Different Kinds of Entangled Networks by Varying N‑Donor Ligands: From Self-Penetrating to Multi-interpenetrating Jin-Xia Yang, Ye-Yan Qin, Jian-Kai Cheng, and Yuan-Gen Yao* Key Laboratory of Coal to Ethylene Glycol and Its Related Technology, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian 350002, China S Supporting Information *

ABSTRACT: Via hydrothermal synthesis, the self-assembly of Zn(II) ions and H2fum with four flexible N-donor ligands, bpp, bib, bix, and bmix, generated five interesting entanglement systems (H2fum = fumaric acid, bpp = 1,3-bi(4-pyridyl)propane, bib = 1,4-bis(N-imidazolyl)butane, bix = 1,4bis(imidazol-1-ylmethyl)-benzene, bmix = 1,4-bis(2-methylimidazol-1-ylmethyl)-benzene): {[Zn(fum)(bpp)]·H2O}n (1), {[Zn(fum) 0.5 (bib) 1.5 (H 2 O)]·NO 3 ·3H 2 O} n (2), {Zn(fum)(bib)} n (3), {[Zn2(fum)2(bix)2]·3H2O}n (4), and {[Zn(fum)(bmix)0.5]·0.5H2O}n (5). Their structures have been determined by single-crystal X-ray diffraction analyses, elemental analyses, IR spectra, X-ray powder diffraction (XRPD), and thermogravimetric (TG) analyses. Compound 1 exhibits a rare 3D selfpenetrating network with an unprecedented (85·10) topology. Compound 2 features a normal mode of 4-fold diamondoid interpenetrating net. However, in compound 3, five diamond networks interweave to form an interpenetrated diamond framework in an “abnormal” [3 + 2] mode. Compound 4 crystallizes in the orthorhombic crystal system and chiral space group P212121, which can be defined as an unusual 4-fold [2 + 2] interpenetrated unc-c net. Compound 5 displays a 2-fold interpenetrated 3D network with the classical pcu topology. A comparison of all compounds demonstrates that the structural characteristics of flexible N-donor ligands play a great role in the assembly of such different frameworks. Moreover, the luminescent properties of compounds 1−5 in the solid state have also been investigated.

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INTRODUCTION The current upsurge in studying metal−organic frameworks (MOFs) with entangled architectures is aimed not only at understanding their intriguing aesthetic structures and topological features but also in probing their numerous practical applications and remarkable range of physical properties.1 So far, a variety of remarkable entangled systems of MOFs have been documented, which include polycatenane, polyrotaxane, or polyknotted species (self-penetrating networks), interweaved arrays of polymeric chains or helixes, polythreaded networks, and interlocking topologies of the same or different motifs and/ or dimensionality.2 The characteristics of various entangled systems have been well discussed in some comprehensive reviews by Robson and Batten and Ciani et al.3 However, the modulation of the entangled motifs, which is more closely related to chemical environments, such as the coordination mode of metal nodes, metal-to-ligand ratio, and backbones of organic ligands, is still a significant challenge fraught with difficulties.4,5 An effective and controllable route in building such networks is to employ appropriate bridging ligands that can bind metal ions in different modes and provide a possible way to achieve more new materials with intriguing aesthetic structures and topological features.6 To our knowledge, polycarboxylate ligands are some of the most important families of organic building blocks, which have © 2014 American Chemical Society

been justified as efficient and versatile candidates for structural assembly of various entangled coordination polymers.7 In this work, we selected fumaric acid as polycarboxylate ligand to construct entangled networks based on the following considerations: (i) Compared with plentiful research on aromatic dicarboxylate ligands, the aliphatic carboxylate ligands as building blocks in the construction of entangled frameworks remain underdeveloped, perhaps because of a diminished possibility for a priori structure prediction or crystal design.8 (ii) The rigid bidentate linear ligands may tend to form large voids, and the resulting compounds may have good tendency to the form entanglements.9 (iii) Up to now, the systematic studies concerned with the mediation of the entangled structures of the fumarate ligands have not been well investigated. There are only several complexes that have been structurally characterized to date using fumarate anion with entangled features.10 In addition, a careful selection of N-donor ligands with different conformations as secondary auxiliary ligands, such as 4,4′-bpy (4,4′-bipyridine), bpe (1,2-bis(4-pyridyl)ethane), and bib (1,4-bis(N-imidazolyl)butane), is a key step for the rational Received: October 13, 2013 Revised: January 13, 2014 Published: January 17, 2014 1047

dx.doi.org/10.1021/cg401519w | Cryst. Growth Des. 2014, 14, 1047−1056

Crystal Growth & Design

Article

Scheme 1. Structures of the Organic Ligands Used in This Work

Table 1. Summary of Crystal Data and Structure Refinements for 1−5 compd empirical formula formula wt crystal system space group a (Å) b (Å) c (Å) α (deg) β (deg) γ (deg) V (Å3) Z Dcalcd (mg m−3) F (000) reflns collected/unique GOF on F2 R1, wR2 [I > 2σ(I)]a R1, wR2 (all data)b Flack param a

1 C17H18ZnN2O5 395.71 hexagonal P6422 11.5714(5) 11.5714(5) 22.773(2) 90 90 120 2640.7(3) 6 1.485 1212.0 5502/1562 0.985 0.0684, 0.1916 0.1150, 0.2333 0.01(7)

2 C17H30ZnN7O9 541.87 triclinic P1̅ 8.301(3) 11.146(4) 13.363(5) 86.427(7) 84.122(7) 83.573(8) 1220.5(8) 2 1.474 360 7755/4092 0.988 0.0394, 0.0981 0.0446, 0.1020

3 C14H16ZnN4O4 369.70 triclinic P1̅ 8.1767(7) 9.8286(5) 10.5904(12) 96.118(6) 110.718(9) 98.952(6) 774.24(12) 2 1.612 380.0 5160/2726 0.989 0.0473, 0.0932 0.0689, 0.1077

4 C36H38Zn2N8O11 889.48 orthorhombic P212121 14.774(6) 15.653(7) 16.871(7) 90 90 90 3902(3) 4 1.504 1808.0 31178/8848 1.044 0.0900, 0.2053 0.1190, 0.2249 0.00

5 C24H24Zn2N4O9 643.25 monoclinic C2/c 17.370(5) 12.694(4) 12.332(4) 90 92.587(6) 90 2716.3(14) 4 1.573 1312.0 10604/3069 1.049 1.049, 0.1332 0.0475, 0.1470

R1 = ∑||Fo| − |Fc||/∑|Fo|. bwR2 = [∑w(Fo2 − Fc2)2/∑w(Fo2)2]1/2. for C, H, N were carried out on an EA1110 CHNS-0 CE elemental analyzer. Emission and excitation spectra were recorded on an Edinburgh FLS920 TCSPC fluorescence spectrophotometer equipped with 450 W xenon light. X-ray powder diffraction (XPRD) analyses were collected on a Rigaku DMAX2500 diffractometer using Cu Kα radiation (λ = 0.154 nm) at a scanning rate of 5° min−1 for 2θ ranging from 5° to 50°. Thermogravimetric spectrometric analysis (TGA) was carried out on a NETZSCH STA-449C thermoanalyzer with a heating rate of 10 °C/min under an air atmosphere. Synthesis of {[Zn(fum)(bpp)]·H2O}n (1). A mixture of Zn(NO3)2· 6H2O (0.119 g, 0.4 mmol), fumaric acid (H2fum) (0.048 g, 0.4 mmol), bpp (0.079 g, 0.4 mmol), NaHCO3(0.034, 0.4 mmol), and H2O (10 mL) was placed in a 25 mL Parr Teflon-lined stainless steel vessel and then the vessel was sealed and heated to 120 °C. The temperature was held for 60 h. After slowly cooling to room temperature over 60 h, colorless crystals of 1 were collected in 73% yield (based on Zn). Anal. Calcd for C17H18ZnN2O5 (395.71): C, 51.55; H, 4.55; N, 7.08. Found: C, 51.21; H, 4.36; N, 7.23. IR (cm−1): 3437 (w), 3223 (w), 1603 (s), 1508 (w), 1462 (m), 1431 (s), 1374 (s), 1223 (w), 1189 (w), 1067 (m), 1030 (m), 979 (m), 867 (w), 808 (w), 728 (w), 694 (m), 626 (w), 602 (w). Synthesis of {[Zn(fum)0.5(bib)1.5(H2O)]·NO3·3H2O}n (2). A mixture of Zn(NO3)2·6H2O (0.119 g, 0.4 mmol), fumaric acid (H2fum) (0.024 g, 0.2 mmol), bib (0.114 g, 0.6 mmol), and NaHCO3 (0.034, 0.4 mmol) in molar ratio 2:1:3:2 was dissolved in 10 mL of H2O. The final mixture was placed in a Parr Teflon-lined stainless steel vessel (25 mL) and heated at 120 °C for 60 h and then allowed to cool to 30 °C for 60 h. Colorless crystals of compound 2 were obtained in 46% yield (based on Zn). Anal. Calcd for C17H30ZnN7O9 (541.87): C, 37.65; H, 5.54;

design of structures with specific physical and chemical properties. According to the literature reported previously, they have proven to be good candidates for the organization of beautiful interpenetrating or self-penetrating networks because of their length and flexibility.11 In order to explore the influence of N-donor ligands on the tuning of entangled networks and achieve different topological structures, four conformationally flexible N-donor ligands, namely, bpp (1,3-di(4-pyridyl)propane), bib (1,4-bis(N-imidazolyl)butane), bix (1,4-bis(imidazol-1-ylmethyl)-benzene), and bmix (1,4-bis(2-methylimidazol-1-ylmethyl)-benzene), were introduced into the Znfum system (Scheme 1). Five interesting entangled coordination polymers, {[Zn(fum)(bpp)]·H 2 O} n (1), {[Zn(fum)0.5(bib)1.5(H2O)]·NO3·3H2O}n (2), {Zn(fum)(bib)}n (3), {[Zn 2 (fum) 2 (bix) 2 ]·3H 2 O} n (4) and {[Zn(fum)(bmix)0.5]·0.5H2O}n (5), have been successfully synthesized and structurally characterized. Furthermore, luminescent properties of the compounds 1−5 are also investigated in detail.

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EXPERIMENTAL SECTION

Materials and Instrumentation. Bib, bix, and bmix were synthesized by the literature method.12 All other reagents were reagent grade and used as purchased without further purification. All syntheses were carried out in 25 mL polytetrafluoroethylene lined stainless steel containers under autogenous pressure. The FT-IR spectra were recorded on a Nicolet Magna 750 FT-IR spectrometer using KBr pellets in the range of 4000−400 cm−1. Elemental analyses 1048



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Figure 1. (a) View of asymmetric unit for 1 (symmetry codes, a = 1 − x, 1 − y, 1/3 − z; b = 3 − x + y, y, −z; c = 1 − x, −1 − y, z). (b) Perspective views of the double-stranded helices in 1. (c) View of the packing of the 1D double-stranded helix showing the three identical domains A, B, and C along the a axis and (e) along the c axis; (d) Space-filling views of the double-stranded helices of domains A. (f) Perspective view of the [Zn(fum)] helical chain. (g) Perspective view of the 3D open framework of 1. N, 18.06. Found: C, 37.86; H, 5.69; N, 17.92. IR (cm−1): 3421 (w), 3125 (m), 2933 (w), 1602 (s), 1532 (m), 1451 (m), 1383 (s), 1282 (m), 1235 (m), 1184 (w), 1093 (s), 1032(w), 980 (w), 954 (m), 841 (w), 761 (m), 698 (m), 655 (m). Synthesis of {Zn(fum)(bib)}n (3). The same synthetic method as that for 2 was used except that the molar ratio of reactants was changed to 1:1:1:1. Yield: 39% based on Zn. Anal. Calcd for C14H16ZnN4O4 (369.70): C, 45.44; H, 4.33; N, 15.15. Found: C, 46.01; H, 4.17; N, 15.04. IR (cm−1): 3127 (w), 2930 (w), 1611 (s), 1523 (m), 1473 (w), 1449 (w), 1375 (s), 1279 (m), 1234 (m), 1184 (w), 1110(m), 1091 (m), 994 (m), 945 (m), 849 (m), 765 (m), 697 (s), 655 (s). Synthesis of {[Zn2(fum)2(bix)2]·3H2O}n (4). The preparation of 4 was similar to that of 1 except that bix (0.095 g, 0.4 mmol) was used instead of bpp. Colorless crystals of 4 were obtained in 82% yield based on Zn. Anal. Calcd for C36H38Zn2N8O11 (889.48): C, 48.57; H, 4.27; N, 12.59. Found: C, 47.26; H, 4.69; N, 12.63. IR (cm−1): 3127 (m), 1610 (s), 1560 (s), 1522 (m), 1440 (m), 1364 (s), 1287 (w), 1234 (m), 1200 (w), 1107(s), 1029 (w), 979 (w), 953 (m), 846 (w), 768 (m), 717 (m), 688 (m), 654 (m). Synthesis of {[Zn(fum)(bmix)0.5]·0.5H2O}n (5). The preparation of 5 was similar to that of 1 except that bmix (0.104 g, 0.4 mmol) was used instead of bpp. Colorless crystals of 5 were obtained in 26% yield based on Zn. Anal. Calcd for C24H24Zn2N4O9 (643.25): C, 44.77; H, 3.73; N, 8.71. Found: C, 44.92; H, 3.65; N, 8.66. IR (cm−1): 3417 (m), 3094 (w), 1605 (s), 1558 (s), 1506 (m), 1436 (s), 1303 (m), 1227 (s), 1142 (w), 1119 (w), 1038(w), 991 (w), 884 (w), 835 (w), 806 (m), 742 (w). Single-Crystal Structure Determination. Suitable single crystals of compounds 1−5 were carefully selected under an optical microscope and glued to thin glass fibers. The intensity data were

collected on an Oxford Xcalibur E diffractometer for compounds 1 and 3 and on a Saturn 724 CCD diffractometer for compounds 2, 4, and 5 with a graphite-monochromated Mo Kα radiation (λ = 0.71073 Å) at room temperature. Empirical absorption corrections were applied to the data using the SADABS program.13 All of the structures were solved by the direct method and refined by full-matrix least-squares fitting on F2 by SHELX-97.14 All non-hydrogen atoms were refined with anisotropic thermal parameters. The hydrogen atoms bound to carbon were located at geometrically calculated positions and were refined by riding. The hydrogen atoms of the water molecules were found in the electron density map and were refined by riding. Crystallographic data and structure refinement parameters for compounds 1−5 are summarized in Table 1. Selected bond lengths and bond angles are listed in Tables S1−S5, Supporting Information. More details on the crystallographic studies as well as atomic displacement parameters are given in the CIF files.

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RESULTS AND DISCUSSION Description of Crystal Structures. Structure of {[Zn(fum)(bpp)]·H2O}n (1). A single-crystal X-ray diffraction study performed on compound 1 reveals the formation of a 3D fourconnected network that crystallizes in the chiral space group P6422. As shown in Figure 1a, the Zn atom is situated on a 2fold axis, and the fum2− anion and bpp ligand also have imposed crystallographic 2-fold symmetry; thus, the asymmetric unit comprises one-half of the formula. Each Zn(II) atom is coordinated by two carboxylic O atoms from two fum2− anions and two N atoms from two bpp ligands to furnish a distorted tetrahedral geometry. The bpp ligand exhibits TT (T 1049



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Figure 2. (a) Perspective (left) and schematic (right) view of the self-penetrating motif. (b) Schematic representation of the four-connected (85·10) topology in 1.

Figure 3. Perspective views of (a) triple-stranded helices and (b) right-handed helical chain in 1, (c) schematic representations of entangled triplestranded helices and right-handed helical chain, and space-filling views of (d) left-handed helical chain and (e) double-stranded helices in 1.

2a) are catenated with each other to give a self-penetrating (self-catenation or polyknotting) 3D structure (Figure 2b). Therefore, the net in 1 defines a new topology for fourconnected self-penetrating networks that is unobserved according to electronic databases EPINET, RCSR, and TOPOS TTD.15 A more interesting feature of 1 is that a triple-stranded molecular braid and a right-handed helical chain entwist each other along the crystallographic a-axis. As depicted in Figure 3a,b, the Zn atoms are bridged by the fum2− and bpp ligands to form the triple-stranded molecular braid with a pitch of 34.71 Å and the right-handed helical chain with a pitch of 11.57 Å running along the crystallographic a axis. The two types of entwined chains entangle together with identical composition [Zn4(fum)2(bpp)2] (Figure 3c). To our knowledge, this unusual manner of entanglement is particularly scarce in the field of self-penetrating systems and coordination polymers. Apart from the intrinsic interest of two types of molecular braids, another notable feature of 1 is the existence of two types of helical chains running along the crystallographic a axis coexisting in the 3D network. The first type of helical chain is composed of [Zn6(fum)4(bpp)2] groups with a pitch of 11.57 Å (Figure 3d), whereas the second type of helical chain is a double-stranded helix with a pitch of 23.14 Å (Figure 3e). Structure of {[Zn(fum)0.5(bib)1.5(H2O)]·NO3·3H2O}n (2). In compound 2, the more flexible N-donor ligand bib is selected. The asymmetric unit contains one independent Zn(II) atom, half a fum2− ligand, three half bib ligands, one coordinated water molecule, one nitrate ion, and three lattice water molecules. As shown in Figure 4a, each Zn(II) atom is five coordinated and resides in a trigonal bipyramidal coordination environment. Three N atoms, N1, N2, and N3, belonging to three different bib ligands form the equatorial plane, and the

= trans) conformation and acts as a bidentate ligand coordinated to two Zn(II) centers to form the double-stranded left-handed helices with a pitch of 23.14 Å (Figure 1b). All the double-stranded helices lie parallel to each other in the ab plane due to interdigitation, which can be divided into three structurally identical domains, labeled A, B, and C and stacked in an ABCABC... fashion along the c direction (Figure 1c). Each domain can itself be viewed as a stack of the doublestranded helices (Figure 1d). Indeed, these domains strictly possess the same arrangement, but they are rotated by 120° along the c-axis with respect to each other to create 1D pseudohexagonal channels of 6.56 Å in dimension (Figure 1e). Furthermore, each fum2− ligand inserts regularly in the pseudohexagonal channel by coordinating with the Zn atoms to generate a novel 3D framework (Figure 1g). A better insight into the nature of the involved framework can be achieved by the application of a topological approach. To illustrate the unique structure of 1, each Zn(II) center, being connected by two fum2− and two bpp ligands, can be simplified as a four-connected node; each fum2− and bpp ligand is simplified by a linear linker. Accordingly, the whole network can be extended to an unusual 3D four-connected net with the total point symbol of (85·10) and the vertex symbol of (8.8.8.8.8(4).10(14)). This net is clearly different from other known four-connected topological nets, of which the most common are dia (66), cds (65·8), sra (42·63·8), and qtz (64·82), where the smallest ring is four-membered or six-membered, whereas in the net described there are eight-membered rings representing a new topological prototype. The discovery of this new topology is useful at the basic level in the crystal engineering of coordination networks. Remarkably, a careful examination of the 3D structure reveals that two eightmembered rings with composition [Zn8(fum)6(bpp)2] (Figure 1050



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different bib ligands (namely, bib1(N1−N2), bib2(N3−N4), and bib3(N5−N6)) can be divided into two types, which show distinct GTG (bib1 and bib2) (T = trans and G = gauche) and TTT (bib3) conformations. All Zn(II) atoms are linked by bib ligands to generate a 2D puckered (6,3) net (Figure 4b), which is further pillared by the fum2− ligands to give a 3D open framework with the point symbol 66 and the long symbol 62·62· 62·62·62·62, typical of a diamondoid topology (Figure 4c). A single adamantanoid framework is illustrated in Figure 4d, which possesses maximum dimensions (the longest intracage distances across the unit along the directions) of 33.32 × 22.29 × 26.77 Å3 (4a × 2b × 2c). Because of the spacious nature of the single network, the potential voids are filled via mutual interpenetration of identical 3D frameworks, generating a 4-fold interpenetrating architecture (Figure 4e). Despite the nature of the 4-fold interpenetration, compound 2 still forms 1D open channels with the dimensions ca. 13 Å × 11 Å without subtraction of the van der Waals radii of the channel-defining atoms, in which the water molecules and nitrate ions are trapped (Figure S1, Supporting Information). Structure of {Zn(fum)(bib)}n (3). With change of molar ratio of Zn(NO3)2·6H2O, fumaric acid, and bib liagnd under uniform reaction conditions, a structurally different compound, 3, was obtained. Compound 3 crystallizes in the triclinic space group P1̅ and exhibits an unusual 5-fold interpenetrating diamond topological framework. As shown in Figure 5a, the asymmetric unit is composed of one Zn(II) ion, two half fum2− ligands, and two half bib ligands. The coordination geometry of the Zn(II) ion can be described as a distorted tetrahedral configuration completed by four atoms, including two carboxylic O atoms from two different fum2− ligands and two N atoms from two bib ligands; the whole net is also a diamondoid framework topologically (Figure 5c). The four-connected metal center significantly deviates from the ideal tetrahedral angle, and the Zn···Zn separations and Zn···Zn···Zn angles among each network are in the range of 8.82−13.92 Å and 95.14−120.0°, respectively. A single adamantanoid framework is illustrated in

Figure 4. (a) View of the coordination environment of Zn(II) centers in compound 2 (symmetry codes: a = −1 − x, 1 − y, 2 − z; b = −1 − x, 1 − y, 2 − z; c = 1 − x, −y, 2 − z; d = 1 − x, 1 − y, 1 − z). Lattice water molecules and hydrogen atoms have been omitted for clarity. (b) A (6,3) sheet in the structure of 2. (c) The single adamantanoid cage and topology in 2. (d) Schematic representation of the four interpenetrating diamond networks of 2.

apical positions are occupied by O1 from the fum2− ligand and O1w from a coordinated water molecule. Three kinds of

Figure 5. (a) View of the coordination environment of Zn(II) centers in compound 3 (symmetry codes: a = −1 − x, 1 − y, −z; b = −x, −y, 1 − z; c = 1 − x, −y, −z; d = 1 − x, 2 − y, 1 − z). Hydrogen atoms have been omitted for clarity. (b) The single adamantanoid cage and topology in 3. (c) A schematic view of a single diamond framework. 1051



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Figure 5b, which possesses maximum dimensions of 25.08 × 19.7 × 31.78 Å3 (3a × 2b × 3c). Such a cavity is large enough to be filled via mutual interpenetration of four independent equivalent frameworks, leading to a 5-fold interpenetrated diamond net without available space. In the general n-fold interpenetrating case, the translation of 1/n times the length of the adamantine unit along the direction of the shared 2-fold axis corresponds to one of the unit cell dimension.3a However, in the case of compound 3, the interpenetration mode differs from the normal mode in 2 and can be described as two sets of normal 3- and 2-fold nets, that is, an unusual [3 + 2] mode of interpenetration, and the independent equivalent cages are separated from each other by 9.83 Å (Figure 6a,b). The two sets of 3- and 2-fold nets are

fum2− anions are linkers, this framework can be simplified into a four-connected unc-c net with short and long Schläfli symbols 66 and 6·6·62·62·63·63, which is clearly different from the diamondoid topology despite having the same short vertex symbol (Figure 7c). In the single 3D framework, there exist two kinds of pore apertures with rectangular shapes running along the a axis; the size of the large channels is about 19.08 × 19.81 Å2, whereas that of the small channels is about 8.71 × 8.78 Å2. As is usually found, the potential voids are large enough to be filled via mutual interpenetration of three independent equivalent frameworks, generating a 4-fold interpenetrating 3D architecture. Despite this 4-fold interpenetration, compound 4 still contains a small solvent-accessible void space of 12.2% (463.5 Å3 per unit cell) of the total crystal volume calculated by PLATON.17 By further carefully looking into the structure, we surprisingly discovered that there are two types of interpenetrating patterns (Figure 7d, type A, red−green; type B, red−blue) coexisting in the compound 4. As shown in Figure 7d,e, interpenetrating nets of red−blue are rotationally equivalent with red−purple net interpenetration, while red−blue and purple−green nets are translationally equivalent. Therefore, the four interpenetrated nets can be regarded as an unusual [2 + 2] interpenetrating system. As far as we know, only a few desirable examples18 showing a three-dimensional 4-fold [2 + 2] net have been characterized. However, most of these examples originate from the interpenetration of the diamondoid nets. Compared with the reported results, the structure of 4 presented here with uncc topology containing an abnormal [2 + 2] 4-fold interpenetration character is rarely reported. Structure of {[Zn(fum)(bmix)0.5]·0.5H2O}n (5). When a new type of bis(imidazole) ligand, bmix, was introduced in the Znfum system, compound 5 with a pillared structure was obtained. It exhibits a 2-fold interpenetrated 3D framework with the classic pcu topology. The asymmetric unit of compound 5 contains one Zn(II) atom, one fum2− ligand, one-half bmix ligand and one-half lattice water molecule. As shown in Figure 8a, the Zn(II) atom is five-coordinated and has a square pyramidal environment with four oxygen atoms from four fum2− ligands in the basal plane and one nitrogen atom in the axial position from a bmix ligand. As illustrated in Figure 8b, two adjacent crystallographically equivalent Zn(II) atoms are connected by two pairs of carboxylates to form a paddle-wheel shaped [Zn2(RCO2)4] dimer with a Zn(II)···Zn(II) distance of 3.02 Å. Each [Zn2(RCO2)4] subunit is bonded to four identical dimeric units through four bridging fum2− ligands to afford an extended 2D square-grid (4,4) layer along the bc plane. Each bmix ligand connects two Zn atoms from the adjacent 2D layers and extends the 2D layer substructures into a pillaredlayer porous 3D framework with 1D channels running along the c axis (Figure 8c). The distance between the two neighboring layers is 17.37 Å. From the topological view, the [Zn2(RCO2)4] dimer can be simplified as a six-connected node, the pillared bmix ligands are taken as linkers, and the 3D structure can be classified as a classical pcu architecture (α-Po topology).19 In order to stabilize the framework, the cavities in a single 3D framework allow another identical framework to interpenetrate it, thus giving a 2-fold interpenetrated framework (Figure 8d). In addition, a close inspection of the porous compound discloses that there is one type of rhombic channel, which is filled by free water molecules along the b axis (Figure S2, Supporting Information). The potential free volume of 5 is

Figure 6. (a) Schematic representation of the five interpenetrating diamond networks. (b) Space-filling diagram of the five interpenetrating adamantanoid cages of 3.

translationally equivalent and are generated by a unique interpenetration vector16 Ti = a/2 + b/2 with a relative displacement distance of 8.20 Å. To the best of our knowledge, such 5-fold interpenetrating dimondoid networks with “abnormal” [3 + 2] interpenetration mode are still extremely rare, which could help us deeply understand the nature of coordination polymer frameworks and better design new functional materials. Structure of {[Zn2(fum)2(bix)2]·3H2O}n (4). When the semiflexible bix ligand was used instead of the flexible bib ligand, a different structural type from others was obtained. Compound 4 crystallizes in the chiral orthorhombic space group P212121. As depicted in Figure 7a, there are two crystallographically independent Zn centers in the asymmetric unit of 4. Zn1 and Zn2 show four-coordinated tetrahedral geometries that are surrounded by two oxygen atoms from two fum2− ligands and two nitrogen atoms from two bix ligands, respectively. The fum2− anions bridge two kinds of Zn(II) atoms by bis(monodentate) coordination mode to form an infinite left-handed 21 helical chain along the a-axis (Figure 7b, left). The helical chains have a pitch of 14.77 Å, and adjacent helical chains are further pillared by bix ligands to generate a 3D open framework (Figure 7b, right). The chiral information may be transferred to the 3D framework by helical units with 2fold rotation. From the topological point of view, if each Zn(II) ion is considered as a four-connected node and bix ligands and 1052



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Figure 7. (a) View of the coordination environment of Zn(II) centers in compound 4 (symmetry codes: a = 1/2 + x, 5/2 − y, −z; b = 1/2 + x, 3/2 − y, −1 − z; c = 1/2 + x, 7/2 − y, −1 − z). Hydrogen atoms have been omitted for clarity. (b) Space-filling diagram of the left-handed helical chain (left) and perspective view of the 3D open framework of 4 (right). (c) Schematic view of the 66 topology of 4. (d) Schematic representation of the interpenetration pattern of red and green nets (type A, upper) and the interpenetration pattern of red and blue nets (type B, bottom). (e) Schematic representation of the overall [2 + 2] interpenetrating mode of 4-fold interpenetrating frameworks.

about 338.1 Å3 (12.4% of the unit cell) as calculated by PLATON program after removal of guest water molecules. Effects of the N-Donor Ligands on the Entangled Coordination Polymers. Although we are unable to propose definitive reasons as to why each compound adopts a different topology with our present state of knowledge, better insight into these structures can still provide useful information for constructing coordination polymers. As we know, in the generation of ternary MOFs, N-donor ligands play a dual role of building units and templates. So here we have adopted four such N-donor ligands viewing their difference of length and configuration and influence on the final entangled structures. In compounds 1−5, although the N-donor ligands adopts similar μ 2 bridging coordination modes, their spatial orientations are quite different, which result in variable dihedral angles between the pyridine rings or imidazole rings. In 1, the bpp ligand adopts a TT conformation with a dihedral angle of 78.07° and length of 9.93 Å. Among the four N-donor liagnds, bpp is the shortest one and has the maximal inclination in

dihedral angle. Therefore, bpp ligands combine with fum2− to link the Zn(II) ions to form an involved self-penetrating 3D framework instead of interpenetration structure. When the longer N-donor ligand bib was introduced into the reaction system, compounds 2 and 3 with interpenetrated diamond networks were obtained. The dihedral angles between imidazole rings in all bib ligands are 0° for 2 and 3. Although the bib ligand has a more flexible carbon bone than bpp, the parallel imidazole rings can keep the same linking direction to the Zn(II) ion, which favors the formation of the interpenetrating networks as a result of larger free voids. In 2, there are four interpenetrating diamondoid nets, and they show the usual mode of interpenetration. For 3, however, five diamond networks interweave to form an interpenetrated diamond framework in an “abnormal” [3 + 2] mode. In comparison of 2 and 3, the GTG and TTT conformations of bib ligand were found in 2, while a TTT conformation was found in 3. Thus, the differences in interpenetrating modes between 2 and 3 mainly arise from the different conformations of the bib ligand. 1053



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Figure 8. (a) View of the asymmetric unit for 5 (symmetry codes: a = x, y, 1/2 + z; b = −1/2 − x, 1/2 + y, 5/2 − z; c = −1/2 − x, 1/2 − y, 2 − z; d = 1 − x, 1 − y, 1 − z). (b) (top) The 2D sheet shaped by fum2− ligands and metal centers (the green atoms correspond to the [Zn2(RCO2)4] fragment) and (bottom) the bmix ligand acted as a molecular pillar. (c) View of 3-D open framework of 5 overlaid by the topological edges (orange and green) (solvent molecules and hydrogen atoms have been omitted for clarity). (d) Schematic representation of the 2-fold interpenetrating pcu framework.

nature. The photoluminescent spectrum of H2fum does not show obvious luminescence in the range 400−800 nm at room temperature. Compounds in this work display strong emission bands centered at 460 nm (λex = 360 nm) for 1, 443 nm (λex = 360 nm) for 2, 440 nm (λex = 360 nm) for 3, 450 nm (λex = 360 nm) for 4, and 453 nm (λex = 360 nm) for 5 (Figure 9). In

However, when semiflexible N-donor ligands with a longer spacer were used, structurally different compounds 4 and 5 were obtained. In 4, two bix ligands coordinate to the Zn(II) ions in the same conformation with the similar dihedral angle (14.09° and 15.19°) combined with fum2− to form a 4-fold uncc network showing an unusual [2 + 2] mode of interpenetration. Compared with bix ligand, the bmix ligand has an extra methyl group on each imidazole ring. Obviously, the extra methyl groups of the bmix ligands will increase the steric hindrances when coordinated with the metal atoms. Therefore, in 5, the bmix ligand keeps the same linking direction with a dihedral angle of 0° to link the 2D [Zn(fum)] sheet yielding a pillared-layer porous 3D framework with the pcu topology. Two independent nets interlock each other to form a 2-fold interpenetrating framework. Consequently, it is believed that the introduction of suitable N-containing ligands into a metal− polycarboxylate system is a feasible route for the construction of metal−organic frameworks with various types of entanglements. Luminescent Properties. In this work, the solid-state luminescent behaviors of compounds 1−5 have been investigated at room temperature because they are insoluble in the common solvents such as water, methanol, ethanol, acetone, benzene, and so forth. In order to understand the origin of the emissions, the photoluminescence properties of the free H2fum, bpp, bib, bix, and bmix ligands were also studied under the same experimental conditions. As shown in Figure S3, Supporting Information, the free Ndonor ligands emit strong fluorescence centered at 536 nm (λex = 368 nm) for bpp, 436 nm (λex = 360 nm) for bib, 422 nm (λex = 340 nm) for bix, and 457 nm (λex = 340 nm) for bmix. Usually, the fluorescence observed for these organic ligands arises from π* → n and π* → π transitions of intraligand

Figure 9. The emission spectra of 1−5 in the solid state at room temperature.

comparison to the free ligands, the emission peaks of compound 2, 3, and 5 are close to that of the relevant Ndonor ligands, so the emission band of these compounds can probably be attributed to the intraligand fluorescent emission.20 However, the emission band for compound 1 exhibit a blue shift relative to the free bpp ligand, and the emission band of 4 is red-shifted by 28 nm compared with the free bix ligand. It is 1054



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well-known that the Zn(II) ion is difficult to oxidize or reduce because of the d10 configuration.21 Therefore, the emissions of these compounds are neither MLCT nor LMCT. The emissions of these compounds can be assigned to intraligand transitions that are tuned by the metal−ligand interactions. The corresponding decay lifetimes and quantum yields of compounds 1−5 are 2.44, 3.66, 3.27, 1.69, and 2.25 ns and 1.35%, 7.21% 5.46%, 1.78%, and 2.33%, respectively. XRPD Patterns and Thermal Properties. X-ray powder diffractions of compounds 1−5 were recorded to confirm the purity and homogeneity of the bulk products. As shown in Figures S4−S8 in the Supporting Information, the measured XRPD patterns of 1−5 are in good agreement with the ones simulated from their respective single-crystal X-ray data, which clearly indicate the good purity and homogeneity of the synthesized samples. To characterize the thermal stability of these compounds, thermogravimetric (TG) measurements were carried out in the temperature range of 30−900 °C under N2 atmosphere with a heating rate of 10 °C min−1 (Figure S9, Supporting Information). For compound 1, the weight loss in the range of room temperature to 140 °C is attributed to the departure of lattice water molecules (obsd 4.29%, calcd 4.55%), and then the decomposition of organic ligands occurs in the range of 260− 900 °C (obsd 74.48%, calcd 74.88%). The remaining weight corresponds to the formation of ZnO (obsd 21.23%, calcd 20.57%). The TGA curve of 2 shows that the first weight loss from room temperature to 90 °C corresponds to the loss of the uncoordinated water molecules (obsd 10.49%, calcd 9.97%). Further weight loss corresponding to bib and aqua ligands (observed 55.39%, calculated 54.31%) was observed between 270 and 670 °C. Upon further heating, the coordinated ligands were lost until the residue was ZnO. The weight loss is observed owing to the direct decomposition of organic ligands for 3. No mass loss occurs until 290 °C at which point a series of mass losses ensued. Compound 3 can remain stabile at high temperature because it does not include guest solvent molecule. A total loss of 6.15% is observed for 4 in the temperature range of 30−150 °C, which can be attributed to the loss of lattice water molecules (calcd 6.07%), and the anhydrous compound begins to decompose at 270 °C forming an unidentified product. Compound 5 first lost weight corresponding to one lattice water molecule (observed 2.69%, calculated 2.80%) from room temperature to 100 °C. The decomposition of the organic components occurs at 320 °C forming an unidentified product.

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ASSOCIATED CONTENT

S Supporting Information *

Crystallographic data for compounds 1−5 in CIF format (CCDC 941229 and 941230 for 1 and 2, CCDC 979603 and 979604 for 3 and 4, and CCDC 941233 for 5), tables of selected bond lengths and angles, experimental powder and simulated XRPD patterns, and additional structural figures. This material is available free of charge via the Internet at http://pubs.acs.org.

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AUTHOR INFORMATION

Corresponding Author

*E-mail: [email protected]. Notes

The authors declare no competing financial interest.

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ACKNOWLEDGMENTS This work was supported by 973 Program of China (Grant 2011CBA00505), the “Strategic Priority Research Program” of the Chinese Academy of Sciences (Grants XDA07070200, XDA09030102), National Key Technology R&D Program (Grant 2012BAE06B08), and the Chinese Academy of Sciences (Grant KJCX2-YW-H30).

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REFERENCES

(1) (a) Eddaoudi, M.; Li, H.; Yaghi, O. M. J. Am. Chem. Soc. 2000, 122, 1391. (b) Noro, S.; Kitaura, R.; Kondo, M.; Kitagawa, S.; Ishii, T.; Matsuzaka, H.; Yamashita, M. J. Am. Chem. Soc. 2002, 124, 2568. (c) Kitaura, R.; Seki, K.; Akiyama, G.; Kitagawa, S. Angew. Chem., Int. Ed. 2003, 42, 428. (d) Czarna, A.; Beck, B.; Srivastava, S.; Popowicz, G. M.; Wolf, S.; Huang, Y.; Bista, M.; Holak, T. A.; Dömling, A. Angew. Chem., Int. Ed. 2010, 49, 5352. (e) Chen, X. D.; Zhao, X. H.; Chen, M.; Du, M. Chem.Eur. J. 2009, 15, 12974. (f) Yang, Q. Y.; Li, K.; Luo, J.; Pana, M.; Su, C. Y. Chem. Commun. 2011, 47, 4234. (g) Qin, C.; Wang, X. L.; Wang, E. B.; Su, Z. M. Inorg. Chem. 2008, 47, 5555. (h) Guo, Q. Q.; Xu, C. Y.; Zhao, B.; Jia, Y. Y.; Hou, H. W.; Fan, Y. T. Cryst. Growth Des. 2012, 12, 5439. (2) (a) Lipatov, Y. S.; Alekseeva, T. T. Polym. Adv. Technol. 1996, 7, 234. (b) Wang, X. L.; Qin, C.; Wang, E. B.; Su, Z. M. Chem.Eur. J. 2006, 12, 2680. (c) Lan, Y. Q.; Li, S. L.; Qin, J. S.; Du, D. Y.; Wang, X. L.; Su, Z. M.; Fu, Q. Inorg. Chem. 2008, 47, 10600. (d) Wu, Y. P.; Li, D. S.; Fu, F.; Dong, W. W.; Zhao, J.; Zou, K.; Wang, Y. Y. Cryst. Growth Des. 2011, 11, 3850. (e) Yang, Q. X.; Chen, X. Q.; Cui, J. H.; Hu, J. S.; Zhang, M. D.; Qin, L.; Wang, G. F.; Lu, Q. Y.; Zheng, H. G. Cryst. Growth Des. 2012, 12, 4072. (f) Yang, J.; Ma, J. F.; Batten, S. R. Chem. Commun. 2012, 48, 7899. (g) Zhang, M. D.; Di, C. M.; Qin, L.; Yang, Q. X.; Li, Y. Z.; Guo, Z. J.; Zheng, H. G. CrystEngComm 2013, 15, 227. (3) (a) Batten, S. R.; Robson, R. Angew. Chem., Int. Ed. 1998, 37, 1460. (b) Batten, S. R. CrystEngComm 2001, 3, 67. (c) Carlucci, L.; Ciani, G.; Proserpio, D. M. Coord. Chem. Rev. 2003, 246, 247. (d) Blatov, V. A.; Carlucci, L.; Ciani, G.; Proserpio, D. M. CrystEngComm 2004, 6, 377. (e) Baburin, I. A.; Blatov, V. A.; Carlucci, L.; Ciani, G.; Proserpio, D. M. J. Solid State Chem. 2005, 178, 2452. (f) Baburin, I. A.; Blatov, V. A.; Carlucci, L.; Ciani, G.; Proserpio, D. M. Cryst. Growth Des. 2008, 8, 519. (4) (a) Guo, H. D.; Qiu, D. F.; Guo, X. M.; Batten, S. R.; Zhang, H. J. CrystEngComm 2009, 11, 2611. (b) Duan, X. Y.; Cheng, X. J.; Lin, G.; Zang, S. Q.; Li, Y. Z.; Zhu, C. G.; Meng, Q. J. CrystEngComm 2008, 10, 706. (c) Zhang, L. P.; Yang, J.; Ma, J. F.; Jia, Z. F.; Xie, Y. P.; Wei, G. H. CrystEngComm 2008, 10, 1410. (d) Guo, H. D.; Qiu, D. F.; Guo, X. M.; Zheng, G. L.; Wang, X.; Dang, S.; Zhang, H. J. CrystEngComm 2009, 11, 2425. (e) Qi, Y.; Luo, F.; Che, Y. X.; Zheng, J. M. Cryst. Growth Des. 2008, 8, 606. (f) Cui, G. H.; Li, J. R.; Tian, J. L.; Bu, X. H.; Batten, S. R. Cryst. Growth Des. 2005, 5, 1775.

CONCLUSION

In this study, the simultaneous use of the linear dicarboxylic acid and a series of rationally selected N-donor ligands with different conformation to react with zinc salts afforded five new entangled metal−organic frameworks with interesting architectures. These results suggest that not only the chemical nature of N-containing ligands (e.g., length, flexibility, and conformations) but also the molar ratio of starting materials play a significant role in tuning the entangled modes of coordination networks. In a word, this work provides a promising route for constructing functional self-penetrating and interpenetrating networks to further develop the research fields of crystal engineering and coordination chemistry. 1055



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(5) (a) Qi, Y.; Luo, F.; Batten, S. R.; Che, Y. X.; Zheng, J. M. Cryst. Growth Des. 2008, 8, 2806. (b) Doonan, C. J.; Tranchemontagne, D. J.; Grant Glover, T.; Hunt, J. R.; Yaghi, O. M. Nat. Chem. 2010, 2, 235. (c) Zhang, Z. H.; Du, M. CrystEngComm 2008, 10, 1350. (d) Luo, F.; Yang, Y. T.; Che, Y.-X.; Zheng, J. M. CrystEngComm 2008, 10, 981. (e) Chen, X. M.; Liu, G. F. Chem.Eur. J. 2002, 8, 4811. (f) Noh, T. H.; Choi, Y. J.; Ryu, Y. K.; Lee, Y. A.; Jung, O. S. CrystEngComm 2009, 11, 2371. (6) (a) Robson, R. J. Chem. Soc., Dalton Trans. 2000, 3735. (b) Qi, C.; Wang, X. L.; Carlucci, L.; Tong, M. L.; Wang, E. B.; Hu, C. W.; Xu, L. Chem. Commun. 2004, 1876. (c) Yang, J.; Ma, J. F.; Batten, S. R.; Su, Z. M. Chem. Commun. 2008, 2233. (d) Yao, Q. X.; Ju, Z. F.; Jin, X. H.; Zhang, J. Inorg. Chem. 2009, 48, 1266. (e) Wu, H.; Yang, J.; Su, Z. M.; Batten, S. R.; Ma, J. F. J. Am. Chem. Soc. 2011, 133, 11406. (f) Li, S. L.; Tan, K.; Lan, Y. Q.; Qin, J. S.; Li, M. N.; Du, D. Y.; Su, Z. M. CrystEngComm 2011, 13, 4945. (g) Wu, H.; Lin, H. Y.; Yang, J.; Liu, B.; Ma, J. F.; Liu, Y. Y.; Liu, Y. Y. Cryst. Growth Des. 2011, 11, 2317. (h) Yang, J. X.; Zhang, X.; Cheng, J. K.; Zhang, J.; Yao, Y. G. Cryst. Growth Des. 2012, 12, 333. (i) Hu, F. L.; Zou, H. H.; Zhao, X. B.; Mi, Y.; Luo, C. L.; Wang, Y. X. CrystEngComm 2013, 15, 1068. (7) (a) Yang, G. P.; Wang, Y. Y.; Liu, P.; Fu, A. Y.; Zhang, Y. N.; Jin, J. C.; Shi, Q. Z. Cryst. Growth Des. 2010, 10, 1443. (b) Selvakumar, K.; Singh, H. B.; Goel, N.; Singh, U. P.; Butcher, R. J. Dalton Trans. 2011, 40, 9858. (c) Li, B. Y.; Yang, F.; Li, G. H.; Liu, D.; Zhou, Q.; Shi, Z.; Feng, S. H. Cryst. Growth Des. 2011, 11, 1475. (d) Yang, G. P.; Zhou, J. H.; Wang, Y. Y.; Liu, P.; Shi, C. C.; Fu, A. Y.; Shi, Q. Z. CrystEngComm 2011, 13, 33. (e) Mihalcea, I.; Henry, N.; Clavier, N.; Dacheux, N.; Loiseau, T. Inorg. Chem. 2011, 50, 6243. (f) Hijikata, Y.; Horike, S.; Tanaka, D.; Groll, J.; Mizuno, M.; Kim, J.; Takata, M.; Kitagawa, S. Chem. Commun. 2011, 47, 7632. (g) He, W. W.; Yang, J.; Yang, Y.; Liu, Y. Y.; Ma, J. F. Dalton Trans. 2012, 41, 9737. (h) Kan, W. Q.; Ma, J. F.; Liu, B.; Yang, J. CrystEngComm 2012, 14, 286. (i) Luebke, R.; Eubank, J. F.; Cairns, A. J.; Belmabkhout, Y.; Wojtas, L.; Eddaoudi, M. Chem. Commun. 2012, 48, 1455. (j) Lama, P.; Sanudo, E. C.; Bharadwaj, P. K. Dalton Trans. 2012, 41, 2979. (8) (a) Liao, J. H.; Cheng, S. H.; Tsai, H. L.; Yang, C. I. Inorg. Chim. Acta 2002, 338, 1. (b) Rather, B.; Zaworotko, M. J. Chem. Commun. 2003, 830. (c) Ying, S.; Mao, J.; Sun, Y.; Zeng, H.; Dong, Z. Polyhedron 2003, 22, 3097. (d) Hao, N.; Shen, E.; Li, Y.; Wang, E.; Hu, C.; Xu, L. Eur. J. Inorg. Chem. 2004, 4102. (e) Lloyd, G. O.; Atwood, J. L.; Barbour, L. J. Chem. Commun. 2005, 1845. (f) Xu, X.; Ma, Y.; Wang, E. J. Solid State Chem. 2007, 180, 3136. (g) Montney, M. R.; Mallika Krishnan, S.; Supkowski, R. M.; LaDuca, R. L. Inorg. Chem. 2007, 46, 7362. (h) Martin, D. P.; Montney, M. R.; Supkowski, R. M.; LaDuca, R. L. Cryst. Growth Des. 2008, 8, 3091. (i) Shyu, E.; Supkowski, R. M.; LaDuca, R. L. Cryst. Growth Des. 2009, 9, 2481. (j) Banisafar, A.; Martin, D. P.; Lucas, J. S.; LaDuca, R. L. Cryst. Growth Des. 2011, 11, 1651. (k) Li, C. Y.; Liu, C. S.; Li, J. R.; Bu, X. H. Cryst. Growth Des. 2007, 7, 286. (l) Konar, S.; Zangrando, E.; G. B. Drew, M.; Ribas, J.; Chaudhuri, N. R. Dalton Trans. 2004, 260. (9) Pan, Z. R.; Xu, J.; Zheng, H. G.; Huang, K. X.; Li, Y. Z.; Guo, Z. J.; Batten, S. R. Inorg. Chem. 2009, 48, 5772. (10) (a) Farmum, G. A.; Martin, D. P.; Sposato, L. K.; Supkowski, R. M.; LaDuca, R. L. Inorg. Chim. Acta 2010, 363, 250. (b) Do, J.; Lee, Y.; Kang, J.; Jacobson, A. J. Inorg. Chim. Acta 2012, 382, 191. (c) Mir, M. H.; Koh, L. L.; Tan, G. K.; Vittal, J. J. Angew. Chem., Int. Ed. 2010, 49, 390. (d) Yang, J.; Ma, J. F.; Liu, Y. Y.; Li, S. L.; Zheng, G. L. Eur. J. Inorg. Chem. 2005, 2174. (e) Uebler, J. W.; Wilson, J. A.; LaDuca, R. L. CrystEngComm 2013, 15, 1586. (f) Ni, T. J.; Xing, F. F.; Shao, M.; Zhao, Y. M.; Zhou, S. R.; Li, M. X. Cryst. Growth Des. 2011, 11, 2999. (11) (a) Goodgame, D. M. L.; Menzer, S.; Williams, D. J. Chem. Commun. 1996, 2127. (b) Hoskins, B. F.; Robson, R.; Slizys, D. A. J. Am. Chem. Soc. 1997, 119, 2952. (c) Ma, J. F.; Liu, J. F.; Xing, Y.; Jia, H. Q.; Lin, Y. H. J. Chem. Soc., Dalton Trans. 2000, 2403. (d) Carlucci, L.; Ciani, G.; Proserpio, D. M. Chem. Commun. 2004, 380. (e) Carlucci, L.; Ciani, G.; Proserpio, D. M. Cryst. Growth Des. 2005, 5, 37. (f) Lin, J. D.; Li, Z. H.; Li, J. R.; Du, S. W. Polyhedron 2007, 26, 107. (g) Li, Z. X.; Zhao, J. P.; Sanudo, E. C.; Ma, H.; Pan, Z. D.; Zeng, Y. F.; Bu, X. H. Inorg. Chem. 2009, 48, 11601. (h) Li, Z. X.; Xu, Y.; Zuo, Y.; Li, L.;

Pan, Q. H.; Hu, T. L.; Bu, X. H. Cryst. Growth Des. 2009, 9, 3904. (i) Sun, L. X.; Qi, Y.; Wang, Y. M.; Che, Y. X.; Zheng, J. M. CrystEngComm 2010, 12, 1540. (j) Liu, J. Q.; Wang, Y. Y.; Huang, Y. S. CrystEngComm 2011, 13, 3733. (k) Ma, L. F.; Li, X. Q.; Meng, Q. L.; Wang, L. Y.; Du, M.; Hou, H. W. Cryst. Growth Des. 2011, 11, 175. (l) He, X.; Lu, X. P.; Li, M. X.; Morris, R. E. Cryst. Growth Des. 2013, 13, 1649. (12) (a) Schutze, V. W.; Schubert, H. J. Prakt. Chem. 1959, 8, 307. (b) Hoskins, B. F.; Robson, R.; Slizys, D. A. J. Am. Chem. Soc. 1997, 119, 2952. (13) Sheldrick, G. M. SADABS, Program for Area Detector Adsorption Correction, Institute for Inorganic Chemistry, University of Göttingen, Göttingen, Germany, 1996. (14) Sheldrick, G. M. SHELXL-97, Program for Solution of Crystal Structures, Institute for Inorganic Chemistry, University of Göttingen, Göttingen, Germany, 1997. (15) (a) O’ Keeffe, M.; Peskov, M. A.; Ramsden, S. J.; Yaghi, O. M. Acc. Chem. Res. 2008, 41, 1782. Database available at http://rcsr.anu. edu.au/. (b) Ramsden, S. J.; Robins, V.; Hyde, S. T. Acta Crystallogr. 2009, A65, 81. Database available at http://epinet.anu.edu.au. (16) Carlucci, L.; Ciani, G.; Proserpio, D. M.; Rizzato, S. Chem. Eur. J. 2002, 8, 1519. (17) Spek, A. L. J. Appl. Crystallogr. 2003, 36, 7. (18) (a) Lee, H. Y.; Park, J.; Lah, M. S.; Hong, J.-I. Cryst.Growth Des. 2008, 8, 587. (b) Lan, Y. Q.; Li, S. L.; Fu, Y. M.; Xu, Y. H.; Li, L.; Su, Z. M.; Fu, Q. Dalton Trans. 2008, 6796. (c) Wang, J. Y.; You, H. P. Z. Anorg. Allg. Chem. 2011, 637, 415. (d) Cui, K. H.; Yao, S. Y.; Li, H. Q.; Li, Y. T.; Zhao, H. P.; Jiang, C. J.; Tian, Y. Q. CrystEngComm 2011, 13, 3432. (e) Zhou, X. J.; Li, B. Y.; Li, G. H.; Zhou, Q.; Shi, Z.; Feng, S. H. CrystEngComm 2012, 14, 4664. (f) Wang, S.; Yun, R. R.; Peng, Y. Q.; Zhang, Q. F.; Lu, J.; Dou, J. M.; Bai, J. F.; Li, D. C.; Wang, D. Q. Cryst. Growth Des. 2012, 12, 79. (19) Lin, L.; Yu, R. M.; Yang, W. B.; Wu, X. Y.; Lu, C. Z. Cryst. Growth Des. 2012, 12, 3304. (20) (a) Zhang, L. Y.; Zhang, J. P.; Lin, Y. Y.; Chen, X. M. Cryst. Growth Des. 2006, 6, 1684. (b) Chu, Q.; Liu, G. X.; Huang, Y. Q.; Wang, X. F.; Sun, W. Y. Dalton Trans. 2007, 4302. (c) Wang, X. L.; Qin, C.; Wang, E. B.; Li, Y. G.; Hao, N.; Hu, C. W.; Xu, L. Inorg. Chem. 2004, 43, 1850. (d) Chen, Z. L.; Su, Y.; Xiong, W.; Wang, L. X.; Liang, F. P.; Shao, M. CrystEngComm 2009, 11, 318. (21) (a) Wen, L.; Lu, Z.; Lin, J.; Tian, Z.; Zhu, H.; Meng, Q. Cryst. Growth Des. 2007, 7, 93. (b) Lin, J. G.; Zang, S. Q.; Tian, Z. F.; Li, Y. Z.; Xu, Y. Y.; Zhu, H. Z.; Meng, Q. J. CrystEngComm 2007, 9, 915. (c) Wu, H.; Liu, H. Y.; Liu, Y. Y.; Yang, J.; Liu, B.; Ma, J. F. Chem. Commun. 2011, 47, 1818. (d) Guo, F.; Wang, F.; Yang, X. L.; Zhang, J. Inorg. Chem. 2012, 51, 9677.

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Tuning Different Kinds of Entangled Networks by Varying N-Donor

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