Unusual 2D â 3D Polycatenane Frameworks Based on 1D â 2D

Article pubs.acs.org/crystal

Unusual 2D → 3D Polycatenane Frameworks Based on 1D → 2D Interdigitated Layers: From Single Crystals to Submicrometer Fibers with Enhanced UV Photocatalytic Degradation Performances Jiao Guo, Jian-Fang Ma,* Jun-Jie Li, Jin Yang, and Shuang-Xi Xing* Key Lab of Polyoxometalate Science, Department of Chemistry, Northeast Normal University, Changchun 130024, People’s Republic of China S Supporting Information *

ABSTRACT: Four unusual isomorphous metal−organic frameworks, [M2(L1)(L2)2] (M = Co for 1, Mn for 2, Zn for 3, and Cd for 4), where H4L1 = tetrakis[4-(carboxyphenyl)-oxamethyl]methane acid and L2 = 4-tolyl-2,2′:6′,2″-terpyridine, have been synthesized under hydrothermal conditions. Their structures have been determined by single-crystal X-ray diffraction analyses and further characterized by infrared spectra, elemental analyses, powder X-ray diffraction, UV−vis absorption spectra, and optical energy gaps. In compounds 1−4, the metal atoms are linked by the L1 anions to yield a chain with a loop. Every loop of each chain is penetrated by two L2 ligand rods belonging to the two nearest chains, resulting in an unusual 1D → 2D interdigitated network. In the 2D interdigitated network, there exist weak π−π interactions between pyridyl groups of L2 ligands. If the π−π interactions are regarded as linkers, the 2D interdigitated network belongs to an uneven (3,4)-connected layer. Furthermore, each individual (3,4)-connected layer is polycatenated with an infinite number of other perpendicular layers, yielding an unusual 2D → 3D polycatenane framework. The luminescent properties of compounds 3 and 4 have been studied. In addition, compounds 1−4 exhibit photocatalytic activities for MB degradation under UV irradiation. Submicrometer fiber 1′ shows high photocatalytic efficiency for MB degradation with respect to its corresponding macroscaled crystalline 1.

■

INTRODUCTION The current interest in the crystal engineering of metal−organic frameworks (MOFs) stems not only from their potential application as functional materials but also from their intriguing variety of architectures and topologies.1−3 So far, a variety of appealing entangled structures have been rationally designed and reported.1 Among them, particular attention has been recently devoted to entangled polymeric systems, such as polycatenation, polyrotaxane, and polyknotting.2 For the entangled systems, interpenetration is the most common form, and many appealing interpenetrated frameworks have been constructed, taking advantage of the principles of network-based crystal engineering, which have been discussed in detail in several comprehensive reviews published in the past decade. 1a,d,2a Nevertheless, polycatenation has a higher dimensionality than that of the component motifs, where each individual motif is only catenated with the surrounding ones. As far as we know, although a number of MOFs showing interdigitated or polycatenane characters have been reported so far,3−6 fascinating structures showing both interdigitated and polycatenane characters have been rarely observed.5 Therefore, the design and construction of unusual topological frameworks with both interdigitated and polycatenane characters have become a particularly interesting subject. © 2012 American Chemical Society

Usually, the basic design element of the interdigitated framework is the synthesis of a molecular unit with loops and insertion of a linear rod in those loops. The conformationally flexible tetracarboxylate ligand, tetrakis[4-(carboxyphenyl)oxamethyl]methane acid (H4L1), has an ability to give unusual entanglements involving a loop (Scheme 1).7 The H4L1 ligand possesses four carboxyl group arms with conformational and Scheme 1. Tetracarboxylate Ligand H4L1 and N-Donor Ligand L2

Received: August 21, 2012 Revised: October 18, 2012 Published: November 6, 2012 6074

dx.doi.org/10.1021/cg301208d | Cryst. Growth Des. 2012, 12, 6074−6082

Crystal Growth & Design

Article

Table 1. Crystal Data and Structure Refinements for Compounds 1−4 compound

1

2

3

4

formula fw cryst syst space group a/Å b/Å c/Å α/deg β/deg γ/deg V/Å3 Z Dc/g cm−3 F(000) R(int) GOF on F2 R1 [I > 2σ(I)] wR2 (all data)

C77H58Co2N6O12 1377.66 orthorhombic Pccn 19.6403(15) 21.9093(11) 14.9888(6) 90 90 90 6449.8(6) 4 1.411 2817.4 0.0758 1.0530 0.0736 0.1744

C77H58Mn2N6O12 1369.11 orthorhombic Pccn 19.5953(12) 22.1837(10) 14.9874(8) 90 90 90 6515.0(6) 4 1.388 2800 0.0943 1.194 0.1192 0.2020

C77H58Zn2N6O12 1390.01 orthorhombic Pccn 19.4437(14) 22.1871(9) 14.9011(8) 90 90 90 6428.3(6) 4 1.428 2328.0 0.1034 1.140 0.1060 0.1811

C77H58Cd2N6O12 1483.94 orthorhombic Pccn 19.5908(9) 22.1822(12) 15.0328(5) 90 90 90 6532.8(5) 4 1.486 2928 0.0938 1.169 0.1085 0.1823

■

geometrical flexibility. The carboxyl group arms can rotate freely and adjust themselves sterically around the central C moiety when coordinating to the metal centers. 4-Tolyl2,2′:6′,2″-terpyridine (L2),8 as a long rigid ligand, is a good candidate for a rod in the assembly. The large aromatic system of L2 can provide potential supramolecular recognition sites for π−π stacking interactions that can be used to govern the process of self-assembly. Therefore, it may be possible to construct the new classes of entangled MOFs through combining the two types of different precursors. On the other hand, over the past few years, the research on properties of MOFs, such as catalysis, magnetism, electrical conductivity, recognition, separation, and ion exchange, has received increasing interest.1−3 Therefore, much work has been focused on the preparation of micro- and nanosized MOF particles with various morphologies, as they have substantial potential for use in innovative applications, such as imaging probes, heterogeneous catalysts, and so on.9 In particular, the photocatalytic activities have a close relationship with the shape, size, and dimensionality of particles to some extent. Compared with macroscaled crystalline products, micro- and nanosized particles can significantly improve their photocatalytic properties because of their high surface area. However, we are not aware of the research related to the enhanced photocatalytic properties of MOFs from macroscaled crystalline products to micro- and nanosized particles so far.9e In this work, we report four unusual isomorphous MOFs based on H4L1 and L2 under hydrothermal conditions, namely, [Co2(L1)(L2)2] (1), [Mn2(L1)(L2)2] (2), [Zn2(L1)(L2)2] (3), and [Cd2(L1)(L2)2] (4). Compounds 1−4 show new 2D → 3D polycatenane frameworks based on unusual 1D → 2D interdigitated layers. These compounds are characterized by Xray crystallography, elemental analysis, infrared spectra (IR), powder X-ray diffraction (PXRD), and optical energy gaps. The luminescent properties of compounds 3 and 4 have been studied. In addition, compounds 1−4 exhibit photocatalytic activities for methylene blue (C16H18NS-Cl-3H2O) (MB) degradation under UV irradiation. Submicrometer fiber 1′ shows high photocatalytic efficiency for MB degradation with respect to its corresponding macroscaled crystalline 1.

EXPERIMENTAL SECTION

Materials and Methods. The H4L1 and L2 ligands were synthesized in accordance with the procedure reported.7,8 All reagents and solvents for the syntheses were purchased from commercial sources and used as received. Physical Measurements. The C, H, and N elemental analyses were conducted on a Carlo Erba 1106 elemental analyzer. The FT-IR spectra were recorded from KBr pellets in the range of 4000−400 cm−1 on a Mattson Alpha-Centauri spectrometer. Diffuse reflectivity spectra were collected on a finely ground sample with a Cary 500 spectrophotometer equipped with a 110 mm diameter integrating sphere. Diffuse reflectivity was measured from 200 to 800 nm using barium sulfate as a standard with 100% reflectance. The emission spectra and luminescent decay lifetimes of compounds 3 and 4 were measured on an FLSP920 Edinburgh fluorescence spectrometer. PXRD patterns of the samples were collected on a Rigaku Dmax 2000 X-ray diffractometer with graphite monochromatized Cu Kα radiation (λ = 0.154 nm) and 2θ ranging from 5 to 50°. The morphology of the sample was observed by using a field emission scanning electron microscope (FESEM, JEOL JSM-6700F, 5.0 kV). The Brunauer− Emmett−Teller (BET) surface area was determined from nitrogen adsorption isotherms using a fully automated surface area analyzer ASAP 2020. Photocatalytic properties of the samples were examined by measuring the photodecomposition of 5 × 10−5 mol/L aqueous MB solution. Typically, samples were placed with MB solution in a tubular quartz reactor. To characterize the photocatalytic properties in the UV region, the solution was stirred while being irradiated by the surrounding 125 W UV lamp (wavelength = 365 nm). After the dark adsorption in 30 min, the measurement was carried out. Photodegradation of the MB solution was investigated by measuring the absorption spectra of the solution using a UV−vis spectrophotometer at λmax = 665 nm. Crystal Structure Determination. Single-crystal X-ray diffraction data for 1−4 were recorded on a Oxford Diffraction Gemini R Ultra diffractometer with graphite-monochromated Mo Kα radiation (λ = 0.71073 Å) at 293 K. Absorption corrections were applied using a multiscan technique. All the structures were solved by the Direct Method of SHELXS-97 and refined by full-matrix least-squares techniques using the SHELXL-97 program.10 Non-hydrogen atoms were easily found from the Fourier difference maps and refined anisotropically. All hydrogen atoms bound to carbon were refined using a riding model with d(C−H) = 0.93 Å, Uiso= 1.2Ueq(C) for aromatic and d(C−H) = 0.96 Å, Uiso = 1.5Ueq(C) for CH3 atoms. The hydrogen atoms of the disordered C atoms in compounds 1−4 were not included in the models. The disordered C and O atoms of 6075



Article

Figure 1. (a) Coordination environment of the Co(II) ion in 1 (30% probability displacement ellipsoids). Symmetry codes: #1 = −x + 3/2, −y − 1/ 2, z; #2 = x − 1/2, y + 1/2, −z + 1. (b) View of the 1D chain built from L1, L2, and Co(II) atoms. (c) View of the 1D chain [(Co2L1) windows are considered as loops, and L2 ligands are considered as rods]. compound 1−4 were refined using C and O atoms split over two sites, with a total occupancy of 1. The detailed crystallographic data and structure refinement parameters for these compounds are summarized in Table 1. Selected bond distances and angles are listed in Tables S1−S4 (Supporting Information). Synthesis of [Co2(L1)(L2)2] (1). A mixture of Co(OAc)2·2H2O (50.0 mg, 0.2 mmol), H4L1 (61.6 mg, 0.1 mmol), L2 (32.3 mg, 0.1 mmol), and NaOH (1.6 mg, 0.4 mmol) was dissolved in 8 mL of DMF/H2O (1:1, v/v). The final mixture was placed in a Parr Teflonlined stainless steel vessel (15 mL) under autogenous pressure and heated at 110 °C for 3 days. Brown needle crystals of 1 were collected in a 72% yield based on Co(OAc) 2 ·2H2 O. Anal.Calcd for

C77H58Co2N6O12 (Mr = 1377.66): C, 67.15; H, 4.24; N, 6.10. Found: C, 67.23; H, 4.19; N, 5.99. IR (KBr, cm−1): 3435(w), 1605(w), 1545(m), 1505(s), 1469(s), 1415(w), 1336(m), 1233(w), 1164(m), 1016(s), 859(m), 783(w), 698(s), 504(w), 407(m). Synthesis of [Mn2(L1)(L2)2] (2). The preparation of 2 was similar to that of 1 except that Mn(OAc)2·4H2O (49.2 mg, 0.2 mmol) was used instead of Co(OAc)2·2H2O. Yellow block crystals of 2 were collected in a 63% yield based on Mn(OAc)2·2H2O. Anal. Calcd for C77H58Mn2N6O12 (Mr = 1369.11): C, 67.55; H, 4.27; N, 6.14. Found: C, 67.67; H, 4.19; N, 6.21. IR (KBr, cm−1): 3434(w), 1603(w), 1544(m), 1506(m), 1471(m), 1402(w), 1346(w), 1300(m), 1233(w), 1165(m), 1098(s), 1044(m), 1012(m), 858(m), 783(w), 698(s), 655(s), 631(s), 562(s), 502(s), 404(s). 6076



Article

Synthesis of [Zn2(L1)(L2)2] (3). The preparation of 3 was similar to that of 1 except that Zn(OAc)2·2H2O (43.9 mg, 0.2 mmol) was used instead of Co(OAc)2·2H2O. Colorless block crystals of 3 were collected in a 64% yield based on Zn(OAc)2·2H2O. Anal.Calcd for C77H58Zn2N6O12 (Mr = 1390.01): C, 66.53; H, 4.21; N, 6.05. Found: C, 66.48; H, 4.17; N, 5.98. IR (KBr, cm−1): 3428(w), 3063(m), 2937(m), 1710(s), 1604(w), 1505(m), 1471(w), 1365(w), 1233(w), 1165(w), 1099(m), 1015(w), 855(m), 783(w), 731(s), 696(s), 655(m), 637(m), 566(s), 503(m), 407(s). Synthesis of [Cd2(L1)(L2)2] (4). The preparation of 4 was similar to that of 1 except that Cd(OAc)2·2H2O (54.0 mg, 0.2 mmol) was used instead of Co(OAc)2·2H2O. Colorless block crystals of 4 were collected in a 78% yield based on Cd(OAc)2·2H2O. Anal.Calcd for C77H58Cd2N6O12 (Mr = 1483.94): C, 62.31; H, 3.94; N, 5.66. Found: C, 62.43; H, 3.89; N, 5.69. IR (KBr, cm−1): 3426(w), 1658(m), 1601(w), 1545(w), 1475(w), 1394(w), 1237(w), 1166(m), 1099(m), 1013(m), 858(m), 819(s), 787(m), 726(s), 656(s), 630(s), 502(s). Synthesis of Compound 1′ Submicrometer Fiber. A mixture of Co(OAc)2·2H2O (25.0 mg, 0.1 mmol), H4L1 (30.8 mg, 0.05 mmol), L2 (32.3 mg, 0.1 mmol), polyvinylpyrrolidone (PVP) (2.22 g, 20 mmol) (in monomer concentration), and NaOH (0.8 mg, 0.2 mmol) was dissolved in 8 mL of DMF/H2O (1:1, v/v). The final mixture was stirred and heated at 110 °C for 72 h. The solutions were centrifuged at 2000 rpm for 30 min to isolate the microparticles, which remained in the sediment. The microparticles were transferred to water by first washing with ethanol to remove the excess PVP, centrifugation at 5000 rpm for 5 min, and redispersal of the residue in water. This process was repeated three times.

■

RESULTS AND DISCUSSION Structures of [M2(L1)(L2)2] (M = Co for 1, Mn for 2, Zn for 3, and Cd for 4). Single-crystal structure analysis reveals that 1−4 are isostructural and crystallize in the space group Pccn. Therefore, only the structure of 1 will be described in detail. The asymmetric unit of 1 contains one Co(II) atom, half an L1 anion, and one L2 ligand. As shown in Figure 1a, each Co(II) ion is six-coordinated by three carboxylate oxygen atoms from two L1 anions (Co(1)−O(1) = 2.097(3) Å, Co(1)−O(2) = 2.23(4) Å, and Co(1)−O(6)#2 = 2.006(4) Å) and three nitrogen atoms from one L2 ligand (Co(1)−N(1) = 2.195(5) Å, Co(1)−N(2) = 2.047(3) Å, and Co(1)−N(3) = 2.121(5) Å) in an octahedral coordination geometry. Two carboxylate groups of L1 adopt monodentate (μ1-η1:η1) modes, while the other two show bridging (μ1-η1:η0) modes. In this way, each L1 anion links four Co(II) ions to form an interesting chain (Figure 1b). In the chain, two pairs of carboxyphenyl groups from two L1 anions and two Co(II) ions form a loop with dimensions of 9.8 Å × 10.4 Å, which provides the possibility for the ultimate realization of an interdigitated network (Figure 1c). It is worth noting that each loop is penetrated by two dangling L2 ligand rods that belong to two different chains, one entering from one side and the other from the opposite side (Figure 2a). However, the dangling L2 ligands of the unusual chains do not really penetrate through the loops but are simply interdigitated on the loop surface (Figure 2a and the Supporting Information), generating an unusual 1D → 2D interdigitated layer (Figure 2b).2 As far as we know, this interdigitated mode has only been observed in the reported 0D → 1D complex [Co2(L3)4(NO3)4]·(Me2CO)2 (L3 = 4,4′-bis(pyridin-4ylmethoxy)biphenyl).2c In addition, there exist weak π−π stacking interactions (centroid-to-centroid distance of 4.010 Å and face-to-face distance of 3.431 Å) among pyridyl groups of L2 ligands from neighboring chains, which further stabilize the 2D interdigitated layer of 1. Topologically, with each π−π stacking interaction as

Figure 2. (a) View of the 1D → 2D interdigitated layer of 1. (b) Schematic view of the1D → 2D interdigitated layer of 1.

a bridge, each L1 anion serving as a 4-connected node, and each Co(II) atom as an equivalent 3-connected node (Figure S2, Supporting Information), this 2D interdigitated layer displays an uneven (3,4)-connected (4·62)(42·62·82) topology (Figure 3a,b). As shown in Figure S2 (Supporting Information), the layer is composed of hexagonal and rhombic meshes. The diagonals of the rhombic windows are about 10.4 and 9.8 Å, while the dimensions of the distorted hexagonal windows, estimated from the maximum distances between opposite vertices, are about 23.8 Å × 28.2 Å. 6077



Article

Figure 3. (a) View of the 2D sheet constructed by π−π interactions between the L2 ligands. (b) Schematic view of the 2D sheet constructed by π−π interactions between the L2 ligands.

Figure 4. Schematic views of the polycatenation in 1 and space-filling presentations of the hexagonal windows in one layer unevenly catenated by those from other independent layers (two sets of layers are shown in red and green).

Notably, each individual (3,4)-connected layer is polycatenated with an infinite number of other perpendicular layers, resulting in an overall 2D → 3D polycatenated array based on π−π interactions (Figure 4).11 As illustrated in Figure 4, the perpendicular catenation only occurs on the hexagonal windows. So far, a number of interdigitated MOFs have been reported; however, the MOFs with the coexistence of interdigitated and polycatenane characters are rarely observed in coordination chemistry.3−5 It is noteworthy that our present 2D → 3D polycatenane frameworks based on 1D → 2D interdigitated layers are entirely different from the known related species.5g In those reported examples ([Zn(1,2-BBOMB)(4,4′-bipy)0.5]n, [Zn2(1,3-BBOMB)2(4,4′-bipy)]n, and [Zn4(1,2BBOMB) 4 (bpp) 2 ]n (1,2-BBOMB = 1,2-bis-(benzoato-4oxamethyl)benzene, 1,3-BBOMB = 1,3-bis(benzoato-4oxamethyl)benzene, bpp = 1,3-bis(4-pyridyl)propane, and 4,4′-bipy = 4,4′-bipyridine)), they display a structural evolution from a 2D polyrotaxane and polycatenane framework to a 3D

architecture with the coexistence of polyrotaxane, polycatenane, and interdigitation.5g The successful isolation of 1D → 2D → 3D frameworks of 1−4 not only provides intriguing examples of interdigitated system but also opens up new perspectives to devise novel extended entangled architectures. Optical Energy Gaps. The UV−vis absorption spectra of H4L1, L2, and 1−4 were carried out in the crystalline state at room temperature. The H4L1 and L2 ligands exhibit strong absorption bands in the ranges of 260−280 and 320−340 nm, respectively, which can be ascribed to π*→ π transitions of the ligands (Figure S3, Supporting Information). The lower energy band from 560 to 580 nm for 1 can be considered as metal-toligand charge-transfer (MLCT) transitions, whereas energy bands from 240 to 260 nm for 1, from 280 to 300 nm for 2, from 290 to 310 nm for 3, and from 300 to 320 nm for 4 are assigned as d−d transitions (Figure S4, Supporting Information). Some MOFs have been reported to be potential semiconductors in the previous literature.14f,17d Inspired by these 6078



Article

Figure 5. Diffuse reflectance UV−vis-NIR spectra of K−M functions versus energy (eV) of compounds 1−4.

documents, we explored the conductivities of compounds 1−4. The measurements of diffuse reflectivity for powder samples were performed to obtain their band gaps (Eg), which was determined as the intersection point between the energy axis and the line extrapolated from the linear portion of the adsorption edge in a plot of the Kubelka−Munk function F against energy E.12 The Kubelka−Munk function, (F = (1 − R)2/2R) was transformed from the recorded diffuse reflectance data, where R is the reflectance of an infinitely thick layer at a given wavelength. As shown in Figure 5, the Eg values assessed from the steep absorption edge are 1.98 eV for 1, 3.09 eV for 2, 3.26 eV for 3, and 3.31 eV for 4, respectively. Luminescent Properties. MOFs with d10 metal atoms are promising candidates for photoactive materials with potential applications.13 The solid-state photoluminescent properties of H4L1, L2, and compounds 3 and 4 have been investigated in the solid state at room temperature (Figure 6). The emission spectra of free H4L1 and L2 ligands show the main peaks at 418 and 399 nm, respectively, which are probably attributable to the π* → n or π* → π transitions.9 The emission spectra of the compounds exhibit emissions at about 400 nm (λex = 361 nm) for 3 and 401 nm (λex = 364 nm) for 4, which are similar to that of the L2 ligand. Therefore, the emission bands of compounds 3 and 4 can be attributed to the intraligand (L2) emissions.14 The luminescence decay curves of 3 and 4 at room temperature are well-fit into a double-exponential function as I = A + B1 × exp(−t/τ1) + B2 × exp(−t/τ2). The emission decay lifetimes are τ1 = 1.31 ns (87.38%) and τ2 = 7.70 ns (12.62%) (χ2 = 1.005) for 3 and τ1 = 1.19 ns (81.93%) and τ2 = 3.11 ns (18.07%) (χ2 = 1.010) for 4 (Figure S5, Supporting Information). The luminescence lifetimes of 3 and 4 are

Figure 6. Solid-state emission spectra of H4L1, L2, 3, and 4 at room temperature.

much shorter than the ones from a triplet state (>10−3 s), so their emissions should arise from a singlet state.15,16 Photocatalytic Properties. Photocatalysts have attracted much attention due to their potential applications in purifying water and air by decomposing organic molecules.17 Thus, MB, as a model dye contaminant, was selected to evaluate the photocatalytic effectiveness in the purification of wastewater. Typically, a suspension containing 1−4 or 1′ (30 mg) and 200 mL of MB (5.0 × 10−5 mol·L−1) solution was stirred in the dark for about 30 min. To explore the photocatalytic behavior of the microstructure of the samples relative to their corresponding macroscaled crystalline products, the microstructure of compound 1 was prepared as an example. As a proof of concept, we transferred the synthesis away from the 6079



Article

Figure 7. SEM images of the submicrometer fiber 1′ at low and high magnifications.

Figure 8. Absorption spectra of the MB solution during the decomposition reaction under UV light irradiation with the use of compounds 1−4.

solvothermal system in order to control the morphology of the products. Introducing PVP as a structure-guiding reagent led to the formation of microstructure 1′ with rectangular shapes (Figure 7). The size and morphology of 1′ submicrometer fibers were examined by field emission scanning electron microscopy (FE-SEM). Figure 7 shows typical images of the products at different magnifications. One can notice that the rodlike structures dominate in the full images, indicating a high yield of our products. Closer observations show the detailed structures of these rodlike morphologies, indicating that all of the nanorods are compressed and well-separated from each other, which have widths of about 200−300 nm, thicknesses of 100−200 nm, and lengths ranging from a few hundred nanometers to several micrometers. Note that the morphology control was not carried out. The XRD pattern of the resulting

material shows that the crystalline phase is consistent with that from the typical solvothermal method (Figure S6, Supporting Information). The photocatalytic activity of sample 1′ was studied by the photodegradation of MB under UV light as a model reaction, and the result was compared with those of samples 1−4, shown in Figures 8 and 9. The baseline in Figure 10 represents the MB solution without photocatalyst, and the small change in the MB concentration with UV-light irradiation indicates that the MB solution did not self-decompose. For MB solutions in the presence of compounds 1−4 and 1′ photocatalysts, MB decomposed by about 81, 88, 78, 87 and 94% after 1.5 h under UV irradiation, respectively (Figures 10 and 11). It is noted that the catalytic activity of submicrometer fiber 1′ is much higher than that of 1. The FE-SEM images of 1 (Figure 6080



Article

S6 and S9, Supporting Information). The powder XRD patterns are nearly identical to those of the original compounds, implying that 1−4 maintain their structural integrity after photocatalysis reaction, which confirmed that their stabilities toward photocatalysis are good.

■

CONCLUSIONS Four isomorphous MOFs based on H4L1 and L2 have been successfully synthesized under hydrothermal conditions. These MOFs display unusual 2D → 3D polycatenane frameworks constructed from unusual 1D → 2D interdigitated layers. Solidstate compounds 3 and 4 show intense emissions at room temperature. The photocatalytic behaviors of compounds 1−4 indicate that they are good and stable photocatalysts for the photodegradation of MB. With respect to macroscaled crystalline 1, submicrometer fiber 1′ shows a high photocatalytic performance for the degradation of MB under UV.

Figure 9. Absorption spectra of the MB solution during the decomposition reaction under UV light irradiation with the use of compound 1′.

■

ASSOCIATED CONTENT

S Supporting Information *

Selected bond lengths and angles, view of the dangling L2 ligands interdigitated on the loop surface, view of the 2D sheet of (4·62)(42·62·82) topology, UV−vis absorption spectra of ligands H4L1 and L2 and compounds 1−4, the fitted decay curve monitored at 400 and 401 nm for 3 and 4, PXRD patterns of compound 1′, and PXRD patterns of compounds 1−4. This material is available free of charge via the Internet at http://pubs.acs.org.

■

AUTHOR INFORMATION

Corresponding Author

*E-mail: [email protected] (J.-F.M.), xingsx737@ nenu.edu.cn (S.-X.X.). Notes

Figure 10. Photocatalytic decomposition of MB solution under UV with the use of compounds 1−4, 1′, and the control experiment without any catalyst.

The authors declare no competing financial interest.

■

ACKNOWLEDGMENTS We thank the National Natural Science Foundation of China (Grant Nos. 21071028, 21001023, 21277022), the Science Foundation of Jilin Province (201215005, 20100109), and the Fundamental Research Funds for the Central Universities for support.

S7, Supporting Information) and 1′ (Figure 7) indicate that 1′ has a relatively small size and uniform shape. Moreover, the N2 sorption isotherms (Figure S8, Supporting Information) show that 1′ has a higher BET surface area (62.7509 m2/g) than that of 1 (4.9391 m2/g). Thus, the high photocatalytic activity of 1′ can be attributed to its uniform shape and high surface area. In addition, compounds 1−4 also exhibit similar photocatalytic activities for MB degradation under UV because of their isomorphism. It also can be seen that the central metal is not the main factor that influences their photocatalytic activities. After photocatalysis, the colors of samples 1−4 and 1′ remain unchanged. In addition, the photostability of compounds 1−4 and 1′ was monitored by using powder XRD patterns during the course of photocatalytic reactions (Figures

■

REFERENCES

(1) (a) Batten, S. R.; Robson, R. Angew. Chem., Int. Ed. 1998, 37, 1460. (b) Wu, H.; Yang, J.; Su, Z. M.; Batten, S. R.; Ma, J. F. J. Am. Chem. Soc. 2011, 133, 11406. (c) Wu, H.; Liu, H. Y.; Liu, Y. Y.; Yang, J.; Liu, B.; Ma, J. F. Chem. Commun. 2011, 47, 1818. (d) Batten, S. R. CrystEngComm 2001, 3, 67. (e) He, Y. C.; Yang, J.; Yang, G. C.; Kan, W. Q.; Ma, J. F. Chem. Commun. 2012, 48, 7859. (f) Yang, J.; Ma, J. F.; Batten, S. R. Chem. Commun. 2012, 48, 7899.

Figure 11. Color changes of the solution of MB in the presence of photocatalysts as the irradiation time increases. 6081



Article

(2) (a) Carlucci, L.; Ciani, G.; Proserpio, D. M. Coord. Chem. Rev. 2003, 246, 247. (b) Li, L. J.; Qin, C.; Wang, X. L.; Wang, S.; Zhao, L.; Yang, G. S.; Wang, H. N.; Yuan, G.; Shao, K. Z.; Su, Z. M. CrystEngComm 2012, 14, 124. (c) Banfi, S.; Carlucci, L.; Caruso, E.; Ciani, G.; Proserpio, D. M. J. Chem. Soc., Dalton Trans. 2002, 2714. (3) (a) Carlucci, L.; Ciani, G.; Moret, M.; Proserpio, D. M.; Rizzato, S. Angew. Chem., Int. Ed. 2000, 39, 1506. (b) Li, B. L.; Peng, Y. F.; Li, B. Z.; Zhang, Y. Chem. Commun. 2005, 2333. (c) Carlucci, L.; Ciani, G.; Maggini, M.; Proserpio, D. M. Cryst. Growth Des. 2008, 8, 162. (d) Vishweshwar, P.; Beauchamp, D. A.; Zaworotko, M. J. Cryst. Growth Des. 2006, 6, 2429. (e) Carlucci, L.; Ciani, G.; Proserpio, D. M. Chem. Commun. 2004, 380. (f) Lu, J. Y.; Babb, A. M. Chem. Commun. 2001, 821. (g) Jiang, Y. C.; Lai, Y. C.; Wang, S. L.; Lii, K. H. Inorg. Chem. 2001, 40, 5320. (h) Shin, D. M.; Lee, I. S.; Chung, Y. K.; Lah, M. S. Chem. Commun. 2003, 1036. (i) Shin, D. M.; Lee, I. S.; Cho, D.; Chung, Y. K. Inorg. Chem. 2003, 42, 7722. (j) Carlucci, L.; Ciani, G.; Proserpio, D. M.; Spadacini, L. CrystEngComm 2004, 6, 96. (k) Zhu, H. F.; Fan, J.; Okamura, T.-a.; Sun, W. Y.; Ueyama, N. Cryst. Growth Des. 2005, 5, 289. (l) Sagué, J. L.; Fromm, K. M. Cryst. Growth Des. 2006, 6, 1566. (m) Carlucci, L.; Ciani, G.; Proserpio, D. M. Cryst. Growth Des. 2005, 5, 37. (4) (a) Carlucci, L.; Ciani, G.; Proserpio, D. M. Chem. Commun. 1999, 449. (b) Du, M.; Jiang, X. J.; Zhao, X. J. Chem. Commun. 2005, 5521. (c) Qin, C.; Wang, X. L.; Carlucci, L.; Tong, M. L.; Wang, E. B.; Hu, C. W.; Xu, L. Chem. Commun. 2004, 1876. (d) Du, M.; Jiang, X. J.; Zhao, X. J. Inorg. Chem. 2007, 46, 3984. (e) Lan, Y. Q.; Li, S. L.; Wang, X. L.; Su, Z. M.; Shao, K. Z.; Wang, E. B. Chem. Commun. 2007, 4863. (f) Lan, Y. Q.; Li, S. L.; Wang, X. L.; Shao, K. Z.; Su, Z. M.; Wang, E. B. Inorg. Chem. 2008, 47, 529. (g) Ma, Y.; Cheng, A. L.; Gao, E. Q. Cryst. Growth Des. 2010, 10, 7. (5) (a) Wang, X. L.; Qin, C.; Wang, E. B.; Xu, L. Eur. J. Inorg. Chem. 2005, 3418. (b) Carlucci, L.; Ciani, G.; Macchi, P.; Proserpio, D. M.; Rizzato, S. Chem.Eur. J. 1999, 5, 237. (c) Batten, S. R.; Hoskins, B. F.; Robson, R. Chem.Eur. J. 2000, 6, 156. (d) Ayyappa, P.; Evans, O. R.; Lin, W. Inorg. Chem. 2002, 41, 3328. (e) Wang, X. L.; Qin, C.; Wang, E. B.; Xu, L.; Su, Z. M.; Hu, C. W. Angew. Chem., Int. Ed. 2004, 43, 5036. (f) Fu, Z. Y.; Wu, X. T.; Dai, J. C.; Hu, S. M.; Du, W. X. New J. Chem. 2002, 26, 978. (g) Cao, X. Y.; Yao, Y. G.; Batten, S. R.; Ma, E.; Qin, Y. Y.; Zhang, J.; Zhang, R. B.; Cheng, J. K. CrystEngComm 2009, 11, 1030. (6) (a) Kim, K. Chem. Soc. Rev. 2002, 31, 96. (b) Carlucci, L.; Ciani, G.; Proserpio, D. M. CrystEngComm 2003, 6, 269. (c) Loeb, S. J. Chem. Commun. 2005, 1511. (d) Yang, J.; Ma, J. F.; Batten, S. R.; Su, Z. M. Chem. Commun. 2008, 2233. (e) Carlucci, L.; Ciani, G. F.; Proserpio, D. M. Cryst. Growth Des. 2005, 5, 1. (7) (a) Oike, H.; Imamura, H.; Imaizumi, H.; Tezuka, Y. Macromolecules 1999, 32, 4819. (b) Liu, T. F.; Lü, J.; Guo, Z. G.; Proserpio, D. M.; Cao, R. Cryst. Growth Des. 2010, 10, 1489. (c) Thallapally, P. K.; Tian, J.; Kishan, M. R.; Fernandez, C. A.; Dalgarno, S.; McGrail, P. B.; Warren, J. E.; Atwood, J. L. J. Am. Chem. Soc. 2008, 130, 16842. (d) Guo, Z. G.; Cao, R.; Wang, X.; Li, H. F.; Yuan, W. B.; Wang, G. J.; Wu, H. H.; Li, J. J. Am. Chem. Soc. 2009, 131, 6894. (e) Liang, L. L.; Zhang, J.; Ren, S. B.; Ge, G. W.; Li, Y. Z.; Du, H. B.; You, X. Z. CrystEngComm 2010, 12, 2008. (f) Liu, T. F.; Lü, J.; Lin, X.; Cao, R. Chem. Commun. 2010, 46, 8439. (8) (a) Al-Noaimi, M.; Yap, G. P. A.; Crutchley, R. J. Inorg. Chem. 2004, 43, 1770. (b) Chamchoumis, C. M.; Potvin, P. G. J. Chem. Soc., Dalton Trans. 1999, 1373. (c) Barigelletti, F.; Ventura, B.; Collin, J. P.; Kayhanian, R.; Gavina, P.; Sauvage, J. P. Eur. J. Inorg. Chem. 2000, 113. (d) Yutaka, T.; Obara, S.; Haga, M.; Yokoyama, Y.; Sakai, K. Acta Crystallogr., Sect. E 2005, 61, 1357. (e) Messina, M. T.; Metrangolo, P.; Resnati, G.; Quici, S.; Manfredi, A.; Pilati, T. Supramol. Chem. 2001, 12, 405. (f) Collin, J. P.; Kayhanian, R.; Sauvage, J. P.; Calogero, G.; Barigelletti, F.; Cian, A. D.; Fischer, J. Chem. Commun. 1997, 775. (9) (a) Maji, T. K.; Matsuda, R.; Kitagawa, S. Nat. Mater. 2007, 6, 142. (b) Lee, H. J.; Cho, W.; Jung, S.; Oh, M. Adv. Mater. 2009, 21, 674. (c) Liu, K.; You, H. P.; Zheng, Y. H.; Jia, G.; Song, Y. H.; Huang, Y. J.; Yang, M.; Jia, J. J.; Guo, N.; Zhang, H. J. J. Mater. Chem. 2010, 20, 3272. (d) Makiura, R.; Motoyama, S.; Umemura, Y.; Yamanaka, H.;

Sakata, O.; Kitagawa, H. Nat. Mater. 2010, 9, 565. (e) Yoo, D. H.; Cuong, T. V.; Luan, V. H.; Khoa, N. T.; Kim, E. J.; Hur, S. H.; Hahn, S. H. J. Phys. Chem. C 2012, 116, 7180. (10) (a) Sheldrick, G. M. SHELXS-97: Programs for X-ray Crystal Structure Solution; University of Göttingen: Göttingen, Germany, 1997. (b) Sheldrick, G. M. SHELXL-97: Programs for X-ray Crystal Structure Refinement; University of Göttingen: Göttingen, Germany, 1997. (11) (a) Blake, A. J.; Champness, N. R.; Hubberstey, P.; Li, W. S.; Withersby, M. A.; Schröder, M. Coord. Chem. Rev. 1999, 183, 117. (b) Batten, S. R.; Robson, R. Angew. Chem., Int. Ed. 1998, 37, 1461. (12) (a) Pankove, J. I. Optical Processes in Semiconductors; PrenticeHall, Inc.: Englewood Cliffs, NJ, 1997; p 34. (b) Zhang, L.; Wei, Y.; Wang, C.; Guo, H.; Wang, P. J. Solid State Chem. 2004, 177, 3433. (c) Liao, J. H.; Juang, J. S.; Lai, Y. C. Cryst. Growth Des. 2006, 6, 354. (d) Xia, Y.; Wu, P. F.; Wei, Y. G.; Wang, Y.; Guo, H. Y. Cryst. Growth Des. 2006, 6, 253. (13) (a) McGarrah, J. E.; Kim, Y. J.; Hissler, M.; Eisenberg, R. Inorg. Chem. 2001, 40, 4510. (b) Wu, Q.; Esteghamatian, M.; Hu, N. X.; Popovic, Z.; Enright, G.; Tao, Y.; D’Iorio, M.; Wang, S. Chem. Mater. 2000, 12, 79. (c) Santis, G. D.; Fabbrizzi, L.; Licchelli, M.; Poggi, A.; Taglietti, A. Angew. Chem., Int. Ed. 1996, 35, 202. (14) (a) Shi, X.; Zhu, G.; Wang, X.; Li, G.; Fang, Q.; Wu, G.; Tian, G.; Xue, M.; Zhao, X.; Wang, R.; Qiu, S. Cryst. Growth Des. 2005, 5, 207. (b) Zhang, L.; Qin, Y. Y.; Li, Z. J.; Lin, Q. P.; Cheng, J. K.; Zhang, J.; Yao, Y. G. Inorg. Chem. 2008, 47, 8286. (c) Li, X.; Cao, R.; Sun, D.; Yuan, D.; Bi, W.; Li, X.; Wang, Y. J. Mol. Struct. 2004, 694, 205. (d) Zhang, L. P.; Ma, J. F.; Yang, J.; Pang, Y. Y.; Ma, J. C. Inorg. Chem. 2010, 49, 1535. (e) Liu, H. Y.; Wu, H.; Ma, J. F.; Liu, Y. Y.; Liu, B.; Yang, J. Cryst. Growth Des. 2010, 10, 4795. (f) Guo, J.; Ma, J. F.; Liu, B.; Kan, W. Q.; Yang, J. Cryst. Growth Des. 2011, 11, 3609. (15) (a) Ma, J. F.; Yang, J.; Li, S. L.; Song, S. Y. Cryst. Growth Des. 2005, 5, 807. (b) Ma, J. F.; Yang, J.; Zheng, G. L.; Li, L.; Liu, J. F. Inorg. Chem. 2003, 42, 7531. (16) (a) Li, G. Z.; Wang, Z. L.; Yu, M.; Quan, Z. W.; Lin, J. J. Solid State Chem. 2006, 179, 2698. (b) Li, G. Z.; Yu, M. Z.; Wang, L.; Lin, J.; Wang, R. S.; Fang, J. J. Nanosci. Nanotechnol. 2006, 6, 1416. (17) (a) Liu, B.; Yu, Z. T.; Yang, J.; Wu, H.; Liu, Y. Y.; Ma, J. F. Inorg. Chem. 2011, 50, 8967. (b) Lin, H.; Maggard, P. A. Inorg. Chem. 2008, 47, 8044. (c) Hu, Y.; Luo, F.; Dong, F. F. Chem. Commun. 2011, 47, 761. (d) Kan, W. Q.; Liu, B.; Yang, J.; Liu, Y. Y.; Ma, J. F. Cryst. Growth Des. 2012, 12, 2288.

6082


Unusual 2D â 3D Polycatenane Frameworks Based on 1D â 2D

Recommend Documents

Unusual 2D â 3D Polycatenane Frameworks Based on 1D â 2D