Tailor-Made Zinc Uranyl Diphosphonates from Layered to Framework

Aug 2, 2012 - In the elliptic channels (4.4 × 12.2 Å in aperture) of ZnUP-4, protonated ... additives play a important role in the dimensions of the...
0 downloads 0 Views 5MB Size
Download PDF
Article pubs.acs.org/crystal

Tailor-Made Zinc Uranyl Diphosphonates from Layered to Framework Structures Hong-Yue Wu, Weiting Yang, and Zhong-Ming Sun* State Key Laboratory of Rare Earth Resource Utilization, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences Changchun, 130022, China S Supporting Information *

ABSTRACT: Hydrothermal reactions of zinc uranyl acetate and 1-hydroxyethylidenediphosphonic acid (H4L) with 1,10-phenanthroline (phen), 2,2′bipyridine (bipy), 1H-benzo[d]imidazole (bi), or 1-phenyl-1H-imidazole (pi) resulted in the formation of four new zinc uranyl compounds, namely, [Zn2(phen)2(UO2)2(L)2(H2O)3]·3H2O (ZnUP-1), Zn2(bipy)2(UO2)2(L)2(H2O)2 (ZnUP-2), (Hbi)[Zn0.5(UO2)2(L)(H2L)(H2O)3]·3H2O (ZnUP-3), and (Hpi)[Zn(UO2)2(H2O)4(L)(HL)]·H2O (ZnUP-4). These four structures all comprise uranyl diphosphonate layers formed by UO7 pentagonal bipyramids and PO3C tetrahedra. Such layers are further connected by Zn-centered polyhedra by sharing oxygens from phosphonate groups. For ZnUP-1 and ZnUP-2, the zinc atoms are terminally coordinated by phen and bipy molecules, respectively, resulting in two-dimensional (2-D) hybrid materials. In ZnUP-3 and ZnUP-4, the uranyl phosphonate layers are joined together by Zn−O polyhedra forming three-dimensional (3-D) frameworks. The structures of ZnUP-3 and ZnUP-4 contain large channels along the a-axis with apertures around 3.4 × 13.3 and 4.4 × 12.2 Å2, respectively. Protonated templates exist in the channels, filling the space and compensating the negative charge of the anionic frameworks. Photoluminescent studies reveal that ZnUP-1 and ZnUP-2 exhibit the characteristic vibronically coupled charge-transfer based UO22+ emission.

■

INTRODUCTION Recently, 5f actinide compounds that adopt various topologies and coordination geometries have emerged as a new class of functional materials.1−6 Uranium, as the most representative actinide element, has received considerable attention because of its diverse chemical compositions and architectures as well as its physicochemical properties for elements involved in the nuclear fuel cycle.7 The coordination chemistry of uranium is dominated by U(VI), in the form of uranyl cation UO22+, which features two axial oxygen atoms and favors 4−6 additional coordination sites in the equatorial plane, yielding tetragonal, pentagonal, and hexagonal bipyramidal geometries. The UO22+ species with inactive UO double bonds generally is coordinated only through the equatorial ligands, yielding infinite chains or sheets, while three-dimensional (3-D) framework structures occasionally are formed. As 3-D frameworks usually exhibit many outstanding properties such as porous adsorption,8 photoelectronic effects,9 nonlinear optical properties,10 and superior thermal stability to low-dimensional structures, the construction of 3-D uranyl frameworks is highly desirable. One popular strategy to isolate 3-D uranyl compounds is heteroatom incorporation by introducing extra metal ions to the reaction systems.1,11 These extra metal ions with high crosslinking ability can provide additional connecting nodes for producing the 3-D frameworks. However, it just provides the possibility for construction of 3-D uranyl compounds. This possibility also depends on some other conditions, such as pH © 2012 American Chemical Society

value, concentration, temperature of the reaction system, etc., especially the ligand design.6a,12 Apart from the factors mentioned above, employment of additional templates/second ligands also plays a significant role in the assemble of 3-D uranyl compounds.13 Metal phosphonates are a class of hybrid materials with unique chemical and physical properties, as they can incorporate inorganic and organic characteristics into a single molecular composite. Until now a large number of transition metal phosphonates,14 rare earth phosphonates,15 and 3d-4f mixmetal phosphonates16 have been synthesized. Recent interest in the syntheses of uranyl phosphonates has been raised due to rich structural diversity, as well as other potential applications in ion-exchange,17 proton conductivity,18 chiral materials,19 and biomaterials.20 So far, various uranyl phosphonate structures including one-dimensional (1-D) chains19,21 or tubules,18,22 two-dimensional (2-D) layers,23 and even 3-D frameworks13,24 have been reported. This field has aroused great interest with increasingly attractive structural architectures resulting from various coordination modes of the uranium atom and the modification of the organic residues of phosphonates. For these uranyl phosphonates, the template species (H3O+, NH4+, metal ions, organic components etc.), dimensions, configurations, and Received: July 3, 2012 Revised: July 26, 2012 Published: August 2, 2012 4669

dx.doi.org/10.1021/cg300903w | Cryst. Growth Des. 2012, 12, 4669−4675

Crystal Growth & Design

Article

Energy disperse spectroscopy (EDS) spectra were obtained by using a scanning electron microscope (Hitachi S-4800) equipped with a Bruker AXS XFlash detector 4010. The elemental analyses of C, H, and N were conducted on a Perkin−Elmer 2400 elemental analyzer. All IR measurements were obtained using a Bruker TENSOR 27 Fourier transform infrared spectrometer. Samples were diluted with spectroscopic KBr and pressed into a pellet. Scans were run over the range 400−4000 cm−1. The fluorescence spectra were performed on a Horiba Jobin Yvon Fluorolog-3 fluorescence spectrophotometer, equipped with a 450 W Xe-lamp as the excitation source and a monochromator iHR320 equipped with a liquid-nitrogen-cooled R5509−72 PMT as detector. [Zn2(phen)2(UO2)2(L)2(H2O)3]·3H2O (ZnUP-1). A mixture of Zn(UO2)(OAc)4·7H2O (40 mg, 0.04 mmol), H4L aqueous solution (118 mg, 0.29 mmol), phen (15 mg, 0.083 mmol), 18 M HNO3 (2 drops), and deionized water (1.0 mL) was loaded into a 20-mL Teflon-lined stainless steel autoclave. The autoclave was sealed and heated at 180 °C for 2 days and then cooled to room temperature. Yellow crystals were isolated, yield 12 mg (54% based on uranium) initial pH 1.1, final pH 1.5. Energy dispersive X-ray analysis of several crystals showed the presence of U, Zn, and P with a ratio of around 1:1:2. Elemental analysis observed (Calcd): C 20.76% (21.80%); H 2.63% (2.33%); N 3.59% (3.63%). Zn2(bipy)2(UO2)2(L)2(H2O)2 (ZnUP-2). A mixture of Zn(UO2)(OAc)4·7H2O (40 mg, 0.04 mmol), H4L aqueous solution (118 mg, 0.29 mmol), bipy (10 mg, 0.064 mmol), 18 M HNO3 (2 drops), and deionized water (1.0 mL) was loaded into a 20-mL Teflon-lined stainless steel autoclave. The autoclave was sealed and heated at 180 °C for 2 days and then cooled to room temperature. Yellow crystals were isolated, yield 9 mg (40% based on uranium) initial pH 1.0, final pH 1.4. EDS results on several crystals confirmed the presence of U, Zn, and P. Elemental analysis observed (Calcd): C 20.89% (20.24%); H 2.03% (1.97%); N 3.67% (3.93%). (Hbi)[Zn0.5(UO2)2(L)(H2L)(H2O)3]·3H2O (ZnUP-3). A mixture of Zn(UO 2 )(OAc) 4 ·7H 2 O (40 mg, 0.04 mmol), H 4 L aqueous solution (118 mg, 0.29 mmol), bi (20 mg, 0.169 mmol), and deionized water (1.0 mL) was loaded into a 20-mL Teflon-lined stainless steel autoclave. The autoclave was sealed and heated at 160 °C for 2 days and then cooled to room temperature. Yellow crystals were isolated, yield 10 mg (45% based on uranium) initial pH 1.8, final pH 2.0. EDS results indicated the presence of U/Zn/P (∼2:1:4). Elemental analysis observed (Calcd): C 10.89% (10.95%); H 2.53% (2.40%); N 2.57% (2.32%).

the coordination abilities play very important structure directing roles in constructing new structures. With the idea of multidentate coordination points of phosphonates, and heteroatom incorporation in mind, we investigated the syntheses of zinc uranyl phosphonates in the presence of organic structural directing agents and obtained four new compounds, namely, [Zn2(phen)2(UO2)2(L)2(H2O)3]·3H2O (ZnUP-1), Zn2(bipy)2(UO2)2(L)2(H2O)2 (ZnUP-2), (Hbi)[Zn0.5(UO2)2(L)(H2L)(H2O)3]·3H2O (ZnUP-3), and (Hpi)[Zn(UO2)2(H2O)4(L)(HL)]·H2O (ZnUP-4). Their photoluminescence properties have also been studied.

■

EXPERIMENTAL SECTION

Caution! Standard procedures for handling radioactive material should be followed, although the zinc uranyl acetate heptahydrate ZnUO2(OAc)4·7H2O used in the lab contained depleted uranium. Materials and Methods. All chemicals were purchased commercially and used without further purification. Zinc uranyl acetate heptahydrate (99.8%, Sinpharm Chemical Reagent Co. Ltd.), 1-hydroxyethylidenediphosphonic acid (50% aqueous solution), 1,10phenanthrolline, 2,2′-bipyridine, and imidazole-containing organic templates 1H-benzo[d]imidazole and 1-phenyl-1H-imidazole were purchased from Jinan Henghua Sci. & Tec. Co., Ltd. The diphosphonate ligand and the corresponding templates are listed in Scheme 1.

Scheme 1. Structure of the Ligands and the Templates

Reactions were run in a 20-mL Teflon-lined stainless steel autoclave. Standard precautions were performed for handling radioactive materials during work with uranium-containing materials. The products were thoroughly washed with water and then dried in air.

Table 1. Crystal Data and Structure Refinement for ZnUPs formula fw T (K) λ (Å) space group a (Å) b (Å) c (Å) α (deg) β (deg) γ (deg) V (Å3) Z, ρcalcd (g/cm3) μ (Mo Kα) (mm−1) GOF on F2 R1 [I > 2σ(I)]a wR2a Flack a

ZnUP-1

ZnUP-2

ZnUP-3

ZnUP-4

H36C28N4P4U2Zn2O24 1541.19

H28C24N4P4U2Zn2O20 1423.15

H26C13N2P4U2O23Zn 1243.60

P21/c (No. 14) 9.6541(4) 23.3402(10) 18.1468(8) 90 90.7090(10) 90 4088.7(3) 4, 2.487 9.309 1.047 0.0426 0.0871

Pna21 (No. 33) 18.0978(13) 21.7894(16) 9.6388(7) 90 90 90 3801.0(5) 4, 2.480 9.995 1.046 0.0522 0.1221 0.016(14)

H29C11N2P4U2Zn0.5O24 1205.89 173(2) 0.71073 P21/c (No. 14) 9.7111(5) 16.7387(8) 18.0226(8) 90 90.2900(10) 90 2929.6(2) 4, 2.707 11.760 1.078 0.040 0.0802

P21/c (No. 14) 9.6970(8) 17.5578(14) 17.9345(15) 90 90.3270(10) 90 3053.4(4) 4, 2.688 11.665 1.059 0.0450 0.1089

R1 = Σ||Fo| − |Fc||/Σ|Fo|. wR2 = {Σw(Fo2 − Fc2)2/Σ[w(Fo2)2]}1/2. 4670

dx.doi.org/10.1021/cg300903w | Cryst. Growth Des. 2012, 12, 4669−4675

Crystal Growth & Design

Article

Table 2. Selected Bonds and Angles for ZnUPs ZnUP-1a U(1)−O(12) U(1)−O(11) U(1)−O(7) U(1)−O(1) U(1)−O(16)#1 U(1)−O(3) U(1)−O(14) U(2)−O(6) U(2)−O(2) U(2)−O(8) U(2)−O(5) U(2)−O(4) U(2)−O(13) U(2)−O(9) Zn(1)−O(15) Zn(1)−O(21) Zn(1)−O(20) Zn(1)−N(1) Zn(1)−N(2) Zn(2)−O(10) Zn(2)−O(19)#2 Zn(2)−N(3) Zn(2)−N(4) P(1)−O(10) P(1)−O(8) P(1)−O(16) P(1)−C(2) P(2)−O(15) P(2)−O(3) P(2)−O(4) P(2)−C(1) P(3)−O(5)#3 P(3)−O(19) P(3)−O(1) P(3)−C(2)#1 P(4)−O(7)#4 P(4)−O(20) P(4)−O(13) P(4)−C(1) O(12)−U(1)−O(11) O(6)−U(2)−O(2)

ZnUP-2b 1.766(5) 1.766(6) 2.342(5) 2.377(5) 2.388(5) 2.396(5) 2.431(6) 1.763(5) 1.774(5) 2.329(5) 2.342(5) 2.355(5) 2.435(5) 2.469(5) 1.961(5) 2.017(6) 2.021(6) 2.090(8) 2.186(7) 1.916(6) 1.931(5) 2.043(7) 2.048(8) 1.509(6) 1.515(5) 1.537(5) 1.832(8) 1.518(6) 1.525(5) 1.527(5) 1.841(8) 1.518(5) 1.524(6) 1.530(5) 1.835(8) 1.516(5) 1.525(6) 1.531(5) 1.842(8) 178.9(3) 179.7(3)

U(1)−O(4) U(1)−O(5) U(1)−O(2) U(1)−O(1) U(1)−O(3)#1 U(1)−O(13) U(1)−O(14) U(2)−O(10) U(2)−O(9) U(2)−O(7)#2 U(2)−O(16)#3 U(2)−O(6) U(2)−O(8) U(2)−O(18) Zn(1)−O(11) Zn(1)−O(15) Zn(1)−N(2) Zn(1)−N(1) Zn(2)−O(17) Zn(2)−N(3) Zn(2)−O(12) Zn(2)−N(4) P(1)−O(1) P(1)−O(15) P(1)−O(6) P(1)−C(1) P(2)−O(11) P(2)−O(3) P(2)−O(8) P(2)−C(1) P(3)−O(7) P(3)−O(17) P(3)−O(2) P(3)−C(2) P(4)−O(13) P(4)−O(16) P(4)−O(12) P(4)−C(2) O(4)−U(1)−O(5) O(10)−U(2)−O(9)

ZnUP-3c 1.702(18) 1.755(11) 2.369(14) 2.382(10) 2.394(15) 2.381(14) 2.40(2) 1.750(11) 1.768(13) 2.364(15) 2.342(12) 2.368(13) 2.400(14) 2.460(14) 1.880(14) 1.906(12) 2.015(18) 2.04(2)

U(1)−O(1) U(1)−O(3) U(1)−O(2) U(1)−O(4) U(1)−O(5) U(1)−O(7) U(1)−O(6) U(2)−O(9) U(2)−O(8) U(2)−O(12) U(2)−O(10) U(2)−O(13) U(2)−O(14) U(2)−O(11) Zn(1)−O(17) Zn(1)−O(17)#1 Zn(1)−O(15) Zn(1)−O(15)#1 Zn(1)−O(21) Zn(1)−O(21)#1 P(1)−O(15) P(1)−O(10)#2 P(1)−O(7) P(1)−C(1) P(2)−O(17) P(2)−O(12) P(2)−O(2) P(2)−C(1) P(3)−O(5) P(3)−O(14)#3 P(3)−O(18) P(3)−C(3)#4 P(4)−O(4) P(4)−O(13)#5 P(4)−O(16) P(4)−C(3) O(1)−U(1)−O(3) O(9)−U(2)−O(8)

1.879(13) 1.958(16) 1.962(14) 1.94(2) 1.501(12) 1.526(14) 1.517(14) 1.869(19) 1.503(15) 1.525(15) 1.552(15) 1.781(19) 1.495(15) 1.519(14) 1.582(16) 1.769(17) 1.483(15) 1.510(14) 1.514(15) 1.860(17) 177.4(11) 179.6(10)

ZnUP-4d 1.771(7) 1.773(7) 2.319(6) 2.384(6) 2.400(6) 2.403(6) 2.449(7) 1.763(6) 1.785(6) 2.290(6) 2.327(6) 2.410(6) 2.426(6) 2.426(6) 2.058(6) 2.058(6) 2.069(7) 2.069(7) 2.175(7) 2.175(7) 1.498(7) 1.519(6) 1.522(7) 1.827(9) 1.497(7) 1.524(6) 1.533(6) 1.842(9) 1.502(6) 1.515(6) 1.569(7) 1.843(9) 1.487(7) 1.511(6) 1.563(7) 1.836(8) 179.8(3) 178.0(3)

U(1)−O(2) U(1)−O(1) U(1)−O(3) U(1)−O(6) U(1)−O(4) U(1)−O(5) U(1)−O(7) U(2)−O(8) U(2)−O(9) U(2)−O(12) U(2)−O(14) U(2)−O(13) U(2)−O(10) U(2)−O(11) Zn(1)−O(21)#1 Zn(1)−O(19)#2 Zn(1)−O(16) Zn(1)−O(20) Zn(1)−O(22) P(1)−O(3) P(1)−O(16) P(1)−O(10)#3 P(1)−C(1) P(2)−O(5) P(2)−O(14) P(2)−O(15) P(2)−C(3) P(3)−O(19) P(3)−O(6) P(3)−O(13)#4 P(3)−C(1)#5 P(4)−O(21) P(4)−O(12)#5 P(4)−O(4) P(4)−C(3) O(2)−U(1)−O(1) O(8)−U(2)−O(9)

1.774(7) 1.775(7) 2.314(6) 2.354(6) 2.368(6) 2.423(7) 2.474(7) 1.757(8) 1.769(8) 2.323(6) 2.379(7) 2.383(7) 2.390(6) 2.466(7) 1.870(8) 1.935(8) 1.969(7) 2.055(10) 2.379(15) 1.511(7) 1.527(8) 1.529(7) 1.825(9) 1.507(7) 1.522(8) 1.553(9) 1.842(12) 1.507(9) 1.518(6) 1.540(8) 1.837(9) 1.515(8) 1.521(7) 1.531(7) 1.844(10) 179.2(3) 178.4(4)

a Symmetry code: #1 x − 1, −y + 3/2, z − 1/2; #2 x + 1, −y + 3/2, z + 1/2; #3 x − 1, y, z; #4 x, −y + 3/2, z + 1/2. bSymmetry code: #1 x+1/2, −y+1/2, z; #2 x−1/2, −y+1/2, z−1; #3 x, y, z−1. cSymmetry code: #1 −x + 1, −y + 1, −z + 1; #2 x, −y + 3/2, z + 1/2; #3 x + 1, y, z; #4 x, −y + 3/2, z − 1/2; #5 x + 1, −y + 3/2, z + 1/2. dSymmetry code: #1 −x + 1, y − 1/2, −z + 1/2; #2 x, −y + 1/2, z + 1/2; #3 x − 1, y, z; #4 x − 1, −y + 1/2, z − 1/2; #5 x, −y + 1/2, z − 1/2.

(Hpi)[Zn(UO2)2(H2O)4(L)(HL)]·H2O (ZnUP-4). A mixture of Zn(UO2)(OAc)4·7H2O (40 mg, 0.04 mmol), H4L aqueous solution (118 mg, 0.29 mmol), pi (22 mg, 0.152 mmol), and deionized water (4.0 mL) was loaded into a 20-mL Teflon-lined stainless steel autoclave. The autoclave was sealed and heated at 160 °C for 2 days and then cooled to room temperature. Yellow crystals were isolated, yield 12 mg (54% based on uranium) initial pH 2.3, final pH 2.1. EDS results gave U/Zn/P in a ratio of ∼2:1:4. Elemental analysis observed (Calcd): C 12.97% (12.54%); H 2.14% (2.09%); N 2.36% (2.25%). X-ray Crystal Structure Determination. Suitable single crystals for title compounds were selected for single-crystal X-ray diffraction analyses. Crystallographic data were collected at 173 K on a Bruker Apex II CCD diffractometer with graphite monochromated Mo−Kα radiation (λ = 0.71073 Å). Data processing was accomplished with the SAINT program.25 The structure was solved by direct methods and refined on F2 by full-matrix least-squares using SHELXTL-97.26

Non-hydrogen atoms were refined with anisotropic displacement parameters during the final cycles. All hydrogen atoms were placed by geometrical considerations and were added to the structure factor calculation. There are several nonpositive definite atoms in ZnUP-2 and some disorder of one bipy. Attempts to obtain better single crystals and data failed. A summary of the crystallographic data for these two complexes is listed in Table 1. Selected bond distances and angles are given in Table 2. More details on the crystallographic studies are given in the Supporting Information.

■

RESULTS AND DISCUSSION Syntheses. The title compounds are typically synthesized under mild hydrothermal treatment of the appropriate starting materials. The acidity of the reaction mixtures is very crucial for the syntheses. For ZnUP-1 and ZnUP-2, the crystallization

4671

dx.doi.org/10.1021/cg300903w | Cryst. Growth Des. 2012, 12, 4669−4675

Crystal Growth & Design

Article

uranium atoms are seven coordinated to two axial O atoms (UO: 1.763(5)−1.774(5) Å, OUO: 178.9(3) and 179.7(3)o), four μ-O atoms sharing with three adjacent L groups (U−O: 2.329(5)−2.435(5) Å), and one water (U−Ow: 2.431(6) and 2.469(5) Å). The Zn(1) atom is five coordinated by two μ-O atoms from one L group (Zn−O: 1.961(5) and 2.021(6) Å), two N atoms from one phen molecule (Zn−N: 2.090(8) and 2.186(7) Å), and leaving one terminal aqua ligand (Zn-Ow: 2.017(6) Å). The Zn(2) atom is tetrahedrally coordinated to two μ-O atoms sharing with one L (Zn−O: 1.916(6) and 1.930(5) Å) and two N atoms from one phen (Zn−N: 2.043(7) and 2.048(8) Å). The layered inorganic− organic hybrid structure is constructed by uranium-, phosphorus-, and zinc-centered polyhedra (Figure 1b). Such layers are stacked in a sequence of A, -A, and further interact though π···π stacking of the phen molecules (3.5 Å) to stabilize the structure (Figure 1c). ZnUP-2 is isostructural to ZnUP-1. The difference is that the bipy molecules are coordinated to Zn atoms instead of phen (Figure 2). Moreover, both of the two crystallographically

occurred only at pH values of about 1.0, which are adjusted by adding nitric acid. Besides, the reaction temperature is also relative to the morphology of ZnUP-3 and ZnUP-4. Heating at 180 °C also led to these two complexes but with lower crystallity. Structure of [Zn2(phen)2(UO2)2(L)2(H2O)3]·3H2O (ZnUP-1) and Zn2(bipy)2(UO2)2(L)2(H2O)2 (ZnUP-2). The asymmetric unit of ZnUP-1 contains two crystallographically unique uranium atoms, two crystallographically unique zinc atoms, two L groups, and two phen molecules (Figure 1a). Both of the two

Figure 2. The layered structure of ZnUP-2 viewed along the [001] direction.

unique zinc atoms are in a tetrahedral environment coordinated by two μ-O atoms and two N atoms (Figure S1). Structure of (Hbi)[Zn0.5(UO2)2(L)(H2L)(H2O)3]·3H2O (ZnUP-3) and (Hpi)[Zn(UO2)2(H2O)4(L)(HL)]·H2O (ZnUP-4). ZnUP-3 and ZnUP-4 are also constructed by uranium-, phosphorus-, and zinc-centered polyhedra. The asymmetric unit of ZnUP-3 contains two crystallographically unique uranium atoms, one crystallographically unique zinc atom, and two L groups (Figure 3a). The two uranium atoms are both in pentagonal bipyramidal coordination by two axial O atoms (UO: 1.763(6)−1.785(6) Å, OUO: 179.8(3) and 178.0(3)°), and four μ-O atoms from three adjacent L groups (U−O: 2.290(6)−2.426(6) Å), leaving one water (U−Ow: 2.449(7) and 2.426(6) Å). The zinc atom is located on 2-fold axis and octahedrally coordinated to four μ-O atoms from two adjacent L groups (Zn−O: 2.058(6)−2.069(7) Å), and two lattice water (Zn−Ow: 2.175(7) Å). The UO7 pentagonal bipyramids and ZnO6 octahedra are connected by L groups to form the 3-D framework of ZnUP-3, which comprises large elliptic channels along the a axis with the aperture

Figure 1. (a) The representation of the asymmetric units of ZnUP-1. The hydrogen atoms are omitted for clarity. (b) The layer formed by UO7 pentagonal bipyramids, PO3C tetrahedra, and Zn-centered polyhedra in ZnUP-1; the phen is ignored for clarity. (c) The whole structure of ZnUP-1; the phen molecules are coordinated to the Zn atoms to stabilize the layer. 4672

dx.doi.org/10.1021/cg300903w | Cryst. Growth Des. 2012, 12, 4669−4675

Crystal Growth & Design

Article

Figure 4. The layers are stacked in A, -A sequence and further connected by ZnO3N2 pyramids to form the layered structure of ZnUP-1, by ZnO2N2 tetrahedra to construct the 2-D structure of ZnUP-2, by ZnO6 octahedra to form the 3-D framework of ZnUP-3, and by ZnO5 pyramids to form 3-D network of ZnUP-4. Color code: U, brilliant blue; Zn, orange; P, pink; N, blue; O, red.

Compared the 2-D with 3-D zinc uranyl diphosphonates, the organic additives play a important role in the dimensions of these structures. When bidentate ligands, phen or bipy, were used in the synthesis, they are chelated to the zinc atoms of the layers to form the hybrid materials. If unidentate ligands, di and pi, were used instead, they just act as the templates to fill space of the channels and compensate the negative charge of the anionic frameworks. Infrared Spectroscopy. The IR spectra of the title uranyl diphosphonates are shown in Figure 5. The asymmetric and

Figure 3. (a) The representation of the asymmetric units of ZnUP-3. The hydrogen atoms are omitted for clarity. (b) The whole structure of ZnUP-3 viewed along the [100] direction with the bi located in the channels. (c) The whole structure of ZnUP-4 viewed along the [100] direction with the pi located in the channels.

about 3.4 × 13.3 Å (Figure 3b). Protonated bi cations are positioned in the channels to compensate the negative charge of the network. In the elliptic channels (4.4 × 12.2 Å in aperture) of ZnUP4, protonated pi cations are located instead (Figure 3c). Apart from that, there is minor difference in ZnUP-4 from ZnUP-3. The Zn atom is in a general position and in the pyramidal environment where it is coordinated by three μ-O atoms (Zn− O: 1.870(8)−1.969(7) Å) and two lattice water (Zn−Ow: 2.055(10) and 2.379(15) Å) in ZnUP-4 (Figure S2). It is very significant that ZnUP-1 to ZnUP-4 all comprise the same uranyl phosphonate layer [(UO2)(H2O)(L)]2n. As shown in Figure 4, the layers are stacked in A, -A sequence and further connected by Zn-centered polyhedra to form the 2-D structures of ZnUP-1 and ZnUP-2, and 3-D frameworks of ZnUP-3 and ZnUP-4. For ZnUP-1 and ZnUP-2, the layers are joined by Zn-centered pyramids and tetrahedra, respectively. Meanwhile, the Zn atoms are stabilized by phen and bipy molecules, respectively, that interdict the further connection between the layers, and finally result in 2-D structure. For ZnUP-3 and ZnUP-4, such layers are directly connected by ZnO6 octahedra and ZnO5 pyramids, respectively, to form 3-D frameworks. It is notable that the zinc atoms are solely coordinated to the [PO3] units from L ligands, and no Zn−O−U interaction is observed.

Figure 5. The IR spectra of ZnUP-1 to ZnUP-4.

symmetric stretching modes of UO22+ are observed from about 830 to 954 cm−1. The vibration peaks around 2900−3000 cm−1 are attributed to the stretching vibrations of phenyl ring. The bands between 1380−1450 cm−1 are dominated by CH3 4673

dx.doi.org/10.1021/cg300903w | Cryst. Growth Des. 2012, 12, 4669−4675

Crystal Growth & Design

Article

and structural chemistry of uranyl phosphonates. On the basis of these observations, we intend to incorporate other transition metals and lanthanides under the structural directing agent of second organic species to obtain richer structural variations and optical properties in the ongoing studies.

stretching vibrations. The group of peaks around 1004−1112 cm−1 is at expected values for symmetric and asymmetric vibrations of C−OH in phosphonate ligand. The bands located at about 970 cm−1 and in the low wavenumber region from 770 to 540 cm−1 are due to the O−P−O bending, P−C, and phenyl ring stretching vibrations. The stretching vibrations of H2O and OH are indicated around 1630 and 3400 cm−1. Fluorescence Spectroscopy. The luminescent spectra for these synthesized compounds and zinc uranyl acetate were depicted in Figure 6. Five prominent peaks, 484, 499, 521, 545,

■

ASSOCIATED CONTENT

* Supporting Information S

The asymmetric units of ZnUP-2 and ZnUP-4, X-ray crystallographic files in cif format for [Zn2(phen)2(UO2)2(L)2(H2O)3]·3H2O (ZnUP-1), Zn2(bipy)2(UO2)2(L)2(H2O)2 (ZnUP-2), (Hbi) [Zn0.5(UO2)2(L)(H2L)(H2O)3]·3H2O (ZnUP-3), and (Hpi) [Zn(UO2)2(H2O)4(L)(HL)]·H2O (ZnUP-4). This material is available free of charge via the Internet at http://pubs.acs.org.

■

AUTHOR INFORMATION

Corresponding Author

*E-mail: [email protected]. Notes

The authors declare no competing financial interest.

■

ACKNOWLEDGMENTS This work was supported by the National Nature Science Foundation of China (No. 21171662), SRF for ROCS (State Education Ministry) and CIAC startup fund.

■

Figure 6. The luminescent spectra of ZnUP-1 and ZnUP-2 showing the emission of green light (excited at 440 nm).

REFERENCES

(1) Wang, K. X.; Chen, J. S. Acc. Chem. Res. 2011, 44, 531−540. (2) (a) Ling, J.; Qiu, J.; Sigmon, G. E.; Ward, M.; Szymanowski, J. E. S.; Burns, P. C. J. Am. Chem. Soc. 2010, 132, 13395−13402. (b) Sigmon, G. E.; Burns, P. C. J. Am. Chem. Soc. 2011, 133, 9137− 9139. (c) Ling, J.; Wallace, C. M.; Szymanowski, J. E. S.; Burns, P. C. Angew. Chem., Int. Ed. 2010, 49, 7271−7275. (3) (a) Wang, S.; Alekseev, E. V.; Diwu, J.; Casey, W. H.; Phillips, B. L.; Depmeier, W; Albrecht-Schmitt, T. E. Angew. Chem., Int. Ed. 2010, 49, 1057−1060. (b) Polinski, M. J.; Wang, S.; Alekseev, E. V.; Depmeier, W.; Albrecht-Schmitt, T. E. Angew. Chem., Int. Ed. 2011, 50, 8891−8894. (c) Wu, S. J.; Wang, S. A.; Diwu, J.; Depmeier, W.; Malcherek, T.; Alekseev, E. V.; Albrecht-Schmitt, T. E. Chem. Commun. 2012, 48, 2334−2336. (4) (a) Ok, K. M.; Sung, J.; Hu, G.; Jacobs, R. M. J.; O’Hare, D. J. Am. Chem. Soc. 2008, 130, 3762−3769. (b) Ok, K. M.; O’Hare, D. Dalton Trans. 2008, 5560−5562. (5) (a) Mihalcea, I.; Henry, N.; Volkringer, C.; Loiseau, T. Cryst. Growth Des. 2012, 12, 526−535. (b) Mihalcea, I.; Henry, N.; Clavier, N.; Dacheux, N.; Loiseau, T. Inorg. Chem. 2011, 50, 6243−6249. (6) (a) Wu, H. Y.; Wang, R. X.; Yang, W. T.; Chen, J. L.; Sun, Z. M.; Li, J.; Zhang, H. J. Inorg. Chem. 2012, 51, 3103−3107. (b) Wu, H. Y.; Yang, X. Y.; Li, Y. H.; Yang, W. T. Inorg. Chem. Commun. 2012, DOI: 10.1016/j.inoche.2012.06.002. (7) (a) Ewing, R. C. Elements 2006, 2, 331−334. (b) Bruno, J.; Ewing, R. C. Elements 2006, 2, 343−349. (8) Alsobrook, A. N.; Hauser, B. G.; Hupp, J. T.; Alekseev, E. V.; Depmeierc, W.; Albrecht-Schmitt, T. E. Chem. Commun. 2010, 46, 9167−9169. (9) Chen, W.; Yuan, H. M.; Wang, J. Y.; Liu, Z. Y.; Xu, J. J.; Yang, M.; Chen, J. S. J. Am. Chem. Soc. 2003, 125, 9266−9267. (10) Wang, S.; Alekseev, E. V.; Ling, J.; Liu, G.; Depmeier, W.; Albrecht-Schmitt, T. E. Chem. Mater. 2010, 22, 2155−2163. (11) (a) Chen, W.; Yuan, H. M.; Wang, J. Y.; Liu, Z. Y.; Xu, J. J.; Yang, M.; Chen, J. S. J. Am. Chem. Soc. 2003, 125, 9266−9267. (b) Wang, C. M.; Liao, C. H.; Kao, H. M.; Lii, K. H. Inorg. Chem. 2005, 44, 6294−6298. (c) Cahill, C. L.; de Lill, D. T.; Frisch, M. CrystEngComm 2007, 9, 15−26. (d) Adelani, P. O.; Albrecht-Schmitt, T. E. Cryst. Growth Des. 2011, 11, 4676−4683.

and 570 nm, are clearly observed for ZnUP-1, corresponding to the electronic and vibronic transitions S11−S00 and S10−S0v (v = 0−4). Such a spectrum is typical for most uranyl compounds, which exhibit green light centered near 520 nm and often consist of several peaks.27 Compared to a benchmark compound ZnUO2(OAc)4·7H2O, the luminescence spectrum of ZnUP-1 exhibits a slight red shift by a value of 16 nm. The luminescent spectrum of ZnUP-2 is similar to that of ZnUP-1, with only minor difference in the peak resolution, while for ZnUP-3 and ZnUP-4, no classic emissions of uranyl cations are observed. This is a common phenomenon because not all uranyl compounds exhibit luminescent properties due to their interior nature in bonding,24a size, and quality of the crystals,27 etc.

■

CONCLUSION In this report, we have demonstrated four heterobimetallic zinc uranyl diphosphonates with H4L as the ligand. These synthesized compounds all feature the same uranyl diphosphonate layer [(UO2)(L)(H2O)]2n. In ZnUP-1 and ZnUP-2, the Zn(phen) and Zn(bipy) moieties are coordinated to the layers to form the 2-D structures, respectively. For ZnUP-3 and ZnUP-4, the uranyl diphosphonate layers are connected by Zncentered polyhedra to construct the 3-D frameworks with large channels, and the protonated bi and pi cations locate in the channels, respectively. Among them, ZnUP-1 and ZnUP-2 exhibit the characteristic emission of uranyl cations. These results reveal that incorporating Zn to uranyl phosphonate system clearly substantially increases the structural diversity of not just the 3-D topologies but also more complicated hybrid complexes assisted with organic additives. This series of heterobimetallic hybrid complexes considerably expand the synthetic 4674

dx.doi.org/10.1021/cg300903w | Cryst. Growth Des. 2012, 12, 4669−4675

Crystal Growth & Design

Article

(12) Borkowski, L. A.; Cahill, C. L. Inorg. Chem. 2003, 42, 7041− 7045. (13) Adelani, P. O.; Albrecht-Schmitt, T. E. Inorg. Chem. 2009, 48, 2732−2734. (14) (a) Gagnon, K. J.; Perry, H. P.; Clearfield, A. Chem. Rev. 2012, 112, 1034−1054. (b) Guo, Y. Q.; Yang, B. P.; Song, J. L.; Mao, J. G. Cryst. Growth Des. 2008, 8, 600−605. (c) Wang, P. F.; Duan, Y.; Clemente-Juan, J. M.; Song, Y.; Qian, K.; Gao, S.; Zheng, L. M. Chem.Eur. J. 2011, 17, 3579−3583. (15) (a) Dong, D. P.; Liu, L.; Sun, Z. G.; Jiao, C. Q.; Liu, Z. M.; Li, C.; Zhu, Y. Y.; Chen, K.; Wang, C. L. Cryst. Growth Des. 2011, 11, 5346−5354. (b) Du, Z. Y.; Xu, H. B.; Mao, J. G. Inorg. Chem. 2006, 45, 9780−9788. (16) Zheng, Y. Z.; Evangelisti, M.; Tuna, F.; Winpenny, R. E. P. J. Am. Chem. Soc. 2012, 134, 1057−1065. (17) (a) Adelani, P. O.; Albrecht-Schmitt, T. E. Angew. Chem., Int. Ed. 2010, 49, 8909−8911. (b) Adelani, P. O.; Albrecht-Schmitt, T. E. Inorg. Chem. 2011, 50, 12184−12191. (18) Grohol, D.; Subramanian, M. A.; Poojary, D. M.; Clearfield, A. Inorg. Chem. 1996, 35, 5264−5271. (19) Diwu, J.; Albrecht-Schmitt, T. E. Chem. Commun. 2012, 48, 3827−3829. (20) (a) Wang, L.; Yang, Z. M.; Gao, J. H.; Xu, K. M.; Gu, H. W.; Zhang, B.; Zhang, X. X.; Xu, B. J. Am. Chem. Soc. 2006, 128, 13358− 13359. (b) Yang, Z. M.; Xu, K. M.; Wang, L.; Gu, H. W.; Wei, H.; Zhang, M. J.; Xu, B. Chem. Commun. 2005, 4414−4416. (21) (a) Knope, K. E.; Cahill, C. L. Eur. J. Inorg. Chem. 2010, 1177− 1185. (b) Grohol, D.; Gingl, F.; Clearfield, A. Inorg. Chem. 1999, 38, 751−756. (c) Grohol, D.; Clearfield, A. J. Am. Chem. Soc. 1997, 119, 4662−4668. (d) Alsobrook, A. N.; Zhan, W.; Albrecht-Schmitt, T. E. Inorg. Chem. 2008, 47, 5177−5183. (e) Adelani, P. O.; AlbrechtSchmitt, T. E. Inorg. Chem. 2010, 49, 5701−5705. (22) (a) Poojary, D. M.; Cabeza, A.; Aranda, M. A. G.; Bruque, S.; Clearfield, A. Inorg. Chem. 1996, 35, 1468−1473. (b) Aranda, M. A. G.; Cabeza, A.; Bruque, S.; Poojary, D. M.; Clearfield, A. Inorg. Chem. 1998, 37, 1827−1832. (c) Grohol, D.; Clearfield, A. J. Am. Chem. Soc. 1997, 119, 9301−9302. (23) (a) Knope, K. E.; Cahill, C. L. Inorg. Chem. 2009, 48, 6845− 6851. (b) Knope, K. E.; Cahill, C. L. Inorg. Chem. 2008, 47, 7660− 7672. (c) Adelani, P. O.; Oliver, A. G.; Albrecht-Schmitt, T. E. Cryst. Growth Des. 2011, 11, 1966−1973. (24) (a) Adelani, P. O.; Albrecht-Schmitt, T. E. Cryst. Growth Des. 2011, 11, 4227−4237. (b) Adelani, P. O.; Albrecht-Schmitt, T. E. J. Solid State Chem. 2011, 184, 2368−2373. (c) Adelani, P. O.; Oliver, A. G.; Albrecht-Schmitt, T. E. Cryst. Growth Des. 2011, 11, 3072−3080. (d) Alsobrook, A. N.; Albrecht-Schmitt, T. E. Inorg. Chem. 2009, 48, 11079−11084. (25) SMART and SAINT (software packages); Siemens Analytical Xray Instruments, Inc.: Madison, WI, 1996. (26) SHELXTL Program, version 5.1; Siemens Industrial Automation, Inc.: Madison, WI, 1997. (27) Liu, G.; Beitz, J. V. In The Chemistry of the Actinide and Transactinide Elements; Morss, L. R.; Edelstein, N. M.; Fuger, J., Eds.; Springer: Heidelberg, 2006; p 2088.

4675

dx.doi.org/10.1021/cg300903w | Cryst. Growth Des. 2012, 12, 4669−4675