New 3D Lanthanide Phosphonates: Syntheses, Crystal Structure

Article pubs.acs.org/crystal

New 3D Lanthanide Phosphonates: Syntheses, Crystal Structure, Thermal Stability, Luminescence, and Magnetism Ruibiao Fu,* Shengmin Hu, and Xintao Wu State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Science, Fuzhou, Fujian 350002 China S Supporting Information *

ABSTRACT: Hydrothermal reactions of lanthanide oxide or lanthanide chloride with 3-ammonium-1-hydroxypropylidene-1,1-diphosphonic acid ( + H 3 NCH2CH2C(OH)(PO3H2)(PO3H−), H4L) afforded seven new lanthanide phosphonates, namely, [Ln(HL)] (Ln = Eu (1), Tb (2), Sm (3), Gd (4), Er (5), Nd (6), and Pr (7)). Compounds 1−7 are characterized by single-crystal Xray diffraction, powder XRD, elemental analysis, IR spectroscopy, and thermogravimetric analysis (TGA). Compounds 1−5 crystallize in the orthorhombic Pnma space group, whereas compounds 6 and 7 crystallize in the monoclinic P2(1)/c space group. Compounds 1−7 exhibit a similar 3D open framework with eight-membered ring channels, which are occupied by organic pendants of CH2CH2NH3. TGA and PXRD reveal that compound 1 is thermally stable up to 350 °C under an air atmosphere. It is interesting that compounds 1 and 2 display bright red and green luminescence, respectively, which can be further enhanced obviously upon cooling to 10 K. It is worth noting that the bright red emission of compound 1 can be preserved after heat-treatment at 350 °C under an air atmosphere. Compounds 6 and 7 can give off NIR luminescence and near UV emission, respectively. Furthermore, the magnetic properties of solids 1 and 3−6 have also been studied.

■

INTRODUCTION Metal phosphonates have received continuous attention owing to their structural diversities, higher thermal stabilities, as well as potential applications as porous materials, proton conductors, magnets, Langmuir−Blodgett films, ion-exchangers, nonlinear optics, molecular sensors, catalysts, and so on.1−3 Phosphonate has three oxygen atoms capable of bonding to metals, resulting in the low solubility and crystallinity of metal phosphonates in nature. Thus, it is still difficult to grow single crystals with suitable size and high quality for X-ray structural analysis. However, this obstacle has been conquered to a certain extent, by modifying phosphonic acid with additional groups such as amino, carboxylate, thienyl, pyridyl, hydroxyl, triazole, imidazole, piperidine, pyrazine, thiophene, and sulfonate.4−15 This is due to that additional groups can enrich coordination modes to improve the solubility and crystallinity of metal phosphonates. As a result, many intriguing metal phosphonates have been designed and synthesized during the past 5 years, such as cobalt-lanthanide phosphonates possessing a potential capability for magnetic cooling at low temperature and high magnetocaloric effects,2c,14c a heterometallic phosphonate with interesting relaxometric properties,14a as well as a copper phosphonate displaying a strong breathing effect.4a However, only several lanthanide phosphonates have been reported because they are rarely crystalline for they are highly insoluble.2c,3b,c,14,15 In this regard, many efforts have been devoted to obtain suitable single crystals of lanthanide © 2014 American Chemical Society

phosphonates to determine their accurate structures by single-crystal X-ray diffraction and investigate their properties. Herein, we have selected 3-ammonium-1-hydroxypropylidene1,1-diphosphonic acid ( + H 3 NCH 2 CH 2 C(OH)(PO 3 H 2 )(PO3H−), H4L) with three functional groups (OH, NH2, and PO3H2) to construct new lanthanide phosphonates in view of the following aspects. First, 3-ammonium-1-hydroxypropylidene-1,1-diphosphonic acid is a potent inhibitor of osteoclast-mediated bone resorption and in clinical practice is used to treat hypercalcemia, tumor bone metastases, and Paget’s disease.16,17 Second, only some divalent metal 3ammonium-1-hydroxypropylidene-1,1-diphosphonates based on Ca, Mn, Fe, Co, Ni, Cu, and Zn have been reported in previous work. Third, metal 3-ammonium-1-hydroxypropylidene-1,1-diphosphonates based on Mn, Co, Ni, and Cu show no toxicity for mammalian cells and are active against the amastigote form of Trypanosoma cruzi (T. cruzi), which is the etiological agent of Chagas disease.16a Finally, it is wellknown that trivalent lanthanide ions have promising application in television sets, fluorescent lights, bioimaging, and biosensing owing to their superior luminescent features, such as intense, long photoluminescence (PL) lifetime and multicolor emissions.18 In this paper, we report the synthesis, crystal structure, Received: May 15, 2014 Revised: October 17, 2014 Published: November 11, 2014 6197

dx.doi.org/10.1021/cg501355t | Cryst. Growth Des. 2014, 14, 6197−6204

Crystal Growth & Design

Article

Table 1. Crystal Data and Refinement Details for Compounds 1−3 and 6

a

compounds

1

2

3

6

formula FW space group a (Å) b (Å) c (Å) β (deg) V (Å3) Z T (K) measured/unique/observed reflections Dcalcd (g cm3) μ (mm−1) GOF on F2 Rint R1a [I > 2σ(I)] wR2b [all data]

C3H8NO7P2Eu 384.00 Pnma 9.9906(10) 8.1942(9) 10.2599(12) 90 839.93(16) 4 293(2) 6155/1030/1004 3.037 7.861 1.067 0.0297 0.0290 0.0698

C3H8NO7P2Tb 390.96 Pnma 9.965(4) 8.170(3) 10.155(4) 90 826.7(5) 4 293(2) 6052/1013/992 3.141 8.954 1.098 0.0221 0.0251 0.0665

C3H8NO7P2Sm 382.39 Pnma 9.9759(14) 8.2021(17) 10.2816(16) 90 841.3(2) 4 293(2) 5627/1025/1012 3.019 7.373 1.048 0.0322 0.0284 0.0653

C3H8NO7P2Nd 376.28 P2(1)/c 8.202(5) 10.383(7) 10.070(7) 94.826(10) 854.6(10) 4 293(2) 6257/1958/1784 2.925 6.462 1.265 0.0686 0.0688 0.1905

R1 = ∑(∥Fo| − |Fc∥)/∑|Fo|. bwR2 = {∑w[(Fo2 − Fc2)]/∑w[(Fo2)2]}0.5. (υP−O), 1067s(υP−O), 1034m(υP−O), 997m, 939w, 864w, 770w, 683m, 590m, 554w. Synthesis of [Sm(HL)] (3). A mixture of Sm2O3 (0.0343 g, 0.0984 mmol) and H4L (0.0455 g, 0.194 mmol) in 8.0 mL of distilled water with the pH value adjusted to 0.65 by adding a few drops of concentrated hydrochloric acid was sealed into a Parr Teflon-lined autoclave (23 mL) and heated at 160 °C for 48 h. After slow cooling to room temperature, colorless crystals were obtained as a homogeneous phase based on powder XRD patterns. Yield: 0.0502 g (68%). Anal. Calc. for C3H8NO7P2Sm: C 9.42, H 2.11, N 3.66%. Found: C 9.20, H 2.31, N 3.69%. IR (KBr pellet, cm−1): 3435m(υO−H), 3140m, 2995w(υC−H), 2673w, 2360w, 1607w, 1582w, 1522m, 1468w, 1387w, 1342w, 1092s(υP−O), 1028m(υP−O), 993m, 935w, 860w, 768w, 679m, 582m, 552w. Synthesis of [Gd(HL)] (4). A mixture of GdCl3·6H2O (0.0820 g, 0.221 mmol) and H4L (0.0459 g, 0.195 mmol) in 8.0 mL of distilled water with the pH value adjusted to 1.18 by adding a few drops of concentrated hydrochloric acid was sealed into a Parr Teflon-lined autoclave (23 mL) and heated at 160 °C for 48 h. After slow cooling to room temperature, small colorless crystals were obtained as a homogeneous phase based on powder XRD patterns. Yield: 0.0103 g (14%). Anal. Calc. for C3H8NO7P2Gd: C 9.38, H 2.10, N 3.65%. Found: C 8.78, H 2.57, N 3.37%. IR (KBr pellet, cm−1): 3431m(υO−H), 3136m, 2997w(υC−H), 1609w, 1582w, 1524m, 1468w, 1387w, 1344w, 1107s(υP−O), 1082s(υP−O), 1067s(υP−O), 1032m(υP−O), 995m, 937w, 862w, 770w, 683m, 588m, 552w. Synthesis of [Er(HL)] (5). A mixture of Er2O3 (0.0384 g, 0.100 mmol), H4L (0.0494 g, 0.210 mmol), and 1,4-butanediamine dihydrochloride (0.6316 g, 3.921 mmol) in 8.0 mL of distilled water with the pH value adjusted to 0.75 by adding a few drops of concentrated hydrochloric acid was sealed into a Parr Teflon-lined autoclave (23 mL) and heated at 160 °C for 67 h. After slow cooling to room temperature, small light pink crystals were obtained as a homogeneous phase based on powder XRD patterns. Yield: 0.0100 g (25%). Anal. Calc. for C3H8NO7P2Er: C 9.02, H 2.02, N 3.51%. Found: C 9.56, H 2.53, N 3.56%. IR (KBr pellet, cm−1): 3437m(υO−H), 3213w, 2995w(υC−H), 1612w, 1581w, 1528m, 1468w, 1387w, 1113s(υP−O), 1088s(υP−O), 1036m(υP−O), 997m, 941w, 868w, 770w, 687m, 590m, 555w. Synthesis of [Nd(HL)] (6). A mixture of Nd2O3 (0.0354 g, 0.100 mmol) and H4L (0.0463 g, 0.197 mmol) in 8.0 mL of distilled water with the pH value adjusted to 0.47 by adding a few drops of concentrated hydrochloric acid was sealed into a Parr Teflon-lined autoclave (23 mL) and heated at 160 °C for 48 h. After slow cooling to room temperature, purple crystals were obtained as a homogeneous phase based on powder XRD patterns. Yield: 0.0465 g (63%). Anal.

thermal stability, luminescence, and magnetism of seven new lanthanide phosphonates, namely, [Ln(HL)] (Ln = Eu (1), Tb (2), Sm (3), Gd (4), Er (5), Nd (6), and Pr (7)).

■

EXPERIMENTAL SECTION

General. The 3-ammonium-1-hydroxypropylidene-1,1-diphosphonic acid was prepared by acidifying disodium 3-ammonium-1hydroxypropylidene-1,1-diphosphonate solution. Other chemicals were obtained from commercial sources without further purification. Elemental analyses were carried out with a Vario EL III element analyzer. Infrared spectra were obtained on a VERTEX 70 FT-IR spectrometer. Photoluminescent properties were investigated in solid state with a F-7000 FL spectrophotometer and an Edinburgh FLS920 fluorescence spectrometer. Thermogravimetric analysis (TGA) was performed on a Netzsch STA449C at a heating rate of 10 °C·min−1 from room temperature to 1000 °C under an air (for compound 1) and a nitrogen (for compound 6) gas flow. Powder XRD patterns were acquired on a DMAX-2500 diffractometer using Cu Kα radiation under an ambient environment. Magnetic measurements were carried out with a Quantum Design PPMS model 6000 magnetometer at a magnetic field of 5000 Oe from 2 K to room temperature. Synthesis of [Eu(HL)] (1). A mixture of Eu2O3 (0.0419 g, 0.119 mmol) and H4L (0.0469 g, 0.200 mmol) in 8.0 mL of distilled water with the pH value adjusted to 0.58 by adding a few drops of concentrated hydrochloric acid was sealed into a Parr Teflon-lined autoclave (23 mL) and heated at 160 °C for 36 h. After slow cooling to room temperature, colorless crystals were obtained as a homogeneous phase based on powder XRD patterns. Yield: 0.0381 g (50%). Anal. Calc. for C3H8NO7P2Eu: C 9.38, H 2.10, N 3.65%. Found: C 9.06, H 2.32, N 3.58%. IR (KBr pellet, cm−1): 3431m(υO−H), 3138m, 2997w(υC−H), 1607w, 1582w, 1524m, 1468w, 1387w, 1344w, 1107s(υP−O), 1086s(υP−O), 1069s(υP−O), 1030m(υP−O), 995m, 937w, 862w, 812w, 770w, 681m, 588m, 551w. Synthesis of [Tb(HL)] (2). A mixture of TbCl3·6H2O (0.0726 g, 0.194 mmol) and H4L (0.0465 g, 0.198 mmol) in 8.0 mL of distilled water with the pH value adjusted to 0.73 by adding a few drops of concentrated hydrochloric acid was sealed into a Parr Teflon-lined autoclave (23 mL) and heated at 160 °C for 48 h. After slow cooling to room temperature, colorless crystals were obtained as a homogeneous phase based on powder XRD patterns. Yield: 0.0246 g (32%). Anal. Calc. for C3H8NO7P2Tb: C 9.21, H 2.06, N 3.58%. Found: C 9.23, H 2.15, N 3.62%. IR (KBr pellet, cm−1): 3441m(υO−H), 3134m, 2999w(υC−H), 2972w, 2928w, 2853w, 2360w, 1608w, 1581w, 1523m, 1468w, 1387w, 1348w, 1107s(υP−O), 1082s6198



Article

Table 2. Selected Bond Lengths (Å) and Angles (deg) for 1a Eu(1)−O(1) Eu(1)−O(1)e Eu(1)−O(2)a Eu(1)−O(2)b O(1)−Eu(1)−O(1)e O(1)−Eu(1)−O(2)a O(1)−Eu(1)−O(2)b O(1)−Eu(1)−O(3)c O(1)−Eu(1)−O(3)d O(1)−Eu(1)−O(4) O(1)e−Eu(1)−O(2)a O(1)e−Eu(1)−O(2)b O(1)e−Eu(1)−O(3)c O(1)e−Eu(1)−O(3)d O(1)e−Eu(1)−O(4) a

Eu(1)−O(3)c Eu(1)−O(3)d Eu(1)−O(4)

2.339(5) 2.339(5) 2.319(4) 2.319(4) 84.3(3) 146.71(18) 91.12(19) 73.72(16) 124.11(18) 67.72(16) 91.12(19) 146.71(18) 124.11(18) 73.72(16) 67.72(16)

O(2)a−Eu(1)−O(2)b O(2)a−Eu(1)−O(3)c O(2)a−Eu(1)−O(3)d O(2)a−Eu(1)−O(4) O(2)b−Eu(1)−O(3)c O(2)b−Eu(1)−O(3)d O(2)b−Eu(1)−O(4) O(3)c−Eu(1)−O(3)d O(3)c−Eu(1)−O(4) O(3)d−Eu(1)−O(4)

2.320(4) 2.320(4) 2.645(7) 75.0(2) 133.19(16) 85.49(16) 80.00(17) 85.49(16) 133.19(17) 80.00(17) 77.7(2) 138.26(13) 138.26(13)

Symmetry codes: a −x, y − 1/2, −z + 1; b −x, −y + 2, −z + 1; c x − 1/2, y, −z + 3/2; d x − 1/2, −y + 3/2, −z + 3/2; e x, −y + 3/2, z.

Calc. for C3H8NO7P2Nd: C 9.58, H 2.14, N 3.72%. Found: C 9.42, H 2.26, N 3.73%. IR (KBr pellet, cm−1): 3433m(υO−H), 3147m, 2974w(υC−H), 1607m, 1531m, 1468w, 1385w, 1330w, 1090s(υP−O), 1053s(υP−O), 1026m(υP−O), 1001m, 966m, 935w, 862w, 797w, 770w, 679m, 584m, 552w. Synthesis of [Pr(HL)] (7). A mixture of Pr6O11 (0.0335 g, 0.0328 mmol) and H4L (0.0455 g, 0.194 mmol) in 8.0 mL of distilled water with the pH value adjusted to 0.74 by adding a few drops of concentrated hydrochloric acid was sealed into a Parr Teflon-lined autoclave (23 mL) and heated at 160 °C for 48 h. After slow cooling to room temperature, green crystals were obtained as a homogeneous phase based on powder XRD patterns. Yield: 0.0298 g (41%). Anal. Calc. for C3H8NO7P2Pr: C 9.66, H 2.16, N 3.76%. Found: C 9.25, H 2.25, N 3.70%. IR (KBr pellet, cm−1): 3437m(υO−H), 3435m(υO−H), 3213m, 3066w, 2931w(υC−H), 1630m, 1591w, 1500m, 1460w, 1400m, 1323w, 1128s(υP−O), 1094s(υP−O), 1069s(υP−O), 1020m(υP−O), 988m, 949w, 900m, 770w, 698m, 573m, 503w. Heating Treatment. Solids 1−300 and 1−350 were obtained after polycrystalline of 1 was heated at 300 and 350 °C for 2 h under an air atmosphere, respectively, and then naturally cooled to room temperature. X-ray Crystallography. X-ray data for compounds 1−3 and 6 were collected at 293(2) K on a Rigaku Mercury CCD/AFC diffractometer using graphite-monochromated Mo Kα radiation (λ(Mo−Kα) = 0.71073 Å). Data of compounds 1−3 and 6 were reduced with CrystalClear v1.3.29 Their structures were solved by direct methods and refined by full-matrix least-squares techniques on F2 using SHELXTL-97.19 All non-hydrogen atoms were treated anisotropically. The H2 atom in compounds 1 and 2 and all hydrogen atoms in compound 6 were generated geometrically, while the other hydrogen atoms in compounds 1 and 2 and all hydrogen atoms in compound 3 were located from the difference Fourier map and assigned with fixed isotropic thermal parameter. Crystallographic data for compounds 1−3 and 6 are summarized in Table 1. Selected bond lengths and angles for compound 1 are listed in Table 2: CCDC 1002369 (1), 1002370 (2), 1002371 (3), and 1002372 (6).

verified by the fact that IR spectra of compounds 2−5 are similar to that of compound 1. On the other hand, unit cell parameters of compound 7 are a = 8.223(3) Å, b = 10.421(2) Å, c = 10.099(3) Å, β = 95.19(2)°, V = 861.8129 Å3, which are similar to those of compound 6. The experimental powder XRD pattern of compound 7 is also in agreement with that simulated from single-crystal X-ray data of compound 6. These suggest that compound 7 is isomorphous with compound 6. Furthermore, elemental analyses of compounds 1−7 are in accord with the respective calculated values. The above results show that final products of compounds 1−7 are in the homogeneous phase, respectively. Structural Descriptions. Since crystal structures of compounds 2−7 are similar to that of compound 1, only compound 1 has been selected as a representative example to describe their structures in detail. The Eu1 is surrounded by four HL3− anions into a distorted [EuO7] monocapped trigonal prism geometry (Figure 1a), which is the same to those of [H3N(CH2)4NH3]Ln[hedpH][hedpH2] (Ln = La, Eu, Tb; hedp = 1-hydroxyethylidenediphosphonates).20d One HL3− anion is chelated to Eu1 via two phosphonate oxygen atoms (O1, O1e) and one hydroxyl oxygen atom (O4), resulting in two five-membered rings (Eu-O-P-C-O). As a result, the bond angle of O1−Eu1−O4 is only 67.72(16)°. Another HL3− anion is chelated to Eu1 through two phosphonate oxygen atoms (O3c, O 3d) to form a six-membered ring (Eu-O-P-C-P-O). The other two HL3− anions contact with Eu1 by two phosphonate oxygen atoms (O2a, O2b), respectively. The distances between Eu1 and phosphonate oxygen atoms are in the range of 2.319(4)−2.339(5) Å. These are obvious shorter than the distance between Eu1 and hydroxyl oxygen atom (Eu1−O4, 2.645(7) Å). Same to divalent metal 3-ammonium1-hydroxypropylidene-1,1-diphosphonates, the amino group in compound 1 is also protonated and does not take part in coordination with Eu(III) atom. All oxygen atoms of the HL3− anion have been coordinated to Eu(III) atoms. That is to say, the HL3− anion acts as a heptadentate mode to combine four Eu(III) atoms through six phosphonate atoms and one hydroxyl oxygen atom. This coordination mode is the same to those in [Cu3(HL)2(H2O)2] and lanthanide 1-hydroxyethylidenediphosphonates.15c,16b,20a As a result, the [EuO7] polyhedron shares corners with the [PCO3] tetrahedron into a three-dimensional framework with eight-membered ring channels along the b axis (Figure 1b,c), which are similar to

■

RESULTS AND DISCUSSION Synthesis and Characterization. Compounds 1−7 were synthesized by the reaction of lanthanide oxide or chloride with H4L under hydrothermal conditions, and satisfactorily characterized by single-crystal X-ray diffraction, powder XRD, IR, and elemental analyses (EA). Single-crystal X-ray diffraction reveals that compounds 2 and 3 are isomorphous with compound 1. Experimental powder XRD patterns of compounds 4 and 5 are consistent with that simulated from single-crystal X-ray data of compound 1, which indicate that compounds 4 and 5 are also isomorphous with compound 1. These results are further 6199



Article

phosphonate groups are deprotonated, compound 1 and [Cu3(HL)2(H2O)2] exhibit a 3D framework. In contrast, one or two phosphonate oxygen atoms are protonated, so other divalent metal 3-ammonium-1-hydroxypropylidene-1,1-diphosphonates show cluster, 1D, or 2D frameworks. Thermal Stabilities. Thermogravimetric analysis (TGA) were performed under an air (for compound 1) and a nitrogen (for compound 6) atmosphere. Since the TGA curve of solid 1 is similar to that of solid 6, solid 1 was selected as an example to describe their thermal stabilities. The TGA curve of compound 1 illustrates that there is a little weight loss up to 400 °C under an air atmosphere. Upon further heating, an abrupt weight loss stage appears due to the decomposition of HL3− anions, resulting in the collapse of the 3D framework. Furthermore, powder XRD patterns of solids 1-300 and 1-350 are essentially in agreement with those of as-prepared 1 (Figure 2). These results suggest that the 3D framework of compound 1 is thermally stable up to 350 °C under an air atmosphere.

Figure 2. Powder XRD patterns of 1 (a) simulated from single-crystal X-ray data, and experimental data for solids 1 (b), 1-300 (c), and 1350 (d).

Luminescent Properties. Solid-state luminescent properties of solids 1, 2, and 5−7 were investigated. As expected, solid 1 displays bright red luminescence under excitation at 393 nm (Figure 3a). The emission profile contains a very strong band at 615 nm, which is ascribed to the 5D0 → 7F2 transition. The emission profile also consists of other four sets of characteristic emission bands for Eu3+ ion, including 580 nm (very weak, 5D0 → 7F0), 588, 593, and 597 nm (weak, 5D0 → 7F1), 656 nm (very weak, 5D0 → 7F3), as well as 694 and 702 nm (very weak, 5 D0 → 7F4). The 5D0 → 7F2 transition is allowed by electric dipole and is hypersensitive to the environment in the vicinity of Eu3+ ion, while the 5D0 → 7F1 transition is a magnetic dipole which is insensitive to the site symmetry. The intensity of the 5 D0 → 7F2 transition is stronger than that of the 5D0 → 7F1 transition, indicating that the Eu3+ ion is devoid of an inversion center. This accords with that the Eu3+ ion occupies a site without an inversion center in the structure of compound 1. At 298 K, the external quantum yield reaches 23.7% under excitation at 394 nm. Upon cooling to 10 K, solid 1 displays more bright red luminescence under excitation at 393 nm. Under the same measurement conditions, the intensity of λem = 614 nm at 10 K is almost 3.6 times of that at 298 K. At 298 K, luminescent decay from λem = 613 nm fits well to a single-

Figure 1. Ball-and-stick view of (a) the coordination environment of Eu(III) atom and the coordination mode of HL3− anion, (b) the EuO-P chain, and (c) polyhedral view of the 3D framework in 1. [EuO7] and [PCO3] polyhedra are represented in green and yellow, respectively. Unrelated atoms are omitted for clarity. Symmetry codes: a −x, y − 1/2, −z + 1; b −x, −y + 2, −z + 1; c x − 1/2, y, −z + 3/2; d x − 1/2, −y + 3/2, −z + 3/2; e x, −y + 3/2, z.

those in lanthanide 1-hydroxyethylidenediphosphonates.15c,20a In the field of lanthanide phosphonates, such a threedimensional “lanthanum-phosphate” framework is rarely reported in previous work.15c,20 The organic pendants of CH2CH2NH3 from HL3− anions are included into the eightmembered ring channels to compensate the negative charge of the 3D framework. It is interesting that neither free nor coordinated water molecules are in compound 1. This is obviously different from the reported lanthanide phosphonates.14,15,20 Comparing the structure of compound 1 with those of divalent metal 3ammonium-1-hydroxypropylidene-1,1-diphosphonates, the protonation of the L4− anion plays an important role on dimensionalities of the framework. Since all hydrogen atoms of 6200



Article

stable up to 350 °C under an air atmosphere. In addition, the excitation profile consists of many peaks in the range of 275− 550 nm. Except for the intensities, those emission profiles are similar upon excitation at 286, 319, 361, 381, 393, 413, 465, and 533 nm. This suggests that solid 1 not only can transfer UV radiation into red light but also can transfer purple, blue, and green light into red emission. As shown in Figure 4, solid 2 exhibits bright green luminescence under excitation at 250 nm. The emission profile

Figure 4. Emission spectrum for compound 2 at ambient temperature. Inset: photograph of compound 2 under a UV lamp at 254 nm.

contains four characteristic emission bands for Tb3+ ion, including 483 and 491 nm (5D4 → 7F6), 542 and 549 nm (very strong, 5D4 → 7F5), 589 nm (5D4 → 7F4), as well as 622 nm (very weak, 5D4 → 7F3). Among these emission bands, the strongest one is the green luminescence of the 5D4 → 7F5 transition. At 298 K, the external quantum yield reaches 11.0% under excitation at 267 nm. Upon cooling to 10 K, solid 2 displays more bright green luminescence under excitation at 267 nm. Under the same measurement conditions, the intensity of λem = 542 nm at 10 K is almost 2.6 times of that at 298 K. At 298 K, luminescent decay from λem = 542 nm also fits well to a single-exponential function, and the lifetime was determined to be 1.231 ± 0.004 ms. The lifetime value is slightly shorter than that of Tb-DTPA-cs124 chelate, which is a commercially available Tb3+-based time-resolved luminescent bioprobe.22 Upon cooling to 77 K, the lifetime for λem = 542 nm would be prolonged to 1.616 ± 0.006 ms. This is similar to that of solid 1. The excitation profile includes many peaks in UV region, as well as a peak at 483 nm. This indicates that solid 2 not only can transfer UV radiation into green light but also can transfer blue-green light into green emission. It is interesting that high thermal stabilities, bright emission, and millisecond luminescent lifetimes would make solids 1 and 2 as excellent candidates for potential photoactive materials. Solid 6 shows NIR luminescence under excitation at 580 nm (Figure 5). The emission profile contains three characteristic emission bands for Nd3+ ion. These bands are 884 nm (4F3/2 → 4 I9/2), 1063 nm (4F3/2 → 4I11/2), and 1345 nm (4F3/2 → 4 I13/2).22,23 At 298 K, luminescent decay from λem = 1063 nm fits well to a double-exponential function with τ1 = 0.058 ± 0.001 ms and τ2 = 0.33 ± 0.01 ms. The lifetime is obviously longer than those of other Nd(III) complexes.24 High thermal stability and long luminescent lifetime suggest that compound 6 may be used as NIR luminescent materials. As shown in Figure

Figure 3. Emission spectra for solids 1 (a), 1-300 (b), and 1-350 (c) at ambient temperature under excitation at 393 nm. Inset: photographs of compound 1 under a UV lamp at 254 nm.

exponential function, and the lifetime was determined to be 0.602 ± 0.001 ms. The lifetime value is close to that of EuDTPA-cs124 chelate.21 Upon cooling to 77 K, the lifetime for λem = 613 nm would be prolonged to 0.717 ± 0.001 ms. Such single-exponential decay behavior indicates a homogeneous crystal-field environment around Eu3+ in the lattice sites, which coincides with that the asymmetry unit of compound 1 only contains one Eu3+ ion. On the other hand, both solids 1-300 and 1-350 can also emit bright red emission upon excitation at 393 nm (Figure 3b,c). These emission profiles are the same to that of as-prepared 1, indicating that the red luminescence can be preserved up to 350 °C under an air atmosphere. This is in agreement with that the 3D framework of solid 1 is thermally 6201



Article

= −0.0947 K. These results suggest the possible presence of paramagnetic behavior in compound 4.26,27 At 300 K, the observed χmT values for per Nd3+ ion in compound 6 and per Pr3+ ion in compound 7 are 1.55 and 1.44 cm3 K mol−1, respectively. Both χmT values decrease gradually over the whole temperature range, which are also the same to those of reported compounds.26,28

■

CONCLUSION In summary, we have described syntheses, crystal structures, and properties of seven new lanthanide phosphonates, [Ln(HL)] (Ln = Eu (1), Tb (2), Sm (3), Gd (4), Er (5), Nd (6), and Pr (7)). Compounds 1−7 exhibit a similar 3D open framework with eight-membered ring channels, which are occupied by organic pendants of CH2CH2NH3. It is interesting that solids 1 and 2 display bright red and green luminescence, respectively, which can be enhanced obviously upon cooling to 10 K. Both the 3D framework and bright red emission of compound 1 can be preserved after heat-treatment at 350 °C under an air atmosphere. Solids 6 and 7 display NIR luminescence and near UV emission, respectively. Future efforts are focused on the rational design and synthesis of new phosphonic acids with other functional groups. We will also introduce organic amines as structure-directing agents, as well as second ligands to expand lanthanide phosphonates and investigate their structures and properties.

Figure 5. Emission spectrum for compound 6 at ambient temperature.

6, solid 7 exhibits near UV emission under excitation at 287 or 301 nm. The emission profile contains one characteristic

■

ASSOCIATED CONTENT

S Supporting Information *

Crystallographic data in CIF format (CCDC 1002369 (1), 1002370 (2), 1002371 (3), and 1002372 (6)), PXRD patterns, additional structural figure, TGA curves, and additional luminescent and magnetic plots. This material is available free of charge via the Internet at http://pubs.acs.org.

■

Figure 6. Emission spectrum for compound 7 under different excited wavelengths at ambient temperature.

*E-mail: [email protected]. Fax: +86-591-83714946. Tel: +86591-63173277 (R.F.).

emission band at 350 nm ( S0 → D2) for Pr ion. In addition, no near-infrared (NIR) fluorescent emissions of compound 5 were observed, though NIR luminescence of Er3+ ion can be achieved by suitable ligands.23a,25 This indicates that 3ammonium-1-hydroxypropylidene-1,1-diphosphonate cannot sensitize the NIR luminescence of Er3+ ion. Magnetic Properties. The temperature-dependent magnetic susceptibilities of compounds 1, 3, 4, 6, and 7 were investigated in the temperature range of 2−300 K at the magnetic field of 5000 Oe. The temperature dependence of the χmT product for compounds 1, 3, 4, 6, and 7 are shown in Figures S13−17 (Supporting Information). At 300 K, the observed χmT values per Eu3+ ion in compound 1 and per Sm3+ ion in compound 3 are 1.33 and 0.262 cm3 K mol−1, respectively. Both χmT values decrease linearly upon cooling to 2.0 K, which are similar to those of reported coordination polymers.26 The observed χmT value per Gd3+ ion in compound 4 is 7.64 cm3 K mol−1 at 300 K, which is close to the expected value for a mononuclear compound of gadolinium (7.88 cm3 K mol−1). Upon lowering of the temperature, the χmT remains almost constant until 15 K and then falls sharply down to 2 K. In the temperature range of 2−300 K, the magnetic susceptibility follows the Curie−Weiss law [χm−1 = 0.012(3) + 0.1311(2) T] (r > 0.9999), with C = 7.63 cm3 K mol−1 and θ 1

1

AUTHOR INFORMATION

Corresponding Author

3+

Notes

The authors declare no competing financial interests.

■

ACKNOWLEDGMENTS This research was supported by grants from the National Science Foundation of China (21173220 and 21373219) and the National Basic Research Program of China (973 Program, 2012CB821702).

■

REFERENCES

(1) (a) Gagnon, K. J.; Perry, H. P.; Clearfield, A. Chem. Rev. 2012, 112, 1034−1054. (b) Clearfield, A., Demadis, K., Eds. Metal Phosphonate Chemistry From Synthesis to Applications; The Royal Society of Chemistry: Cambridge, U.K., 2012. (c) Boldog, I.; Domasevitch, K. V.; Baburin, I. A.; Ott, H.; Gil-Hernández, B.; Sanchiz, J.; Janiak, C. CrystEngComm 2013, 15, 1235−1243. (2) (a) Gagnon, K. J.; Beavers, C. M.; Clearfield, A. J. Am. Chem. Soc. 2013, 135, 1252−1258. (b) Liang, X. Q.; Zhang, F.; Feng, W.; Zou, X. Q.; Zhao, C. J.; Na, H.; Liu, C.; Sun, F. X.; Zhu, G. S. Chem. Sci. 2013, 4, 983−992. (c) Zheng, Y. Z.; Evangelisti, M.; Tuna, F.; Winpenny, R. E. P. J. Am. Chem. Soc. 2012, 134, 1057−1065. (3) (a) Zhang, L.; Clérac, R.; Heijboer, P.; Schmitt, W. Angew. Chem., Int. Ed. 2012, 51, 3007−3011. (b) Zheng, Y. Z.; Pineda, E. M.; Helliwell, M.; Winpenny, R. E. P. Chem.Eur. J. 2012, 18, 4161−

6202



Article

4165. (c) Zheng, Y. Z.; Evangelisti, M.; Winpenny, R. E. P. Chem. Sci. 2011, 2, 99−102. (d) Xie, Y. P.; Mak, T. C. W. Dalton Trans. 2013, 42, 12869−12872. (4) (a) Taddei, M.; Costantino, F.; Ienco, A.; Comotti, A.; Daud, P. V.; Cohend, S. M. Chem. Commun. 2013, 49, 1315−1317. (b) Yang, X. J.; Bao, S. S.; Zheng, T.; Zheng, L. M. Chem. Commun. 2012, 48, 6565−6567. (c) Alsobrook, A. N.; Hauser, B. G.; Hupp, J. T.; Alekseev, E. V.; Depmeierc, W.; Albrecht-Schmitt, T. E. Chem. Commun. 2010, 46, 9167−9169. (5) (a) Zheng, T.; Clemente-Juan, J. M.; Ma, J.; Dong, L.; Bao, S. S.; Huang, J.; Coronado, E.; Zheng, L. M. Chem.Eur. J. 2013, 19, 16394−16402. (b) Huang, J.; Bao, S. S.; Ling, L. S.; Zhu, H.; Li, Y. Z.; Pi, L.; Zheng, L. M. Chem.Eur. J. 2012, 18, 10839−10842. (c) Guo, L. R.; Bao, S. S.; Liu, B.; Zeng, D.; Zhao, J.; Du, J.; Zheng, L. M. Chem.Eur. J. 2012, 18, 9534−9542. (6) (a) 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. (b) Zhou, T. H.; He, Z. Z.; Xu, X.; Qian, X. Y.; Mao, J. G. Cryst. Growth Des. 2013, 13, 838−843. (c) Costantino, F.; Sassi, P.; Geppi, M.; Taddei, M. Cryst. Growth Des. 2012, 12, 5462−5470. (7) (a) Adelani, P. O.; Albrecht-Schmitt, T. E. Cryst. Growth Des. 2011, 11, 4676−4683. (b) Chen, K.; Sun, Z. G.; Zhu, Y. Y.; Liu, Z. M.; Tong, F.; Dong, D. P.; Liu, L.; Jiao, C. Q.; Li, C.; Wang, C. L. Cryst. Growth Des. 2011, 11, 4623−4631. (c) Adelani, P. O.; Oliver, A. G.; Albrecht-Schmitt, T. E. Cryst. Growth Des. 2011, 11, 3072−3080. (8) (a) Demadis, K. D.; Papadaki, M.; Aranda, M. A. G.; Cabeza, A.; Olivera-Pastor, P.; Sanakis, Y. Cryst. Growth Des. 2010, 10, 357−364. (b) Zhou, W.; Zhu, Y. Y.; Jiao, C. Q.; Sun, Z. G.; Shi, S. P.; Dai, L. L.; Sun, T.; Li, W. Z.; Ma, M. X.; Luo, H. CrystEngComm 2014, 16, 1174− 1186. (c) Zhai, F. P.; Zheng, Q. S.; Chen, Z. X.; Ling, Y.; Liu, X. F.; Weng, L. H.; Zhou, Y. M. CrystEngComm 2013, 15, 2040−2043. (9) (a) Kan, W. Q.; Ma, J. F.; Liu, Y. Y.; Liu, B. CrystEngComm 2012, 14, 2268−2277. (b) Zavras, A.; Fry, J. A.; Beavers, C. M.; Talboa, G. H.; Richards, A. F. CrystEngComm 2011, 13, 3551−3561. (c) Chen, Z. X.; Ling, Y.; Yang, H. Y.; Guo, Y. F.; Weng, L. H.; Zhou, Y. M. CrystEngComm 2011, 13, 3378−3382. (10) (a) Zhang, X. L.; Cheng, K.; Wang, F.; Zhang, J. Dalton Trans. 2014, 43, 285−289. (b) Chen, Z. X.; Yang, H. Y.; Deng, M. L.; Ling, Y.; Weng, L. H.; Zhou, Y. M. Dalton Trans. 2012, 41, 4079−4083. (c) Perry, H. P.; Gagnon, K. J.; Law, J.; Teat, S.; Clearfield, A. Dalton Trans. 2012, 41, 3985−3994. (11) (a) Ma, Y. S.; Tang, X. Y.; Yin, W. Y.; Wu, B.; Xue, F. F.; Yuan, S.; Roy, R. X. Dalton Trans. 2012, 41, 2340−2345. (b) Gudima, A. O.; Shovkova, G. V.; Trunova, O. K.; Grandjean, F.; Long, G. J.; Gerasimchuk, N. Inorg. Chem. 2013, 52, 7467−7477. (c) Beavers, C. M.; Prosverin, A. V.; Cashion, J. D.; Dunbar, K. R.; Richards, A. F. Inorg. Chem. 2013, 52, 1670−1672. (12) (a) Weber, J.; Grossmann, G.; Demadis, K. D.; Daskalakis, N.; Brendler, E.; Mangstl, M.; auf der Günne, J. S. Inorg. Chem. 2012, 51, 11466−11477. (b) Rueff, J. M.; Perez, O.; Pautrat, A.; Barrier, N.; Hix, G. B.; Hernot, S.; Couthon-Gourvès, H.; Jaffrès, P. A. Inorg. Chem. 2012, 51, 10251−10261. (c) Demadis, K. D.; Famelis, N.; Cabeza, A.; Aranda, M. A. G.; Colodrero, R. M. P.; Infantes-Molina, A. Inorg. Chem. 2012, 51, 7889−7896. (13) (a) Adelani, P. O.; Oliver, A. G.; Albrecht-Schmitt, T. E. Inorg. Chem. 2012, 51, 4885−4887. (b) Schmidt, C.; Stock, N. Inorg. Chem. 2012, 51, 3108−3118. (c) Zhou, T. H.; Yi, F. Y.; Li, P. X.; Mao, J. G. Inorg. Chem. 2010, 49, 905−915. (d) Colodrero, R. M. P.; OliveraPastor, P.; Cabeza, A.; Papadaki, M.; Demadis, K. D.; Aranda, M. A. G. Inorg. Chem. 2010, 49, 761−768. (14) (a) Carné-Sánchez, A.; Bonnet, C. S.; Imaz, I.; Lorenzo, J.; Tóth, É.; Maspoch, D. J. Am. Chem. Soc. 2013, 135, 17711−17714. (b) Colodrero, R. M. P.; Papathanasiou, K. E.; Stavgianoudaki, N.; Olivera-Pastor, P.; Losilla, E. R.; Aranda, M. A. G.; León-Reina, L.; Sanz, J.; Sobrados, I.; Choquesillo-Lazarte, D.; García-Ruiz, J. M.; Atienzar, P.; Rey, F.; Demadis, K. D.; Cabeza, A. Chem. Mater. 2012, 24, 3780−3792. (c) Pineda, E. M.; Tuna, F.; Pritchard, R. G.; Regan, A. C.; Winpenny, R. E. P.; McInnes, E. J. L. Chem. Commun. 2013, 49, 3522−3524. (d) Chen, K.; Dong, D. P.; Sun, Z. G.; Jiao, C. Q.; Li, C.;

Wang, C. L.; Zhu, Y. Y.; Zhao, Y.; Zhu, J.; Sun, S. H.; Zheng, M. X.; Tian, H.; Chu, W. Dalton Trans. 2012, 41, 10948−10956. (15) (a) Liu, L.; Sun, Z. G.; Zhang, N.; Zhu, Y. Y.; Zhao, Y.; Liu, X.; Tong, F.; Wang, W. N.; Huang, C. Y. Cryst. Growth Des. 2010, 10, 406−413. (b) Feyand, M.; Näther, C.; Rothkirch, A.; Stock, N. Inorg. Chem. 2010, 49, 11158−11163. (c) 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. (d) Jiao, C. Q.; Zhang, J. C.; Zhao, Y.; Sun, Z. G.; Zhu, Y. Y.; Dai, L. L.; Shi, S. P.; Zhou, W. Dalton Trans. 2014, 43, 1542−1549. (16) (a) Demoro, B.; Caruso, F.; Rossi, M.; Benítez, D.; González, M.; Cerecetto, H.; Galizzi, M.; Malayil, L.; Docampo, R.; Faccio, R.; Mombrú, Á . W.; Gambino, D.; Otero, L. Dalton Trans. 2012, 41, 6468−6476. (b) Gong, Y.; Tang, W.; Hou, W. B.; Zha, Z. Y.; Hu, C. W. Inorg. Chem. 2006, 45, 4987−4995. (c) Liu, D. M.; Kramer, S. A.; Huxford-Phillips, R. C.; Wang, S. Z.; Rocca, J. D.; Lin, W. B. Chem. Commun. 2012, 48, 2668−2670. (17) (a) Habib, H. A.; Gil-Hernandez, B.; Abu-Shandi, K.; Sanchiz, J.; Janiak, C. Polyhedron 2010, 29, 2537−2545. (b) Abu-Shandi, K.; Janiak, C. Z. Naturforsch. 2005, B60, 1250−1254. (c) Kubicek, V.; Kotek, J.; Hermann, P.; Lukes, I. Eur. J. Inorg. Chem. 2007, 333−344. (d) Li, G.; Fan, Y. T.; Zhang, T. J.; Ge, T. Z.; Hou, H. W. J. Coord. Chem. 2008, 61, 540−549. (18) (a) Bünzli, J. C. G. Chem. Rev. 2010, 110, 2729−2755. (b) Wang, F.; Han, Y.; Lim, C. S.; Lu, Y. H.; Wang, J.; Xu, J.; Chen, H. Y.; Zhang, C.; Hong, M. H.; Liu, X. G. Nature 2010, 463, 1061−1065. (19) Sheldrick, G. M. SHELXT 97: Program for Crystal Structure Refinement; University of Göttingen: Göttingen, Germany, 1997. (20) (a) Shi, F. N.; Cunha-Silva, L.; Ferreira, R. A. S.; Mafra, L.; Trindade, T.; Carlos, L. D.; Paz, F. A. A.; Rocha, J. J. Am. Chem. Soc. 2008, 130, 150−167. (b) Gentili, P. L.; Presciutti, F.; Evangelisti, F.; Costantino, F. Chem.Eur. J. 2012, 18, 4296−4307. (c) Shi, F. N.; Trindade, T.; Rocha, J.; Paz, F. A. A. Cryst. Growth Des. 2008, 8, 3917−3920. (d) Liu, F. Y.; Rocrs, L.; Ferreira, R. A. S.; García-Granda, S.; García, J. R.; Carlos, L. D.; Rocha, J. J. Mater. Chem. 2007, 17, 3696−3701. (21) Li, M.; Selvin, P. R. J. Am. Chem. Soc. 1995, 117, 8132−8138. (22) (a) Pettinari, C.; Marchetti, F.; Pettinari, R.; Drozdov, A.; Troyanov, S.; Voloshin, A. I.; Shavaleev, N. M. J. Chem. Soc., Dalton Trans. 2002, 1409−1415. (b) Davies, G. M.; Aarons, R. J.; Motson, G. R.; Jeffery, J. C.; Adams, H.; Faulkner, S.; Ward, M. D. Dalton Trans. 2004, 1136−1144. (c) Romanelli, M.; Kumar, G. A.; Emge, T. J.; Riman, R. E.; Brennan, J. G. Angew. Chem., Int. Ed. 2008, 47, 6049− 6051. (23) (a) Albrecht, M.; Osetska, O.; Klankermayer, J.; Fröhlich, R.; Gumy, F.; Bünzli, J. C. G. Chem. Commun. 2007, 1834−1838. (b) Song, J. L.; Lei, C.; Mao, J. G. Inorg. Chem. 2004, 43, 5630−5634. (c) Comby, S.; Imbert, D.; Chauvin, A. S.; Bünzli, J. C. G. Inorg. Chem. 2006, 45, 732−743. (24) (a) Zhang, L. Y.; Song, T. Y.; Xu, J. N.; Sun, J. Y.; Zeng, S. L.; Wu, Y. C.; Fan, Y.; Wang, L. CrystEngComm 2014, 16, 2440−2451. (b) Li, W. Z.; Li, J. Y.; Li, H. F.; Yan, P. F.; Hou, G. F.; Li, G. M. J. Lumin. 2014, 146, 205−210. (c) Li, W. Z.; Yan, P. F.; Hou, G. F.; Li, H. F.; Li, G. M. RSC Adv. 2013, 3, 18173−18180. (d) Bassett, A. P.; Magennis, S. W.; Glover, P. B.; Lewis, D. J.; Spencer, N.; Parsons, S.; Williams, R. M.; Cola, L. D.; Pikramenou, Z. J. Am. Chem. Soc. 2004, 126, 9413−9424. (25) Sun, L. N.; Zhang, H. J.; Meng, Q. G.; Liu, F. Y.; Fu, L. S.; Peng, C. Y.; Yu, J. B.; Zheng, G. L.; Wang, S. B. J. Phys. Chem. B 2005, 109, 6174−6182. (26) (a) Andruh, M.; Bakalbassis, E.; Kahn, O.; Trombe, J. C.; Porchers, P. Inorg. Chem. 1993, 32, 1616−1622. (b) Cepeda, J.; Balda, R.; Beobide, G.; Castillo, O.; Fernández, J.; Luque, A.; Pérez-Yáñez, S.; Román, P.; Vallejo-Sánchez, D. Inorg. Chem. 2011, 50, 8437−8451. (27) Sun, M. L.; Zhang, J.; Lin, Q. P.; Yin, P. X.; Yao, Y. G. Inorg. Chem. 2010, 49, 9257−9264. (28) Wang, S. N.; Sun, R.; Wang, X. S.; Li, Y. Z.; Pan, Y.; Bai, J. F.; Scheerb, M.; You, X. Z. CrystEngComm 2007, 9, 1051−1061. 6203



Article

(29) CrystalClear v1.3; Molecular Structure Corporation: Orem, UT, 2001.

6204


New 3D Lanthanide Phosphonates: Syntheses, Crystal Structure

Recommend Documents