Syntheses, Structures, and Photoluminescence of One-Dimensional

Jul 21, 2007 - Synopsis. Three different one-dimensional chains were obtained by the reaction of rare earth salts and 2,4,6-pyridinetricarboxylic acid...
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Syntheses, Structures, and Photoluminescence of One-Dimensional Lanthanide Coordination Polymers with 2,4,6-Pyridinetricarboxylic Acid Hong-Sheng Wang, Bin Zhao, Bin Zhai, Wei Shi, Peng Cheng,* Dai-Zheng Liao, and Shi-Ping Yan

CRYSTAL GROWTH & DESIGN 2007 VOL. 7, NO. 9 1851-1857

Department of Chemistry, Nankai UniVersity, Tianjin 300071, P. R. China ReceiVed June 4, 2007; ReVised Manuscript ReceiVed June 19, 2007

ABSTRACT: Nine one-dimensional (1D) lanthanide(III) coordination polymers with the formulas {[La(pta)(H2O)4]‚2H2O}n (1), {[Ln(pta)(H2O)5]‚4H2O}n [Ln ) Sm (2), Eu (3), Tb (4), Ho (5)], and {[Ln(pta)(H2O)3]‚4H2O}n [Ln ) Dy (6), Er (7), Tm (8), Yb (9)] (H3pta ) 2,4,6-pyridinetricarboxylic acid) have been synthesized by reacting the corresponding rare earth salts with H3pta at room temperature. The X-ray structure analyses show three kinds of 1D chain structures. Complexes 2-5 and 6-9 are isostructural, respectively. Complex 1 crystallized in the triclinic with P1 space group, 2-5 crystallized in the orthorhombic with Pna21 space group and 6-9 crystallized in the monoclinic with P21/c space group. In the three kinds of structures, H3pta displays two different coordination modes, and there are intramolecular π-π stacking interactions between the pyridyl ring planes. The complexes of Sm(III), Eu(III), Tb(III), and Dy(III) exhibit the corresponding characteristic luminescence in the visible region at an excitation of 305 nm, and the complexes of Er(III) and Yb(III) show luminescence in the near-infrared region upon excitation of UV rays. Introduction Since the photoluminescence of Eu(III) complexes was discovered in the 1940s,1 research of luminescent lanthanide complexes has been of great interest in the chemical2 and physical3 fields. In recent years, the design and synthesis of metal organic frameworks (MOFs) with lanthanide have attracted much attention due to their potential applications in luminescent materials,4 magnetic,5 catalyst,6 and gas absorption.7 Multicarboxylic acids were widely used as organic linkers in the syntheses of MOFs such as phthalic acid,8 isophthalic acid,9 terephthalic acid,10 trimesic acid,11 pyromellitic acid,12 and 1,3,5benenetriacetic acid.13 In addition, pyridinecarboxylic acids are also important organic ligands in MOFs, and all kinds of pyridinedicarboxylic acids (2,3-, 2,4-, 2,5-, 2,6-, 3,4-, 3,5-) have been used and some complexes with novel structures were obtained.14 Pyridinetricarboxylic acid has more coordination sites than pyridinedicarboxylic acid. Several examples of 2,4,6pyridinetricarboxylic acid have been reported by our group15 and others.16 To our knowledge, only three coordination polymers containing lanthanide with H3pta (H3pta ) 2,4,6pyridinetricarboxylic acid) were structurally characterized and reported so far.15b,16d We were mainly concerned with the photoluminescence of lanthanide complexes with 2,4,6-pyridinetricarboxylic acid and have obtained nine complexes by reacting it with rare earth salts at room temperature. Herein, we report the syntheses and structures of a series of rare earth complexes and the luminescent properties of Sm(III), Eu(III), Tb(III), Dy(III), Er(III), and Yb(III) complexes. Experimental Section Syntheses. 2,4,6-Pyridinetricarboxylic acid was synthesized by oxidization of 2,4,6-trimethylpyridine with potassium permanganate. The rare earth salts were obtained by reacting perchlorate acid, nitric acid, or chloride acid with the corresponding lanthanide oxides (99.99%) purchased from Grirem Advanced Materials Co. Ltd., Beijing. Preparation of {[La(pta)(H2O)4]‚2H2O}n (1). A mixture of La(NO3)3‚nH2O (0.1 mmol) and H3pta (0.1 mmol) was dissolved in 30 * Corresponding author. Fax: +86-2223502458. E-mail: pcheng@ nankai.edu.cn.

mL of water at room temperature, and 3 drops of nitric acid (3 mol/L) were added; then the sample was filtered in a 50 mL beaker after it was stirred for an hour. The colorless crystals were obtained after the beaker was allowed to stand for about 2 months. Yield: 31%. Anal. Calcd. for C8H14NO12La (%): C, 21.11; H, 3.10; N, 3.08. Found: C, 21.52; H, 2.92; N, 2.98. IR bands (KBr pellets, cm-1): 3399sbr, 1614s, 1566s, 1435s, 1369s, 1265m, 1015w, 941w, 783m, 715m. Preparation of {[Sm(pta)(H2O)5]‚4H2O}n (2). A mixture of Sm(ClO4)3‚nH2O (0.1 mmol) and H3pta (0.1 mmol) was dissolved in 30 mL of water at room temperature, and 3 drops of perchloric acid (3 mol/L) were added; then the sample was filtered in a 50 mL beaker after it was stirred for an hour. The light yellow crystals were obtained after the beaker was allowed to stand for about 2 months. Yield: 39%. Anal. Calcd. for C8H20NO15Sm (%): C, 18.46; H, 3.87; N, 2.69. Found: C, 18.58; H, 3.66; N, 2.74. IR bands (KBr pellets, cm-1): 3229sb, 1621s, 1549s, 1437s, 1369s, 1268m, 1097w, 1020w, 782m, 694m. Preparation of {[Eu(pta)(H2O)5]‚4H2O}n (3). A mixture of EuCl3‚ nH2O (0.1 mmol) and H3pta (0.1 mmol) was dissolved in 30 mL of water at room temperature, and 3 drops of hydrochloric acid (6 mol/L) were added;then the sample was filtered in a 50 mL beaker after it was stirred for an hour. The colorless crystals were obtained after the beaker was allowed to stand for about 2 months. Yield: 36%. Anal. Calcd. for C8H20NO15Eu (%): C, 18.39; H, 3.86; N, 2.68. Found: C, 18.23; H, 3.49; N, 2.87. IR bands (KBr pellets, cm-1): 3356sb, 1624s, 1550s, 1439s, 1371s, 1268m, 1096w, 1020w, 781m, 742m. Preparation of {[Tb(pta)(H2O)5]‚4H2O}n (4). The procedure was the same as that in 1 except that nitric acid was not added. Colorless crystals were obtained. Yield: 34%. Anal. Calcd. for C8H20NO15Tb (%): C, 18.16; H, 3.81; N, 2.65. Found: C, 19.34; H, 3.43; N, 2.66. IR bands (KBr pellets, cm-1): 3252sb, 1617s, 1550s, 1438s, 1366s, 1271m, 1098w, 1021w, 785m, 698m. Preparation of {[Ho(pta)(H2O)5]‚4H2O}n (5). A mixture of Ho(ClO4)3‚nH2O (0.1 mmol) and H3pta (0.1 mmol) was dissolved in 30 mL of water at room temperature, and the pH value was adjusted to 4 by adding a solution of LiOH (0.5 mol/L); then the sample was filtered in a 50 mL beaker after it was stirred for an hour. The light pink crystals were obtained after the beaker was allowed to stand for about 2 months. Yield: 43%. Anal. Calcd. for C8H20NO15Ho (%): C, 17.95; H, 3.77; N, 2.62. Found: C, 18.82; H, 3.07; N, 2.83. IR bands (KBr pellets, cm-1): 3201sb, 1645s, 1560s, 1453s, 1375s, 1269m, 1225w, 1025w, 943w, 787m, 748m, 717m. Preparation of {[Dy(pta)(H2O)3]‚4H2O}n (6). The procedure was the same as that in 5 except that Ho(ClO4)3‚nH2O was replaced by Dy(ClO4)3‚nH2O at pH ) 3. Colorless crystals were obtained. Yield:

10.1021/cg0705052 CCC: $37.00 © 2007 American Chemical Society Published on Web 07/21/2007

C8H16-NO13Yb 507.26 293(2) 0.71073 monoclinic P21/c 9.3875(6) 14.0961(10) 10.9245(7) 90 92.6090(10) 90 1444.11(17) 4 980 1.085 6.549 R1 ) 0.0173, wR2 ) 0.0409 R1 ) 0.0198, wR2 ) 0.0415 R indices (all data)

9 8

C8H16-NO13Tm 503.15 293(2) 0.71073 monoclinic P21/c 9.4004(12) 14.1098(18) 10.9211(14) 90 92.583(2) 90 1447.1(3) 4 976 1.047 6.204 R1 ) 0.0210, wR2 ) 0.0516 R1 ) 0.0242, wR2 ) 0.0526 C8H16-NO13Er 501.48 294(2) 0.71073 monoclinic P21/c 9.4389(11) 14.1624(18) 10.9400(13) 90 92.614(2) 90 1460.9(3) 4 972 1.029 5.817 R1 ) 0.0222, wR2 ) 0.0492 R1 ) 0.0295, wR2 ) 0.0512

7 6

C8H16-NO13Dy 496.72 293(2) 0.71073 monoclinic P21/c 9.463(3) 14.190(4) 10.944(3) 90 92.677(4) 90 1468.0(8) 4 964 1.037 5.162 R1 ) 0.0159, wR2 ) 0.0374 R1 ) 0.0180, wR2 ) 0.0378 C8H20-NO15Ho 535.18 294(2) 0.71073 ortho-rhombic Pna21 6.7382(8) 13.1824(17) 17.537(2) 90 90 90 1557.7(3) 4 1048 1.019 5.164 R1 ) 0.0171, wR2 ) 0.0324 R1 ) 0.0239, wR2 ) 0.0347

5 4

C8H20-NO15Tb 529.17 294(2) 0.71073 ortho-rhombic Pna21 6.7491(12) 13.186(2) 17.566(3) 90 90 90 1563.3(5) 4 1040 1.138 4.609 R1 ) 0.0343, wR2 ) 0.0800 R1 ) 0.0382, wR2 ) 0.0812 C8H20-NO15Eu 522.21 294(2) 0.71073 ortho-rhombic Pna21 6.7850(9) 13.2552(17) 17.693(2) 90 90 90 1591.3(4) 4 1032 1.021 4.025 R1 ) 0.0260, wR2 ) 0.0552 R1 ) 0.0355, wR2 ) 0.0583

3 2 1

Syntheses. The nine lanthanide complexes with pta were synthesized under different conditions at room temperature. Since light rare earth ions (La3+, Sm3+, Eu3+) were easily precipitated when reacting with H3pta, the inorganic acids containing anions corresponding to the rare earth salts were employed to prevent the metal ions from being precipitated based on acid effects. The heavy rare earth ions (Tb3+, Dy3+, Ho3+, Er3+, Tm3+, Yb3+) were not easy to crystallize with H3pta under strong acid, so LiOH solution was used to adjust pH values of the reaction solution. Compared to the structures of Pr(III) and Nd(III) complexes reported before,15b,16d they had completely different structures. Description of Crystal Structures. In the nine complexes, there were three types of crystal structures defined as I (1), II (2, 3, 4, 5), and III (6, 7, 8, 9). All the complexes were stable in air. In the IR spectra, each showed two strong absorption bands at 1614 to 1646 cm-1 and 1366 to 1377 cm-1,

C8H20-NO15Sm 520.60 294(2) 0.71073 ortho-rhombic Pna21 6.7888(8) 13.2489(15) 17.704(2) A 90 90 90 1592.4(3) 4 1028 1.030 3.771 R1 ) 0.0257, wR2 ) 0.0612 R1 ) 0.0292, wR2 ) 0.0630

Results and Discussion

C8H14-NO12La 455.11 293(2) 0.71073 triclinic P1 6.6841(5) 9.7404(8) 11.2125(9) 70.1110(10) 85.0550(10) 87.2180(10) 683.76(9) 2 444 1.049 3.191 R1 ) 0.0165, wR2 ) 0.0418 R1 ) 0.0176, wR2 ) 0.0421

Table 1. Crystallographic Data for 1-9

37%. Anal. Calcd. for C8H16NO13Dy (%): C, 19.34; H, 3.25; N, 2.82. Found: C, 20.55; H, 2.83; N, 2.74. IR bands (KBr pellets, cm-1): 3383sb, 1624s, 1560s, 1448s, 1369s, 1273m, 1230w, 1092w, 1024w, 928w, 780m, 739m, 539m. Preparation of {[Er(pta)(H2O)3]‚4H2O}n (7). The procedure was the same as that in 5 except that Ho(ClO4)3‚nH2O was replaced by Er(ClO4)3‚nH2O and the pH value is 2. The pink crystals were obtained. Yield: 48%. Anal. Calcd. for C8H16NO13Er (%): C, 19.16; H, 3.22; N, 2.79. Found: C, 18.88; H, 3.03; N, 2.89. IR bands (KBr pellets, cm-1): 3509sb, 1646s, 1560s, 1454s, 1375s, 1270m, 1225w, 1025w, 943w, 787m, 745m, 716m. Preparation of {[Tm(pta)(H2O)3]‚4H2O}n (8). The procedure was the same as that in 5 except that Ho(ClO4)3‚nH2O was replaced by Tm(ClO4)3‚nH2O. The colorless crystals were obtained. Yield: 57%. Anal. Calcd. for C8H16NO13Tm (%): C, 19.10; H, 3.21; N, 2.78. Found: C, 18.45; H, 3.21; N, 2.71. IR bands (KBr pellets, cm-1): 3270sb, 1644s, 1561s, 1453s, 1376s, 1270m, 1226w, 1026w, 943w, 786m, 747m, 716m. Preparation of {[Yb(pta)(H2O)3]‚4H2O}n (9). The procedure was the same as that in 5 except that Ho(ClO4)3‚nH2O was replaced by Yb(ClO4)3‚nH2O. The colorless crystals were obtained. Yield: 60%. Anal. Calcd. for C8H16NO13Yb (%): C, 18.94; H, 3.18; N, 2.76. Found: C, 18.65; H, 3.14; N, 2.82. IR bands (KBr pellets, cm-1): 3271sb, 1645s, 1561s, 1454s, 1377s, 1271m, 1226w, 1026w, 944w, 748w, 716m. General Characterization. Elemental analyses were performed in a Perkin-Elmer 240 analyzer. IR spectra were recorded with a Tensor 27 FTIR spectrophotometer (KBr pellets, range in 4000-400 cm-1). The emission spectra in the visible region were tested on a Cary Eclipse fluorescence spectrophotometer and those in near-infrared region were measured on an FLS920 fluorescence spectrophotometer. X-ray Diffraction Analysis. Crystallographic data of 2, 3, 4, 5, and 7 were collected with a Bruker SMART 1000 CCD area detector, and data of 1, 6, 8, and 9 were collected with a Bruker SMART APEX II CCD area detector. Both detectors were equipped with graphite monochromatic Mo KR radiation (λ ) 0.71073 Å). Structures were solved by direct methods with the SHELXTL-97 program and refined by full-matrix least-squares techniques against F2 with the SHELXTL97 program package.17 All non-hydrogen atoms were refined anisotropically, and hydrogen atoms were located and refined isotropically. Crystallographic data for the nine compounds are listed in Table 1 and the selected bond lengths and bond angles are listed in Supporting Information. Crystallographic data for the nine complexes in this paper have been deposited at the Cambridge Crystallographic data center, CCDC Nos. 606047, 606042, 606043, 606044, 272842, 606046, 606045, 272840, and 286198 are for complexes 1-9, respectively. These data can be obtained free of charge at http://www.ccdc.cam.ac.uk/conts/retrieving.html (or from the Cambridge Crystallographic Data Center, 12 Union Road, Cambridge CB2 1EZ, UK; fax: (+44) 1223-336-033; e-mail: [email protected]).

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empirical formula M T/K λ/Å cryst system space group a/Å b/Å c/Å R/deg β/deg γ/deg V/Å3 Z F(000) GOF on F2 µ/mm-1 final R [I > 2σ(I)]

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Figure 1. (a) ORTEP representation of 1 showing the coordination environment of La(III) ion with 30% probability of thermal ellipsoids. (b) The 1D chain structure of 1. Hydrogen atoms were omitted for clarity. (c) The 2D layer structure constructed by hydrogen bonds between the 1D chains. (d) The 3D framework of Structure I, constructed with the corresponding 2D layer by hydrogen bonds.

Scheme 1. (a) Coordination Modes of PTA in Structures I and III and (b) Coordination Modes of PTA in Structure II.

respectively. They corresponded to asymmetrical and symmetrical stretching vibration of carboxyl groups. Structure I. In Structure I, the center metal was La(III) ion, and it was nine coordinated by eight oxygen atoms and one nitrogen atom, as shown in Figure 1a. Four coordination oxygen atoms (O(7), O(8), O(9), and O(10)) were from water molecules, the La-O bond lengths were 2.574(1), 2.564(2), 2.523(2), and 2.683(2) Å, respectively; the other four (O(1), O(6), O(3A), and O(4A)) were from the carboxyl groups and the La-O bond lengths were 2.5713(19), 2.5358(19), 2.5268(19), and 2.4924(19) Å, respectively; the nitrogen atom N(1) was from pyridyl ring and the La-N bond length was 2.694(2) Å. The bond angles of O-La-O ranged between 65.47(6)° and 150.76(7)° and that of O-La-N ranged between 60.00(6)° and 143.44(9)°. The coordination mode of pta in Structure I was shown in Scheme 1a. One pta connects three La(III) ions by O(1), O(3), O(4), O(6), and N(1). Among them O(1), O(6), and N(1) bonded to a La(III) ion by chelating mode, while O(3) and O(4) of the 4-carboxyl group bonded to two La(III) ions. A 1D alternating

chain was formed by the connection of 2-, 4-, and 6-carboxyl groups and La(III) ions, shown in Figure 1b. The twodimensional (2D) layer was obtained by hydrogen bonds formed between the carboxyl groups and the water molecules among the neighboring 1D chains, as shown in Figure 1c. The layertype structure was further assembled into the three-dimensional (3D) framework by hydrogen bonds, as shown in Figure 1d. Structure II. Complex 2 was taken as an example to describe Structure II in detail, as shown in Figure 2a. The coordination number of Sm(III) ion was also nine. Among them five oxygen atoms (O(7), O(8), O(9), O(10), and O(11)) were from water molecules, and the Sm-O bond lengths were 2.493(3), 2.437(3), 2.459(4), 2.447(3), and 2.529(3) Å, respectively; the other three oxygen atoms (O(1), O(3), and O(4A)) were from carboxyl groups, and the Sm-O bond lengths were 2.410(4), 2.445(3), and 2.480(3) Å, respectively; the nitrogen atom N(1) was from the pyridyl ring, and the Sm-N bond length was 2.551(4) Å. The bond angles of O-Sm-O ranged between 68.46(11)° and 139.03(13)° and that of O-Sm-N ranged between 62.88(12)° and 136.61(13)°. The coordination mode of pta was different from that in Structure I, as shown in Scheme 1b. The O(1), O(3), and N(1) chelated one Sm(III) ion in a tridentate way. The 4-carboxyl group was deprotonated but did not bond to any Sm(III) ions. By the connections of [Sm(pta)(H2O)5]‚4H2O units with O(4), 1D zigzag chain was formed in 2, as shown in Figure 2b. The similar structures were formed in 3-5. The 2D layer (Figure 2c) and 3D framework (Figure 2d) were also formed by the interchain hydrogen bonds. Structure III. The structure of complex 6 was described in detail to introduce the Structure III. The center Dy(III) ion was eight-coordinated by seven oxygen atoms and one nitrogen atom, as shown in Figure 3a. Three coordination oxygen atoms (O(7), O(8), and O(9)) were from water molecules, and the Dy-O

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Figure 2. (a) ORTEP representation of 2 showing the coordination environment of the Ln(III) ion (Ln ) Sm, Eu, Tb, Ho) with 30% probability of thermal ellipsoids. (b) The 1D chain structure of 2-5. (c) The 2D layer structure constructed by hydrogen bonds between the 1D chains. (d) The 3D framework of Structure II constructed with the corresponding 2D layer by hydrogen bonds.

bond lengths were 2.395(2), 2.395(2), and 2.330(2) Å, respectively; the other four oxygen atoms (O(1), O(6), O(3A), and O(4A)) were from the carboxyl groups and bond length was 2.425(2), 2.344(2), 2.334(2), and 2.341(2) Å, respectively; the nitrogen atom [N(1)] was from pyridyl ring and Dy-N is 2.461(2) Å. The bond angles of O-Dy-O ranged between 67.72(7)° and 149.65(7)° and that of O-Dy-N ranged between 65.60(7)° and 143.37(8)°. The coordination modes of carboxyl groups of pta are the same as that in Structure I (1). The coordination number of the rare earth ions changed from nine to eight because the number of coordination water molecules decreased from four in Structure I to three in Structure III. The change maybe resulted from the lanthanide contraction effect. The 1D alternating chain similar to that in 1 was obtained in complexes 6-9 (Figure 3b). Similarly, the 2D layer (Figure 3c) and 3D framework (Figure 3d) are constructed by hydrogen bonds. Comparison of the Structures. In the three types of structures, the coordination number (CN) of the La(III) ion in Structure I is nine, and the La(III) ion is located in the distorted monocapped square antiprism. The CN of Ln(III) ions in Structure II (Ln ) Sm, Eu, Tb, and Ho) were also nine, but the rare earth ions are located in the distorted tricapped trigonal prism, while the CN of the Ln(III) ions (Ln ) Dy, Er, Tm, and Yb) in Structure III were eight, and rare earth ions are located in the distorted square antiprism, shown in Figure 4. Although Structure I and III displayed a similar 1D chain-type structure and the same coordination modes of pta, the 3D frameworks in 1 and 6 constructed by various hydrogen bonds exhibit differences, as shown in Figures 1d and 3d. It may be explained

as follows: The hydrogen bonds between the 2D layers were formed among carboxyl groups, lattice water, and coordination water molecules. In Structure I, the numbers of the coordination water molecules and lattice water molecules were 4 and 2, respectively, while corresponding those in Structure III were 3 and 4. From Figures 1c and 3c, the form of hydrogen bonds in 6 was more complex than that in 1 due to more lattice water molecules. So the difference of the 3D structures in Structures I and III should be ascribed to the different hydrogen bonds in the complexes. Furthermore, the crystal system and space group for Structure I were triclinic and P1 as well as monoclinic and P21/c for Structure III. We can see that the cell parameters’ values of a, b, c, and V decreased with an increase in the atomic number for Structures II and III from Table 1. The CN of rare earth ions and average bond lengths in 1-9 were listed in Table 2. In complexes 2-5, the Ln-O average bond lengths decreased from 2.445 to 2.385 Å (Ln-Ocarboxylate) and from 2.477 to 2.417 Å (Ln-Owater), and the Ln-N bond lengths decreased from 2.551 to 2.492 Å with an increase in atomic number. In the same way in complexes 6-9, the bond average length of LnOcarboxylate, Ln-Owater, and Ln-N also decreased with an increase in the atomic number. All these should be ascribed to the lanthanide contraction effect. The rare earth salts with different anions have been used in the syntheses of the complexes such as perchlorates, nitrates, or chlorides. The results indicated that the anions have no influence on the structures of the complexes. All these anions have not emerged in the coordination polymers. It should be noted to the structures of Dy(III) and Ho(III) complexes. In the normal rare earth order the Dy(III) complex should be isostructural with Tb(III) as well as the Ho(III)

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Figure 3. (a) ORTEP representation of 6 showing the coordination environment of the Ln(III) ion (Ln ) Dy, Er, Tm, Yb) with 30% probability of thermal ellipsoids. (b) The 1D chain structure of 6-9. (c) The 2D layer structure constructed by hydrogen bonds between the 1D chains. (d) The 3D framework of Structure III constructed with the corresponding 2D layer by hydrogen bonds.

Figure 4. The coordination polyhedron of structure I (a), II (b), and III (c). Table 2. Coordination Number (CN) and Average Bond Lengths (Å) in 1-9

Structure I Structure II

Structure III

complex

CN

Ln-Ocarboxylate

Ln-O water

Ln-N

1 2 3 4 5 6 7 8 9

9 9 9 9 9 8 8 8 8

2.532 2.445 2.431 2.401 2.385 2.361 2.341 2.327 2.319

2.586 2.477 2.466 2.431 2.417 2.373 2.352 2.337 2.328

2.694 2.551 2.537 2.514 2.492 2.461 2.441 2.422 2.410

complex with Er(III) complex, but it is the reverse herein. Perhaps it resulted from the different pH values of the reaction solution. π-π Stacking Interaction. There are intramolecular π-π stacking interactions between the pyridyl ring planes in all the three kinds of structures, as shown in Figures 1b, 2b, and 3b. The distances of the centroids of pyridyl ring plane 1a and 1b, 2a and 2b, and 3a and 3b (named P1a, P1b, P2a, P2b, P3a,

P3b) are 3.482, 3.673, and 3.451 Å, respectively. The P1a and P1b and P3a and P3b are perfectly parallel to each other. The P2a and P2b are not parallel, and the dihedral angle between them is 18.8°. In these complexes, the intramolecular π-π stacking interactions are slipped packing rather than a perfect face-to-face array of atoms as that in many other complexes.18 Photoluminescent Properties of Complexes 2, 3, 4, 6, 7, and 9. The emission spectra with solid samples for complexes 2, 3, 4, and 6 were determined in the visible region at the excitation wavelength of 305 nm under ambient temperature. Fortunately, the four complexes all displayed their characteristic emission. For the four luminescent lanthanide complexes of Sm(III), Eu(III), Tb(III), and Dy(III), usually the emitting intensity of Sm(III) complex is the weakest. The three characteristic emission bands in visible region can be seen from the emitting spectra of 2, as shown in Figure 5a. The three peaks at 558, 592, and 639 nm corresponded to the transition of Sm(III) from 4G 6 5/2 to HJ (J ) 5/2, 7/2, 9/2), respectively. In emitting spectra of Eu(III) in 3 (Figure 5b), not only the transitions of 5D0 to

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Figure 5. Emission spectra for complex 2(a), 3(b), 4(c), 6(d), 7(e), 9(f).

[J ) 1 (589 nm), 2 (613 nm), 3 (647 nm), 4 (695 nm)] but also that of 5D1 to 7FJ [J ) 1 (533 nm), 2 (552 nm)] can be observed clearly. The intensity radio of 5D0 f 7F2 transition (electric dipole transition) to 5D0 f 7F1 transition (magnetic dipole transition) is 2.8, and it shows that the symmetry of the coordination environment of Eu(III) ions is low,19 which agrees with the result of X-ray single-crystal diffraction. Figure 5c shows emitting spectra of Tb(III) ion in complex 4. The four peaks at 491, 546, 584, and 623 nm are assigned to the transition of 5D4 to 7FJ (J ) 6, 5, 4, 3). The characteristic emissions of Dy(III) ion in 6 are shown in Figure 5d. Two peaks at 476 and 569 nm are assigned to the transition of 4F9/2 f 6H15/2 and 4F9/2 f 6H13/2, respectively. In the four complexes, the emissions of 7F J

Sm(III), Eu(III), Tb(III), and Dy(III) ion have all been sensitized by pta ligand. Much research has shown that the coordinating solvent molecules can reduce the luminescent intensity of the rare earth ions.20 However, in 2, 3, 4, and 6, although at least four water molecules coordinate to the rare earth ions, the characteristic emissions of them are still strong. With the theory of energy transfer,21 it should be ascribed to the high efficiency of energy transfer from ligand to lanthanide ions. The photoluminescence of the complexes of Er(III) and Yb(III) ions in near-infrared region were also tested at excitation of UV rays. Er(III) complex displays an emission band at 1438 nm under the excitation of 300 nm, and it should be attributed to the transition of 4I13/2 f 4I15/2.22 The Yb(III) complex also

1D Lanthanide Coordination Polymers

displays a strong emission band at 980 nm upon excitation of 302 nm, and it resulted from the 2F5/2 f 2F7/2 transition.23 In summary, we have synthesized a series of 1D lanthanide coordination polymers with three types of structures by using 2,4,6-pyridinetricarboxylic acid as the organic linker. H3pta showed two coordination modes. The lanthanide contraction effect was embodied in Structures II and III. Furthermore, the polymers of Sm(III), Eu(III), Tb(III), and Dy(III) show strong luminescence in the visible region at excitation and that of Er(III) and Yb(III) display their characteristic luminescence in the near-infrared region. Acknowledgment. This work was supported by the National Natural Science Foundation of China (Nos. 90501002, 20501012, and 20425103), the NSF of Tianjin (No. 06YFJZJC009000), and the State Key Project of Fundamental Research of MOST (2005CCA01200), P. R. China. Supporting Information Available: Selected bond lengths and angles for compounds 1-9. This material is available free of charge via the Internet at http://pubs.acs.org.

References (1) Weissman, S. I. J. Chem. Phys. 1942, 31, 214. (2) (a) Bunzli, J. C. G.; Piguet, C. Chem. Soc. ReV. 2005, 34, 1048. (b) Puntus, L. N.; Schenk, K. J.; Bu¨nzli, J. C. G. Eur. J. Inorg. Chem. 2005, 4739. (c) Zhang, T.; Spitz, C.; Antonietti, M.; Faul, C. F. J. Chem.sEur. J. 2005, 11, 1001. (d) Yu, J. B.; Zhou, L.; Zhang, H. J.; Zheng, Y. X.; Li, H. R.; Deng, R. P.; Peng, Z. P.; Li, Z. F. Inorg. Chem. 2005, 44, 1611. (e) Yang, J.; Yue, Q.; Li, G. D.; Cao, J. J.; Li, G. H.; Chen, J. S. Inorg. Chem. 2006, 45, 2857. (f) Mancino, G.; Ferguson, A. J.; Beeby, A.; Long, N. J.; Jones, T. S. J. Am. Chem. Soc. 2005, 127, 524. (g) 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. (3) (a) Pivin, J. C.; Podhorodecki, A.; Kudrawiec, R.; Misiewicz, J. Opt. Mater. 2005, 27, 1467. (b) An, B. L.; Gong, M. L.; Cheah, K. W.; Zhang, J. M.; Li, K. F.; Chem. Phys. Lett. 2004, 385, 345. (c) Xu, H.; Wang, L. H.; Zhu, X. H.; Yin, K.; Zhong, G. Y.; Hou, X. Y.; Huang, W. J. Phys. Chem. B 2006, 110, 3023. (d) Liu, G. K.; Jensen, M. P.; Almond, P. M. J. Phys. Chem. A, 2006, 110, 2081. (e) Faustino, W. M.; Malta, O. L.; Teotonio, E. E. S.; Brito, H. F.; Simas, A. M.; Sa, G. F. J. Phys. Chem. A 2006, 110, 2510. (4) (a) Harrison, B. S.; Foley, T. J.; Knefely, A. S.; Mwaura, J. K.; Cunningham, G. B.; Kang, T. S.; Bouguettaya, M.; Boncella, J. M.; Reynolds, J. R.; Schanze, K. S. Chem. Mater. 2004, 16, 2938. (b) He, H. S.; Guo, J. P.; Zhao, Z. X.; Wong, W. K. Wong, W. Y.; Lo, W. K.; Li, K. F.; Luo, L.; Cheah, K. W. Eur. J. Inorg. Chem. 2004, 837. (c) Parkar, D. Coord. Chem. ReV. 2000, 205, 109. (5) Morrish, A. H. The Physical Principles of Magnetism; Wiley: New York, 1965. (6) (a) Dickins, R. S.; Gaillard, S.; Hughes, S. P.; Badari, A. Chirality 2005, 17, 357. (b) Yao, Y. M.; Zhang, Z. Q.; Peng, H. M.; Zhang, Y.; Shen, Q.; Lin, J. Inorg. Chem. 2006, 45, 2175. (c) Wang, S. W.; Zhou, S. L.; Sheng, E. H.; Xie, M. H.; Zhang, K. H.; Cheng, L.; Feng, Y.; Mao, L. L.; Huang, Z. X. Organometallics 2003, 22, 3546. (d) Tobisch, S. J. Am. Chem. Soc. 2005, 127, 11979. (7) Pan, L.; Adams, K. M.; Hernandez, H. E.; Wang, X.; Zheng, C.; Hattori, Y.; Kaneko, K. J. Am. Chem. Soc. 2003, 125, 3062. (8) (a) Yan, B.; Song, Y. S.; Chen, Z. X. J. Mol. Struct. 2004, 694, 115. (b) Wan, Y. H.; Jin, L. P.; Wang, K. Z.; Zhang, L. P.; Zheng, X. J.; Lu, S. Z. New J. Chem. 2002, 26, 1590.

Crystal Growth & Design, Vol. 7, No. 9, 2007 1857 (9) (a) de Bettencourt-Dias, A. Inorg. Chem. 2005, 44, 2734. (b) Ma, C. B.; Chen, C. N.; Liu, Q. T.; Chen, F.; Liao D. Z.; Li, L. C.; Sun L. C. Eur. J. Inorg. Chem. 2004, 3316. (10) (a) Thirumurugan, A.; Natarajan, S. Inorg. Chem. Commun. 2004, 7, 395. (b) Sun, D. F.; Cao, R.; Liang, Y. C.; Shi, Q.; Su, W. C.; Hong, M. C. J. Chem. Soc., Dalton Trans., 2001, 2335. (11) (a) Daiguebonne, C.; Guilloa, O.; Gerault, Lecerf, Y., A.; Boubekeur, K. Inorg. Chim. Acta 1999, 284, 139. (b) Paz, F. A. A.; Klinowski, J. Inorg. Chem. 2004, 43, 3882. (12) (a) Wang, Z. M.; Burgt, L. J.; Choppin, G. R. Inorg. Chim. Acta 1999, 293, 167. (b) Ganesan, S. V.; Natarajan, S. Inorg. Chem. 2004, 43, 198. (13) Zhang, Z. H.; Okamura, T. A.; Hasegawa, Y.; Kawaguchi, H.; Kong, Sun, L. Y., W. Y.; Ueyama, N. Inorg. Chem. 2005, 44, 6219. (14) See for examples: (a) Tong, M. L.; Wang, J.; Hu, S. J. Solid State Chem. 2005, 178, 1518. (b) Yue, Q.; Yang, J.; Li, G. H.; Li, G. D.; Xu, W.; Chen, J. S.; Wang, S. N. Inorg. Chem. 2005, 44, 5241. (c) Wang, X. L.; Qin, C.; Wang, E. B.; Li, Y. G.; Hao, N.; Xu, L. Inorg. Chem. 2004, 43, 1850. (d) Liang, Y. C.; Cao, R.; Hong, M. C.; Sun, D. F.; Zhao, Y. J.; Weng, J. B.; Wang, R. H. Inorg. Chem. Commun. 2002, 5, 366. (e) Qin, C.; Wang, X. L.; Wang, E. B.; Su, Z. M. Inorg. Chem. 2005, 44, 7122. (f) Gao, H. L.; Cheng, C.; Ding, B.; Shi, W.; Song, H. B.; Cheng, P.; Liao, D. Z.; Yan, S. P.; Jiang, Z. H. J. Mol. Struct. 2005, 738, 105. (g) Zhao, B.; Cheng, P.; Dai, Y.; Cheng, C.; Liao, D. Z.; Yan, S. P.; Jiang, Z. H.; Wang, G. L. Angew. Chem., Int. Ed. 2003, 42, 934. (h) Zhao, B.; Cheng, P.; Chen, X. Y.; Cheng, C.; Shi, W.; Liao, D. Z.; Yan, S. P.; Jiang, Z. H. J. Am. Chem. Soc. 2004, 126, 3012. (i) Ghosh, S. K.; Bharadwaj, P. K. Inorg. Chem. 2005, 44, 3156. (j) Zhao, B.; Gao, H. L.; Chen, X. Y.; Cheng, P.; Shi, W.; Liao, D. Z.; Yan, S. P.; Jiang, Z. H. Chem. Eur. J. 2006, 12, 149. (15) (a) Gao, H. L.; Ding, B.; Yi, L.; Cheng, P.; Liao, D. Z.; Yan, S. P.; Jiang, Z. H. Inorg. Chem. Commun. 2005, 8, 151. (b) Gao, H. L.; Yi, L.; Ding, B.; Wang, H. S.; Cheng, P.; Liao, D. Z.; Yan, S. P. Inorg. Chem. 2006, 45, 481. (16) (a) Ghosh, S. K.; Bharadwaj, P. K. Inorg. Chim. Acta 2006, 359, 1685. (b) Ghosh, S. K.; El, Fallah, M. S.; Ribas, J.; Bharadwaj, P. K. Inorg. Chim. Acta 2006, 359, 468. (c) Ghosh, S. K.; Savitha, G.; Bharadwaj, P. K. Inorg. Chem. 2004, 43, 5495. (d) Ghosh, S. K.; Bharadwaj, P. K. Eur. J. Inorg. Chem. 2005, 4886. (17) (a) Sheldrick, G. M. SHELXS 97, Program for the Solution of Crystal Structures; University of Go¨ttingen: Germany, 1997. (b) G. M. Sheldrick, SHELXL 97, Program for the Refinement of Crystal Structures; University of Go¨ttingen: Germany, 1997. (18) (a) Yong, G. P.; Wang, Z. Y.; Chen, J. T. J. Mol. Struct. 2004, 707, 223. (b) Chipot, C.; Jaffe, R.; Maigret, B.; Pearlman, D. A.; Kollman, P. A. J. Am. Chem. Soc. 1996, 118, 11217. (c) Hobza, P.; Selzle, H. L.; Schlag, E. W. J. Am. Chem. Soc. 1994, 116, 3500. (19) Kirby, A. F.; Foster, D.; Richardson, F. S. Chem. Phys. Lett. 1983, 95, 507. (20) Du, C. X.; Wang, Z. Q.; Xin, Q.; Wu, Y. J.; Li, W. L. Acta Chim. Sin. 2004, 62, 2265. (21) (a) Dexter, D. L. J. Chem. Phys. 1953, 21, 836. (b) Brown, T. D.; Shepherd, T. M. J. Chem. Soc. Dalton Trans. 1973, 336. (22) (a) Li, B.; Gu, W.; Zhang, L. Z.; Qu, J.; Ma, Z. P.; Liu, X.; Liao, D. Z. Inorg. Chem. 2006, 45, 10425. (b) Sun, L. N.; Yu, J. B.; Zheng, G. L. Eur. J. Inorg. Chem. 2006, 3962. (c) Wang, H.; Qian, G.; Wang, Z. et al. J. Lumin. 2005, 113, 214. (d) Bellusci, A.; Barberio, G.; Crispini, A. Inorg. Chem. 2005, 44, 1818. (23) (a) Deun, R. V.; Fias, P.; Nockemann, P. Inorg. Chem. 2006, 45, 10416. (b) Shavaleev, N. M.; Accorsi, G.; Virgili, D. Inorg. Chem. 2005, 44, 61. (c) Ziessel, R. F.; Ulrich, G.; Charbonnie`re, L. Chem. Eur. J. 2006, 12, 5060.

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