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Synthesis, crystal structures and photoluminescence properties of two silver(I) coordination polymers with nano size channels based on 2-sulfoterephthalic acid ligand
Inorganica Chimica Acta 394 (2013) 466–471
Contents lists available at SciVerse ScienceDirect
Inorganica Chimica Acta journal homepage: www.elsevier.com/locate/ica
Synthesis, crystal structures and photoluminescence properties of two silver(I) coordination polymers with nano size channels based on 2-sulfoterephthalic acid ligand Jie Wang a, Jin-Min Cai a, Ai-Yin Wang a,⇑, Bi-Feng Huang a, Hong-Ping Xiao a, Xin-Hua Li a, Ali Morsali b,⇑ a b
College of Chemistry and Materials Engineering, Wenzhou University, Wenzhou 325035, PR China Department of Chemistry, Faculty of Sciences, Tarbiat Modares University, P.O. Box 14155-4838, Tehran, Iran
a r t i c l e
i n f o
Article history: Received 27 June 2012 Received in revised form 21 August 2012 Accepted 29 August 2012 Available online 14 September 2012 Keywords: Crystal structure Ag(I) Coordination polymer, 2-sulfoterephthalic acid Photoluminescence Nano-channels
a b s t r a c t Self-assembly of silver nitrate with 2-sulfoisophthalic acid monosodium salt (NaH2stp) produced two novel Ag(I) coordination polymers, [Ag3(2-stp)(H2O)]n (1) and [Ag2(2-Hstp)]n (2), respectively. Singlecrystal X-ray diffraction reveals that compound 1 has a 3D supramolecular structure containing Ag. . .Ag and Ag. . .O weak interactions. Compound 2 also features a 3D supramolecular network formed by Hstp2 ligands and p. . .p stacking interactions. In the solid state and at room temperature, compound 1 exhibits blue photoluminescence with a maximum at 453 nm upon excitation at 383 nm. Compound 2 shows green photoluminescence with a maximum at 524 nm upon excitation at 330 nm. Ó 2012 Elsevier B.V. All rights reserved.
1. Introduction
2. Experimental
The logical design and controlled synthesis of metal–organic polymers is throughout of great interest in the field of crystal engineering and supramolecular chemistry because of not only their fascinating structural diversities [1–7] but also their potential uses as functional materials [8–13] in various fields. So far, metal carboxylate frameworks have afforded the most diversity in this area because of their chemical stability and appropriate connectivity [4,5,14,15]. The sulfonate group, which is generally regarded as weakly ligating, can make its coordination mode more flexible and sensitive to the chemical environment, which is a source of greater coordination versatility and ultimately of structural diversity. Herein, 2-sulfoisophthalic acid (H3stp) ligand attracted our attention not only because the bifunctional sulfonate-carboxylate ligands which can exhibit discriminative coordination abilities, but also the coordination of the metal with H2-stp ligands has been less investigated [6,16–26]. In this paper we report two new Ag(I) coordination polymers with 2-sulfoisophthalic acid (H3stp), [Ag3(2-stp)(H2O)]n (1) and [Ag2(2-Hstp)]n (2).
2.1. Materials and measurements
⇑ Corresponding authors. E-mail addresses: [email protected] (A.-Y. Wang), morsali_a@ modares.ac.ir (A. Morsali). 0020-1693/$ - see front matter Ó 2012 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.ica.2012.08.029
All chemicals and solvents were obtained from commercial sources with reagent grade and used without further purification in the syntheses. Elemental analyses for C, H, and N were carried out on a CHN–O-Rapid Analyzer and an Elemental Vario Microanalyzer. The infrared spectra were taken on a Bruker Equinox 55 FTIR spectrometer as KBr pellets in the 400–4000 cm 1 region. The fluorescence spectra were measured using SHIMADZU RF-7000 spectrometer on powdered sample in the solid state at room temperature. The measurements for electric conductivity were made by Crystallographic measurements at 298(2) K using a Bruker Smart Apex II CCD area detector diffractometer. The intensity data were collected using graphite monochromated Mo Ka radiation (k = 0.71073 Å). Accurate unit cell parameters and orientation matrix for data collection were obtained from least-squares refinement. The structures have been solved by direct methods and refined by full-matrix least-squares techniques on F2. Details of crystal data, data collection, structure solution and refinement are given in Table 1. 2.1.1. Synthesis of [Ag3(2-stp)(H2O)]n (1) A mixture of AgNO3 (0.0169 g, 0.10 mmol), 2-sulfoterephthalic acid monosodium salt (0.0268 g, 0.10 mmol), NaOH (0.008 g,
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J. Wang et al. / Inorganica Chimica Acta 394 (2013) 466–471 Table 1 Crystal data and structure refinement for compounds 1 and 2.
Table 2 Selected bond lengths (Å) and angles (°) for 1.
Complex
1
2
Empirical formula Mr Crystal system Space group Unit cell dimensions a (Å) b (Å) c (Å) a (°) b (°) c (°) V (Å3) Z Dc (mg m 3) l (mm 1) h range Reflections collected Unique reflections No. of parameter F(0 0 0) R1a [I > 2ó], wR2b (all data) Goodness-of-fit (GOF) on F2 Largest and hole (e A 3)
C8H5Ag3O8S 584.79 Monoclinic P21/c
C8H4Ag2O7S 459.91 Monoclinic P21/c
13.5508(10) 7.0200(5) 12.2693(9) 90 108.574(2 90 1106.34(14) 4 3.511 5.484 1.59–25.20 11292 1973 181 1096 0.0394, 0.1088 1.072 1.840, 1.819
11.186(2) 7.8121(14) 12.710(2) 90 117.012(14) 90 989.5(3) 4 3.087 4.194 2.04–25.69 7126 1862 163 872 0.0197, 0.0661 1.046 0.504, 0.731
P P R1a = ||Fo| |Fc||/ Fo|. P P wR2b = [ w(Fo2 Fc2)2/ w(Fo2)]1/2.
Lengths (Å) Ag(1)–O(1) Ag(1)–O(7)#1 Ag(1)–O(3)#2 Ag(2)–O(3)#4 Ag(2)–O(4) Angles (°) O(1)–Ag(1)–O(7)#1 O(1)–Ag(1)–O(3)#2 O(7)#1–Ag(1)– O(3)#2 O(3)#4–Ag(2)–O(4) O(3)#4–Ag(2)– O(5)#5
2.209(5) 2.297(4) 2.384(4) 2.234(4) 2.356(4) 135.70(17) 127.97(16) 96.07(15) 143.48(16) 115.45(16)
Symmetry codes: #1( x, y 1/2, #4( x + 1, y + 2, z + 1); #5(x, #7( x + 1, y + 1/2, z + 1/2).
Ag(2)–O(6)#6 Ag(3)–O(2)#3 Ag(3)–O(8) Ag(1). . .Ag(3)#3 Ag(2). . .Ag(2)#4
2.509(4) 2.193(5) 2.266(5) 3.0215(9) 2.9710(14)
O(4)–Ag(2)–O(5)#5 O(3)#4–Ag(2)– O(6)#6 O(4)–Ag(2)–O(6)#6
87.64(16) 93.13(16)
O(5)#5–Ag(2)– O(6)#6 O(2)#3–Ag(3)–O(8)
135.68(15)
87.76(14)
155.16(17)
z 1/2); #2 ( x, y + 2, z); #3 ( x, y + 1, z); y + 3/2, z + 1/2); #6 ( x + 1, y 1/2, z + 1/2);
0.20 mmol) was dissolved in distilled water (10 mL) and ethylalcohol (5 mL) and allowed to evaporate in the dark. After 3 days, colorless block-shaped crystals were obtained. Anal. Calc. for C8H5Ag3O8S (%): C, 16.43; H, 0.86; Found: C, 16.29; H, 0.78. FT-IR (KBr pellet, cm 1) selected bands: m = 3388 m, 1587s, 1368s, 1200s, 1072w, 1021w, 817w, 678w, 622s, 570w, 501w.
Fig. 1. Perspective view of the coordination environment of the Ag(I) ion in compound 1. Hydrogen atoms were removed for clarity. Symmetry codes: #1( x, y 2); #2( x, y + 2, z); #3( x, y + 1, z); #4( x + 1, y + 2, z + 1); #5(x, y + 3/2, z + 1/2); #6( x + 1, y 1/2, z + 1/2).
Fig. 2. Perspective views of the 2-D layer through hydrogen bonds interactions.
1/2,
z
1/
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J. Wang et al. / Inorganica Chimica Acta 394 (2013) 466–471
Fig. 3. Perspective views of the 3-D framework through polyhedral representation (Ag1: red, Ag2: blue, and Ag3: green). (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.)
Table 3 Selected bond lengths (Å) and angles (°) for 2. Lengths (Å) Ag(1)–O(1) Ag(1)–O(3) Ag(1)–O(7)#1 Ag(1)–O(1)#2 Ag(1)–O(4)#2 Angles (°) O(7)#1–Ag(1)–O(4)#2 O(7)#1–Ag(1)–O(1) O(4)#2–Ag(1)–O(1) O(7)#1–Ag(1)–O(3) O(4)#2–Ag(1)–O(3) O(1)–Ag(1)–O(3) O(7)#1–Ag(1)–O(1)#2 O(4)#2–Ag(1)–O(1)#2
2.444(2) 2.574(3) 2.343(2) 2.579(2) 2.427(3) 138.76(9) 128.76(9) 82.72(8) 101.69(9) 114.17(9) 73.01(8) 88.95(8) 75.81(7)
Ag(2)–O(3) Ag(2)–O(2)#2 Ag(2)–O(1)#3 Ag(2)–O(4)#4 Ag(2). . .Ag(2)#5
2.568(3) 2.232(2) 2.305(2) 2.505(2) 2.8981(7)
O(1)–Ag(1)–O(1)#2 O(3)–Ag(1)–O(1)#2 O(2)#2–Ag(2)–O(1)#3 O(2)#2–Ag(2)–O(4)#4 O(1)#3–Ag(2)–O(4)#4 O(2)#2–Ag(2)–O(3) O(1)#3–Ag(2)–O(3) O(4)#4–Ag(2)–O(3)
138.51(5) 83.97(8) 157.54(9) 116.93(9) 83.88(8) 88.74(9) 99.68(8) 91.39(8)
Symmetry transformations used to generate equivalent #1( x + 1, y + 1, z + 1); #2( x + 2, y 1/2, z + 3/2); #3(x, y + 3/2, z ( x + 2, y + 2, z + 1); #5( x + 2, y + 1, z + 1).
Found: C, 20.71; H, 0.79. FT-IR (KBr pellet, cm Fig. 4. Perspective view of the coordination environment of the Ag(I) ion in compound 2. Hydrogen atoms were removed for clarity. Symmetry codes: #1 ( x + 1, y + 1, z + 1); #2( x + 2, y 1/2, z + 3/2); #3(x, y + 3/2, z 1/2); #4( x + 2, y + 2, z + 1).
atoms: 1/2); #4
1
) selected bands:
m = 3424 m, 2926w, 1674 m, 1578s, 1359s, 1176s, 1068w, 1013w, 870w, 798w, 721s, 615w, 521w.
3. Results and discussion 2.1.2. Synthesis of [Ag2(2-Hstp)]n (2) A mixture of AgNO3 (0.0169 g, 0.10 mmol) and 2-sulfoterephthalic acid monosodium salt (0.0268 g, 0.10 mmol) was dissolved in distilled water (10 mL) and ethylalcohol (5 mL) and allowed to evaporate in the dark. After 1 month, light yellow slice crystals were obtained. Anal. Calc. for C8H4Ag2O7S (%): C, 20.89; H, 0.88;
3.1. Structure of [Ag3(2-stp)H2O]n (1) X-ray analysis reveals that complex 1 crystallizes in a monoclinic system with space group P21/c. The asymmetric unit consists of three crystallographically independent Ag(I) ions, one 2-stp and one coordinated water molecule. As illustrated in Fig. 1, The Ag1
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Ag(I) ions, extend 2D layers into 3D framework (Fig. 3). Additionally, weak Ag2. . .Ag3 and Ag3. . .O (Ag2. . .Ag3 = 3.1932(8), Ag3. . .O5#3 = 2.641(3), Ag3. . .O6#2 = 2.650(2) Å) interactions occur between the adjacent 2D layers, which further enhances the stability of the 3D framework. The closest Ag–Ag interaction in compound 1 is same with similar complexes [27–32], indicating that there are argentophilic interactions in compound 1.
3.2. Structure of [Ag2(2-Hstp)]n(2)
Scheme 1. The coordination modes of ligand in compounds 1 and 2.
adopts a T-shaped geometry completed by three oxygen atoms from three different 2-stp (Ag(1)–O(1) = 2.209(5), Ag(1)– O(7)#1 = 2.297(4), Ag(1)–O(3)#2 = 2.384(4) Å). The maximum angle around Ag1 is 135.70(17). The Ag2 is a four-coordinated distorted tetrahedron geometry completed by four oxygen atoms from four different 2-stp (Ag(2)–O(3)#4 = 2.234(4), Ag(2)–O(4) = 2.356(4), Ag(2)–O(5)#5 = 2.377(4), Ag(2)–O(6)#6 = 2.509(4) Å). The Ag3 is located in a nearly linear two-coordinate geometry with one water molecule and one oxygen atom of 2-stp as donors (Ag(3)–O(2)#3 = 2.193(5), Ag(3)–O(8) = 2.266(5) Å) (Table 2). Complex 1 exhibits an intricate 3-D supramolecular structure, which can be understood in the following manner. First, the carboxyl groups of 2-stp ligands bridges adjacent Ag(I) ions in l3g1:g1:g1 and l2-g1:g1mode to generate a 1-D chain, in which contains two kinds of Ag. . .Ag interactions, one of which is between the symmetric Ag2 ions, being 3.0215(7) Å, and the other of which is between Ag1 and Ag3 ions, being 2.9710(5) Å. Subsequently, the coordinated water molecule form hydrogen bonds (O(8)– H(8B). . .O(4) = 1.980(2) Å) with the coordinated O4 atom of the carboxyl groups and generate a 2-D layers (Fig. 2). Finally, the sulfo groups of 2-stp ligands, adopt the l3-g1:g1:g1mode to bind three
A single-crystal X-ray diffraction analysis for complex 2 reveals that it crystallizes in the P21/c space group with a 3D supramolecular architecture. Each independent asymmetrical unit consists of two Ag(I) ions, one 2-Hstp. As illustrated in Fig. 4, Ag1 shows a rarely distorted trigonal bipyramidal geometry with five-coordination surrounded by five oxygen atoms from three different 2-Hstp (Ag(1)– O(1) = 2.444(2), Ag(1)–O(3) = 2.574(3), Ag(1)–O(7)#1 = 2.343(2), Ag(1)–O(4)#2 = 2.427(3), Ag(1)–O(1)#2 = 2.579(2) Å), while Ag2 is coordinated to four oxygen atoms from four different 2-Hstp (Ag(2)–O(1)#3 = 2.305(2), Ag(2)–O(3) = 2.568(3), Ag(2)–O(2)#2 = 2.232(2), Ag(2)–O(4)#4 = 2.505(2) Å) (Table 3), and it shows a distorted tetrahedron geometry. In complex 2, 2-Hstp ligand shows a complicated coordination mode of l7-g3:g2:g2:g1:g1 (Scheme 1b) in comparison with complex 1 (Scheme 1a). Such complicated coordination modes of the 2-Hstp bridge adjacent Ag(I) ions into the 2D infinite inorganic network substructure as illustrated in Fig. 5, which consists of chains of edge-sharing Ag1 polyhedra and vertex-sharing Ag2 polyhedra interlinked by sharing edges (O1 and O4 from 2-Hstp). The Ag2. . .Ag2 distance of 2.8981(7) Å is significantly shorter than the sum of van der Waals radii of two silver atoms (3.44 Å) [33] indicates the argentophilic interaction. The aromatic rings of 2-Hstp moieties in complex 2 bearing carboxyl groups and sulfo groups from different layers bridge the layers into a pillared framework as shown in Fig. 6, Furthermore, the hydrogen bonds between 2-Hstp ligands (O(6)–H (6). . .O(5)#8 = 1.840(4) Å) and weak p. . .p interactions occur between the adjacent aromatic rings with the
Fig. 5. Polyhedral representation of the Ag–O layer formed by Ag1 dimers (purple polyhedra) and Ag2 dimers (blue polyhedra). (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.)
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Fig. 6. Illustration of the 3D pillared layered structure in compound 2, showing nano-channels.
than that of the free ligand, which eliminate an intra-ligand IL excited for both compounds. The emission of compound 1 can be tentatively assigned to the silver(I) cluster metal-centred (MC) d–s transition, which is consistent with other luminescent polynuclear silver compounds with Ag. . .Ag interactions. The emission of 2 occurs at quite a low energy of 524 nm with large Stokes shift. The low-energy emissions associated with large Stokes shifts have also been observed for other silver(I) complexes, which can be assigned to a ligand-to-metal charge transfer transition (LMCT). As described above, we can conclude that the different emission spectra of 1 and 2 are significantly influenced by their crystal structures. In summary, two silver(I) coordination polymers 2-sulfoisophthalic acid, [Ag3(2-stp)(H2O)]n (1) and [Ag2(2-Hstp)]n (2), have been synthesized, structurally characterized. The photoluminescent properties of the coordination polymers were investigated. The structures of coordination polymers 1 and 2 are twodimensional layer structures consisting of nano-dimensional square grid units. Fig. 7. The solid-state emission photoluminescent spectra of 1 (kex = 383 nm), 2 (kex = 330 nm) and free 2-stp (kex = 321 nm) at room temperature.
centroid-to-centroid distance of 3.5817(6) Å, enhance the stability of the three-dimensional framework.
Acknowledgments This work was supported by the Nation Natural Science Foundation of China (Grant Nos. 21271143 and 21171133), the Opening Foundation of Zhejiang Provincial Top Key Discipline (No. 100061200132) and by Tarbiat Modares university.
3.3. Photoluminescence properties The photoluminescence properties of 1 and 2 as well as free ligand were examined in the solid state at room temperature (Fig. 7). The free 2-stp displays photoluminescent emission at 436 nm under 321 nm radiation. Compound 1 exhibits photoluminescent emission with a maximum at 453 nm upon excitation at 383 nm. In the case of 2, photo-luminescence with a maximum emission at 524 nm upon excitation at 330 nm was observed. The emission energies of 1 and 2 occur at much lower radiation
Appendix A. Supplementary material CCDC-888381 and 888380 contains the supplementary crystallographic data for this paper. These data can be obtained free of charge from The Cambridge Crystallographic Data Centre via www.ccdc.cam.ac.uk/data_request/cif. Supplementary data associated with this article can be found, in the online version, at http://dx.doi.org/10.1016/j.ica.2012.08.029.
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Contents lists available at SciVerse ScienceDirect
Inorganica Chimica Acta journal homepage: www.elsevier.com/locate/ica
Synthesis, crystal structures and photoluminescence properties of two silver(I) coordination polymers with nano size channels based on 2-sulfoterephthalic acid ligand Jie Wang a, Jin-Min Cai a, Ai-Yin Wang a,⇑, Bi-Feng Huang a, Hong-Ping Xiao a, Xin-Hua Li a, Ali Morsali b,⇑ a b
College of Chemistry and Materials Engineering, Wenzhou University, Wenzhou 325035, PR China Department of Chemistry, Faculty of Sciences, Tarbiat Modares University, P.O. Box 14155-4838, Tehran, Iran
a r t i c l e
i n f o
Article history: Received 27 June 2012 Received in revised form 21 August 2012 Accepted 29 August 2012 Available online 14 September 2012 Keywords: Crystal structure Ag(I) Coordination polymer, 2-sulfoterephthalic acid Photoluminescence Nano-channels
a b s t r a c t Self-assembly of silver nitrate with 2-sulfoisophthalic acid monosodium salt (NaH2stp) produced two novel Ag(I) coordination polymers, [Ag3(2-stp)(H2O)]n (1) and [Ag2(2-Hstp)]n (2), respectively. Singlecrystal X-ray diffraction reveals that compound 1 has a 3D supramolecular structure containing Ag. . .Ag and Ag. . .O weak interactions. Compound 2 also features a 3D supramolecular network formed by Hstp2 ligands and p. . .p stacking interactions. In the solid state and at room temperature, compound 1 exhibits blue photoluminescence with a maximum at 453 nm upon excitation at 383 nm. Compound 2 shows green photoluminescence with a maximum at 524 nm upon excitation at 330 nm. Ó 2012 Elsevier B.V. All rights reserved.
1. Introduction
2. Experimental
The logical design and controlled synthesis of metal–organic polymers is throughout of great interest in the field of crystal engineering and supramolecular chemistry because of not only their fascinating structural diversities [1–7] but also their potential uses as functional materials [8–13] in various fields. So far, metal carboxylate frameworks have afforded the most diversity in this area because of their chemical stability and appropriate connectivity [4,5,14,15]. The sulfonate group, which is generally regarded as weakly ligating, can make its coordination mode more flexible and sensitive to the chemical environment, which is a source of greater coordination versatility and ultimately of structural diversity. Herein, 2-sulfoisophthalic acid (H3stp) ligand attracted our attention not only because the bifunctional sulfonate-carboxylate ligands which can exhibit discriminative coordination abilities, but also the coordination of the metal with H2-stp ligands has been less investigated [6,16–26]. In this paper we report two new Ag(I) coordination polymers with 2-sulfoisophthalic acid (H3stp), [Ag3(2-stp)(H2O)]n (1) and [Ag2(2-Hstp)]n (2).
2.1. Materials and measurements
⇑ Corresponding authors. E-mail addresses: [email protected] (A.-Y. Wang), morsali_a@ modares.ac.ir (A. Morsali). 0020-1693/$ - see front matter Ó 2012 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.ica.2012.08.029
All chemicals and solvents were obtained from commercial sources with reagent grade and used without further purification in the syntheses. Elemental analyses for C, H, and N were carried out on a CHN–O-Rapid Analyzer and an Elemental Vario Microanalyzer. The infrared spectra were taken on a Bruker Equinox 55 FTIR spectrometer as KBr pellets in the 400–4000 cm 1 region. The fluorescence spectra were measured using SHIMADZU RF-7000 spectrometer on powdered sample in the solid state at room temperature. The measurements for electric conductivity were made by Crystallographic measurements at 298(2) K using a Bruker Smart Apex II CCD area detector diffractometer. The intensity data were collected using graphite monochromated Mo Ka radiation (k = 0.71073 Å). Accurate unit cell parameters and orientation matrix for data collection were obtained from least-squares refinement. The structures have been solved by direct methods and refined by full-matrix least-squares techniques on F2. Details of crystal data, data collection, structure solution and refinement are given in Table 1. 2.1.1. Synthesis of [Ag3(2-stp)(H2O)]n (1) A mixture of AgNO3 (0.0169 g, 0.10 mmol), 2-sulfoterephthalic acid monosodium salt (0.0268 g, 0.10 mmol), NaOH (0.008 g,
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J. Wang et al. / Inorganica Chimica Acta 394 (2013) 466–471 Table 1 Crystal data and structure refinement for compounds 1 and 2.
Table 2 Selected bond lengths (Å) and angles (°) for 1.
Complex
1
2
Empirical formula Mr Crystal system Space group Unit cell dimensions a (Å) b (Å) c (Å) a (°) b (°) c (°) V (Å3) Z Dc (mg m 3) l (mm 1) h range Reflections collected Unique reflections No. of parameter F(0 0 0) R1a [I > 2ó], wR2b (all data) Goodness-of-fit (GOF) on F2 Largest and hole (e A 3)
C8H5Ag3O8S 584.79 Monoclinic P21/c
C8H4Ag2O7S 459.91 Monoclinic P21/c
13.5508(10) 7.0200(5) 12.2693(9) 90 108.574(2 90 1106.34(14) 4 3.511 5.484 1.59–25.20 11292 1973 181 1096 0.0394, 0.1088 1.072 1.840, 1.819
11.186(2) 7.8121(14) 12.710(2) 90 117.012(14) 90 989.5(3) 4 3.087 4.194 2.04–25.69 7126 1862 163 872 0.0197, 0.0661 1.046 0.504, 0.731
P P R1a = ||Fo| |Fc||/ Fo|. P P wR2b = [ w(Fo2 Fc2)2/ w(Fo2)]1/2.
Lengths (Å) Ag(1)–O(1) Ag(1)–O(7)#1 Ag(1)–O(3)#2 Ag(2)–O(3)#4 Ag(2)–O(4) Angles (°) O(1)–Ag(1)–O(7)#1 O(1)–Ag(1)–O(3)#2 O(7)#1–Ag(1)– O(3)#2 O(3)#4–Ag(2)–O(4) O(3)#4–Ag(2)– O(5)#5
2.209(5) 2.297(4) 2.384(4) 2.234(4) 2.356(4) 135.70(17) 127.97(16) 96.07(15) 143.48(16) 115.45(16)
Symmetry codes: #1( x, y 1/2, #4( x + 1, y + 2, z + 1); #5(x, #7( x + 1, y + 1/2, z + 1/2).
Ag(2)–O(6)#6 Ag(3)–O(2)#3 Ag(3)–O(8) Ag(1). . .Ag(3)#3 Ag(2). . .Ag(2)#4
2.509(4) 2.193(5) 2.266(5) 3.0215(9) 2.9710(14)
O(4)–Ag(2)–O(5)#5 O(3)#4–Ag(2)– O(6)#6 O(4)–Ag(2)–O(6)#6
87.64(16) 93.13(16)
O(5)#5–Ag(2)– O(6)#6 O(2)#3–Ag(3)–O(8)
135.68(15)
87.76(14)
155.16(17)
z 1/2); #2 ( x, y + 2, z); #3 ( x, y + 1, z); y + 3/2, z + 1/2); #6 ( x + 1, y 1/2, z + 1/2);
0.20 mmol) was dissolved in distilled water (10 mL) and ethylalcohol (5 mL) and allowed to evaporate in the dark. After 3 days, colorless block-shaped crystals were obtained. Anal. Calc. for C8H5Ag3O8S (%): C, 16.43; H, 0.86; Found: C, 16.29; H, 0.78. FT-IR (KBr pellet, cm 1) selected bands: m = 3388 m, 1587s, 1368s, 1200s, 1072w, 1021w, 817w, 678w, 622s, 570w, 501w.
Fig. 1. Perspective view of the coordination environment of the Ag(I) ion in compound 1. Hydrogen atoms were removed for clarity. Symmetry codes: #1( x, y 2); #2( x, y + 2, z); #3( x, y + 1, z); #4( x + 1, y + 2, z + 1); #5(x, y + 3/2, z + 1/2); #6( x + 1, y 1/2, z + 1/2).
Fig. 2. Perspective views of the 2-D layer through hydrogen bonds interactions.
1/2,
z
1/
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Fig. 3. Perspective views of the 3-D framework through polyhedral representation (Ag1: red, Ag2: blue, and Ag3: green). (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.)
Table 3 Selected bond lengths (Å) and angles (°) for 2. Lengths (Å) Ag(1)–O(1) Ag(1)–O(3) Ag(1)–O(7)#1 Ag(1)–O(1)#2 Ag(1)–O(4)#2 Angles (°) O(7)#1–Ag(1)–O(4)#2 O(7)#1–Ag(1)–O(1) O(4)#2–Ag(1)–O(1) O(7)#1–Ag(1)–O(3) O(4)#2–Ag(1)–O(3) O(1)–Ag(1)–O(3) O(7)#1–Ag(1)–O(1)#2 O(4)#2–Ag(1)–O(1)#2
2.444(2) 2.574(3) 2.343(2) 2.579(2) 2.427(3) 138.76(9) 128.76(9) 82.72(8) 101.69(9) 114.17(9) 73.01(8) 88.95(8) 75.81(7)
Ag(2)–O(3) Ag(2)–O(2)#2 Ag(2)–O(1)#3 Ag(2)–O(4)#4 Ag(2). . .Ag(2)#5
2.568(3) 2.232(2) 2.305(2) 2.505(2) 2.8981(7)
O(1)–Ag(1)–O(1)#2 O(3)–Ag(1)–O(1)#2 O(2)#2–Ag(2)–O(1)#3 O(2)#2–Ag(2)–O(4)#4 O(1)#3–Ag(2)–O(4)#4 O(2)#2–Ag(2)–O(3) O(1)#3–Ag(2)–O(3) O(4)#4–Ag(2)–O(3)
138.51(5) 83.97(8) 157.54(9) 116.93(9) 83.88(8) 88.74(9) 99.68(8) 91.39(8)
Symmetry transformations used to generate equivalent #1( x + 1, y + 1, z + 1); #2( x + 2, y 1/2, z + 3/2); #3(x, y + 3/2, z ( x + 2, y + 2, z + 1); #5( x + 2, y + 1, z + 1).
Found: C, 20.71; H, 0.79. FT-IR (KBr pellet, cm Fig. 4. Perspective view of the coordination environment of the Ag(I) ion in compound 2. Hydrogen atoms were removed for clarity. Symmetry codes: #1 ( x + 1, y + 1, z + 1); #2( x + 2, y 1/2, z + 3/2); #3(x, y + 3/2, z 1/2); #4( x + 2, y + 2, z + 1).
atoms: 1/2); #4
1
) selected bands:
m = 3424 m, 2926w, 1674 m, 1578s, 1359s, 1176s, 1068w, 1013w, 870w, 798w, 721s, 615w, 521w.
3. Results and discussion 2.1.2. Synthesis of [Ag2(2-Hstp)]n (2) A mixture of AgNO3 (0.0169 g, 0.10 mmol) and 2-sulfoterephthalic acid monosodium salt (0.0268 g, 0.10 mmol) was dissolved in distilled water (10 mL) and ethylalcohol (5 mL) and allowed to evaporate in the dark. After 1 month, light yellow slice crystals were obtained. Anal. Calc. for C8H4Ag2O7S (%): C, 20.89; H, 0.88;
3.1. Structure of [Ag3(2-stp)H2O]n (1) X-ray analysis reveals that complex 1 crystallizes in a monoclinic system with space group P21/c. The asymmetric unit consists of three crystallographically independent Ag(I) ions, one 2-stp and one coordinated water molecule. As illustrated in Fig. 1, The Ag1
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Ag(I) ions, extend 2D layers into 3D framework (Fig. 3). Additionally, weak Ag2. . .Ag3 and Ag3. . .O (Ag2. . .Ag3 = 3.1932(8), Ag3. . .O5#3 = 2.641(3), Ag3. . .O6#2 = 2.650(2) Å) interactions occur between the adjacent 2D layers, which further enhances the stability of the 3D framework. The closest Ag–Ag interaction in compound 1 is same with similar complexes [27–32], indicating that there are argentophilic interactions in compound 1.
3.2. Structure of [Ag2(2-Hstp)]n(2)
Scheme 1. The coordination modes of ligand in compounds 1 and 2.
adopts a T-shaped geometry completed by three oxygen atoms from three different 2-stp (Ag(1)–O(1) = 2.209(5), Ag(1)– O(7)#1 = 2.297(4), Ag(1)–O(3)#2 = 2.384(4) Å). The maximum angle around Ag1 is 135.70(17). The Ag2 is a four-coordinated distorted tetrahedron geometry completed by four oxygen atoms from four different 2-stp (Ag(2)–O(3)#4 = 2.234(4), Ag(2)–O(4) = 2.356(4), Ag(2)–O(5)#5 = 2.377(4), Ag(2)–O(6)#6 = 2.509(4) Å). The Ag3 is located in a nearly linear two-coordinate geometry with one water molecule and one oxygen atom of 2-stp as donors (Ag(3)–O(2)#3 = 2.193(5), Ag(3)–O(8) = 2.266(5) Å) (Table 2). Complex 1 exhibits an intricate 3-D supramolecular structure, which can be understood in the following manner. First, the carboxyl groups of 2-stp ligands bridges adjacent Ag(I) ions in l3g1:g1:g1 and l2-g1:g1mode to generate a 1-D chain, in which contains two kinds of Ag. . .Ag interactions, one of which is between the symmetric Ag2 ions, being 3.0215(7) Å, and the other of which is between Ag1 and Ag3 ions, being 2.9710(5) Å. Subsequently, the coordinated water molecule form hydrogen bonds (O(8)– H(8B). . .O(4) = 1.980(2) Å) with the coordinated O4 atom of the carboxyl groups and generate a 2-D layers (Fig. 2). Finally, the sulfo groups of 2-stp ligands, adopt the l3-g1:g1:g1mode to bind three
A single-crystal X-ray diffraction analysis for complex 2 reveals that it crystallizes in the P21/c space group with a 3D supramolecular architecture. Each independent asymmetrical unit consists of two Ag(I) ions, one 2-Hstp. As illustrated in Fig. 4, Ag1 shows a rarely distorted trigonal bipyramidal geometry with five-coordination surrounded by five oxygen atoms from three different 2-Hstp (Ag(1)– O(1) = 2.444(2), Ag(1)–O(3) = 2.574(3), Ag(1)–O(7)#1 = 2.343(2), Ag(1)–O(4)#2 = 2.427(3), Ag(1)–O(1)#2 = 2.579(2) Å), while Ag2 is coordinated to four oxygen atoms from four different 2-Hstp (Ag(2)–O(1)#3 = 2.305(2), Ag(2)–O(3) = 2.568(3), Ag(2)–O(2)#2 = 2.232(2), Ag(2)–O(4)#4 = 2.505(2) Å) (Table 3), and it shows a distorted tetrahedron geometry. In complex 2, 2-Hstp ligand shows a complicated coordination mode of l7-g3:g2:g2:g1:g1 (Scheme 1b) in comparison with complex 1 (Scheme 1a). Such complicated coordination modes of the 2-Hstp bridge adjacent Ag(I) ions into the 2D infinite inorganic network substructure as illustrated in Fig. 5, which consists of chains of edge-sharing Ag1 polyhedra and vertex-sharing Ag2 polyhedra interlinked by sharing edges (O1 and O4 from 2-Hstp). The Ag2. . .Ag2 distance of 2.8981(7) Å is significantly shorter than the sum of van der Waals radii of two silver atoms (3.44 Å) [33] indicates the argentophilic interaction. The aromatic rings of 2-Hstp moieties in complex 2 bearing carboxyl groups and sulfo groups from different layers bridge the layers into a pillared framework as shown in Fig. 6, Furthermore, the hydrogen bonds between 2-Hstp ligands (O(6)–H (6). . .O(5)#8 = 1.840(4) Å) and weak p. . .p interactions occur between the adjacent aromatic rings with the
Fig. 5. Polyhedral representation of the Ag–O layer formed by Ag1 dimers (purple polyhedra) and Ag2 dimers (blue polyhedra). (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.)
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Fig. 6. Illustration of the 3D pillared layered structure in compound 2, showing nano-channels.
than that of the free ligand, which eliminate an intra-ligand IL excited for both compounds. The emission of compound 1 can be tentatively assigned to the silver(I) cluster metal-centred (MC) d–s transition, which is consistent with other luminescent polynuclear silver compounds with Ag. . .Ag interactions. The emission of 2 occurs at quite a low energy of 524 nm with large Stokes shift. The low-energy emissions associated with large Stokes shifts have also been observed for other silver(I) complexes, which can be assigned to a ligand-to-metal charge transfer transition (LMCT). As described above, we can conclude that the different emission spectra of 1 and 2 are significantly influenced by their crystal structures. In summary, two silver(I) coordination polymers 2-sulfoisophthalic acid, [Ag3(2-stp)(H2O)]n (1) and [Ag2(2-Hstp)]n (2), have been synthesized, structurally characterized. The photoluminescent properties of the coordination polymers were investigated. The structures of coordination polymers 1 and 2 are twodimensional layer structures consisting of nano-dimensional square grid units. Fig. 7. The solid-state emission photoluminescent spectra of 1 (kex = 383 nm), 2 (kex = 330 nm) and free 2-stp (kex = 321 nm) at room temperature.
centroid-to-centroid distance of 3.5817(6) Å, enhance the stability of the three-dimensional framework.
Acknowledgments This work was supported by the Nation Natural Science Foundation of China (Grant Nos. 21271143 and 21171133), the Opening Foundation of Zhejiang Provincial Top Key Discipline (No. 100061200132) and by Tarbiat Modares university.
3.3. Photoluminescence properties The photoluminescence properties of 1 and 2 as well as free ligand were examined in the solid state at room temperature (Fig. 7). The free 2-stp displays photoluminescent emission at 436 nm under 321 nm radiation. Compound 1 exhibits photoluminescent emission with a maximum at 453 nm upon excitation at 383 nm. In the case of 2, photo-luminescence with a maximum emission at 524 nm upon excitation at 330 nm was observed. The emission energies of 1 and 2 occur at much lower radiation
Appendix A. Supplementary material CCDC-888381 and 888380 contains the supplementary crystallographic data for this paper. These data can be obtained free of charge from The Cambridge Crystallographic Data Centre via www.ccdc.cam.ac.uk/data_request/cif. Supplementary data associated with this article can be found, in the online version, at http://dx.doi.org/10.1016/j.ica.2012.08.029.
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