- Email: [email protected]
Two novel linear arrangement d10 hexamers with isonicotinic acid: Structures, blue luminescent and semiconducting properties
Inorganic Chemistry Communications 8 (2005) 1022–1024 www.elsevier.com/locate/inoche
Two novel linear arrangement d10 hexamers with isonicotinic acid: Structures, blue luminescent and semiconducting properties Bing Liu a
a,*
, Qi Yuan
b
State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, 155 Yangqiao West Road, Fuzhou, Fujian 350002, PR China b The Pharmacy College of Henan University, Kaifeng, Henan 475001, PR China Received 25 March 2005; accepted 29 July 2005 Available online 5 October 2005
Abstract The reactions of isonicotinic acid (HIso) with metal salts of Ag(I) or Cu(I) yielded two hexamers [Ag6(Iso)6(H2O)2] Æ H2O (1), [Cu6(Iso)6] Æ 2H2O (2). 1 and 2 are rare hexanuclear linear arrangement coordination complexes containing HIso. Solid state emission spectra of 1 and 2 show interesting pale blue luminescence with emission peaks in the range of 408 and 438 nm, which are assigned to LMCT. The energy gaps from the absorption spectra are 2.37 eV for 1 and 2.88 eV for 2, showing the present compounds behave as semiconductors. Ó 2005 Elsevier B.V. All rights reserved. Keywords: Isonicotinic acid; Hexanuclear linear arrangement; Solid-state emission spectra; Diffuse reflectance UV–Vis spectra
Isonicotinic acid (HIso), namely 4-pyridinecarboxylate, a multi-functional chelating and/or bridging anionic ligand, has proved to be very powerful for the construction of multi-dimensional metal–organic coordination networks [1]. Furthermore, the isonicotinic acid complexes has raised much interest in fluorescence probing with numerous potential applications for studies of microsecond diffusion and dynamics of membranes [2]. Metal centers are potential carriers of electrochemical, magnetic, catalytic, or optical properties that may be introduced into the inorganic–organic hybrid materials [3]. d10 metal with rich photophysical and photochemical character raised much interest to synthesize inorganic–organic hybrid polynuclear complexes [4]. Considering the versatile coordination abilities of HIso, we employ the ligand to coordinate with d10 transitional metals to fabricate coordination complexes with excel*
Corresponding author. Tel.: +865 918 379 2840; fax: +865 918 371 4946. E-mail address: [email protected] (B. Liu). 1387-7003/$ - see front matter Ó 2005 Elsevier B.V. All rights reserved. doi:10.1016/j.inoche.2005.07.019
lent fluorescence properties. Herein we report the syntheses, crystal structures and properties of fluorescence and absorption spectra of two new d10 coordination complexes [Ag6(Iso)6(H2O)2] Æ H2O (1), [Cu6(Iso)6] Æ 2H2O (2). The reactions of isonicotinic acid (HIso) with metal salts of Ag(I) and Cu(I) yielded two hexamers [Ag6 (Iso)6(H2O)2] Æ H2O (1), [Cu6(Iso)6] Æ 2H2O (2) [5]. The crystal structures of 1 and 2 were determined from single crystal X-ray diffraction data [6]. It is noteworthy that transition metal coordination complexes with HIso of linear arrangement as 1 and 2 are very rare. The crystallographic asymmetric unit in 1 comprises three silver(I) atoms and three isonicotinic moieties. As shown in Fig. 1(a), the complex is best described as two [Ag3(Iso)3] subunits to form a molecule with a crystallographic inversion center with the Ag2 Ag2A (Symmetry code A: 1 x, 1 y, z) dis˚ . Ag3 is coordinated to two isonitance of 2.8808(8) A cotinic moieties through the nitrogen atoms [Ag3– ˚ , Ag3–N21 = 2.1306(17) A ˚ ]. The N11 = 2.1302(18) A
B. Liu, Q. Yuan / Inorganic Chemistry Communications 8 (2005) 1022–1024
1023
˚ ) and bond angles Fig. 1. Molecular structures of 1 (a) and 2 (b). For clarity, the hydrogen atoms are omitted for clarity. Selected bond distances (A (°): [Ag6(Iso)6(H2O)2] Æ H2O (1). Ag1–O2, 2.1351(15); Ag1–N31, 2.1478(17); Ag1–Ag2A, 3.3783(10); Ag2–O6B, 2.1853(15); Ag2–O5, 2.2002(15); Ag2–O2W, 2.4696(17); Ag2–Ag2B, 2.8808(8); Ag2–Ag1C, 3.3783(10); Ag3–N11, 2.1302(18); Ag3–N21, 2.1306(17) and; O2–Ag1–N31, 176.62(6); O2–Ag1–Ag2A, 110.90(4); N31–Ag1–Ag2A, 72.37(5); O6B–Ag2–O5, 163.14(6); O6B–Ag2–O2W, 105.36(5); O5–Ag2–O2W, 90.73(5); O6B–Ag2– Ag2B, 80.10(4); O5–Ag2–Ag2B, 83.34(4); O2W–Ag2–Ag2B, 151.41(4); O6B–Ag2–Ag1C, 108.64(4); O5–Ag2–Ag1C, 69.48(4); O2W–Ag2–Ag1C, 77.25(4); Ag2B–Ag2–Ag1C, 74.47(2); N11–Ag3–N21, 177.62(7). Symmetry code A: x 1, y, z; B: x + 1, y + 1, z; C: x + 1, y, z. [Cu6(Iso)6] Æ 2H2O (2). Cu1–O4A, 2.1869(14); Cu1–O3, 2.1919(14); Cu1–Cu1A, 2.8956(7); Cu2–N31, 2.1389(15); Cu2–N21, 2.1410(16); Cu3–O1, 2.1367(14); Cu3–N11, 2.1538(15) and O4A–Cu1–O3, 162.56(5); O4A–Cu1–Cu1A, 79.66(4); O3–Cu1–Cu1A, 83.23(4); N31–Cu2–N21, 176.62(6); O1– Cu3–N11, 177.03(5). Symmetry code A: x, y + 1, z.
coordination environment of Ag1 is similar to Ag3, which is in a linear geometry consisting of one oxygen atom from carboxylate groups of the isonicotinic moiety and one nitrogen atom from a pyridine ring [Ag1– ˚ ]. Atom Ag2 O2 = 2.1351(15), Ag1–N31 = 2.1478(17) A lies in a distorted triangular geometry with the mean ˚ , consisting of two oxygen atoms deviation of 0.0360 A from carboxylate groups of two different isonicotinic moieties and one water molecule. The bond distances and angles of Ag–O and Ag–N in 1 are comparable with those found in {[Ag(Iso)(HIso)]1/2 Æ [Ag(Iso)]}, but Ag Ag interactions are much shorter than that of ˚ [4]. 3.804 A In the crystal structure of 1, it is possible to observe many types of hydrogen bonds and Ag Ag interactions. Besides Ag2 Ag2A interaction, there is still another ˚ (Symmetype of Ag1 Ag2B interaction of 3.3783(10) A try code B: x 1, y, z). The hydrogen bonds, ˚ , O1W O1C = 2.877(2) A ˚ O1W O6A = 3.111(2) A ˚ (C: x, 1 y, z), O1W O1D = 2.813(2) A (D: ˚ (E: 3 + x, 1 + x, 1 + y, z), O2W O3E = 2.793(2) A ˚ 1 + y, z), O2W O4F = 2.798(2) A (F: 1.5 x, 0.5 + y, 0.5 z), are formed between water molecules and the oxygen atom of the carboxylate groups as shown in Fig. 2(a). The shortest centroid-to-centroid distance be˚ , indicating there are tween two pyridine rings is 3.516 A p–p stacking interactions in 1. As shown in Fig. 1(b), the structure of 2 is very similar to that of 1, in which all copper(I) atoms are two coordinated. The coordination environments of Atoms Cu2, Cu3 in 2 are corresponding to that of Ag(3) and Ag(1) in 1. Atom Cu1 in 2 is also similar to that of Ag2 in 1, except that no water molecule is coordinated
Fig. 2. 5 Packing drawings of 1 and 2 with hydrogen bondings.
to Cu1 center. There exists Cu1 Cu1A interactions ˚ . In the structure of (A: x, 1 y, z) of 2.8956(7) A ˚ (B: 2, the hydrogen bonds, O2W O4B = 3.125(2) A ˚ 1 + x, y, z), O2W O2C = 2.844(2) A (C: 2 x, ˚ (D: 2.5 x, 2 y, z), O1W O5D = 2.796(2) A ˚ (E: 3 + x, 0.5 + y, 0.5 + z), O1W O6E = 2.840(2) A 1 + y, z), linked the isolated molecules into 3-D structure. Significant absorption bands in the IR of free ligand HIso are observed at 3550(m), 1656(m) cm1 assigned
1024
B. Liu, Q. Yuan / Inorganic Chemistry Communications 8 (2005) 1022–1024
to m(OH) and m(CO). The absorption bands in the infrared spectrum of 1 and 2 are observed at 1609 and 1639 cm1, respectively, due to the carboxyl group (m(CO)). The significant blue shifts of the carboxyl group take place because of the coordination through the carboxyl oxygen. This situation indicates that coordination of Iso take place via the carboxyl oxygen to the metal ions [7]. In contrast to the rich structural chemistry of isonicotinic acid coordination complexes, to our knowledge, the luminescence data were quite limited, but there are the related rare earth complexes with nicotinic and isonicotinic acid N-oxides that included data for erbium and europium site distortions from the changes of the photoluminescence and absorption of the rare earth line spectra [8]. Herein, solid state emission spectra of the two d10 complexes of 1, 2 and HIso show interesting luminescence features at room temperature as given in Fig. S1. Excitation of the solid sample of 1 at kex = 348 nm produces an intensive dual luminescence: a high-energy band at approximately 420 nm and a lower energy emission at about 438 nm. 2 with kex = 362 nm produced a cuspidal emission at 408 nm. A significant blue shift can be found in all emission wavelengths of 1 and 2 when compared with that of free ligand HIso (broad peak at about 460 nm, kex = 362 nm). The emissions of 1 and 2 are assigned to ligand-to-metal transfer (LMCT) (Iso ! M, M = Ag, Cu). Though the structures of 1 and 2 are very similar, but the emissions of 1 and 2 indicate a significant and interesting difference, in which water molecule in 1 may play an important role in splitting the energy level of silver(I). The absorption spectrum was calculated from reflection spectrum by the Kubelka–Munk function [9] as shown in Fig. S2. The energy gaps of the present compounds determined by extrapolation from the linear portion of the absorption edge in a (a/S) versus energy plot are 2.37 for 1 and 2.88 eV for 2, which suggests that the title compounds are semiconductors and consistent with the yellow color of the crystals. The observation suggests that the optical absorption of is likely originated from the charge transfer from Iso groups valence band to CuI or AgI conduction band.
Acknowledgments We gratefully acknowledge the financial support of the National Natural Science Foundation of China (20001007, 20131020) and Natural Sciences Foundation of Fujian Province (2003I031).
Appendix A. Supplementary data Supplementary data associated with this article can be found, in the online version, at doi:10.1016/ j.inoche.2005.07.019. References [1] (a) L.R. MacGillivray, R.H. Groeneman, J.L. Atwood, J. Am. Chem. Soc. 120 (1998) 2676; (b) O.R. Evans, R.-G. Xiong, Z. Wang, G.K. Wong, W. Lin, Angew. Chem. Int. Ed. 38 (1999) 536. [2] L. Li, F.N. Castellano, I. Gryczynski, J.R. Lakowicz, Chem. Phys. Lipids 99 (1999) 1. [3] D. Braga, F. Grepioni, Coord. Chem. Rev. 183 (1999) 19. [4] B. Cova, A. Bricen˜o, R. Atencio, New J. Chem. 25 (2001) 1516. [5] [Ag6(Iso)6(H2O)2] Æ H2O (1): the synthesis of (2) is similar to (1), except that CH3COOAg (0.033 g, 0.2 mmol) dissolved in hot water in 70 °C for (2). Pale yellow platelet single crystals suitable for Xray diffraction could be obtained. Yield: 21%. Anal. Calc. for C18H16Ag3N3O8 (%): C, 29.78; H, 2.22; N, 5.79. Found: C, 29.88; H, 2.32; N, 5.63. IR (KBr, cm1): 3435 (vs), 2977 (w), 2919 (w), 1609 (m), 1548 (m), 1452 (m), 1384 (m), 1211 (w), 1048 (w), 838 (w), 880 (w), 766 (w), 688 (w). 1 can also be obtained from the hydrothermal reaction by using Ag2CO3. [Cu6(Iso)6] Æ 2H2O (2): a solution of Iso (0.025 g, 0.2 mmol) in ethanol (20 cm3) was added dropwise to 5 cm3 stirred aqueous solution of [Cu(CH3CN)4]ClO4 (0.065 g, 0.2 mmol) under nitrogen atmosphere. After the resulting pale yellow suspension stirred for about 6 h, the mixture was cooled and filtered. Pale yellow prism crystals were obtained by layering diethyl ether into the filtrate that was carefully placed in refrigerator. Yield: 18%. Anal. Calc. for C18H16Cu3N3O8 (%): C, 36.46; H, 2.72; N, 7.09. Found: C, 36.52; H, 2.83; N, 6.99. IR (KBr, cm1): 3410 (vs), 2975 (s), 2901 (m), 1639 (m), 1549 (w), 1452 (m), 1406 (m), 1383 (m), 1271 (w), 1084 (s), 1050 (s), 880 (m), 621 (w). [6] Intensity data collections were collected with a Rigaku Mercury CCD ˚) using graphite monochromatized Mo Ka radiation (k = 0.71073 A at 293(2) K. The crystal date reduction and cell refinement were applied with CrystalClear program. The structures were solved by direct methods and refined by the full-matrix least-squares method on F2 using Siemens SHELXTL-93 PC package. Crystal data for [Ag6(Iso)6(H2O)2] Æ H2O (1): C18H16Ag3N3O8, Mr = 725.95, mono˚ , b = 10.302(3) A ˚, clinic, space group P21/n (No. 14), a = 8.769(3) A ˚ , b = 96.590(2)°, V = 1959.3(11) A ˚ 3, Z = 4, c = 21.832(7) A Dc = 2.461 g cm3, l = 3.025 cm1, F(000) = 1400. Data collection (3.06 < h < 25.03°) gave the final R1 = 0.0224 and wR2 = 0.0578 for 3283 observed reflections with I > 2(I) out of 3449 unique reflections (Rint = 0.0232). Crystal data for [Cu6(Iso)6] Æ 2H2O (2): C18H16Cu3N3O8, Mr = 592.96, monoclinic, space group P21/n (No. ˚, ˚, ˚, 14), a = 8.743(3) A b = 10.3918(3) A c = 22.029(7) A 3 3 ˚ b = 96.4190(10)°, V = 1988.9(9) A , Z = 4, Dc = 1.980 g cm , l = 3.233 cm1, F(000) = 1184. Data collection (3.06 < h < 25.03°) gave the final R1 = 0.0465 and wR2 = 0.1436 for 3188 observed reflections with I > 2(I) out of 3407 unique reflections (Rint = 0.0235). Deposition CCDC reference numbers: 267190 for 1 and 267191 for 2. [7] R. Sekiya, S.-I. Nishikiori, Chem. Eur. J. 8 (2002) 4803. [8] J.-G. Mao, H.-J. Zhang, J.-Z. Ni, S.-B. Wang, T.C.W. Mak, Polyhedron 17 (1998) 3999. [9] (a) W.W. Wendlandt, H.G. Hecht, Reflectance Spectroscopy, Interscience Publishers, New York, 1966; (b) G. Kotuem, Reflectance Spectroscopy, Springer-Verlag, New York, 1969.
Two novel linear arrangement d10 hexamers with isonicotinic acid: Structures, blue luminescent and semiconducting properties Bing Liu a
a,*
, Qi Yuan
b
State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, 155 Yangqiao West Road, Fuzhou, Fujian 350002, PR China b The Pharmacy College of Henan University, Kaifeng, Henan 475001, PR China Received 25 March 2005; accepted 29 July 2005 Available online 5 October 2005
Abstract The reactions of isonicotinic acid (HIso) with metal salts of Ag(I) or Cu(I) yielded two hexamers [Ag6(Iso)6(H2O)2] Æ H2O (1), [Cu6(Iso)6] Æ 2H2O (2). 1 and 2 are rare hexanuclear linear arrangement coordination complexes containing HIso. Solid state emission spectra of 1 and 2 show interesting pale blue luminescence with emission peaks in the range of 408 and 438 nm, which are assigned to LMCT. The energy gaps from the absorption spectra are 2.37 eV for 1 and 2.88 eV for 2, showing the present compounds behave as semiconductors. Ó 2005 Elsevier B.V. All rights reserved. Keywords: Isonicotinic acid; Hexanuclear linear arrangement; Solid-state emission spectra; Diffuse reflectance UV–Vis spectra
Isonicotinic acid (HIso), namely 4-pyridinecarboxylate, a multi-functional chelating and/or bridging anionic ligand, has proved to be very powerful for the construction of multi-dimensional metal–organic coordination networks [1]. Furthermore, the isonicotinic acid complexes has raised much interest in fluorescence probing with numerous potential applications for studies of microsecond diffusion and dynamics of membranes [2]. Metal centers are potential carriers of electrochemical, magnetic, catalytic, or optical properties that may be introduced into the inorganic–organic hybrid materials [3]. d10 metal with rich photophysical and photochemical character raised much interest to synthesize inorganic–organic hybrid polynuclear complexes [4]. Considering the versatile coordination abilities of HIso, we employ the ligand to coordinate with d10 transitional metals to fabricate coordination complexes with excel*
Corresponding author. Tel.: +865 918 379 2840; fax: +865 918 371 4946. E-mail address: [email protected] (B. Liu). 1387-7003/$ - see front matter Ó 2005 Elsevier B.V. All rights reserved. doi:10.1016/j.inoche.2005.07.019
lent fluorescence properties. Herein we report the syntheses, crystal structures and properties of fluorescence and absorption spectra of two new d10 coordination complexes [Ag6(Iso)6(H2O)2] Æ H2O (1), [Cu6(Iso)6] Æ 2H2O (2). The reactions of isonicotinic acid (HIso) with metal salts of Ag(I) and Cu(I) yielded two hexamers [Ag6 (Iso)6(H2O)2] Æ H2O (1), [Cu6(Iso)6] Æ 2H2O (2) [5]. The crystal structures of 1 and 2 were determined from single crystal X-ray diffraction data [6]. It is noteworthy that transition metal coordination complexes with HIso of linear arrangement as 1 and 2 are very rare. The crystallographic asymmetric unit in 1 comprises three silver(I) atoms and three isonicotinic moieties. As shown in Fig. 1(a), the complex is best described as two [Ag3(Iso)3] subunits to form a molecule with a crystallographic inversion center with the Ag2 Ag2A (Symmetry code A: 1 x, 1 y, z) dis˚ . Ag3 is coordinated to two isonitance of 2.8808(8) A cotinic moieties through the nitrogen atoms [Ag3– ˚ , Ag3–N21 = 2.1306(17) A ˚ ]. The N11 = 2.1302(18) A
B. Liu, Q. Yuan / Inorganic Chemistry Communications 8 (2005) 1022–1024
1023
˚ ) and bond angles Fig. 1. Molecular structures of 1 (a) and 2 (b). For clarity, the hydrogen atoms are omitted for clarity. Selected bond distances (A (°): [Ag6(Iso)6(H2O)2] Æ H2O (1). Ag1–O2, 2.1351(15); Ag1–N31, 2.1478(17); Ag1–Ag2A, 3.3783(10); Ag2–O6B, 2.1853(15); Ag2–O5, 2.2002(15); Ag2–O2W, 2.4696(17); Ag2–Ag2B, 2.8808(8); Ag2–Ag1C, 3.3783(10); Ag3–N11, 2.1302(18); Ag3–N21, 2.1306(17) and; O2–Ag1–N31, 176.62(6); O2–Ag1–Ag2A, 110.90(4); N31–Ag1–Ag2A, 72.37(5); O6B–Ag2–O5, 163.14(6); O6B–Ag2–O2W, 105.36(5); O5–Ag2–O2W, 90.73(5); O6B–Ag2– Ag2B, 80.10(4); O5–Ag2–Ag2B, 83.34(4); O2W–Ag2–Ag2B, 151.41(4); O6B–Ag2–Ag1C, 108.64(4); O5–Ag2–Ag1C, 69.48(4); O2W–Ag2–Ag1C, 77.25(4); Ag2B–Ag2–Ag1C, 74.47(2); N11–Ag3–N21, 177.62(7). Symmetry code A: x 1, y, z; B: x + 1, y + 1, z; C: x + 1, y, z. [Cu6(Iso)6] Æ 2H2O (2). Cu1–O4A, 2.1869(14); Cu1–O3, 2.1919(14); Cu1–Cu1A, 2.8956(7); Cu2–N31, 2.1389(15); Cu2–N21, 2.1410(16); Cu3–O1, 2.1367(14); Cu3–N11, 2.1538(15) and O4A–Cu1–O3, 162.56(5); O4A–Cu1–Cu1A, 79.66(4); O3–Cu1–Cu1A, 83.23(4); N31–Cu2–N21, 176.62(6); O1– Cu3–N11, 177.03(5). Symmetry code A: x, y + 1, z.
coordination environment of Ag1 is similar to Ag3, which is in a linear geometry consisting of one oxygen atom from carboxylate groups of the isonicotinic moiety and one nitrogen atom from a pyridine ring [Ag1– ˚ ]. Atom Ag2 O2 = 2.1351(15), Ag1–N31 = 2.1478(17) A lies in a distorted triangular geometry with the mean ˚ , consisting of two oxygen atoms deviation of 0.0360 A from carboxylate groups of two different isonicotinic moieties and one water molecule. The bond distances and angles of Ag–O and Ag–N in 1 are comparable with those found in {[Ag(Iso)(HIso)]1/2 Æ [Ag(Iso)]}, but Ag Ag interactions are much shorter than that of ˚ [4]. 3.804 A In the crystal structure of 1, it is possible to observe many types of hydrogen bonds and Ag Ag interactions. Besides Ag2 Ag2A interaction, there is still another ˚ (Symmetype of Ag1 Ag2B interaction of 3.3783(10) A try code B: x 1, y, z). The hydrogen bonds, ˚ , O1W O1C = 2.877(2) A ˚ O1W O6A = 3.111(2) A ˚ (C: x, 1 y, z), O1W O1D = 2.813(2) A (D: ˚ (E: 3 + x, 1 + x, 1 + y, z), O2W O3E = 2.793(2) A ˚ 1 + y, z), O2W O4F = 2.798(2) A (F: 1.5 x, 0.5 + y, 0.5 z), are formed between water molecules and the oxygen atom of the carboxylate groups as shown in Fig. 2(a). The shortest centroid-to-centroid distance be˚ , indicating there are tween two pyridine rings is 3.516 A p–p stacking interactions in 1. As shown in Fig. 1(b), the structure of 2 is very similar to that of 1, in which all copper(I) atoms are two coordinated. The coordination environments of Atoms Cu2, Cu3 in 2 are corresponding to that of Ag(3) and Ag(1) in 1. Atom Cu1 in 2 is also similar to that of Ag2 in 1, except that no water molecule is coordinated
Fig. 2. 5 Packing drawings of 1 and 2 with hydrogen bondings.
to Cu1 center. There exists Cu1 Cu1A interactions ˚ . In the structure of (A: x, 1 y, z) of 2.8956(7) A ˚ (B: 2, the hydrogen bonds, O2W O4B = 3.125(2) A ˚ 1 + x, y, z), O2W O2C = 2.844(2) A (C: 2 x, ˚ (D: 2.5 x, 2 y, z), O1W O5D = 2.796(2) A ˚ (E: 3 + x, 0.5 + y, 0.5 + z), O1W O6E = 2.840(2) A 1 + y, z), linked the isolated molecules into 3-D structure. Significant absorption bands in the IR of free ligand HIso are observed at 3550(m), 1656(m) cm1 assigned
1024
B. Liu, Q. Yuan / Inorganic Chemistry Communications 8 (2005) 1022–1024
to m(OH) and m(CO). The absorption bands in the infrared spectrum of 1 and 2 are observed at 1609 and 1639 cm1, respectively, due to the carboxyl group (m(CO)). The significant blue shifts of the carboxyl group take place because of the coordination through the carboxyl oxygen. This situation indicates that coordination of Iso take place via the carboxyl oxygen to the metal ions [7]. In contrast to the rich structural chemistry of isonicotinic acid coordination complexes, to our knowledge, the luminescence data were quite limited, but there are the related rare earth complexes with nicotinic and isonicotinic acid N-oxides that included data for erbium and europium site distortions from the changes of the photoluminescence and absorption of the rare earth line spectra [8]. Herein, solid state emission spectra of the two d10 complexes of 1, 2 and HIso show interesting luminescence features at room temperature as given in Fig. S1. Excitation of the solid sample of 1 at kex = 348 nm produces an intensive dual luminescence: a high-energy band at approximately 420 nm and a lower energy emission at about 438 nm. 2 with kex = 362 nm produced a cuspidal emission at 408 nm. A significant blue shift can be found in all emission wavelengths of 1 and 2 when compared with that of free ligand HIso (broad peak at about 460 nm, kex = 362 nm). The emissions of 1 and 2 are assigned to ligand-to-metal transfer (LMCT) (Iso ! M, M = Ag, Cu). Though the structures of 1 and 2 are very similar, but the emissions of 1 and 2 indicate a significant and interesting difference, in which water molecule in 1 may play an important role in splitting the energy level of silver(I). The absorption spectrum was calculated from reflection spectrum by the Kubelka–Munk function [9] as shown in Fig. S2. The energy gaps of the present compounds determined by extrapolation from the linear portion of the absorption edge in a (a/S) versus energy plot are 2.37 for 1 and 2.88 eV for 2, which suggests that the title compounds are semiconductors and consistent with the yellow color of the crystals. The observation suggests that the optical absorption of is likely originated from the charge transfer from Iso groups valence band to CuI or AgI conduction band.
Acknowledgments We gratefully acknowledge the financial support of the National Natural Science Foundation of China (20001007, 20131020) and Natural Sciences Foundation of Fujian Province (2003I031).
Appendix A. Supplementary data Supplementary data associated with this article can be found, in the online version, at doi:10.1016/ j.inoche.2005.07.019. References [1] (a) L.R. MacGillivray, R.H. Groeneman, J.L. Atwood, J. Am. Chem. Soc. 120 (1998) 2676; (b) O.R. Evans, R.-G. Xiong, Z. Wang, G.K. Wong, W. Lin, Angew. Chem. Int. Ed. 38 (1999) 536. [2] L. Li, F.N. Castellano, I. Gryczynski, J.R. Lakowicz, Chem. Phys. Lipids 99 (1999) 1. [3] D. Braga, F. Grepioni, Coord. Chem. Rev. 183 (1999) 19. [4] B. Cova, A. Bricen˜o, R. Atencio, New J. Chem. 25 (2001) 1516. [5] [Ag6(Iso)6(H2O)2] Æ H2O (1): the synthesis of (2) is similar to (1), except that CH3COOAg (0.033 g, 0.2 mmol) dissolved in hot water in 70 °C for (2). Pale yellow platelet single crystals suitable for Xray diffraction could be obtained. Yield: 21%. Anal. Calc. for C18H16Ag3N3O8 (%): C, 29.78; H, 2.22; N, 5.79. Found: C, 29.88; H, 2.32; N, 5.63. IR (KBr, cm1): 3435 (vs), 2977 (w), 2919 (w), 1609 (m), 1548 (m), 1452 (m), 1384 (m), 1211 (w), 1048 (w), 838 (w), 880 (w), 766 (w), 688 (w). 1 can also be obtained from the hydrothermal reaction by using Ag2CO3. [Cu6(Iso)6] Æ 2H2O (2): a solution of Iso (0.025 g, 0.2 mmol) in ethanol (20 cm3) was added dropwise to 5 cm3 stirred aqueous solution of [Cu(CH3CN)4]ClO4 (0.065 g, 0.2 mmol) under nitrogen atmosphere. After the resulting pale yellow suspension stirred for about 6 h, the mixture was cooled and filtered. Pale yellow prism crystals were obtained by layering diethyl ether into the filtrate that was carefully placed in refrigerator. Yield: 18%. Anal. Calc. for C18H16Cu3N3O8 (%): C, 36.46; H, 2.72; N, 7.09. Found: C, 36.52; H, 2.83; N, 6.99. IR (KBr, cm1): 3410 (vs), 2975 (s), 2901 (m), 1639 (m), 1549 (w), 1452 (m), 1406 (m), 1383 (m), 1271 (w), 1084 (s), 1050 (s), 880 (m), 621 (w). [6] Intensity data collections were collected with a Rigaku Mercury CCD ˚) using graphite monochromatized Mo Ka radiation (k = 0.71073 A at 293(2) K. The crystal date reduction and cell refinement were applied with CrystalClear program. The structures were solved by direct methods and refined by the full-matrix least-squares method on F2 using Siemens SHELXTL-93 PC package. Crystal data for [Ag6(Iso)6(H2O)2] Æ H2O (1): C18H16Ag3N3O8, Mr = 725.95, mono˚ , b = 10.302(3) A ˚, clinic, space group P21/n (No. 14), a = 8.769(3) A ˚ , b = 96.590(2)°, V = 1959.3(11) A ˚ 3, Z = 4, c = 21.832(7) A Dc = 2.461 g cm3, l = 3.025 cm1, F(000) = 1400. Data collection (3.06 < h < 25.03°) gave the final R1 = 0.0224 and wR2 = 0.0578 for 3283 observed reflections with I > 2(I) out of 3449 unique reflections (Rint = 0.0232). Crystal data for [Cu6(Iso)6] Æ 2H2O (2): C18H16Cu3N3O8, Mr = 592.96, monoclinic, space group P21/n (No. ˚, ˚, ˚, 14), a = 8.743(3) A b = 10.3918(3) A c = 22.029(7) A 3 3 ˚ b = 96.4190(10)°, V = 1988.9(9) A , Z = 4, Dc = 1.980 g cm , l = 3.233 cm1, F(000) = 1184. Data collection (3.06 < h < 25.03°) gave the final R1 = 0.0465 and wR2 = 0.1436 for 3188 observed reflections with I > 2(I) out of 3407 unique reflections (Rint = 0.0235). Deposition CCDC reference numbers: 267190 for 1 and 267191 for 2. [7] R. Sekiya, S.-I. Nishikiori, Chem. Eur. J. 8 (2002) 4803. [8] J.-G. Mao, H.-J. Zhang, J.-Z. Ni, S.-B. Wang, T.C.W. Mak, Polyhedron 17 (1998) 3999. [9] (a) W.W. Wendlandt, H.G. Hecht, Reflectance Spectroscopy, Interscience Publishers, New York, 1966; (b) G. Kotuem, Reflectance Spectroscopy, Springer-Verlag, New York, 1969.