English

• 1. INTRODUCTION

  Lanthanide coordination complexes have gained much interest due to their broad applications in light emitting diodes, fluorescent probes, sensors, bioimaging utilities, time-resolved luminescent immunoassays, and anion sensing^[1-3]. In particular, the photoluminescent properties of lanthanide complexes are notable due to their unique properties such as sharp emission bands, long emission lifetime and large stokes shift^[4-7]. Therefore, researches on crystal and molecular structures of Y(III) complexes are needed. Yttrium element is an optical inert element with weak fluorescence performance, and the study on its complex properties mainly focuses on biological activity^[8-10], while the study on rare earth ion perturbation ligand luminescence is seldom reported^[11-13]. In order to obtain luminescent lanthanide complexes, the selection and design of organic ligand are very important, and it should be able to efficiently absorb and transfer energy to the central metal ion and encapsulate and protect the lanthanide ion from the coordination of solvent molecules^{[14, 15]}. As an important organic and inorganic intermediate, 2, 4, 6-trimethylbenzoic acid is widely used in dye synthesis, pesticide, medicine, photo sensitized initiation reagent, flavor synthesis, photomechanical process and analytic reagent. With the aim of proceeding previous jobs^[16-18], we report herein a new yttrium(III) complex Y₂(TMBA)₆(phen)₂ with 2, 4, 6-trimethylbenzoic acid(TMBA) and 1, 10-phenanthroline(phen). The TG analysis and fluorescent properties of 1 were also reported.

  2. EXPERIMENTAL

  2.1 Materials and instruments

  All reagents were of analytical grade and used as obtained from commercial sources without further purification. Crystal structure determination was carried out on a Bruker SMART CCD 6000 single-crystal diffractometer. Elemental analyses were performed on a Perkin-Elmer 2400 elemental analyzer. XT4 binocular microscope melting point apparatus was used to measure the melting point with thermometer unadjusted. IR spectra were recorded on a Bruker Vector22 FT-IR spectrophotometer using KBr discs. The fluorescent spectra for the powdered samples were measured on a RF-5301PC spectrofluorometer with a xenon arc lamp as the light source. In the measurement of emission and excitation spectra, the pass width is 5 nm, and all the measurements were carried out in the solid state at room temperature. Thermogravimetric analyses were performed on a simultaneous SPRT-2 pyris1 thermal analyzer at a heating rate of 10 K/min.

  2.2 Synthesis of 1

  A mixture of TMBA (98.52 mg, 0.6 mmol), phen (54.0 mg, 0.3 mmol) and Y(NO₃)₃·4H₂O (70.50 mg, 0.2 mmol) was dissolved in 25 mL of mixed solvent (The volume ratio of ethanol and water is 1:1). The pH value of the resultant mixture was adjusted to 6.8 by adding sodium hydroxide solution. The reaction was kept at 140 ℃ for 68 h, and it was cooled to room temperature at the speed of 10 ℃/h. Colorless crystals of 1 suitable for X-ray diffraction analysis were obtained in 60.26% yield. m.p.: 257~259 ℃. Anal. Calcd. (%) for C₈₄H₈₂N₄O₁₂Y₂: C, 66.49; H, 5.45; N, 3.69. Found (%): C, 66.35; H, 5.43; N, 3.71. Main IR (KBr, cm^–1): IR (v/cm^–1): 2920(s), 1626(vs), 1528(m), 1443(m), 1429(vs), 1185(w), 1109(w), 1240(w), 1063(m), 847(m), 729(m), 604(w), 478(w).

  2.3 Determination of the crystal structure

  A single crystal with dimensions of 0.20mm × 0.20mm × 0.20mm was put on a Bruker SMART CCD 6000 diffractometer equipped with a graphite-monochromatic MoKα radiation (λ = 0.71076 Å) using an ω scan mode at 296(2) K. A total of 22328 reflections were collected in the range of 2.92≤θ≤27.24°, of which 6503 were independent (R_int = 0.0864) and 5394 were observed (I > 2σ(I)). All data were corrected by Lp factors and empirical absorption. The crystal structure was solved directly by program SHELXS-2008, and refined by program SHELXL-2013^[19]. The hydrogen and non-hydrogen atoms were corrected by isotropic and anisotropic temperature factors respectively through full-matrix least-squares method. The final R = 0.0353, wR = 0.0826 (w = 1/[σ²(F_o²) + (0.0486P)² + 0.0000P], where P = (F_o² + 2F_c²)/3), (∆/σ)_max = 0.001, S = 1.039, (∆ρ)_max = 0.335 and (∆ρ)_min = –0.253 e·Å^–3.

  3. RESULTS AND DISCUSSION

  3.1 Crystal structure of 1

  The coordination structure of 1 is revealed in Fig. 1, square antiprism coordination geometry of the central Y(III) ion of 1 is shown in Fig. 2, and its packing diagram is given in Fig. 3. Selected bond lengths and bond angles are shown in Table 1.

  Figure 1

  

  Figure 1.  Coordination structure of complex 1(Undo part carbon atoms)A: 1 – x, 1 – y, 1 – z

  DownLoad: Full-Size Img PowerPoint

  Figure 2

  

  Figure 2.  Square antiprism coordination geometry of the central Y(III) ion of 1

  DownLoad: Full-Size Img PowerPoint

  Figure 3

  

  Figure 3.  Packing diagram of the title complex in a cell

  DownLoad: Full-Size Img PowerPoint

  Table 1

  

  Table 1.  Selected Bond Lengths (Å) and Bond Angles (°) of Complex 1

  DownLoad: CSV

  Bond	Dist.		Bond	Dist.		Bond	Dist.
  Y(1)–O(4)	2.2891(17)		Y(1)–O(6)	2.2989(18)		Y(1)–O(3)	2.3122(16)
  Y(1)–O(5)	2.3387(17)		Y(1)–O(1)	2.3533(18)		Y(1)–O(2)	2.3897(17)
  Y(1)–N(7)	2.540(2)		Y(1)–N(8)	2.565(2)
  Angle	(°)		Angle	(°)		Angle	(°)
  O(4)–Y(1)–O(6)	81.47(7)		O(4)–Y(1)–O(3)	126.18(6)		O(6)–Y(1)–O(3)	76.51(6)
  O(4)–Y(1)–O(5)	77.34(6)		O(5)–Y(1)–O(6)	126.36(7)		O(3)–Y(1)–O(5)	77.60(6)
  O(4)–Y(1)–O(1)	134.37(6)		O(6)–Y(1)–O(1)	80.06(7)		O(3)–Y(1)–O(1)	89.02(6)
  O(5)–Y(1)–O(1)	144.97(6)		O(4)–Y(1)–O(2)	80.85(6)		O(6)–Y(1)–O(2)	78.09(7)
  O(3)–Y(1)–O(2)	138.66(6)		O(5)–Y(1)–O(2)	143.38(6)		O(1)–Y(1)–O(2)	54.65(6)
  O(4)–Y(1)–N(7)	139.30(7)		O(6)–Y(1)–N(7)	139.21(7)		O(3)–Y(1)–N(7)	77.15(7)
  O(5)–Y(1)–N(7)	76.57(6)		O(1)–Y(1)–N(7)	68.89(7)		O(2)–Y(1)–N(7)	102.89(7)
  O(4)–Y(1)–N(8)	78.69(7)		O(6)–Y(1)–N(8)	148.08(7)		O(3)–Y(1)–N(8)	135.37(6)
  O(5)–Y(1)–N(8)	72.86(7)		O(1)–Y(1)–N(8)	96.37(7)		O(2)–Y(1)–N(8)	74.27(7)
  N(7)–Y(1)–N(8)	64.04(7)

  Y₂(TMBA)₆(phen)₂ (1) is a binuclear cage-like structure complex in space group P$ \overline 1 $. As illustrated in Fig. 1, the complex is inclusive of two Y(III) ions, two phen molecules and six TMBA^–1 anions. As depicted in Fig. 2, the coordination polyhedron of the yttrium cations is formed by two equivalent nitrogen atoms from phen molecule and six oxygen atoms from five TMBA^–1 anions, giving a distorted square antiprism coordination geometry. Atoms O(1), O(2), N(8) and N(7) give a upper plane of the square antiprism, and O(6), O(4), O(5) and O(3) determine the plane below, respectively. Their dihedral angle of the two planes is 3.3°. The bond length average Y–N is 2.553 Å, bridging Y–O is 2.3097 Å and the chelation Y–O is 2.3715 Å. All average bond lengths are shorter than the same complex (Tb₂(TMBA)₆(phen)₂, Tb–N = 2.596 Å, bridging Y–O = 2.324 Å, chelation Y–O = 2.440 Å^[18], respectively) because the yttrium has smaller atomic radius than terbium. The Y(1)–O(2) = 2.3897(17) Å is longer than the other Y–O, and the bond angle O(5)–Y(1)–O(1) of 144.97(6)° is greater than the other angles. All above bond features are characteristic of this type of polyhedron. The coordination modes of the carboxylate groups are bidentate chelate or bridge with the average Y–O_(carboxyl) distance to be 2.3303 Å, which is longer than Tb₂(TMBA)₆(phen)₂ (Y–O = 2.363 Å). The Y···Y distance, 4.256(3) Å, is slightly longer than that in similar Y(III) complexes ([Y^III(hpdta)(H₂O)]₂·6H₂O, Y···Y = 3.878(3) Å^[20] and [Y₂L₂(NO₃)]_n·2H₂O, Y···Y = 3.7230(11) Å)^[21], which falls in the normal range. In addition, as given in Fig. 3, the shortest center distance between aromatic cycles of 2, 4, 6-trimethyl-benzoic group and phenanthroline is 0.3454 Å, smaller than 0.3700 Å, indicating a weak π-π stacking interaction between the aromatic cycles^[22].

  3.2 Spectroscopic characterization of 1

  Infrared spectrum of the complex demonstrates an absorption peak at 2292 cm^–1 ascribed to the characteristic absorption peak of CH₃- in TMBA. The antisymmetrical and symmetrical stretching vibration absorption peaks of carboxylic group in the ligand appear at 1626, 1528 cm^–1 and 1626 and 1443, which are in contrast with the corresponding peaks of free ligands (at 1686 and 1436 cm^–1, respectively) and shift remarkably. The Δv_coo– (v_as(coo–) –v_s(coo–)) of the complex is 98 and 183 cm^–1, one of which is smaller than 100 cm^–1, and the other falls between 100 and 200 cm^–1, so the carboxyl in the complex is coordinated with bidentate chelate and bidentate bridge modes^[23]. The strong peaks at 1429, 847 and 729 cm^–1 are ascribe to the characteristic absorption peaks of phen ligand.

  The fluorescent properties of 1 and the free ligand TMBA have also been studied, as shown in Fig. 4. The title complex displays characteristic emission peaks at λ_em = 398 nm (λ_ex = 360 nm), while at λ_em = 394 nm (λ_ex = 360 nm) for the TMBA. Compared with that of free ligand TMBA, the emission spectrum of the title complex has the same characteristic emission peak and similar figure, suggesting that fluorescence of the title complex may be mainly ascribed to electronic transition of the intra ligand TMBA because the Y(III) ion has the electron configuration of ns²np⁶ and its electron transition requires high energy, thereby the fluorescence emission of the complex is the ligand fluorescence of the center ion perturbation type^[24].

  Figure 4

  

  Figure 4.  Fluorescence of complex 1 and ligands

  a: excitation spectrum of 1; b: emission spectrum of 1;c: excitation spectrum of TMBA; d: emission spectrum of TMBA

  DownLoad: Full-Size Img PowerPoint

  3.3 Thermal stability of 1

  The thermogravimetric analysis (Fig. 5) of 1 demonstrated that the weight loss of the complex in the air from room temperature to 600 ℃ occurred mainly in 2 stages. The first stage occurs from 140~260 ℃ with the weight loss of 23.70%, resulting from the loss of two phen molecules (calcd.: 23.75%). The second stage takes place from 260 to 390 ℃ with the weight loss of 61.40% due to the departure of six TMBA anions (calcd.: 61.37%). In air, the final product is yttrium oxide with the final residual rate to be about 14.90% (calcd.: 14.88%).

  Figure 5

  

  Figure 5.  TG of complex 1

  DownLoad: Full-Size Img PowerPoint
  
  
• 1. [1]

     Jung, J.; Puget, M.; Cador, O.; Bernot, K.; Calzado, C.; Guennic, B. L. Analysis of the magnetic exchange interactions in yttrium(III) complexes containing nitronyl nitroxide radicals. Inorg. Chem. 2017, 56, 6788–6801. doi: 10.1021/acs.inorgchem.6b02952

  2. [2]

     Sodpiban, O.; Del Gobbo, S.; Barman, S.; Aomchad, V.; Kidkhunthod, P.; Ould-Chikh, S.; Poater, A.; D Elia, V.; Basset, J. M. Synthesis of well-defined yttrium-based Lewis acids by capturing a reaction intermediate and catalytic application for cycloaddition of CO₂ to epoxides under atmospheric pressure. Catal. Sci. Technol. 2019, 9, 6152–6165. doi: 10.1039/C9CY01642B

  3. [3]

     Zhao, P.; Zhu, Q. H.; Fettinger, J. C.; Power, P. Characterization of a monomeric, homoleptic, solvent free samarium bis(aryloxide). Inorg. Chem. 2018, 57, 14044–14046. doi: 10.1021/acs.inorgchem.8b02677

  4. [4]

     Silva, I. G. N.; Morals, A. F.; Mustafa, D. Synthesis, characterization and Judd-Ofelt analysis of Sm³⁺-doped anhydrous yttrium trimesate MOFs and their Y₂O₃: Sm³⁺ low temperature calcination products. J. Lumin. 2019, 210, 335–341. doi: 10.1016/j.jlumin.2019.02.048

  5. [5]

     Pousaneh, E.; Preuss, A.; Assim, K.; Ruffer, T.; Korb, M.; Tittmann, J.; Hermann, S.; Schulz, S. Z.; Lang, H. Tetranuclear yttrium and gadolinium 2-acetylcyclopentanoate clusters: synthesis and their use as spin-coating precursors for metal oxide film formation for field-effect transistor fabrication. J. Rare Earths 2018, 36, 1098–1105. doi: 10.1016/j.jre.2018.02.010

  6. [6]

     Veauthler, J. M.; Schelter, E. J.; Carlson, C. N.; Scott, B. L.; Re, R. E.; Thopson, J. D.; Klpllnger, J. L.; Morrls, D. E.; John, K. D. Direct comparison of the magnetic and electronic properties of samarocene and ytterbocene terpyridine complexes. Inorg. Chem. 2008, 47, 5841–5849. doi: 10.1021/ic8001465

  7. [7]

     Ligny, R.; Guillaume, S. M.; Carpentier, J. F. Yttrium-mediated ring-opening copolymerization of oppositely configurated 4-alkoxymethylene-beta-propiolactones: effective access to highly alternated isotactic functional PHAs. Chem. Eur. J. 2019, 25, 6412–6424. doi: 10.1002/chem.201900413

  8. [8]

     Su, Y. C.; Chiu, T. Y.; Liu, Y. T.; Lin, P. H.; Ko, B. T. Significant enhancement of catalytic properties in mononuclear yttrium complexes by nitrophenolate-type ligands: synthesis, structure, and catalysis for lactide polymerization. J. Poly. SCi. Part. A-Poly. Chem. 2019, 57, 2038–2047. doi: 10.1002/pola.29468

  9. [9]

     Peewasan, K.; Merkel, M. P.; Fuhr, O.; Powell, A. K. A designed and potentially decadentate ligand for use in lanthanide(III) catalysed biomass transformations: targeting diastereoselective trans-4, 5-diaminocyclopentenone derivatives. Dalton Trans. 2020, 49, 2331–2336. doi: 10.1039/D0DT00183J

  10. [10]

      Wu, H. L.; Pan, G. L.; Bai, Y. C.; Wang, H.; Kong, J.; Shi, F. R.; Zhang, Y. R.; Wang, X. L. A. Schiff base bis(N-salicylidene)-3-oxapentane-1, 5-diamine and its yttrium(III) complex: synthesis, crystal structure, DNA-binding properties, and antioxidant activities. J. Coord. Chem. 2013, 64, 2634–2646.

  11. [11]

      Lu, G.; Wang, K.; Kong, X.; Pan, H.; Zhang, J. H.; Chen, Y. L.; Zhuang, J. Binuclear phthalocyanine dimer-containing yttrium double-decker ambipolar semiconductor with sensitive response toward oxidizing NO₂ and reducing NH₃. Chem. Electro. Chem. 2018, 5, 605–609.

  12. [12]

      Gao, J. Q.; Li, D.; Wang, J.; Jin, X. D.; Kang, P. L.; Wu, T.; Li, K.; Zhang, X. D. Synthesis and crystal structure of a 2-D yttrium coordination network with propylenediamine-N, N, N΄, N΄-tetraacetic acid. J. Coord. Chem. 2011, 64, 2284–2291. doi: 10.1080/00958972.2011.594163

  13. [13]

      Lu, J. T.; Wang, H. L.; Zhang, X. M. Synthesis and crystal structure of a mixed (phthalocyaninato)(porphyrinato)yttrium double-decher complex. Chin. J. Struct. Chem. 2011, 30, 872–976.

  14. [14]

      Bhattacharjee, C. R.; Das, G.; Goswami, P.; Mondal, P.; Prasad, K.; Rao, D. S. S. Norel photoluminescent lanthaidomesogens forming bilayer Yectic phase derived from blue light emitting liquid crystalline, one ring o-donor Schiff-base ligands. Polyhedraon 2011, 30, 1040–1047. doi: 10.1016/j.poly.2011.01.015

  15. [15]

      Wu, A. Q.; Zheng, F. K.; Liu, X.; Guo, G. C.; Cai, L. Z.; Dong, Z. C.; Takano, Y.; Huang, J. S. A novel bi-layered samarium complex with an unprecedented coordination mode of orotic acid [Y₂(HL)₂(OX)(H₂O)₂]_n·2.5nH₂O (H₃L = orotic acid, ox^2– = oxalate^2–): synthesis, crystal structure and physical properties. Inorg. Chem. Commun. 2006, 9, 347–350. doi: 10.1016/j.inoche.2005.12.014

  16. [16]

      Li, W.; Li, C. H.; Yang, Y. Q.; Kuang, Y. F. Synthesis, crystal structure and electrochemical properties of one-dimensional chain coordination polymer [Cu(phen)(2, 4, 6-TMBA)₂(H₂O)]_n. Chin. J. Struct. Chem. 2008, 27, 210–214.

  17. [17]

      Li, W.; Li, C. H.; Yang, Y. Q.; Li, D. P.; Peng, Y. L.; Kuang, Y. F. Hydrothermal synthesis, crystal structure and thermal stability properties of one dimensional chain coordination polymer [Cd(phen)(2, 4, 6-TMBA)₂(H₂O)]_n. Chin. J. Inorg. Chem. 2007, 23, 2013–2017.

  18. [18]

      Li, D. P.; Feng, Y. L.; Chen, Z. M.; Kuang, D. Z.; Zhang, C. H.; Yang, Y. Q.; Li, W. Synthesis, crystal structure of a binuclear terbium complex with 2, 4, 6-trimethylbenzoic acid and 1, 10-phenanthroline. Chin. J. Inorg. Chem. 2006, 22, 2097–2100.

  19. [19]

      (a) Sheldrick, G. M. Program for Bruker Area Detector Absorption Correction. University of Gottingen: Gottingen, Germany 2008. (b) Sheldrick, G. M. SHELXS-97, Program for Crystal Structure Solution. University of Gottingen: Gottingen, Germany 2013.

  20. [20]

      Gao, J. Q.; Li, D.; Wang, J.; Jin, X. D.; Kang, P. L.; Wu, T.; Li, K.; Zhang, X. D. Synthesis and crystal structure of a 2-D yttrium coordination network with propylenediamine-N, N, N΄, N ΄-tetraacetic acid. J. Coord. Chem. 2011, 64, 2284–2291. doi: 10.1080/00958972.2011.594163

  21. [21]

      Wu, H. L.; Pan, G. L.; Bai, Y. C.; Wang, H.; Kong, J.; Shi, F. R.; Zhang, Y. H.; Wang, X. L. A Schiff base bis(N-salicylidene)-3-oxapentane-1, 5-diamine and its yttrium(III) complex: synthesis, crystal structure, DNA-binding properties, and antioxidant activities. J. Coord. Chem. 2013, 66, 2634–2646. doi: 10.1080/00958972.2013.812725

  22. [22]

      Chen, X. M.; Cai, J. W. Principle and Practice of Single Crystal Structural Analysis. The first edition, Beijing, Science press 2004.

  23. [23]

      Nakamota, K. Translated by Huang, D. R.; Wang, R. Q. Infrared and Raman Spectra of Inorganic and Coordination Compounds, 3rd edn. Beijing: Chemical Industry Press 1986.

  24. [24]

      (a) El, A.; Mohamed, S. Spectroscopic, thermal analysis, and nematicidal evaluation of new mixed ligand complexes of bidentate Schiff base and 1, 10 phenanthroline with some transition metals. J. Chin. Chem. Soci. 2018, 65, 1188–1198. (b) Li, C. H.; Li, W.; Hu, H. X.; Jiang, M. L. Synthesis, crystal structure and fluorescent and thermal stability properties of the zinc(II) complex [Zn(C₁₅H₁₁O₃)₂(C₁₂H₈N₂)₂]·5H₂O. Chin. J. Struct. Chem. 2014, 33, 947–951. (c) Li, J. Rare earth luminescent materials and their applications. Chemical Industry Press. China 2003, 170–172.

• 

  Figure 1  Coordination structure of complex 1(Undo part carbon atoms)A: 1 – x, 1 – y, 1 – z

  下载: 全尺寸图片 幻灯片
  

  Figure 2  Square antiprism coordination geometry of the central Y(III) ion of 1

  下载: 全尺寸图片 幻灯片
  

  Figure 3  Packing diagram of the title complex in a cell

  下载: 全尺寸图片 幻灯片
  

  Figure 4  Fluorescence of complex 1 and ligands

  a: excitation spectrum of 1; b: emission spectrum of 1;c: excitation spectrum of TMBA; d: emission spectrum of TMBA

  下载: 全尺寸图片 幻灯片
  

  Figure 5  TG of complex 1

  下载: 全尺寸图片 幻灯片

  Table 1.  Selected Bond Lengths (Å) and Bond Angles (°) of Complex 1

  Bond	Dist.		Bond	Dist.		Bond	Dist.
  Y(1)–O(4)	2.2891(17)		Y(1)–O(6)	2.2989(18)		Y(1)–O(3)	2.3122(16)
  Y(1)–O(5)	2.3387(17)		Y(1)–O(1)	2.3533(18)		Y(1)–O(2)	2.3897(17)
  Y(1)–N(7)	2.540(2)		Y(1)–N(8)	2.565(2)
  Angle	(°)		Angle	(°)		Angle	(°)
  O(4)–Y(1)–O(6)	81.47(7)		O(4)–Y(1)–O(3)	126.18(6)		O(6)–Y(1)–O(3)	76.51(6)
  O(4)–Y(1)–O(5)	77.34(6)		O(5)–Y(1)–O(6)	126.36(7)		O(3)–Y(1)–O(5)	77.60(6)
  O(4)–Y(1)–O(1)	134.37(6)		O(6)–Y(1)–O(1)	80.06(7)		O(3)–Y(1)–O(1)	89.02(6)
  O(5)–Y(1)–O(1)	144.97(6)		O(4)–Y(1)–O(2)	80.85(6)		O(6)–Y(1)–O(2)	78.09(7)
  O(3)–Y(1)–O(2)	138.66(6)		O(5)–Y(1)–O(2)	143.38(6)		O(1)–Y(1)–O(2)	54.65(6)
  O(4)–Y(1)–N(7)	139.30(7)		O(6)–Y(1)–N(7)	139.21(7)		O(3)–Y(1)–N(7)	77.15(7)
  O(5)–Y(1)–N(7)	76.57(6)		O(1)–Y(1)–N(7)	68.89(7)		O(2)–Y(1)–N(7)	102.89(7)
  O(4)–Y(1)–N(8)	78.69(7)		O(6)–Y(1)–N(8)	148.08(7)		O(3)–Y(1)–N(8)	135.37(6)
  O(5)–Y(1)–N(8)	72.86(7)		O(1)–Y(1)–N(8)	96.37(7)		O(2)–Y(1)–N(8)	74.27(7)
  N(7)–Y(1)–N(8)	64.04(7)

  下载: 导出CSV
•