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吡罗昔康镧配合物的合成与表征

来源:用户上传      作者: 张艳军

  摘要:本论文合成了吡罗昔康和稀土金属镧的配合物,通过紫外光谱、红外光谱、元素分析、电导率、差热-热重等方法对其进行了表征,最后确定其组成为La(pir)2C2H5OHCl3・2H2O。
  关键词:吡罗昔康稀土金属配合物镧
  
  Synthesis,characterization of the complexe of piroxicam and lanthanum(La)
  
  Abstract:A new rare earth complexe was sythesised by rare earth chloride(LaCl3)and piroxicam in anhydrous ethanol .The chemical composition and structure of the compound were characterized by IR, UV-Vis , elemental analysis, TG-DTA,conductance. The results show that the chemical composition of the complexe is La (pir)2C2H5OH Cl3・2H2O.
  Keywordspiroxcam , rare earth , complexe , lanthanum
  
  
  一、Introduction
  Metal complexes containing non-steroidal anti-inflammatory drugs (NSAIDs ) are among those compounds which have received much attention and increasing interest from a medicinal inorganic chemistry viewpoint[1]. Metal complexes of anti-inflammatory drugs can also be potentially active against other diseases such as cancer and bacterial infections. Piroxicam(Pir) is a potent and extensively used non-steroidal anti-inflammatory (NSAIDs), anti-arthritic drug with a long biological half-life. It is known to react as a monodentate ligand through the pyridyl nitrogen towards Pt(II)[2], as a bidentate chelating ligand via the pyridyl nitrogen and the amide oxygen towards Cu(II) and Cd(II) [3]and as a singly deprotonated tridentate ligand through the enolic oxygen,the pyridyl and the amidenitrogen atoms in the Sn(IV) complex [5]. Iron(II), cobalt(II), nickel(II) ,zinc(II) VO2+, MoO22+ ,Mn2+and UO22+ almost certainly behave similarly to cadmium(II) [3,4,5].
  二、Experimental
  1、Materials and measurements
  Piroxicam was a gift from Taiyuan satellite pharmaceutical Factory in shanxi province. All reagents and solvents were of analytical grade. IR spectra were recorded on NICOLET-380 FI-IR in the wavenumber region 4000-500 cm-1. UV-Vis spectra were recorded on LENG GUANG 760 -CRT DOUBLE BEAM UV-Vis spectrophotometer. The spectra were recorded as nujol mulls and in dmf solution in range λ=200-800 nm. C, H and N elemental analysis were performed on a Perkin-Elmer 2400 elemental Analyzer. The thermogravimetric analysis (DTA and TG) were carried out in dynamic nitrogren atmosphere (40 ml min-1) with a heating rate of 10℃ min-1 using ZRT-2P thermal analyzer.
  2、Synthesis of complexe
  A warm ethanolic solution (25ml) of piroxicam(0.5mmol,166.5mg) was added to a warm ethanolic solution(25ml) of LaCl3・6H2O (0.25mmol,88.38mg). The resulting mixture was stirred under reflux for 6h. The complexes were precipitated as lemon powders.They ware removed by filtration and washed with hot ethanol and dried in a vacuum desiccator.
  3、Results and discussion
  The synthesized compexe is lemon powers,The m.p is much higher than piroxicam. The complexe is less soluble than piroxicam ligand in solvents, such as alcohols , acetone and tetrahydrofuran. The content of La is analysised in using EDTA titrimetric analysis. The analysis result :the elemental analyses are list in below. Analytical data: Calcd for La (pir)2C2H5OHCl3・2H2O (C32H36N6O11S2 La) (MW = 954): La 14.56, C40.29, H 3.38, N 8.81; found La 15.02, C 39.97, H 3.41, N 8.77. The molar conductance of the complexe in DMSO (the concentration 1×10-4mol・L-1)was measured using DDSJ-308A conductometer. Λm=47.5 s・cm2・mol-1,so it was considered as ion-complexe.

  4、UV-Vis spectroscopy
  UV-Vis spectra of the ligand and complexe have been recorded in dmf solution.The UV spectra of piroxicam complexes in dmf solution are alike (strong absorption occur at about 267 and 357nm), but they differ from that of the parent compound.The band at 371 nm of the piroxicam is attributed to conjugated system of enolate, carboxyl and amide N atoms. It is shifted to 357nm . This may be attributed to the donation of the lone pair of the amide N atom to the La ion center,which destructs the p-π conjugate,and destructs the big conjugated system,which leads the band from 371 nm to 357 nm.
  5、DTA-TG analysis
  The DTA curve show one endothermic peak at 72℃, which is the dehydration,and four indothermic peaks at 376℃, 485℃, 590℃, 782℃, which are the decomposition of the complexe and the ligand .The dehydration step in La-Pir complex is found in the temperature range 65-85℃ (wt. loss: calcd.3.77%, f. 3.89%). The total mass loss % :found 83.47;calcd 82.91.
  6、IR spectra and mode of bonding
  The IR spectrum of piroxicam shows well-defined peaks at 3441 and 3338cm-1 are assigned to the ν(N-H) and (O-H) vibrations,respectively. In the complexe theν(N-H) is shifted to lower wavenumber ~3422 cm-1, supporting the participation of the amide NH of Pir in the coordination to La ion; and the band at 3338cm-1 attributed to the O-H enolate group of the free ligand is not detected in the spectra of complexe,which indicates enolate participating the coordination. In the wave number rang 1700-1000 cm-1,some of the most characteristic bands of these groups are found.The so-called amide I band, which represents mainly the v(C=O) stretching mode is seen as a very strong band at 1361cm-1.In the complexe this band is shifted to higher frequency~1464cm-1, this may be attributed to the donation of the lone pair of the amide N atom to the La ion center,which destructs the p-π conjugate,leading the decrease of electron density of the C=O.
  The band at 1351cm-1 in the piroxicam spectrum attributable to v(SO2)asym vibration undergoes a shift to higher wavenumber ~1554cm-1 in the complexe even though the SO2 group does not interact with the La ion[12].
  The overall spectrum patter of the complexe indicates that piroxicam acts as a bidenate ligand bound to the La ion throuth the enolate O and amide N atoms.
  三、Structural interpretation
  The structure of the complexe was conflrmed by the IR, UV-Vis spectra, elemental analyses
  Conductance and DTA-TG.. It’s struction maybe is as scheme1:
  Scheme1:The struction of complexe (图1:配合物的结构)
  References:
  [1] C. Orvig and M. J. Abrams. Medicinal inorganic chemistry:Introduction[J]. Chem.Rev. 1999,99(9):2201-2204.
  [2] D. Di Leo, S. Grabner, R. Cini, et al. Synthesis and structural characterization of platinum(II)-acyclovir complexes[J].J. Chem. Soc., Dalton Trans.1998,1447-1452.
  [3]R. Cini, G. Giorgi, A. Cinquantini, C. Rossi, et al. Metal complexes of the anti-inflammatory drug piroxicam[J]. Inorg.Chem. 1990,29(26):5179-5200.
  [4]S.K. Hadjikakou, M.A. Demertzis, J.R. Miller, et al. Synthesis and characterisation of the first organotin complex of piroxicam. An extended network system via non-hydrogen, hydrogen bonding linkages and C-H• • • π contacts[J]. J. Chem. Soc., Dalton Trans. 1999,663-666.
  [5]R. Cini.Synthesis, crystal structure and molecular orbital investigation of the first platinum complex of piroxicam [J]. J. Chem. Soc., Dalton Trans. 1996,1:111-116.
  [6]P. Christofls, M.Katsarou, A. Papakyriakou, G. Psomas, et al. Mononuclear metal complexes with piroxicam: synthesis, structure and biological activity[J]. J.Inorg.Biochem, 2005,99(11):2197-2210.
  [7]S.B. Etcheverry, P..A.M. Williams, D.A. Barrio, et al, Synthesis, characterization and bioactivity of a new VO2+/Aspirin complex[J]. J. Inorg. Biochem. 2000,80(1):169-171.


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