1、 PLEASE SCROLL DOWN FOR ARTICLEThis article was downloaded by: Hua Zhou, XiaoOn: 22 October 2008Access details: Access Details: subscription number 904521672Publisher Taylor Xi Rui Zeng b; Xiao Hua Zhou a; Shi Chen a; Chun Lin Ni aa Department of Applied Chemistry, College of Science, South China Ag
2、ricultural University, Guangzhou510642, P.R. China b Provincial Key Laboratory of Coordination Chemistry, Chemistry in final form 21 September 2007)The new complex Cu(phen)(L-arg)Cl2C17H2O was prepared and characterized by elementalanalysis, molar conductivity, IR, UVVis and X-ray diffraction method
3、s. It crystallizesin the triclinic space group PC221 with four molecules in a unit cell of dimensions,a10.3733(13)A, b12.4269(15)A, c18.926(2)A, a94.627(2)C14, C12104.864(2)C14,C13 101.032(2)C14, V2292.8(5)A3, Z2, Dc1.493gcmC03, m1.004mmC01, F(000)1072,Rint1.113 for 7290 unique reflections. The supe
4、roxide dismutase-like activity of the complexfor catalyzing the dismutation of OC1C02was determined by the NBT method. The complex hashigh superoxide dismutase-like activity and the rate constant (KQ) of complex for catalyzing thedismutation of OC1C02is 5.19C2107molC01dm3sC01. CCDC: 645352Keywords:
5、Copper (II); 1,10-Phenanthroline; L-arginine; Crystal structure; Superoxidedismutase(SOD); SOD-like activity1. IntroductionSuperoxide anion (OC1C02) is essential as a defense system against the invasion of bacteriaand viruses and serves important roles as a signaling molecule and even as a terminato
6、rof lipid peroxidation 1. OC1C02is increasingly known to be associated tightly with thepathogenesis of many diseases 2; especially when organisms were under stress such astoxicant, irradiation, hypoxia, freezing, drought, etc., OC1C02would overproduce andbecome poisonous and surplus OC1C02would init
7、iate lipid peroxidation 3, cause nucleicacid and protein damage 46 and influence cellular signaling 7. Thus humans wouldundergo neurondegenerative diseases 8, 9, aging 10 even cancer 11, 12 and plantsmight grow slowly 13, 14 or die. Luckily, in humans, animals and plants there arenative metal enzyme
8、s, superoxide dismutases (SOD), which change the dismutation ofOC1C02into H2O2and O2. Applications in clinical medicine of native SODs have been in adilemma because of huge molecular weight, high costs and the major problem ofoxidantantioxidant balance 2. To make up for such limitations with hope fo
9、r*Corresponding author. Email: Journal of Coordination ChemistryISSN 0095-8972 print/ISSN 1029-0389 online C223 2008 Taylor H, 5.43; N, 16.30. Found: C, 42.03; H, 5.13; N,16.74. Molar conductivity: 35.2ScmC02molC01.2.2. Physical measurementsThe elemental analysis (carbon, nitrogen and hydrogen) was
10、performed on aPerkin-Elmer 240 microanalyzer. The infrared absorption spectra in KBr discs wererecorded in the 4004000cmC01range at room temperature on a Nicolet 170SXspectrophotometer. The electronic absorption spectrum of the complex was measuredin water on a Pharmacia 4000 UVVis spectrophotometer
11、 at room temperature. Molarconductivities were carried out in ethanol using a DDS-11A.2.3. X-ray structural determinationA single crystal (0.28C20.30C20.42mm3) of the complex was selected for X-raydiffraction measurement on a Bruker Smart 1K CCD system diffractometer withgraphite monochromatic Mo-Ka
12、 radiation at C210.71073A. The SMART programwas applied to search for diffraction peaks to determine cell parameters, and the3830 H. F. Ma et al.Downloaded By: Hua Zhou, Xiao At: 01:39 22 October 2008collected data were reduced using the SAINT program 24. Absorption correctionswere applied with the
13、Siemens Area Detector Absorption (SADABS) program 25.The structure was solved by direct and Fourier methods, and refinements werecarried by full-matrix least squares on F2with positional and anisotropic thermalparameters. The atomic coordinates anisotropic thermal parameters for non-hydrogenatoms we
14、re refined to converge. All hydrogen atoms were placed in calculatedpositions. Atomic scattering factors were taken from International Tables for X-rayCrystallography 26. All calculations were performed on a PC with the SiemensSHELXS-97 27 and SHELXL-97 28 program packages. The crystal data andrefin
15、ement parameters are summarized in table 1.2.4. Measurement of SOD activitySOD-like activity of the complex was determined by the modified nitroblue tetrazolium(NBT)photoreduction29.Mixed solutioncontainingNBT(9.32C210C05M),riboflavin(6.80C210C06M), and tetramethyl ethylenediamine (1.0C210C04M) in p
16、hosphate buffer atpH 7.8 was used as blank solution, and solutions containing concentrations of complex(10C06C2410C08M) or native CuZnSOD (0.005C240.0mmoldmC03) in the blank solutionwere considered as competitive solutions. The superoxide anion was generated byillumination under a fluorescence lamp
17、and detected with spectrophotometer bymonitoring the formation of the NBT reduction at 560nm. The NBT reduction ratewas measured in the presence and absence of CuZnSOD or the investigatedcomplex for 210s. All measurements were carried out at 25C60.2C using 1cmC21cmTable 1. Crystal data and structure
18、 refinement for Cu(phen)(L-arg)Cl2C17H2O.Empirical formula C36H56Cl2Cu2N12O11Formula weight 1030.91Temperature (K) 273(2)Wavelength (A) 0.71073Crystal system TriclinicSpace group PC221Unit cells dimensions (A,C14)a 10.3733(13)b 12.4269(15)c 18.926(2)a 94.627(2)C12 104.864(2)C13 101.032(2)V (A3) 2292
19、.8(5)Z 2DCalcd(gcmC03) 1.493F(000) 1072Rint1.113C18 range for data collection (C14) 1.89C2426.10Limiting indices C012C20hC2011, C015C20kC2015, C023C20lC2023Reflections collected/unique 14929/7290Data/restraints/parameters 8282/23/600Goodness-of-fit on F21.004Final R indices I42C27(I) R10.1221; wR20.
20、4596R indices (all data) R10.1168; wR20.4443Largest diff. peak and hole (eAC03) 4.43 and C00.86Synthesis, characterization and SOD-like activity 3831Downloaded By: Hua Zhou, Xiao At: 01:39 22 October 2008thermostatic cuvettes. The IC50(the concentration of CuZnSOD or the complex whichcauses 50% inhi
21、bition of NBT reduction) of native CuZnSOD or the complex wascalculated. Each final result for IC50is the average of at least three independentdeterminations, and the relative error is less than 1.4%.To test the influence of small amounts of copper ions, phen and L-arg, which aredissociated slightly
22、 from the complex, the control experiment was performed withCuCl2, phen and L-arg.3. Results and discussionElemental analysis of the title complex is in good agreement with the formulaCu(phen)(L-arg)Cl2C17H2O. The complex is soluble in water, methanoland ethanol, but not in ether and other low polar
23、ity organic solvents. Molarconductivity measurement in ethanol at 10C03molLC01, C3m35.2Scm2molC01, show anon-electrolyte 30.3.1. Crystal structureFigure 1 shows the perspective view of Cu(phen)(L-arg)Cl2, and figure 2 shows thecrystal packing view of the title complex, in which the hydrogen atoms an
24、d crystalwaters are omitted for clarity.Complex consists of neutral Cu(phen)(L-arg)Cl and seven crystal water molecules.In the unit cell there are four independent molecules and in each molecule the Cu(II)is in a slightly distorted square-pyramidal geometry, with two nitrogen atoms of1,10-phenanthro
25、line(N,N), one amino nitrogen atom and one carboxylate oxygen atomof L-arginate(N,O) in the equatorial plane (d(CuO)1.945C241.960A, d(CuN)1.982C242.043A) and a chloride in the apical position (d(CuCl)2.50C242.62A).The bond lengths in the complex are similar to corresponding values found for Cu(L-val
26、)(phen) (H2O)C1ClO4(Equatorial plane: d(CuO)1.928A, d(CuN)1.991C242.009A; axial: d(CuO)2.272A) 31, Cu2(L-arg)2(bpy)2(m2-ClO4)2C12ClO4C1H2On(Equatorial plane: d(CuO)1.922C241.929A, d(CuN)1.989C242.009A;Figure 1. ORTEP plot showing the structure of Cu(phen)(L-arg)Cl2, and the atom-numbering scheme.383
27、2 H. F. Ma et al.Downloaded By: Hua Zhou, Xiao At: 01:39 22 October 2008axial:d(CuO)2.503C242.593A)32.Thesquare-pyramidal geometryaroundCu(II)isseverelydistorted,withXCuZanglesbeing163.0C14to169.9C14whereXandZareanytwoatoms in para positions and the XCuY angles ranging from 81.9C14to 101.1C14where X
28、andYareanytwoatomsortho.Selectedbondlengthsandanglesaregivenintable2.N1,N2, O1, N5 and Cu1 atoms deviate by 0.3135, 0.6655, 1.0535, 0.3371 and 0.6266A, andN3, N4, O3, N6 and Cu2 atoms deviate by 0.4213, C00.3988, C00.6652, 0.2337 andC00.3183A, respectively, from the least-squares plane (C04.5596xC03
29、.3863yC016.9224Figure 2. Crystal packing view for complex Cu(phen)(L-arg)Cl2C17H2O, in which the crystal waters andhydrogen atoms are omitted for clarity.Table 2. Selected bond lengths (A) and angles (C14) of Cu(phen)(L-arg)Cl2C17H2O.Cu(1)O(1) 1.960(5) Cu(2)O(3) 1.945(5)Cu(1)N(5) 1.982(6) Cu(2)N(4)
30、2.014(7)Cu(1)N(2) 2.000(6) Cu(2)N(6) 2.033(6)Cu(1)N(1) 2.029(6) Cu(2)N(3) 2.043(6)Cu(1)Cl(1) 2.6208(19) Cu(2)Cl(2) 2.5049(19)N(8)C (36) 1.346(10) C (36)N(9) 1.294(11)C(36)N(10) 1.359(10) C(30)N(7) 1.285(11)C(30)N(11) 1.340(10) C(30)N(12) 1.324(11)O(1)Cu(1)N(5) 83.9(2) O(3)Cu(2)N(4) 90.4(2)O(1)Cu(1)N
31、(2) 91.7(2) O(3)Cu(2)N(6) 83.9(2)N(5)Cu(1)N(2) 170.5(2) N(4)Cu(2)N(6) 164.1(3)O(1)Cu(1)N(1) 163.3(3) O(3)Cu(2)N(3) 166.2(2)N(5)Cu(1)N(1) 99.9(2) N(4)Cu(2)N(3) 81.9(3)N(2)Cu(1)N(1) 81.9(3) N(6)Cu(2)N(3) 100.4(3)O(1)Cu(1)Cl(1) 100.88(17) O(3)Cu(2)Cl(2) 99.48(18)N(5)Cu(1)Cl(1) 92.61(19) N(4)Cu(2)Cl(2)
32、99.01(17)N(2)Cu(1)Cl(1) 96.51(18) N(6)Cu(2)Cl(2) 96.5(2)N(1)Cu(1)Cl(1) 95.17(19) N(3)Cu(2)Cl(2) 93.07(17)Synthesis, characterization and SOD-like activity 3833Downloaded By: Hua Zhou, Xiao At: 01:39 22 October 2008zC06.0307), showing that the five ligating atoms in the coordination sphere areapproxi
33、mately coplanar. The nitrogens of L-arginate guanidine are not coordinated tothe central copper and the bond lengths and angles of the guanidine CN bonds areanalogous to literature 32. Thus many intermolecular H-bondsNC1C1C1O2.855C243.076A(moderate strength), NC1C1C1Cl 3.219C243.358A(weakstrength) a
34、re formed among the guanidine nitrogens, seven crystal water oxygens anduncoordinated carboxylate oxygen of L-arginate. In addition, the average distancebetween intermolecular phen-rings is 3.586A, indicating intermolecular phen-ringstacking interactions in the crystal. Figure 3 shows the intermolec
35、ular aromatic-stackinginteraction.Intermolecular aromatic-stackingandhydrogen-bondinteractionsmakethesingle crystal exhibit the -a-b-a-b- type crystal structure similar to that observed inCu(phen)(L-val)(H2O)ClC1H2O 19, Cu(H2O) (L-met)(phen)ClO4C12H2O 33 andCu(L-val)(phen) (H2O)C1ClO431. Selected in
36、termolecular H-bonds are shown intable 3.The oxidation state of central copper in the complex is II although the reactantmaterial is cuprous chloride, explained by the instability of cuprous in water.3.2. Spectra propertiesThe IR spectrum provides further evidence for the structure of the complex. T
37、hestrong broad bands in the range 3440C243376cmC01are attributed to the OHstretching vibrations of water, and the bands in the range of 3267C243114cmC01can be attributed to stretching of the coordinated NH2group. The absence ofFigure 3. Intermolecular aromatic-stacking interaction of complex Cu(phen
38、)(L-arg)Cl2C17H2O Symmetrytransformations used to generate equivalent atoms: C0x, C0y,1C0z.Table 3. Hydrogen bonds lengths (A) for the title complex.N(6)C1C1C1O(8) 3.076(10) N(6)C1C1C1Cl(1) 3.358(8)N(7)C1C1C1O(7) 2.887(11) N(10)C1C1C1Cl(1) 3.219 (8)N(8)C1C1C1O(10) 2.907(13) O(6)C1C1C1O(11) 3.230(13)
39、N(9)C1C1C1O(9)#1 2.855(11) N(2)C1C1C1O(7) 3.021(12)N(10)C1C1C1O(4)#1 3.013(12) O(8)C1C1C1O(5) 3.180(8)N(11)C1C1C1O(2)#2 2.891(11) O(9)C1C1C1O(10)#3 3.016(14)N(5)C1C1C1O(6)#3 2.891(11) O(5)C1C1C1N(12) 3.370(10)Symmetry transformations used to generate equivalent atoms: #1: xC01, y, z; #2: x1, y,z; #3
40、: 1C0x,1C0y,1C0z.3834 H. F. Ma et al.Downloaded By: Hua Zhou, Xiao At: 01:39 22 October 2008any band in the region 1750C241700cmC01in the IR spectra of the isolatedcomplex suggests coordination of the COOC0group of L-arginate to copper(II).Bands in the range of 1650C241635cmC01and 1394C241384cmC01ca
41、n beattributed, respectively, to the antisymmetric and symmetric stretching vibrationsof the coordinated carboxylate, with C1vC0co2values (vasC0co2C0vsC0co2 200cmC01)consistent with monodentate coordination 3134. Thus, one can deduce thatL-arginate coordinates to copper(II) as bidentate N,O-ligands,
42、 confirmed by theresult obtained by X-ray diffraction. Bands at 1575cmC01, from the stretchingvibration of the CN group of phen, is weaker than that of free phen and the C14CH(854, 740cmC01) of phen shift to 851 and 724cmC01, confirming coordination of phennitrogen atoms to Cu(II).The electronic spe
43、ctrum in water presents four important absorption bands. Thebands at about 203, 223 and 274nm, are due to intra-ligand C25a C25* transitions of thephen-rings, showing two nitrogen atoms bonded to copper(II). The peak at 613nm ofthe complex is the d!d* transitions of copper(II) ions 3135.3.3. SOD-lik
44、e activityUnder illumination, riboflavin (VB2) reacts with tetramethylethylenediamine(CH3)2N(CH2)2N(CH3)2 producing superoxide radical anion OC1C02C0C1:VB2CH32NCH22NCH32! OC1C021Nitro blue tetrazolium (NBT) reacts with OC1C02; but complexes or native CuZnSODwill also:NBTOC1C02! blue formazane royal
45、purple2Complexes or native CuZnC0SODOC1C02! P 3Blue formazane may be monitored at 560nm by spectrophotometer. Complex ornative CuZnSOD react with OC1C02by competing with NBT (equation (3) after theyare added to the blank solution, and formation rates of blue formazane woulddecrease. Relationships be
46、tween the absorbence values of the solutions (absence andpresence of the complex or native CuZnSOD in blank solution) and different timesare shown in figure 4. The slope of line shows the rate of NBT reduction by OC1C02(equation (2). Smaller slope values of the lines are correspond to largerconcentr
47、ations of the complex or native CuZnSOD in blank solutions (figure 4),indicating larger inhibition of NBT reduction by complex or native CuZnSOD. Onecan conclude that the rate of OC1C02decaying becomes faster with increasingconcentrations of the complex or native CuZnSOD. We can get the percentagein
48、hibition (C17) of NBT reduction by the complex or native CuZnSOD according tothe formula: C17(1C0k0/k)C2100%, where k0and k are slope values of lines inthe presence and absence of the complex or native CuZnSOD in blanksolution, respectively, and then can obtain relationships between inhibition (C17)
49、 andconcentration (c) of the complex (figure 5). According to the formulaKQKNC1C1C1c(NBT)(k/k0C01)/c(Q), we can get the rate constants KQof the catalyzedSynthesis, characterization and SOD-like activity 3835Downloaded By: Hua Zhou, Xiao At: 01:39 22 October 2008reaction of the complex and native CuZnS
