YANG HongGUO Li-Jun

(Department of Chemistry and Chemical Engineering,Taiyuan Institute of Technology,Taiyuan 030008,China)

Syntheses,Characterization and Radical Scavenging Activity of Two Copper(Ⅱ)Complexes Containing Pyrazoles

YANG Hong＊GUO Li-Jun

(Department of Chemistry and Chemical Engineering,Taiyuan Institute of Technology,Taiyuan 030008,China)

By using a tripodal ligand tris(3,5-bimethyl-pyrazolylmethyl)amine(TMPzA)and a bridged ligand thiophenedicarboxylic acid(H2TPDC),two binuclear copper(Ⅱ)complexes have been synthesized and characterized.It has been found that TMPzA lost an arm and coordinated to copper with di(3,5-bimethylpyrazolylmethyl)amine(DMPzA)in complex[Cu2(DMPzA)2(TPDC)2]ClO4(1).The structure presented a microcycle with the Cu(1)…Cu(1A)distance of 0.786 84 nm.The complex[Cu2(TMPzA)2(TPDC)(H2O)2](ClO4)2(2)is a binuclear structure and with the TMPzA completely.The investigation in Feton system shows that complex 1 has better hydroxyl radicals scavenging property than that of complex 2.CCDC:1411232,1;1411233,2.

binuclear copper(Ⅱ)complexes;Feton system;hydroxyl radicals scavenging

0 Introduction

Oxygen-derived free radicals such as superoxide anion radical(O2·-)and hydroxyl radical(·OH)which can oxidize the proteins,carbonhydrates,nuclein and fats aremost active and harmful radicals in organisms[1-2]. The cells and organs would be injured and cause diseases such as coronary heart disease,rheumatoid arthritis and cancer[3]if these radicals cannot be removed just in time[4-6].So the study of scavenging of oxygen-derived free radicals is more valuable.

It is well-known that free radicals are controlled on human body by some enzymes such as superoxide dismutase and peroxidase[7],but the non-enzymes can also scavenge free radicals and play an important role toprotectbodiesfromfreeradicals.Thepolyfunctionalcoordinatedpolymerandmulti-nuclear complexes can be used to scavenge hydroxyl radicals[8-12].The hydroxyl radicals can be generated via a redox process from Feton system[13].Herein,we report two excellenthydroxylradicalsscavengingbasedon binuclear Cu(Ⅰ)complexes.The two complexes were added to the Feton system to compete the hydroxyl radicals with salicylic acid and the complexes showed good ability and they might be potential hydroxyl radical scavenger.

1 Experimental

1.1 Starting materials and general methods

All commercially available chemicals were of analytical grade and directly used without further purification.Infrared spectra were obtained(KBr disk, 4000～400cm-1)using a sp-100 spectrometer.Elemental analyses were performed in a PE240C elemental analyzer.UV-Vis spectra were carried out with a TU-1901 double beam instrument.

1.2 Synthesis of[Cu2(DMPzA)2(TPDC)2]ClO4(1) and[Cu2(TMPzA)2(TPDC)(H2O)2](ClO4)2(2)

A colorless aqueous solution of 2,5-Thiophenedicarboxylate(17.2 mg,0.1 mmol,deprotonated by reactingwithNaOH)wasaddedtoa10mL acetonitrile solution of Cu(ClO4)2·6H2O(74.2 mg,0.2 mmol)and TMPzA(68.2 mg,0.2 mmol)with stirring for 30 min,filtered and allowed to evaporate at room temperature.Green rectangular crystals of 1 and blue needle crystals of 2 were deposited after a few days, which were separated and air-dried.Yield:40%for 1; 30%for 2(based on copper).Anal.Calcd.for 1 (C36H41ClCu2N10O12S2,%):C,41.84;H,3.96;N,13.56. Found(%):C,41.72;H,4.03;N,13.67.Calcd.for 2 (C42H60Cl2Cu2N14O14S,%):C,41.48;H,4.94;N,16.13. Found(%):C,41.29;H,4.85;N,16.07.IR data(cm-1) for 1:3 434(m),2 925(w),1 639(m),1 585(s),1 554 (m),1 529(m),1 420(w),1 318(m),1 234(w),1 121(s), 1 061(m),808(w),774(w),625(w).For 2:3 435(s),2 925(w),1 627(s),1 557(m),1 468(w),1 393(m),1 349 (m),1 121(vs),797(w),727(w),624(w).

1.3 Crystal structure determination

The X-ray diffraction measurements for 1 and 2 were performed on Bruker SMART APEXⅡCCD diffractometer with graphite-monochromatized Mo Kα radiation(λ=0.071 073 nm)by using φ-ω scan mode at 100(2)K for 1 and 296(2)K for 2.The absorption corrections were applied using SADABS program[14]. All structures were solved by direct methods and refined by full matrix least-square on F2using SHELXTL program package[15].All non-hydrogen atoms were refined with anisotropic displacement parameters.All the hydrogen atoms bonded to carbon atoms were placed in calculated positions and treated in a ridingmodel approximation.The hydrogen atoms of the H2O in complex 2 were located in a difference Fourier map.In complex 1,the part of one DMPzA molecule (N3,N3A,N4,N4A,N5,N5A,C12,C12A,C13, C13A,C14,C14A,C15,C15A,C16,C16A,C17, C17A,C18 and C18A)were disordered by refining over two sides with occupancy of part 21.00 and -21.00.The crystal data and details of structural determination for the complex 1 and 2 are presented in Table 1.

CCDC:1411232,1;1411233,2.

Table 1Crystallographic data and details for complexes 1 and 2

Continued Table 1

1.4 Hydroxyl radical-scavenging essay

1.4.1 Generation and trapping of hydroxyl radicals

The hydroxyl radicals were generated by the well-known Fenton reaction using hydrogen peroxide and ferrous sulfate[16].If the salicylic acid is added to theFentonreactionsystem,thecharacteristic absorption bands at 504 nm will appear due to the hydroxyl radicals trapped and the products(a)and(b) formed,the reaction occurring as Scheme 1[17].The UV absorbanceat504nmwilldecreasewhenthe complexes which can scavenge the hydroxyl radical were added to the solution.That means we can determine the radical-scavenging activities of the complexes by measuring the absorbance of 504 nm.

1.4.2 Hydroxyl radical-scavenging rate measurement

The FeSO4solution(2 mL,1.8 mmol·L-1)was mixed with salicylic acid solution(2 mL,1.8 mmol· L-1)in five 10 mL volumetric flasks,then the solution of the two complexes with differentconcentrations was added to the mixture,respectively.After shaking, 1 mL H2O2was added andthe final volume was made up to 10 mL with double distilled water.The solutionsweretransferredtothecellforthe absorption measurement at 504 nm on a TU-1901 spectrophotometer with the temperature 37℃,the time 30 min and the pH 7.38.The absorption data of a and b(Scheme 1)by the action of the complexes with various concentrations can be obtained.The hydroxyl radical-scavenging activity was calculated.

Scheme 1

2 Results and discussion

2.1 Descriptions of crystal structures

2.1.1 Crystal structure of[Cu2(DMPzA)2(TPDC)2]ClO4(1)

Fig.1Molecular structure of complex 1

Table 2Selected bond lengths(nm)and angles(°)in 1

Complex 1 crystallizes in the monoclinic space group P2/n and has an independent molecule in the centrosymmetric unit,as shown in Fig.1.The tripodal ligand TMPzA lose a pendant arm and turn to DMPzA with the N atom of amine protonated partially,the possiblemechanismhasbeendiscussedinour previous works[18].The molecular structure of 1 consists of two Cu(Ⅰ)ions bridged through two Thiophenedicarboxylate molecular resulting in a microcycle with the intramolecular Cu(1)…Cu(1A)distance of 0.786 84 nm.The copper ions are coordinated with two Npyrazoleatoms,one Naminefrom a DMPzA molecule and two Ocarboxylatoms from two H2DPC molecules,forming a distorted square pyramidal geometry.The Cu-Namineis somewhat longer than Cu-Npyrazoleand it is consistent with this class of complexes.The three N atoms(N2, N3,N4)and O3 define the bottom plane with the Cu atoms protrude out from it by 0.006 75 nm.The Cu1-O1 bond occupy the axial site and is significantly longer than other bonds may be due to the strain of the carboxylate ligand and the Jahn-Teller effect from the copper atom.Selected bond lengths and angles for 1 are listed in Table 2.

2.1.2 [Cu2(TMPzA)2(TPDC)(H2O)2](ClO4)2(2)

Be different from 1,the tripodal ligand TMPzA in 2 has not decomposed and coordinate to the Cu atoms with three Npyrazoleatoms and one Namineatom,as shown in Fig.2.The two Cu(Ⅰ)ions are also linked by the H2TPDC ligand and form a centrasymmetric structure.Each Cu ion is coordinated by four N atoms from TMPzA,one O atom form H2TPDC and one O atom from H2O molecule,forming a distorted octahedral coordination geometry.The three Npyrazoleatoms and O from H2O are located at the equatorial plane of Cu center,while the Namineand Ocarboxylatoms are located at the apical positions.The most distinguished feature of 2 lies in the Cu-Namine(Cu1-N3 0.206 4(7)nm;Cu2-N10 0.207 8(7)nm)bond lengths are significantly shorter than the Cu-Npyrazole(Cu1-N4 0.235 9(6)nm; Cu2-N8 0.238 0(7)nm)bonds,which is very rare in this class of complexes.Selected bond lengths and angles for 2 are listed in Table 3.

Fig.2Molecular structure of complex 2

2.2 Hydroxyl radical-scavenging studies

The absorbance with various concentrations of complexes 1 and 2,Ai,are summarized in Table 4 andtheradical-scavengingratesafteradding complexes are shown in Fig.3.The radical-scavenging rate(η)is calculated by the equation:η=1-and the plots of hydroxyl radical-scavenging rate vs the extent of complexes used can be made from the data, where A0(A0=0.533 5)represents the absorbance of the reaction system without any complex.It is found that the greater the concentration of 1 and 2,thelower the absorbance of a and b in the reaction system and the higher the hydroxyl radical-scavenging rate.Moreover,the radical-scavenging rate of 1 is somewhat higher than that of 2,which may be due to the different coordination environment of Cu ions.In complex 1,the Cu ions are five-coordinated with a potential coordination site that can combine with the hydroxyl radical while the Cu ions in complex 2 are six-coordinated.

Table 3Selected bond lengths(nm)and angles(°)in 2

Table 4Hydroxyl radical-scavenging of 1 and 2

Fig.3Hydroxyl radical-scavenging rate of 1 and 2

3 Conclusions

Two binuclear copper(Ⅱ)complexes containing polyamine and bridged carboxyl ligands were prepared and characterized.In two complexes,the copper ions have square-pyramidal geometry and were bridged by thecarboxylligandviatheoxygenatomsin monodentate mode.The radical-scavenging activity of the two complexes was determined and the results indicate that two complexes present excellent radicalscavenging activities.

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3.2.2 進行教學(xué)改革 首先，按照科學(xué)的標準進行課程設(shè)置。武進少體校必須以本校運動員的現(xiàn)實狀況作為參考，根據(jù)運動員的時間和實際要求，結(jié)合蘇教版教材的特點和學(xué)校實際情況，在不脫離國家義務(wù)教育背景的基本前提下，重新修改和制訂一個既注重運動員基礎(chǔ)文化知識和基本技能的傳授，又利于學(xué)生德、智、體勞全面發(fā)展的課程體系。在此基礎(chǔ)上，建議武進少體校能夠編寫與本校運動員的文化學(xué)習(xí)基礎(chǔ)相適應(yīng)的教學(xué)大綱和教材體系。

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[17]LI Yan(李艷),GONG Shi-Lei(鞏士磊),CHE Ying(車影), et al.Chin.J.Appl.Chem.(應(yīng)用化學(xué)),2015,32(8):948-954

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兩個含吡唑環(huán)的雙核銅配合物的合成、表征及清除自由基活性

楊紅＊郭麗君
(太原工業(yè)學(xué)院化學(xué)與化工系，太原030008)

以三(3,5-二甲基吡唑甲基)胺(TMPzA)及2，5-噻吩二羧酸為配體合成了2個雙核Cu的配合物[Cu2(DMPzA)2(TPDC)2]ClO4(1)和[Cu2(TMPzA)2(TPDC)(H2O)2](ClO4)2(2)。在1中，配體TMPzA發(fā)生裂解，以二(3，5-二甲基吡唑甲基)胺(DMPzA)與Cu配位，并在2個Cu原子之間形成一個大環(huán)，2個Cu原子之間的距離為0.786 84 nm。清除自由基實驗發(fā)現(xiàn)，配合物1比2具有較好的清除自由基活性。

雙核銅配合物；Feton體系；清除羥基自由基

O614.121

A

1001-4861(2017)06-1059-06

2017-01-13。收修改稿日期：2017-04-18。

10.11862/CJIC.2017.125

國家自然科學(xué)基金(No.)資助項目。

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