YANG Qing-Cui　SUN Xio-HongLIU Yun-F　CHEN BngJIN Ru-Yi　MA Hi-Xi（College of Chemil Engineering，Northwest University，Xi’n 710069，Chin）（Shool of Siene，Xi'n University of Arhiteture n Tehnology，Xi’n 710055，Chin）（Chemil Reserh Institute，Northwest University，Xi’n 710069，Chin）（College of Chemistry &Mterils Siene，Northwest University，Xi’n 710069，Chin）

Synthesis,Structure and Biological Activity of3-Methyl-4-(3-nitrobenzylideneamino)-5-ethoxycarbonyl-methylsulfanyl-1,2,4-triazole①

YANG Qing-Cuia，b②SUN Xiao-Honga，c②
LIU Yuan-FadCHEN Bangd
JIN Ru-YiaMA Hai-Xiaaa（College of Chemical Engineering，Northwest University，Xi’an 710069，China）
b（School of Science，Xi'an University of Architecture and Technology，Xi’an 710055，China）
c（Chemical Research Institute，Northwest University，Xi’an 710069，China）
d（College of Chemistry &Materials Science，Northwest University，Xi’an 710069，China）

A Schiff base was synthesized by3-methyl-4-amino-5-ethoxycarbonyl-methylsulfanyl-1，2，4-triazole with3-nitrobenzaldehyde.The structure was confirmed by1H NMR，IR，H RMS，TGA techniques and X-ray diffraction.The crystal belongs to monoclinic system，space group P21/c，with a = 8.965（2），b = 21.903（5），c = 9.197（2）Å，β = 114.011（4）°，C14H15N5O4S，Mr=349.08，V = 1649.7（6）Å3，Dc= 1.407 g·cm-3，Z = 4，F（000）= 728，μ = 0.226 mm-1，the final R = 0.0574 and wR = 0.1336 for 2932 unique reflections with I ＞ 2σ（I）.Furthermore，the biological activity to four vegetable pathogens has been tested.The title compound exhibits better biological activity to four vegetable pathogens compared to the Schiff base without 5-ethoxycarbonyl and to Gibberlla saubinetti in EC95compared with triadimefon.

Schiff base,crystal structure,4H-4-amino-1,2,4-triazole,biological activity

1　INTRODUCTION

It has been found that many 1，2，4-triazoles possess a wide spectrum activities including antibacterial，anticancer，antiviral，anti-infection and herbicidal activity［1-4］.As an important type of fungicides，Schiff bases derived from 1，2，4-triazole compounds attracted growing interest for their high effectiveness and low poisonousness［5-8］.In continuation of our interest in the synthesis and biological activity of 4H-4-amino-1，2，4-triazole Schiff bases［9-12］.In order to obtain higher biological activity compounds，we aimed to obtain new Schiff bases including 5-ethoxycarbonyl which may be more through cell wall of pathogens easily.The structure was confirmed by1H NMR， IR，H RMS and TGA techniques［13，14］.The crystal structure and TGA analysis of the title compound are reported here.In addition，the biological activity of the compounds to four pathogens，containing Gibberlla nicotiancola，Pythium solani，Fusarium oxysporium f.s.p.niveum and Gibberlla saubinetii，has been tested.

2　EXPERIMENTAL

2.1Reagents and instruments

All chemical reagents purchased were of chemical or analytical grade and used without further purification.The melting point determination was performed on a SMP3 melting point apparatus.1H NMR spectra were recorded on a Bruker INOVA-400MHz spectrometer with CDCl3-d3as the solvent and TMS as an internal standard.HRMS was obtained from micrOTOF-Q II mass spectrometer.Infrared spectra （IR）were recorded on an irPrestige-21 FT-IR spectrometer.Thermogravimetric analysis （TGA）data were collected with a Mettler-toledo TGA/SDTA851 analyzer in N2at a heating rate of 10 ℃ min-1.The single-crystal structure of the title compound was determined on a Bruker Smart APEX II CCD diffractometer.

2.2Synthesis of the title compound

The title compound was synthesized by3-methyl-4H-4-amino-3-thiol-1，2，4-triazole according to the reference［14］.Yield:64.2%，m.p.127.3～128.8 ℃.ESI-HRMS for C14H15N5O4S ［M+H］+calcd.:350.0845；found:350.0841.IR （KBr，cm-1）:2942 （C-H），1736 （C=O），1638 （C=N），1613 1503 1460 （C=C），1345 （C-NO2），1301 （C-N），1228 （C-S），1185 （C-O）.1H NMR （CDCl3，400 MHz，TMS）:δ （ppm）8.87 （s，1H），8.71 （s，1H），8.44 （d，J = 18.7 Hz，1H），8.22 （d，J = 7.1 Hz，1H），7.73 （s，1H），4.29～3.96 （m，4H），2.56 （s，4H），1.27 （t，J = 6.9 Hz，3H）.2.3Structure determination and refinement

The crude product was recrystallized from absolute ethanol，and then the title compound dissolved in ethanol was stood at room temperature by slow evaporation.Transparent-yellow single crystal suitable for X-ray analysis was obtained after two months.A yellow single crystal with approximate dimensions of 0.39mm × 0.25mm × 0.20mm was selected for data collection.X-ray diffraction data were collected on a Bruker SMART APEX II CCD diffractometer equipped with a graphite-monochromated MoKα radiation （λ = 0.71073 Ǻ）by using an F-ω scan mode at 296（2）K.A total of 8184 reflections with 2932 independent ones （Rint= 0.0657）were collected in the ranges of 1.86＜θ＜25.10º，-10 ≤h≤10，-26≤k≤17 and -10≤l≤10，of which 2932 with I ＞ 2σ（I）were used in the succeeding refinement.The structure was solved by direct methods with SHELXS-97［15］，and refined using the full-matrix least-squares technique on F2with anisotropic thermal parameters for all non-hydrogen atoms using SHELXL-97［16］.All C-bound H atoms were placed in the geometrically idealized positions and refined isotropically in the riding model approximation with C-H = 0.93 to 0.97 Å and Uiso（H）= 1.2～1.5Ueq（C）.The final refinement give R = 0.0574 and wR = 0.1336，（Δ/σ）max= 0.000，S = 1.037，（Δρ）max= 0.351 and （Δρ）min= -0.268 e/Å3.

2.4Biological activity test

The biological activity of the title compound to four vegetable pathogens，containing Gibberlla nicotiancola （A），Pythium solani （B），Fusarium oxysporium f.s.p.niveum （C）and Gibberlla saubinetii （D），was tested according to the method of the reference［13］.Triadimefon and the Schiff base without 5-ethoxycarbonyl were used as the comparison compounds.

3　RESULTS AND DISCUSSION

3.1Thermogravimetric analysis (TGA) of the title compound

The TGA data of the title compound with 1.4510 mg were collected on a Mettler-toledo TGA/SDTA851 analyzer in N2at a heating rate of 10 ℃ min-1.The TGA curve is illustrated in Fig.1.TGA measurement was conducted to determine the thermal stability of the title compound.It can be found that the compound has an endothermic peak at 128.10，℃ which corresponds to m.p.127.3～128.8 ℃.The TGA curve also reveals that the compound has an exothermic peak at 225.58 ℃，being ascribed to the loss of nitrobenzyl and ethoxycarbonyl （found:64.65%；calcd:64.47%）at 217.42～382.40.℃ The remaining product weight is32.31% when further heating at the range of382.40～418.71 ℃，whichcan be ascribed to3-methyl-4H-4-amino-1，2，4-triazole residue （calcd.:32.05%）.

Fig.1.TGA curve of the title compound at a heating rate 10 ℃ min-1

3.2Crystal structure

A yellow single crystal of the title compound was cultured for X-ray diffraction analysis.The selected bond lengths and bond angles of the title compound are listed in Table 1.The molecular structure is shown in Fig.2.The crystal packing of the compound is presented in Fig.3.

Fig.2.Molecule structure of the title compound

Fig.3.Packing diagram of the title compound of a unit cell

Table 1.Selected Bond Lengths (Å) and Bond Angles (°) Determined by X-ray Diffraction

According to Table 1，the bond length of 1.264（3）Å between atoms N（2）and C（7）is similar to those observed in other Schiff bases［17］，indicating it is a double bond.The results indicate that the carbonnitrogen bond lengths on the triazole ring are also intermediate between typical C-N single （1.47 Å）and C=N double （1.27 Å）bonds［18］from the better conjugated effect of triazole ring.It can be found that the C-S bond lengths are almost within the typical C-S single bond （1.82 Å）［12］from the effect of triazole ring and ethoxycarbonyl.It can be calculated that the torsion angle of N（3）-N（2）-C（7）-C（6）is -177.1°，indicating that the triazole and benzene rings are almost coplanar in the molecular structure.The C-H··N and C-H··O hydrogen bonds in Table 2 contribute to the stability and packing of the structure （Fig.3）.It can be found that the title compound has different hydrogen bond connections compared with N-H··S connections of the Schiff base without 5-ethoxycarbonyl［12］and it could be beneficial to further study the relationship between the structure and properties.

Table 2.Hydrogen Bond Lengths (Å) and Bond Angles (°) for the Compound

3.3Biological activity

In this study，we focus our attention on the structural activity relationship.The biological activity test data are given in Table3.

The results indicate that the tested compounds exhibit different antifungal activity to the four plant pathogens.It is interesting to note that the EC50and EC95values of the title compound are significantly less than the Schiff base without 5-ethoxycarbonyl.It can be also found that the EC95value of the title compound to Gibberlla saubinetti is less than triadimefon.All of this means that the title compoundshowed a good activity compared to the Schiff base without 5-ethoxycarbonyl and to Gibberlla saubinetti in EC95compared with triadimefon.

Table3.Biological Activity Test Results of the Compound to Four Vegetable Pathogens

REFERENCES

（1）Uzgoren-Baran，A.；Tel，B.C.；Sarigol，D.；Ozturk，E.I.；Kazkayasi，I.；Okay，G.；Ertan，M.；Tozkoparan，B.Thiazolo［3，2-b］-1，2，4-triazole-5（6H）-one substituted with ibuprofen:novel non-steroidal anti-inflammatory agents with favorable gastrointestinal tolerance.Eur.J.Med.Chem.2012，57，398-406.

（2）Eweiss，N.F.；Bahajaj，A.A.；Elsherbini，E.A.Synthesis of heterocycles.Part VI ［l］.Synthesis and antimicrobial activity of some amino-5-aryl-l，2，4-triazole-3-thiones and their derivatives.J.Heterocyclic Chem.1986，23，1451-3787.

（3）Liu，X.L.；Liu，Y.H.；Shi，Y.C.；Guan，P.Y.Application of Schiff bases in organic synthesis.Chin.J.Org.Chem.2002，22，482-488.

（4）Khanmohammadi，H.；Abnosi，M.H.；Hosseinzadeh，A.；Erfantalab，M.Synthesis，biological and computational study of new Schiff base hydrazones bearing3-（4-pyridine）-5-mercapto-1，2，4-triazole moiety.Spectrochim Acta Part A 2008，71，1474-1480.

（5）Isloor，A.M.；Kalluraya，B.；Shetty，P.Regioselective reaction:synthesis，characterization and pharmacological studies of some new Mannich bases derived from 1，2，4-triazoles.Eur.J.Med.Chem.2009，44，3784-3787.

（6）Chohan，Z.H.；Sumrra，S.H.；Youssoufi，M.H.；Hadda，T.B.Metal based biologically active compounds:design，synthesis，and antibacterial/antifungal/cytotoxic properties of triazole-derived Schiff bases and their oxovanadium（IV）complexes.Eur.J.Med.Chem.2010，45，2739-2747.

（7）Bektas，H.；Karaali，N.；Sahin，D.；Demirbas，A.；Karaoglu，A.S.；Demirbas，N.Synthesis and antimicrobial activities of some new 1，2，4-triazol-ederivatives.Molecules.2010，15，2427-2438.

（8）Eswaran，S.；Adhikari，A.V.；Shetty，N.S.Synthesis and antimicrobial activities of novel quinoline derivatives carrying 1，2，4-triazole moiety.Eur.J.Med.Chem.2009，44，4637-4647.

（9）Sun，X.H.；Tao，Y.；Liu，Y.F.；Jia，Y.Q.；Chen，B.；Yang，J.W.Synthesis and biological activities of N-（5-Alkyl-2，4-dihydro-3-thioxo-1，2，4-tria-zol-4-yl）Schiff bases.Chin.J.Org.Chem.2008，28，155-159.

（10）Sun，X.H.；Bai，Y.；Liu，Y.F.；Chen，B.Synthesis，structure and biological activities of3-substituted phenoxymethyl-4-amino-1，2，4-triazol-5-thione Schiff bases.Acta Chim.Sinica.2010，68，788-792.

（11）Lu，W.T.；Sun，X.H.；Liu，Y.F.；Jin，R.Y.Synthesis and biological activities of 4-amino-5-benzyl-3-mercapto-1，2，4-triazole Schiff bases.Chin.J.Chem.2012，75，361-364.

（12）Jin，R.Y.；Sun，X.H.；Liu，Y.F.；Chen，B.；Shen，S.Q.；Ma，H.X.Synthesis，structure and biological activity of 5-benzyl-4-amino-1，2，4-triazole-3-thione Schiff base.Chin.J.Struct.Chem.2014，33，253-257.

（13）Yand，Q.C.；Sun，X.H.；Liu，Y.F.；Jin，R.Y.；Ma，H.X.Synthesis and biological activity of Schiff base derivatives of3-methyl-4-amino-5-ethoxycarbonyl-methylsulfanyl-1，2，4-triazole.Chin.J.Chem.2013，76，758-761.

（14）Yand，Q.C.；Sun，X.H.；Liu，Y.F.；Chen，B.；Shen，S.Q.Synthesis and fungicidal activity of Schiff basesof 5-ethoxycarbonyl-methylsulfanyl-1，2，4-triazole.Chin.J.Appl.Chem.2014，31，788-792.

（15）Sheldrick，G.M.SHELXS-97.Program for the Solution of Crystal Structures.University of Göttingen，Germany 1997.

（16）Sheldrick，G.M.SHELXL-97.Program for the Refinement of Crystal Structures.University of Göttingen，Germany 1997.

（17）Pan，X.Q.；Huang，S.S.；Wang，F.；Fan，H.；Leng，H.；Zhang，H.L.；Diao，Y.P.Synthesis，crystal structure and antibacterial activity of two hydrazones derived from 2-fluorobenzhydrazide.Chin.J.Struct.Chem.2013，32，142-148.

（18）Allen，F.H.；Kennard，O.；Watson，D.G.Tables of bond lengths determined by X-ray and neutron diffraction.Part I.Bond lengths in organic compounds.J.Chem.Soc.Perkin.Trans.2 1987，s1--s19.

10.14102/j.cnki.0254-5861.2011-0471

6 August 2014；accepted 11 October 2014 （CCDC 918242）

①This project was supported by the National Natural Science Foundation of China （No.21073141）and the Shaanxi Provincial Education Department Foundation （No.2013JK0666）

②Corresponding authors.Yang Qing-Cui，majoring in organic synthesis and pesticide chemistry.E-mail:yqcsrg@126.com；Sun Xiao-Hong，professor，research field:organic chemistry.E-mail:xhsun888@sohu.com