吡咯甲亞胺鎳/銅/鋅配合物的合成、熒光性質(zhì)及鎳、銅配合物的晶體結(jié)構(gòu)

毛盼東　閆玲玲＊，　吳偉娜＊，　宋藝赫　姚必鑫（河南理工大學(xué)物理化學(xué)學(xué)院，焦作　454000）（河南理工大學(xué)材料科學(xué)與工程學(xué)院，焦作　454000）

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吡咯甲亞胺鎳/銅/鋅配合物的合成、熒光性質(zhì)及鎳、銅配合物的晶體結(jié)構(gòu)

毛盼東1閆玲玲＊，1吳偉娜＊，1宋藝赫2姚必鑫2
（1河南理工大學(xué)物理化學(xué)學(xué)院，焦作454000）
（2河南理工大學(xué)材料科學(xué)與工程學(xué)院，焦作454000）

摘要：合成并表征了3個配合物NiL（1），Cu2L2（2）和Zn2L2（3）（H2L=1，2-雙（3，5-二甲基-4-乙氧羰基-吡咯-2-基）苯）。單晶衍射結(jié)果表明在配合物1中，脫質(zhì)子配體用4個氮原子與金屬Ni(Ⅱ)配位，中心金屬離子為扭曲的平面正方形配位構(gòu)型。而雙核配合物擁有雙螺旋結(jié)構(gòu)，每個配體橋聯(lián)2個具有平面正方形配位構(gòu)型的銅中心。推測配合物3和2的結(jié)構(gòu)類似。此外還研究了配體和配合物的熒光性質(zhì)。

關(guān)鍵詞：席夫堿；配合物；吡咯；熒光

0　Introduction

The metal complexes of Schiff base bearing pyrrole units have been extensively investigated for a long time［1-2］.In particular，linear spaced bis（pyrrol-2 yl-methyleneamine ligands have attracted much recen attention due to the excellent fluorescent properties and good solubilities of their complexes.By varying

國家自然科學(xué)基金（No.21001040，21404033，21401046）和河南省教育廳自然科學(xué)基金（No.12B150011，14B150029）資助項目。

＊通信聯(lián)系人。E-mail：yll@hpu.edu.cn，wuwn08@hpu.edu.cn；會員登記號：S06N6704M1112。the spacers，mono-，bi-，tri-and tetra-nuclear metal complexes of such ligands have been generated［3-7］.

In fact，our previous work demonstrated that several Zn(Ⅱ)/Cu(Ⅱ) complexes with pyrrol-2-yl-methyleneamine ligands show considerable DNA-binding abilities［8-9］.Therefore，as a continuation of our research，Ni(Ⅱ)，Cu(Ⅱ) and Zn(Ⅱ) complexes with a pyrrol-2-ylmethyleneamine ligand derived from ethyl 5-formyl-2，4-dimethyl-pyrrole-3-carboxylate andbenzene-1，2-diamine（Scheme 1）have been synthesized.In addition，the fluorescence properties of the ligand and complexes were discussed in detail.

Scheme 1　Synthesis route of H2L

1　Experimental

1.1Materials and measurements

Solvents and starting materials for synthesis were purchased commercially and used as received.The melting point of the ligand was determined on a SGWX-4 microscopic melting point apparatus（uncorrected，madeinShanghaiPrecisionScientific Instrument Co.，Ltd.，China）.Elemental analyses were carried out on an Elemental Vario EL analyzer.The IR spectra（4 000～400 cm-1）were determined by the KBr pressed disc method on a Bruker V70 FT-IR spectrophotometer.1HNMRspectraofH2Lwas acquired with Bruker AV400 NMR instrument using DMSO-d6solvent.The UV spectra were recorded on a Purkinje General TU-1800 spectrophotometer.Fluorescence spectra were determined on a Varian CARY Eclipse spectrophotometer，and the pass width is 5 nm in the measurements of emission and excitation spectra.

1.2Synthesis of H2L

The ligand H2L was prepared by condension of ethyl 5-formyl-2，4-dimethyl-pyrrole-3-carboxylate（0.38 g，2 mmol）and benzene-1，2-diamine（0.11 g，1 mmol）in ethanol（10 mL）solution under refluxing for 4 h. The separated solids were filtered and washed with cold ethanol.Yield:0.34 g（74%）.m.p.156～157℃. Elemental analysis calcd.for C26H30N4O4（%）:C 67.51，H 6.54，N 12.11；Found（%）:C 67.43，H 6.68，N 11.98.1H NMR（400 MHz，DMSO-d6）δ:8.29（2H，s，CH=N），7.02～7.12（4H，m，Ar-H），4.15～4.20（4H，q，CH2CH3），2.40（6H，s，CH3），2.28（6H，s，CH3），1.23～1.27 （6H，t，CH3CH2）.FT-IR（cm-1）:ν（N-H）3 245，ν（O=C）1 697，ν（C=N）1 640.

1.3Syntheses of complexes 1～3

Complexes 1～3 were synthesized by reacting H2L （0.5 mmol）with Ni（OAc）2·4H2O（1∶1 ligand-metal molar ratio），Cu（OAc）2·2H2O and Zn（OAc）2·2H2O（2∶1 ligand-metal molar ratio）in methanol/THF（10 mL，1∶1，V/V）solution，respectively.The block crystals of 1 and 2 suitable for X-ray diffraction analysis were obtained by evaporating the reaction solutions at room temperature.Yellow powder of complex 3 is generated under same conditions.All complexes are soluble in DMF，DMSO and THF，slightly soluble in methanol，ethanol，ethyl acetate and acetone，insoluble in water and ether.

1:brown block，yield:78%.Anal.Calcd.for C26H28N4O4Ni（%）:C 60.14，H 5.44，N 10.79；Found（%）: C 60.01，H 5.60，N 10.68.FT-IR（cm-1）:ν（O=C）1 662，ν（C=N）1 601.

2:dark green block，yield:66%.Anal.Calcd.for C52H56N8O8Cu2（%）:C 59.59，H 5.39，N 10.69；Found （%）:C 59.40，H 5.51，N 10.55.FT-IR（cm-1）:ν（O=C）1 692，ν（C=N）1 589.

3:yellow powder，yield:84%.Anal.Calcd.for C52H56N8O8Zn2（%）:C 59.38，H 5.37，N 10.65；Found （%）:C 59.48，H 5.26，N 10.49.FT-IR（cm-1）:ν（O=C）1 693，ν（C=N）1 588.

1.4X-ray crystallography

The X-ray diffraction measurement for 1 and 2 were performed on a Bruker SMART APEXⅡ CCD diffractometer equipped with a graphite monochromatized Mo Kα radiation（λ=0.071 073 nm）by using φω scan mode.Semi-empirical absorption correction was applied to the intensity data using the SADABS program［10］.The structures were solved by direct methods and refined by full matrix least-square on F2using the SHELXTL-97 program［11］.All the H atoms were positioned geometrically and refined using a riding model. A summary of crystal data and details of the structure refinements are listed in Table 1.

CCDC:1433711，1；1433712，2.

2　Results and discussion

2.1Crystal structures of 1 and 2

As shown in Fig.1a，the asymmetric unit of complex 1 contains one half of a molecule with Ni(Ⅱ)ionlyingonthetwofoldrationalaxis.The deprotonated ligand uses all of its N atoms to bind to the Ni(Ⅱ)ion，which displays a distorted square plana geometry.The dihedral angle between two pyrrole ring is 22.66°，which is equal divided by the phenyl bridge ring.

Table 1　Selected crystallographic data for 1 and 2

The crystal structure of 2（Fig.1b）consists of two unsymmetrical Cu(Ⅱ) ions situated on the two fold rational axis，and each one bound to four nitrogen atoms from two ligands in an extremely distorted square-planar geometry.Also，the molecule of2 possesses a double-stranded helical geometry.The twist around phenyl bridge divides the ligand into two pyrrol-2-yl-methyleneamine subunits，each of which is bound to a different Cu(Ⅱ)ion.Different from complex 1，the phenyl ring of each independent ligand in complex 2 makes the dihedral angle of 41.20°and 45.28°with two pyrrole units，respectively.In addition the N-Cu-N angles range from 83.70（11）°to 153.86（17）and the bonds distances of Cu-N span from 0.195 5（3 to 0.201 3（3）nm.The distance between two coppe centersis 0.3208nm.Its molecular structure is similaras that of Cu2La2（H2La=bis（3-ethyl-4-methyl-5-ethyloxy -carbonyl-pyrrol-2-yl-methyleneamino）benzene）［3］and Cu2Lb2（H2Lb=1，2-bis［3，4-dimethyl-5-ethyloxy-carbonyl -pyrrol-2-yl-methyleneamino］benzene）［9］.

Fig.1　ORTEP drawing of 1（a）and 2（b）with 10%thermal ellipsoids

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

2.2IR spectra

IR spectra of three complexes 1～3 are similar to those of complexes previously reported［9-10］.The νNHvibration of the free ligand is at 3 279 cm-1［9］，but disappeared in the corresponding complexes，indicating that nitrogen of the pyrrole takes part in coordination and active hydrogens are substituted by metal ions.The νN=Cof the ligand shifts from 1 640 to 1 588～1 601 cm-1in the complexes，indicating azomethine nitrogens coordinate to metal ions［10］.The νO=Cof ester in the complexes 2 and 3（1 693 and 1 692 cm-1，respectively）is similar as that in the ligand（1 697 cm-1）.However，this band shifts to 1 662 cm-1in complex 1，probably due to the strong coordination between nitrogen of the pyrrole and metal centers［9-10］.

2.3UV spectra

The UV spectra of H2L and complexes 1～3 in THF solution（concentration:1×10-5mol·L-1）were measured at room temperature（Fig.2）.The spectra of HL features two main bands located around 293（ε= 20 982 L·mol-1·cm-1）and 368 nm（ε=3 472 L·mol-1· cm-1）.The bands could be assigned to characteristic π-π*transitions centered on pyrrole rings and imine units，respectively［12］.The blue shift and hypochromicity of pyrrole π-π*transitions bands could be observed in complexes 1～3（275 nm，ε=4 676 L·mol-1·cm-1for 1；271 nm，ε=9 370 L·mol-1·cm-1for 2；273 nm，ε= 6 581 L·mol-1·cm-1for 3）.Meanwhile，imine π-π* transitions bands split into two bands in complexes 1～3（1:329 nm，ε=9 473 L·mol-1·cm-1；390 nm，ε= 7837L·mol-1·cm-1.2:342nm，ε=15 588 L·mol-1·cm-1；422 nm，ε=16 123 L·mol-1·cm-1.3:350 nm，ε=25 892L·mol-1·cm-1；432 nm，ε=21 693 L·mol-1·cm-1），accompanyingwithsignificantlyhyperchromiceffect. Furthermore，a new band at 482 nm in complex 1 should be attributed to the Ni(Ⅱ) d-d transition［2］. Different from that of free ligand and complex 1，the similar UV spectra of complexes 2 and 3 indicate that both complexes should be isostructural.Therefore，it can be roughly concluded that the possible composition of the Zn(Ⅱ)complex 3 should be Zn2L2.

Fig.2　UV spectra of the ligand HL（a），1（b），2（c）and 3（d）in THF solution at room temperature

2.4Fluorescence spectra

Fig.3　Fluorescence emission spectra of the ligand HL（a），1（b），2（c）and 3（d）in THF solution at room temperature

The fluorescence spectra of the ligand HL and complexes 1～3 have been studied in THF solution（Concentration:1×10-5mol·L-1）at room temperature The results show that the emission spectra of the three complexes exhibit only one main peak at 550 nm when excited at 331 nm，which is similar as that o the ligand（Fig.3）.It is obvious that the presence o the metal ions in complexes 1～3 could largely quench the fluorescence emission of the ligand［13］.

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中圖分類號：O614.81+3；O614.121；O614.24+1

文獻(xiàn)標(biāo)識碼：A

文章編號：1001-4861（2016）05-0879-05

DOI：10.11862/CJIC.2016.098

收稿日期：2015-12-06。收修改稿日期：2016-01-30。

Ni(Ⅱ)/Cu(Ⅱ)/Zn(Ⅱ)Complexes Baded on a Bis（pyrrol-2-yl-methyleneamine）Ligand：Syntheses，Characterization，F(xiàn)luorescence Properties and Crystal Structures of Ni(Ⅱ)/Cu(Ⅱ)Complexes

MAO Pan-Dong1YAN Ling-Ling＊，1WU Wei-Na＊，1SONG Yi-He2YAO Bi-Xin2
（1Department of Physics and Chemistry，Henan Polytechnic University，Jiaozuo，Henan 454000，China）
（2School of Materials Science and Engineering，Henan Polytechnic University，Jiaozuo，Henan 454000，China）

Abstract：Three complexes，NiL（1），Cu2L2（2）and Zn2L2（3）based on H2L（where H2L=1，2-bis（3，5-dimethyl-4 ethyloxy-carbonyl-pyrrol-2-yl-methyleneamino）benzene）were synthesized and characterized.The X-ray diffraction analyses results show that in complex 1，the deprotonated ligand uses all of its N atoms to bind to the Ni(Ⅱ)ion which displays a distorted square planar geometry.However，the binuclear complex 2 possesses a double stranded helical geometry，in which each Cu(Ⅱ) ion is also four-coordinated with an extremely distorted square planar geometry.The proposed structure of complex 3 is similar as that of 2.In addition，the fluorescenc properties of all compounds are investigated in detail.CCDC:1433711，1；1433712，2.

Keywords：Schiff base；complex；pyrrole；fluorescence