谷長生 郝曉敏＊, 侯煥瑤 陳藝文 黎芷伶 李 泳 宋文東

三個(gè)含2，4-二氯苯乙酸配體的Mg髤、Ca髤和Cd髤配合物的合成及晶體結(jié)構(gòu)

谷長生1郝曉敏＊,1侯煥瑤1陳藝文1黎芷伶1李 泳1宋文東＊,2

(1廣東海洋大學(xué)化學(xué)與環(huán)境學(xué)院應(yīng)用化學(xué)系，湛江 524088)
(2浙江海洋大學(xué)石化與能源工程學(xué)院，舟山 316022)

以2，4-二氯苯乙酸、4，4′-聯(lián)吡啶分別和硫酸鎂、氯化鈣和硝酸鎘反應(yīng)，采用自然揮發(fā)法制備了3個(gè)配合物 [Mg(DCBA)2(H2O)4]·3(4，4′-bipy)(1)、[Ca(DCBA)(H2O)4]·DCBA·H2O(2)和[Cd(DCBA)2(H2O)2]·2H2O(3)(DCBA=2，4-二氯苯乙酸，4,4′-bipy=4，4′-聯(lián)吡啶)，并對其進(jìn)行了元素分析、紅外光譜、熱穩(wěn)定性和X射線單晶衍射的表征，研究了配合物3的熒光性質(zhì)。結(jié)果表明，配合物1、2和3均為零維結(jié)構(gòu)，其中，配合物1中存在O-H…O、O-H…N、C-H…O、C-H…Cl和O-H…π氫鍵作用，而配合物2和3中存在O-H…O和C-H…Cl氫鍵作用，并以此分別形成了3D超分子結(jié)構(gòu)。

配合物；2，4-二氯苯乙酸；晶體結(jié)構(gòu)

0 Introduction

Supramolecular chemistry surpasses conventional molecular chemistry that is based on chemical bonds,in such a way that it aims at developing highly complex chemical systems from different components interacting through non-covalent intermolecular forces[1-4].Noncovalent interactions,including hydrogen bonding,dipole-dipole interactions, steric repulsions and London dispersion are ubiquitous forces which act as“molecular glue” in supramolecular chemistry;they are also important in biology,material chemistry and nano-science[5-8].Hydrogen bonding(O-H…O,O-H…N,C-H…O,C-H…Cl,C-H…π,etc.)besides π…π interaction still remains the most reliable and widely used means/tool for the design and development of novel functional materials[9-11].The topology and functionality of such architectures depends on the choice of metals as well as ligands[12-14].Chloro-benzene carboxylic acid have rich coordination modes such as terminal monodentate,chelating or bridging to more than one metal cations,and therefore they have been extensively employed in the preparation of complexes[15-19].Heterocyclic nitrogen donors,such as 4,4′-bipyridine(4,4′-bipy)have also been proved to be among the most important types of organic ligands for the design and construction of coordination polymers exhibiting remarkable properties for their excellent coordinating ability[20-21].In this study,we introduced 2,4-dichlorophenylacetic acid in order to assemble three Mg髤,Ca髤 and Cd髤 coordination complexes.In addition,thermal stability and fluorescence of complexes were measured and discussed.

1 Experimental

1.1 Materials and measurements

All chemicals purchased were of reagent grade and used withoutfurtherpurification.Elemental analysis were performed on a CARLO ERBA 1106 analyzer.The FT-IR spectra were recorded on a PerkinElmer Spectrum 100 spectrometer using KBr pellet at a resolution of 0.5 cm-1(400～4 000 cm-1).Luminescence spectra for crystal solid samples were recorded at room temperature on a PERKIN ELMER LS 55 luminance meter.Thermogravimetry analyses were performed on an automatic simultaneous thermal analyzer(PE TG/DTA 6300)under a flow of N2at a heating rate of 30℃·min-1between ambient temperature and 800℃.

1.2 Synthesis of[Mg(DCBA)2(H2O)4]·3(4,4′-bipy)(1)

Complex 1 was prepared by the addition of MgSO4·7H2O(0.246 5 g,1.0 mmol),2,4-dichlorophenylacetic acid (DCBA)(0.205 0 g,1.0 mmol)and 4,4′-bipy(0.156 2 g,1.0 mmol)were dissolved in 30 mL methanol/water(3∶10,V/V)solution and the pH value was adjusted to 7 with 0.1 mol·L-1sodium hydroxide solution.After the mixture was stirred for 30 min.Colorless crystals of complex 1 were obtained by evaporation of the solution for 10 days at room temperature in 44%yields (based on Mg).Anal.Calcd.for C36H34N4O8Cl4Mg(%):C 52.91,H 4.33,N 6.89;Found(%):C 52.56,H 4.10,N 6.70.IR(KBr pellet,cm-1):3 154(s),1 587(s),1 534(w),1 478(s),1 378(s),1 286(m),1 100(m),1 052(s),867(s),812(s),768(s),619(s).

1.3 Synthesis of[Ca(DCBA)(H2O)4]·DCBA·H2O(2)

The synthesis of complex 2 was carried out in the same procedure as that of complex 1,except that MgSO4·7H2O was replaced by CaCl2·6H2O.After reaction,colorless crystals were obtained in 39%yields (based on Ca).Anal.Calcd.for C16H20Cl4O9Ca(%):C 35.69,H 3.70;Found(%):C 35.39,H 3.41.IR(KBr pellet,cm-1):3 395(s),1 559(s),1 480(s),1 419(s),1 367(s),1 284(m),1 103(m),1 047(m),939(m),866(m),774(m),681(s).

1.4 Synthesis of[Cd(DCBA)2(H2O)2]·2H2O(3)

The synthesis of complex 3 was carried out in the same procedure as that of complex 1,except that MgSO4·7H2O was replaced by Cd(NO3)2·4H2O.After reaction,colorless crystals were obtained in 51%yields(based on Cd).Anal.Calcd.for C16H18Cl4O8Cd(%):C 32.60,H 3.10;Found(%):C 32.23,H 3.39.IR(KBr pellet,cm-1):3 221(s),1 534(s),1 472(s),1 426(s),1 389v(s),1 291(m),1 182(m),1 098(m),1 047(m),862(s),765(m),678(s).

1.5 Crystal structure determination

Single-crystalX-ray diffraction measurements were carried out on a Bruker SMART APEXⅡCCD diffractometer．The diffraction data were collected with Mo Kα radiation(λ=0.071 073 nm)．Empirical absorption corrections were carried out by using the SADABS program[22]．The structures were solved by direct methods,and all of the non-hydrogen atoms were refined anisotropically on F2by the full-matrix least-squares technique using the SHELXL crystallographic software package[23].The hydrogen atoms were added theoretically,riding on the concerned atoms and refined with fixed thermal factors.The crystal structure data of complexes 1,2 and 3 were listed in Table 1.The selected bond lengths and bond angles were listed in Table 2 and hydrogen bond lengths and bond angles in Table 3.

CCDC:1414729,1;1414726,2;1414727,3.

Table 1 Crystal data and structure refinements of complexes 1 and 2

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

Continued Table 2

Table 3 Hydrogen bond parameters for complexes 1～3

Continued Table 3

2 Results and discussion

2.1 Structure description of[Mg(DCBA)2(H2O)4]·3(4,4′-bipy)(1)

As shown in Fig.1,the asymmetric unit of 1 contains one Mg髤cation,two coordinated DCBA-anions,three 4,4′-bipy ligands and four coordinated water molecules.Two DCBA-ligands have one monodentate coordination mode.The Mg髤ion is sixcoordinated by two carboxylate O atoms from two different DCBA-groups and four coordinated water molecules,and the local coordination sphere around the Mg髤ion can be described as a distorted octahedral chromophore.Atoms OW2,O1,O3 and OW4 define the equatorial plane,while O1W and O3W atoms occupies the apical site(O1W-Mg-O3W 178.68(7)°).The dihedral angle between two benzene ring plane of DCBA-ligand is 30.096(74)°.There are two kinds of intramolecular hydrogen bonds and C-H…π intermolecular interaction in the complex:O-H…O(O2W…O2 0.267 1(2)nm,O4W…O4 0.261 7(2)nm),OH…N(O2W…N4 0.297 2(3)nm,O3W…N2 0.278 0(2)nm)and C36…Cg 0.293 6 nm (Cg:C27,C28,C29,C30,C31,N3),respectively(Fig.1).

Fig.1 Molecular structure of complex 1 with the ellipsoids drawn at the 30%probability level

Fig.2 Two dimensional structure of complex 1

The two-dimensionallayerstructure ofthe complex are formed through intermolecularnoncovalent bonding interactions including intermolecular hydrogen bonds.There are three kinds of hydrogen bonds:O-H…N(O1W…N1iii0.276 8(3)nm),O-H…C(C28…O2 0.331 5(4)nm)and C-H…π(C5…Cg1 0.356 8 nm,Cg1:C32,C33,C34,C35,C36,N4;C16…Cg2 0.331 2 nm,Cg2:C3,C4,C5,C6,C7,C8;Fig.2).With the help of intermolecular hydrogen bonds between adjacent 2D sheet(O1W…O3iv0.277 6(2)nm,O3W…O1v0.273 5(2)nm,O4W…O3Wv0.289 7(2)nm;Symmetry codes:iv-x,-y+2,-z+1;v-x+1,-y+2,-z+1),the polymeric sheets are assembled to form a supramolecular 3D network structure(Fig.3).

Fig.3 Three dimensional structure of complex 1

2.2 Structure description of[Ca(DCBA)(H2O)4]·DCBA·H2O(2)

As shown in Fig.4,the asymmetric unit of 2 contains one Ca髤 cation,one coordinated DCBA-anion,one free DCBA-anion,four coordinated water molecules and one solvate water molecule.The Ca髤ion is seven-coordinated by three carboxylate O atoms from two different coordinated DCBA-groups and four coordinated water molecules,and the local coordination sphere around the Ca髤ion can be described as a distorted pentagonal bipyramid chromophore.Atoms O1,O2,O1i,OW1 and OW2 define the equatorialplane,while OW3 and OW4 atoms occupies the apical site(OW3-Ca1-OW4 171.71(7)°).The dihedral angle between two benzene ring plane of DCBA-ligand is 9.043(9)°,and bond angle(C1-C2-C3 and C9-C10-C11)is 112.97(3)°and 114.51(3)°,respectively.There is one kind of intramolecular hydrogen bond in the complex:OW2…O3 0.251(2)nm,OW4…OW5 0.197 5(5)nm and OW5…O4 0.210 9(7)nm(Fig.4).

Fig.4 Molecular structure of complex 2 with the ellipsoids drawn at the 30%probability level

The two-dimensionallayer structure ofthe complex are formed through intermolecular hydrogen bonds.There is one kind of intramolecular hydrogen bond,with the O-H…O bond length of 0.187 3(6)～0.228 7(9)nm and O-H…O bond angle of 151(3)°～175(3)°(Fig.5).With the help of intermolecular hydrogen bonds between adjacent 2D sheets(C7…Cl2 0.309 0 nm),the polymeric sheets are assembled to form a supramolecular 3D network structure(Fig.6).

2.3 Structure description of[Cd(DCBA)2(H2O)2]·2H2O(3)

As shown in Fig.7,the crystal structure of the complex 3 consists of a neutral Cd髤 complex[Cd(DCBA)2(H2O)2] and two uncoordinated water molecules.A twofold rotation axis passes through Cd髤 ion.The Cd髤 ion displays distorted octahedral geometry,comprising four carboxyl O atoms from two bidentate chelate DCBA-ligands and two coordinated water molecules.Atoms OWi,O1,O1iand O2idefine the equatorial plane,while O2 and OW1 atoms occupies the apical site(OW1-Cd1-O2 144.79(2)°).There are two kinds of intramolecular hydrogen bond in the complex:O-H…O(OW2…O1 0.279 0(4)nm)and C-H…Cl(C2…Cl2 0.275 nm)(Fig.7).The twodimensionallayerstructuresofthecomplexare formed through intermolecular hydrogen bonds.There is one kind of intermolecular hydrogen bond:O-H…O(OW1…OW2ii0.191(2)nm,OW2…OW2ii0.216(2)nm and OW1…O2iii0.184(2)nm;Symmetry codes:ii-x+1/2,y-1/2,-z+1/2;iii-x+1,y-1,-z+1/2;Fig.8).With the help of intermolecular hydrogen bonds between adjacent 2D sheets (C2…Cl2 0.322 8 nm),the polymeric sheets are assembled to form a supramolecular 3D network structure(Fig.9).

Fig.5 Two dimensional structure of complex 2

Fig.6 Three dimensional structure of complex 2

Fig.7 Molecular structure of complex 3 with the ellipsoids drawn at the 30%probability level

Fig.8 Two dimensional structure of complex 3

Fig.9 Three dimensional structure of complex 3

2.4 IR spectrum

The asymmetric νas(COO-) and symmetrical νs(COO-)appear in 1 587,1 559,1 534 cm-1and 1 378,1 419,1 389 cm-1for complexes 1～3,respectively.The separations(Δν)between νas(COO-)and νs(COO-)are 209(1),140(2)and 145 cm-1(3),indicating monodentate coordinating mode in complex 1 and bidentate coordinating mode in 2 and 3.Meanwhile,the bands at 1 534 and 1 478 cm-1are assigned to the stretching vibration of-N=C-of pyridyl in 1.

2.5 Thermal analysis

In complex 1,the weight-loss step occurred from 85 to 150℃(Obsd.8.85%,Calcd.8.82%),which corresponds to the decomposition offramework structure on four coordinated water molecules.The escape of four coordinated water molecules and one free water molecule is observed from 64 to 191℃(Obsd.16.25%,Calcd.16.72%)in complex 2.Complex 1 and 2 start slowly to decompose after 151 and 192℃,respectively.This structure is similarly adopted by[Co(bpp)(H2O)(nip)]n[24].In complex 3,the first step of weight loss corresponds to the escape of two coordinated water molecule and two free water molecule from 63 to 251℃ (Obsd.12.49%,Calcd.12.15%).The second step corresponding to the escape of two DCBA ligands is observed from 251 to 675℃(Obsd.68.21%,Calcd.68.66%).Upon further heating,the final residue is CdO,with a total weight loss of 19.05%(Calcd.21.69%)(Fig.10).

Fig.10 Thermogravimetric curves(TG)for 1,2 and 3

2.6 Photoluminescence properties

Fluorescence was hardly ever observed in DCBA ligand.On complexation of the ligand with Cd髤ion,strong fluorescence with emission broad peak centered at 448 nm (λex=390 nm)for complex 3 was observed at room temperature (Fig.11),which may originate from the πL-πL*transition emission of ligand-to-ligand charge transfer(LLCT)in aromatic rings of the ligand.

Fig.11 Solid-state photoluminescent spectrum for 3

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Syntheses and Crystal Structures of Three Mg髤,Ca髤 and Cd髤Complexes with 2,4-Dichlorophenylacetic Acid Ligand

GU Chang-Sheng1HAO Xiao-Min＊,1HOU Huan-Yao1CHEN Yi-Wen1LI Zhi-Ling1LI Yong1SONG Wen-Dong＊,2
(1Department of Applied Chemistry,School of Chemistry and Environment,Guangdong Ocean University,Zhanjiang,Guangdong 524088,China)
(2School of Petrochemical and Energetic Engineering,Zhejiang Ocean University,Zhoushan,Zhejiang 316022,China)

Three new coordination complexes[Mg(DCBA)2(H2O)4]·3(4,4′-bipy)(1),[Ca(DCBA)(H2O)4]·DCBA·H2O(2)and[Cd(DCBA)2(H2O)2]·2H2O(3)were synthesized by evaporation methods using 2,4-dichlorophenylacetic acid(DCBA),4,4′-bipyridine(4,4′-bipy)to react with MgSO4,CaCl2and Cd(NO3)2,respectively.The complexes were characterized by elemental analysis,FT-IR,thermogravimetrie analysis (TGA)and X-ray single-crystal structure analysis,and fluorescence properties of the complex 3 have been studied.As a result,complexes 1,2 and 3 are zero-dimensional structure.Among others,there are O-H…O,O-H…N,C-H…O,C-H…Cl,C-H…π and O-H…O,C-H…Cl hydrogen bonds contributing 3D supramolecular structure of 1 and 2,3,respectively.CCDC:1414729,1;1414726,2;1414727,3.

complex;2,4-dichlorophenylacetic acid;crystal structure

O614.22；O614.23+1；O614.24+2

A

1001-4861(2017)12-2278-09

10.11862/CJIC.2017.279

2017-04-21。收修改稿日期：2017-10-30。

浙江省自然科學(xué)基金(No.LQ16D060004)和舟山市科技計(jì)劃項(xiàng)目(No.2014C11009)資助。

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