2024年4月9日发(作者:郯承嗣)
第26卷第9期
2010年9月
无 机 化 学 学 报
V01-26 No.9
CHINESE JOURNAL OF INORGANIC CHEMISTRY
1605.161 1
维链状4.乙基苯甲酸镧配合物
[La(EBA)3(EBAH)(H20)1 的合成、晶体结构和性质研究
一
杨 娟* 戴 俊 李飞飞 李建通
f河南理工大学理化学院,焦作454003)
摘要:水热法合成了配位聚合物『IJa(EBA) (EBAH)(H 0)1 (EBA=4.乙基苯甲酸根,EBAH=4.乙基苯甲酸),并通过X一射线衍射单晶
结构分析、红外光谱、紫外光谱、荧光光谱以及热重分析对配合物进行了结构和性质研究。配合物属三斜晶系,Pl空间群。该配
合物具有一维链状结构 La3+离子与9个O原子配位,其中4个O原子来自4个双齿桥联的4.乙基苯甲酸根,3个O原子来自
2个螯合.桥联的4.乙基苯甲酸根.1个O原子来自1个中性的4.乙基苯甲酸,1个O原子来自配位水分子。La 离子处于九配
位扭变的--N三角棱柱构型中 相邻 +离子通过双齿桥联或螯合桥联的4.乙基苯甲酸根联结成一维链状结构。存在于分子内
的氢键使一维链状结构更加稳定 由于相邻一维链的苯环问存在弱的7r…仃堆积作用,使分子沿着a轴堆积形成二维层状结
构。同时.标题配合物固体具有光致发光特性,蓝光区的较强发射归于配体的7『一7r 电子跃迁。
关键词:镧配合物;4一乙基苯甲酸;一维链;晶体结构;荧光
中图分类号:O614.33 1 文献标识码:A 文章编号:1001—4861(2010)09—1605—07
Synthesis,Crystal Structure and Properties Study of 1D Chain-Like
Lanthanum 4-ethylbenzoate Complex[La(EBA)3(EBAH)(HzO)]
YANG Juan DAI Jun LI Fei—Fei LI Jian—Tong
(Department ofPhysical Chemistry,Henan Polytechnic University,Jiaozuo,Henan 454003)
Abstract:The coordination polymer[La(EBA)3(EBAH)(H20)] (EBA=4一ethylbenzoate,EBAH=4一ethylbenzoic acid)
was synthesized by hydrothermal method in the presence of melamine and characterized by X—ray single crystal
structural analysis, IR spectum,r UV spectum,r fluorescence spectrum, and thermogravimetric analysis.The
complex crystallizes in triclinic crystal system and P1 space group with the cell dimensions:a=0.953 1 9(3)nm,
b=1.403 78(5)nm,c=1.498 47(5)nm,a=65.024(2)。,/3=74.942(2)。,T=74.734(2)。.The complex has 1D chain—like
stuctrure.La ion is nine—coordinated by four oxygen atoms from four bridging—bidentate 4-EBA ligands,three
oxygen atoms from two chelating—bridging 4-EBA ligands,one oxygen atom from one neutral 4-EBAH ligand and
one from the coordinated water molecule in a distorted tricapped trigonal—prismatic geomety.The adjacentr La。
ions are linked by the carboxylate groups of 4-EBA ligands in the bridging--bidentate or chelating・・bridging
coordination mode,resulting in an infinite chain stuctrure.The hydrogen bonds involving the water molecules,
carboxylate groups and carboxyl H atoms are formed within the one-dimensional polymer.Viewed along U axis,
two kinds of weak彳r…7r interactions between the benzene rings of the neighboring chains connect the paralleling
1D chain into 2D layer stuctrure.The luminescent property in solid state of complex was also studied and
discussed.The intense blue fluorescence emission of the complex is attibutred to the 7r— 7r electron transition of
the ligands.CCDC:764123.
Key words:lanthanum complex;4-ethylbenzoic acid;1 D chain—like;crystal structure;fluorescence
收稿日期:2010—02—16。收修改稿日期:2010—05.24。
国家自然科学基金(N0.20901028) ̄I南理工大学博士基金(No.B2008.58648265)资助项目。
通讯联系人。E.mail:yangjuan0302@yahoo.(3/1
第一作者:杨娟,女,3O岁,博士,副教授;研究方向:无机材料及功能配合物。
.
无机化学学报 第26卷
0 Introduction
There has been cons iderable interest in coordina-
tion polymers based on metal centers and muhifunc—
tional bridging ligands due to their fascinating struc—
tures and promising applications in practical areas such
as catalysis,magnetism,non-linear optics,sensors and
separation[ ~.To the best of our knowledge carboxylate
coordinates metal in various ways,for example,in the
mode of monodentate,bidentate chelating,bidentate
bridging or chelatin bridging.Lanthanide ions,beca
use of the high and variety coordination numbers,their
carboxylate complexes display a variety of amusing
structures[ ̄1
.
As rigid ligands,benzoic acid and its derivatives
have been widely used because they can bridge the
center ions and form the仃.订stacking to increase the
stability of the structure.Different substituents or
different positions of the substituents on the benzene
ring result in various sturctures of the lanthanide
complexes.For example,many lanthanide complexes
with benzoic acid or its derivatives containing phen or
2.2 .bipy formed the dimeric unit with coordination
number of eight or nine[5-7】.However。lanthanide compl-
exes with only monoacid ligand were usually obtained
in the form of coordination polymer and this kind of
complexes has higher thermal stability and strong
lfuorescence properties[S-91.With the aim of preparing
stbale functional polymer,we used 4-ethylbenzoic acid
(4.EBAH)as ligand in the presence of melamine,and
obtained a new one-dimensional polymeric[La(EBA)3
(EBAH)(H2O)] prepared by hydrothermal method.The
crystal structure,luminescent properties and thermal
stability of the complex are reported in this paper.
1 Experimental
1.1 Reagents and general methods
La(N03)3"6H20,4-ethylbenzoic acid(4-EBAH),
melamine。DMF and DMSO are analytically pure grade
and used as received.Elemental fC and H)analysis was
Derformed on a Perk in—Elmer 2400LS analyzer.
Infrared spectra were collected with a阿R Thermo
Nicolet Impact 4 1 0 spectrometer with KBr pellets in the
4 000~400 cm~regions.The UV-Vis spectra were
measured in DMF solvent f 1 mmo卜L 1 by a UV.260
spectrophotometer.Excitation and luminescent spectra
ofr the powdered solid samples were recorded at room
temperature on a Hitachi F.4500 fluorescence spectro.
lfuorometer(the pass width is 5.0 nm).Thermogravi-
metric analysis was conducted on a Perkin Elmer TG.7
with a heating rate of 10 oC・min一 from 3O to 700 oC in
air.
1.2 Synthesis of[La(EBA)3(EBAH)(H O)
A mixture of La(NO3)3・6H20(0.52 mmo1),4-
EBAH fO.84 mmol1 and melamine (0.4 mmo1)was
added to 1 0 mL distilled water,and pH of the resultant
mixture was 5.5—6.5.The reaction mixture was trans—
ferred to the 25 mL staiuless Teflon—lined autoclave and
heated at 423 K under autogenous pressure for 7 d.
After cooled to room temperature,the colorless prism
crystals were separated from the mixture,washed with
cold deionized water and dried at 350 K for 10 h in air.
The yield was about 58%based on La203.The obtained
complex is hardly soluble in water,methanol,
anhydrous ethanol and acetonitrile,but facilely soluble
in DMF and DMSO.Ana1.Calcd.for C36H3909La(%):C
57.3O H 5.21:found(%):C 57.04,H 5.46.
1.3 X.ray crystal structure determination
A colorless prismatic crystal with dimensions of
0.35 minx0.32 mmx0.23 mm was put on Bruker SMART
APEX 11 CCD diffractometer equipped with a graphite
mo.nochromatized Mo radiation =0.07 1 073 nm)
by using 一 scan mode at 296(2)K.Total of 22 559
reflections were collected in the range of 1.63。≤ ≤
27.43o.of which 7 733 were independent with Rjm=0.050,
and 6 206 with I>o-∽were considered as observed.
Semi—empirical absorption correction was applied to the
intensity data using the SADABS program[ .The struc—
ture was solved by direct methods and refined by full—
matrix least.square on F using the SHELXTL-97 pr0g—
ram[ ”
.
A11 non.hydrogen atoms were refined anisotropi—
cally.A11 H atoms bounded to C atoms were generated
geometrically and refined isotropically using the riding
node.The hydrogen atoms of water molecule and the
carboxylic H atom were located in a difference Fourier
map.The ethyl group C8-C9 was treated as disordered
over two sites,with、refined occupancies 0.7 14(7)and
第9期 杨娟等:一维链状4-乙基苯甲酸镧配合物【【丑(EBA) (EBAH)(H:O)l 的合成、晶体结构和性质研究 1607
O.286(7).A summary of crystal data and details of the
structure refinements are listed in Table 1.
CCDC:764123.
Table 1 Crystal data and structure refinement for the title complex
Empirical formula
Formula weight
C {∞OqLa
754.58
V/nm
D/(g・m )
1.727 91(10)
1.450
Temperature/K
Wavelength/nnl
Crystal system
296(2)
O.07 1 073
Triclinic
///'ia一r
F(O00)
Crystal size/mnl
J.288
768
0.35x0.32 ̄0.23
Space group PI 0 range for data collection/(。) 1.63 to 27.43
a/f1m
b/flln
c/llln
0t/(。)
O.953 19(31
1.403 78(5)
1.498 47(5)
65.024(2)
Reflections collected
Independent reflections )
22 559
7 733(O.050)
6206
1.014
Observed renecti0ns【,>2 (|『)]
Final GooF
卢/(。)
.y/(。)
Z
74.942(2)
74.734(2)
2
R1,wR2【,>2 (川
R1,wR2(all data)
Largest different peak and hole/e-nm一’
0.038 2,0.070 9
0.054 8,O.077 2
676,一737
2 Results and discussion
the carboxyl f03一C 1 0.O41 adopts the monodentate
mode in form of neutral 4一EBAH.
2.1 Crystal structure of【La(EBA)3(EBAH)(H2o)】
The repI。esentative structure of the complex
Each La(皿ion is coordinated with nine oxygen
atoms,in which four oxygen atoms from four bridging-
bidentate 4-EBA ligands,three oxygen atoms from two
including the atomic numbering scheme is described in
Fig.1.The prominent characteristic is the 1 D chain.in
which the center La3 ions act as nodes and are conn—
ected through 4一EBA ligands.Carboxyls fO 1-C 1—02
chelating—bridging 4一EBA ligands,one oxygen atom
rom one neutralf 4-EBAH ligand and one from the
and 07一C28—08)adopt bidentate-bridging coordination
fashion,namely,the two oxygen atoms coordinate to two
coordinated water molecule.So each La0 ion lies in a
distorted tricapped trigonal—prismatic coordination
different La ions.Carboxyl f05.C 19—061 adopts the
chelating—bridging coordination mode,in which 05 and
06 coordinate to one La ion by chelating fashion and
environment(Fig.2).Atoms 02 ,08 and 05 construct
the upper plane of the distorted trigonal prism and
atoms 01,06i and 07i form the below one,with the
dihedral angle of 5.744。between them.The 09.03 and
06 atoms are at the vertices of each square pyramid.
06 simultaneously hridges with another La ion.While
Symmety codesr used to generate equivalent atoms: I q
1 ;”2-x,-y,l-z
,
_y
Symmetry codes:‘1 ,-y,1-z; 。2 ,-y,l
Fig.1 Molecular structure of the complex
Fig.2 Coordination polyhedron of the title complex
无机化学学报 第26卷
And the mean distance from the upper and lower plane
is 0.322 8 nm.
bonds are all intramoleculy.ia.e.stabilize the one—
dimensional chain structure of the polymer,as
indicated in Fig.3.Additionally.at the same side of 1D
chain,the benzene rings of 4-EBA ligands or 4-EBAH
ligand parallel each other and the shortest ve ̄ical
The adjacent LaⅢions aye linked by the cayboxy.
1ate groups of 4-EBA ligands in the bridging-bidentate
or chelating—bridging coordination mode,resulting in an
infinite chain structure Mong the b axis.The distance
distance of the corresponding adjacent benzene tings
are 0.560 8.0.680 3.0.578 l and 0.43l 4 nm for the
between two adjacent La3 ions is 0.426 05(3)nm for
Lali…Lal and O.545 10(31 nm for Lal…Lal .And the
angle of Lal …Lal…Lal i is 157.753(6)。.The bond
lengths of Lal-O,except for Lal一06,range from
0.244 7(2)to 0.267 2(2)nm,with a mean value of 0.252 2
nm.which aye rational as literatures reposed【 .
Whereas,the rather long Lal一06 distance of 0.298 9(2)
nm oversteps the average length of La—O bond【 埘.
And the bond angles of O—Lal—O(carboxy1)range from
45.65(7)。to 154.20(7)。.
As shown in Table 3,the coordinating water,
cayboxylate oxygen atoms of 4-EBA ligands and
carboxylic H atom of 4-EBAH ligand are involved in
7
9
7
8
3
7
7
8
2
2
8
3
3
8
1 0
8
8 8
8
4 5
8
O 2
7
5
7
0 2
8
7 9
8
O-H…O hydrogen-bonding interactions r09-H9B…
Fig.3 Intramolecular hydrogen bonds of extended
chain—like stuctrure along the b axis
02,04-H4A…05).Furthermore,these hydrogen
Table 2 Selected bond lengths(nn1)and angles(。)for the complex
La1—07
0.244 7(2)
0.245 2(2)
Lal—O8
La1.05
0.247 9(21
Lal一09
La1.03
La1.06
0.262 4(2)
0.267 2(2)
0.298 9(2)
Lal—O1
Lal一02
0.258 1(2)
0.246 6(2)
0.245 7(2)
Lal—O6
O7i-Lal—O1
O7 .La1.02
85.28(8)
138.38(8)
88.76(7)
72.12(8)
06 .La1.O8
O7i-Lal一05
01.La1.05
O2ii_La1.05
06’.La1.O9
08.La1。O9
O5.La1一O9
O7 一Lal一03
75.51(8)
65.78(8)
141.11(8)
70.76(8)
67.79(8)
O1.La1.02
O7l-La1.O6
0l-La】.O6
O2 一La1 06—
07LLa1.O8
O1.I丑1—08
88.38(8)
148.91(8)
O6 一La1。O5
O1.Lal—O3
O8.Lal一05
OT-Lal—O9
O1.Im1一O9
02ii_Lal一09
O8一La1.06
05.La1.O6
O9.La1一O6
O2ii—La1.03
O6j-Lal一03
08一Lal一03
05.La1.03
68.89(8)
137.01(8)
142.87(8)
69.82(7)
129.47(8)
134.89(8)
81.26(8)
122.91(7)
69.86(7)
O2ii.La1—08
O9一La1—03
07 一La1—06
O6i.La1.06
02 .La1.06
O3一Lal一06
77.73(7)
1 14.27(7)
108.39(7)
O1.La1.O6
154.20(7)
Symmetry codes used to generate equivalent atoms: 1-x,-y,l-z; 2 ,一Y,1-z
Table 3 Hydrogen bond lengths and angles
第9期 杨娟等:一维链状4-乙基苯甲酸镧配合物[La(EBA)3(EBAH)(H 0)] 的合成、晶体结构和性质研究
nm,0=0.233。,in which Cg is the ring centroid,dc.c is
the centroid-centroid distance,dp P is the vertical
distance,and 0 is the dihedral angle of two neighboring
C2-C4-C6,C1 1一C13-C15,C20-C22-C24 and C29-C31一
C33,respectively.Therefore,there is no obvious 7r…7r
packing effect within the one—dimensional polymer
although the benzene rings parallel highly each other.
To some extent,the structure of the title complex
7r—planes【l8】.Similarly,the benzene ring(C20,C2 1,
C22,C23,C24,C25)and the neighboring B ring are
also parallel highly with dc ̄c=0.394 1 2 nm,dP_P=0.356 02
nm.0:O。.The weak 7『…7r stacking interactions
is similar to that of complex[Eu(2・IBA)3・H20] (2-IBA=
2-iodobenzoate) .The latter complex is also 1 D polymer
chain structure,in which Eu ions are connected
through two carboxyl groups of two 2・IBA ligands via
the bridging--chelating・-bridging tetradentate coordina・・
tion mode.In the structure of 1 D chain polymer
[Eu(2,4-DC1BA)3・(CH3CH2OH)2] (2,4-DC1BA=2,4一
dichlorobenzoate)t .each Eu ion is eight.coordinated
with four oxygen atoms of four bidentate--bridging 2,4--
DC1BA anions,two oxygen atoms of one bidentate—
chelating 2,4一DC1BA anion and two atoms of two
ethanol molecules.Unlike the title complex,in the 1 D
polymeric chain of[Tb(3-IBA)3(H20)2・0.5(4,4 bipy)]
(3-IBA=3一iodobenzoate;4,4 一bipy=4,4 bipyridine),
each Tb ion is connected through four bidentate
bridging 3-IBA ligands and lies in a distorted square-
antiprism geometry.The 4,4 一bipy molecule in the
crystal lattice does not coordinate to Tb ion【垌.In the
dinuclear complex of{La[o—C6H4(NO2)(CO2)]3・(DMF)2}2
o-nitro-benzoic acid),two La㈣ions are bridged by
four 0一nitro-benzoic acid ligands with their carboxyls
and occupy the nine coordination sites,in which two
carboxyl groups adopt bidentate—bridging coordination
mode and the other two take monodentate—bridging
mode【l7】.Obviously.the distinct difference from the ifnal
sturctures of these coordination complexes may be
caused by the different ligands,for example,the
different substituent groups or the different position
locating in the benzene rings.
In addition,each unit cell is packed by six 1 D
polymeric chains along a axis.These 1D chains parallel
each other with the shortest distance between the
adjacent La of 1.474 63(6)nm and 1.498 47(6)nm.
Moreover,there are two kinds of inter.molecular 7r…7r
interactions between the benzene rings of neighboring
polymeric chains.As shown in Fig.4,the benzene ring
(C1 1,C12,C13,C14,C15,C16)and the adjacent A
irng are parallel with dc-c=0.377 35 nm,dp
.
p=O.306 32
assemble the neighboring 1D chains into the two—
dimensional layer structure paralleling to bc plane for
the title complex.
Fig.4 Arrangement of the仃…仃stacking interactions
paralleling to bc plane of the title compound
2.2 IR and UV spectrum of the title complex
The IR specturm of the complex was determined in
the range of 4 000-400 cm—as KBr pellets.Compared
with the 4一EBAH ligand,the IR spectral intensity of the
complex around l 7 10 cm~is significantly weakened,
which is observed for the—COOH【捌.It demonstrates
that there are several different coordinating fashions of
the carboxylate groups in the complex,including the
deprotonated anions and the neutral molecule.Another
feature of the IR data of the complexes iS the separation
between v ̄(COO)and vs(coo-),which have often been
used to discuss the coordination mode of carboxylate
group in the carboxylate complexes.Two strong
peaks at 1 532 and l 383 em一 could be assigned to the
(C00一)and/Ys(coo一)stretching vibration of carboxyl
1610 无机化学学报 第26卷
in 4-EBA ligand.The Av[v (COO一)-v (COO一)]of 149
am一 suggests that the coordination of the carboxylate
groups is most probably of the bridging type ,which is
also supported by the results from single-・crystal X・-ray
diffraction data.Peaks observed at 2 985~2 846 cm-1
are in good agreement with C-H vibrations.and the
wide absorption peak at about 3 405 cm一 is assigned to
the vibrations of water molecules.The weak band at
435 am—may be assigned to the vibrations of La—O
bond{2tJ.
The UV spectra of the free ligand and the complex
were recorded in DMF solvent with the concentration of
1 mmol・IJ_ .Both of the spectra have one strong absorp—
tion peak at 272 nm attributing to 7r 7r transition.
however,the intensities are different.The absorption
intensity of the complex =1.51 xl0。)is evidently
stronger than that of free 4-EBAH ligand(e=0.72x 103),
which is attributed to the coordination between the
ligands and the center La3 ions.Owing to the formation
of complex,the degree of conjugation and intensities of
UV absorption obviously increased.
2.3 Luminescent properties
The solid state fluorescence spectrum of the
complex was measured at room temperature.The
excitation specturm was recorded in the range of 250-
400 am,setting 449 nm as the emission wavelength,in
which there is a strong peak at 335 nm.In contrast to
the weak luminescence of the free ligand,the complex
exhibits one strong band centered at 449 nm excited at
335 nm in the solid state(Fig.5).Since there are no 4f
electrons and the energy level of excited states below
the tirplet levels of the ligand for La㈣ions the energy
Wavelength/ilm
Fig.5 Excitation(a)and emission(b)spectra of the
complex in the solid state
absorbed by the 4-EBA ligand cannot transfer to La㈣
ions.The absorbed energy can only relax through its
own eneryg levels.The intense blue fluorescence
emission of the complex is attributed to the enhanced
7r electron transition of the ligand.Therefore.the
complex emits the ligand.centered lfuorescence.
2.4 Thermogravimetric analysis
The TG—DSC analysis was performed in air
atmosphere with a heating rate of 10 oC・min in tlle
temperature range from 30 to 700℃.The results indic.
ate that the complex involve two steps of weight losses.
The first weight loss of 2.26%from 30 to 246℃
corresponds to the coordinated water molecule fcalcul—
ated 2.39%1.The next mass reduction of 74.79%occurs
in the range 246-625 oC and shows two apparent
exothermie peaks,corresponding to the removal of
organic ligands.The weight of the residue is 22.95%.
Supposing La203 as final residue,calculated residue
weight of the complex is 21.59%,which is in coincide-
nce with experimental value.Results indicate that the
complex is degraded to oxide,completely.
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夏).Chiense Inorg.Chem.(wuji Huaxue Xuebao),2008,24
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【20]Nakamoto K.Inrfared and Raman 5ipectra ofInorganic and
Coordination Compounds:只 B.5th Ed.New York:Wiley.
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Qing—Sen(俞庆森).Chem.tJ=Chiense Universities(Gaodeng
Xuexiao Huaxue Xnebao),1999,20(1 01:1504.1508
2024年4月9日发(作者:郯承嗣)
第26卷第9期
2010年9月
无 机 化 学 学 报
V01-26 No.9
CHINESE JOURNAL OF INORGANIC CHEMISTRY
1605.161 1
维链状4.乙基苯甲酸镧配合物
[La(EBA)3(EBAH)(H20)1 的合成、晶体结构和性质研究
一
杨 娟* 戴 俊 李飞飞 李建通
f河南理工大学理化学院,焦作454003)
摘要:水热法合成了配位聚合物『IJa(EBA) (EBAH)(H 0)1 (EBA=4.乙基苯甲酸根,EBAH=4.乙基苯甲酸),并通过X一射线衍射单晶
结构分析、红外光谱、紫外光谱、荧光光谱以及热重分析对配合物进行了结构和性质研究。配合物属三斜晶系,Pl空间群。该配
合物具有一维链状结构 La3+离子与9个O原子配位,其中4个O原子来自4个双齿桥联的4.乙基苯甲酸根,3个O原子来自
2个螯合.桥联的4.乙基苯甲酸根.1个O原子来自1个中性的4.乙基苯甲酸,1个O原子来自配位水分子。La 离子处于九配
位扭变的--N三角棱柱构型中 相邻 +离子通过双齿桥联或螯合桥联的4.乙基苯甲酸根联结成一维链状结构。存在于分子内
的氢键使一维链状结构更加稳定 由于相邻一维链的苯环问存在弱的7r…仃堆积作用,使分子沿着a轴堆积形成二维层状结
构。同时.标题配合物固体具有光致发光特性,蓝光区的较强发射归于配体的7『一7r 电子跃迁。
关键词:镧配合物;4一乙基苯甲酸;一维链;晶体结构;荧光
中图分类号:O614.33 1 文献标识码:A 文章编号:1001—4861(2010)09—1605—07
Synthesis,Crystal Structure and Properties Study of 1D Chain-Like
Lanthanum 4-ethylbenzoate Complex[La(EBA)3(EBAH)(HzO)]
YANG Juan DAI Jun LI Fei—Fei LI Jian—Tong
(Department ofPhysical Chemistry,Henan Polytechnic University,Jiaozuo,Henan 454003)
Abstract:The coordination polymer[La(EBA)3(EBAH)(H20)] (EBA=4一ethylbenzoate,EBAH=4一ethylbenzoic acid)
was synthesized by hydrothermal method in the presence of melamine and characterized by X—ray single crystal
structural analysis, IR spectum,r UV spectum,r fluorescence spectrum, and thermogravimetric analysis.The
complex crystallizes in triclinic crystal system and P1 space group with the cell dimensions:a=0.953 1 9(3)nm,
b=1.403 78(5)nm,c=1.498 47(5)nm,a=65.024(2)。,/3=74.942(2)。,T=74.734(2)。.The complex has 1D chain—like
stuctrure.La ion is nine—coordinated by four oxygen atoms from four bridging—bidentate 4-EBA ligands,three
oxygen atoms from two chelating—bridging 4-EBA ligands,one oxygen atom from one neutral 4-EBAH ligand and
one from the coordinated water molecule in a distorted tricapped trigonal—prismatic geomety.The adjacentr La。
ions are linked by the carboxylate groups of 4-EBA ligands in the bridging--bidentate or chelating・・bridging
coordination mode,resulting in an infinite chain stuctrure.The hydrogen bonds involving the water molecules,
carboxylate groups and carboxyl H atoms are formed within the one-dimensional polymer.Viewed along U axis,
two kinds of weak彳r…7r interactions between the benzene rings of the neighboring chains connect the paralleling
1D chain into 2D layer stuctrure.The luminescent property in solid state of complex was also studied and
discussed.The intense blue fluorescence emission of the complex is attibutred to the 7r— 7r electron transition of
the ligands.CCDC:764123.
Key words:lanthanum complex;4-ethylbenzoic acid;1 D chain—like;crystal structure;fluorescence
收稿日期:2010—02—16。收修改稿日期:2010—05.24。
国家自然科学基金(N0.20901028) ̄I南理工大学博士基金(No.B2008.58648265)资助项目。
通讯联系人。E.mail:yangjuan0302@yahoo.(3/1
第一作者:杨娟,女,3O岁,博士,副教授;研究方向:无机材料及功能配合物。
.
无机化学学报 第26卷
0 Introduction
There has been cons iderable interest in coordina-
tion polymers based on metal centers and muhifunc—
tional bridging ligands due to their fascinating struc—
tures and promising applications in practical areas such
as catalysis,magnetism,non-linear optics,sensors and
separation[ ~.To the best of our knowledge carboxylate
coordinates metal in various ways,for example,in the
mode of monodentate,bidentate chelating,bidentate
bridging or chelatin bridging.Lanthanide ions,beca
use of the high and variety coordination numbers,their
carboxylate complexes display a variety of amusing
structures[ ̄1
.
As rigid ligands,benzoic acid and its derivatives
have been widely used because they can bridge the
center ions and form the仃.订stacking to increase the
stability of the structure.Different substituents or
different positions of the substituents on the benzene
ring result in various sturctures of the lanthanide
complexes.For example,many lanthanide complexes
with benzoic acid or its derivatives containing phen or
2.2 .bipy formed the dimeric unit with coordination
number of eight or nine[5-7】.However。lanthanide compl-
exes with only monoacid ligand were usually obtained
in the form of coordination polymer and this kind of
complexes has higher thermal stability and strong
lfuorescence properties[S-91.With the aim of preparing
stbale functional polymer,we used 4-ethylbenzoic acid
(4.EBAH)as ligand in the presence of melamine,and
obtained a new one-dimensional polymeric[La(EBA)3
(EBAH)(H2O)] prepared by hydrothermal method.The
crystal structure,luminescent properties and thermal
stability of the complex are reported in this paper.
1 Experimental
1.1 Reagents and general methods
La(N03)3"6H20,4-ethylbenzoic acid(4-EBAH),
melamine。DMF and DMSO are analytically pure grade
and used as received.Elemental fC and H)analysis was
Derformed on a Perk in—Elmer 2400LS analyzer.
Infrared spectra were collected with a阿R Thermo
Nicolet Impact 4 1 0 spectrometer with KBr pellets in the
4 000~400 cm~regions.The UV-Vis spectra were
measured in DMF solvent f 1 mmo卜L 1 by a UV.260
spectrophotometer.Excitation and luminescent spectra
ofr the powdered solid samples were recorded at room
temperature on a Hitachi F.4500 fluorescence spectro.
lfuorometer(the pass width is 5.0 nm).Thermogravi-
metric analysis was conducted on a Perkin Elmer TG.7
with a heating rate of 10 oC・min一 from 3O to 700 oC in
air.
1.2 Synthesis of[La(EBA)3(EBAH)(H O)
A mixture of La(NO3)3・6H20(0.52 mmo1),4-
EBAH fO.84 mmol1 and melamine (0.4 mmo1)was
added to 1 0 mL distilled water,and pH of the resultant
mixture was 5.5—6.5.The reaction mixture was trans—
ferred to the 25 mL staiuless Teflon—lined autoclave and
heated at 423 K under autogenous pressure for 7 d.
After cooled to room temperature,the colorless prism
crystals were separated from the mixture,washed with
cold deionized water and dried at 350 K for 10 h in air.
The yield was about 58%based on La203.The obtained
complex is hardly soluble in water,methanol,
anhydrous ethanol and acetonitrile,but facilely soluble
in DMF and DMSO.Ana1.Calcd.for C36H3909La(%):C
57.3O H 5.21:found(%):C 57.04,H 5.46.
1.3 X.ray crystal structure determination
A colorless prismatic crystal with dimensions of
0.35 minx0.32 mmx0.23 mm was put on Bruker SMART
APEX 11 CCD diffractometer equipped with a graphite
mo.nochromatized Mo radiation =0.07 1 073 nm)
by using 一 scan mode at 296(2)K.Total of 22 559
reflections were collected in the range of 1.63。≤ ≤
27.43o.of which 7 733 were independent with Rjm=0.050,
and 6 206 with I>o-∽were considered as observed.
Semi—empirical absorption correction was applied to the
intensity data using the SADABS program[ .The struc—
ture was solved by direct methods and refined by full—
matrix least.square on F using the SHELXTL-97 pr0g—
ram[ ”
.
A11 non.hydrogen atoms were refined anisotropi—
cally.A11 H atoms bounded to C atoms were generated
geometrically and refined isotropically using the riding
node.The hydrogen atoms of water molecule and the
carboxylic H atom were located in a difference Fourier
map.The ethyl group C8-C9 was treated as disordered
over two sites,with、refined occupancies 0.7 14(7)and
第9期 杨娟等:一维链状4-乙基苯甲酸镧配合物【【丑(EBA) (EBAH)(H:O)l 的合成、晶体结构和性质研究 1607
O.286(7).A summary of crystal data and details of the
structure refinements are listed in Table 1.
CCDC:764123.
Table 1 Crystal data and structure refinement for the title complex
Empirical formula
Formula weight
C {∞OqLa
754.58
V/nm
D/(g・m )
1.727 91(10)
1.450
Temperature/K
Wavelength/nnl
Crystal system
296(2)
O.07 1 073
Triclinic
///'ia一r
F(O00)
Crystal size/mnl
J.288
768
0.35x0.32 ̄0.23
Space group PI 0 range for data collection/(。) 1.63 to 27.43
a/f1m
b/flln
c/llln
0t/(。)
O.953 19(31
1.403 78(5)
1.498 47(5)
65.024(2)
Reflections collected
Independent reflections )
22 559
7 733(O.050)
6206
1.014
Observed renecti0ns【,>2 (|『)]
Final GooF
卢/(。)
.y/(。)
Z
74.942(2)
74.734(2)
2
R1,wR2【,>2 (川
R1,wR2(all data)
Largest different peak and hole/e-nm一’
0.038 2,0.070 9
0.054 8,O.077 2
676,一737
2 Results and discussion
the carboxyl f03一C 1 0.O41 adopts the monodentate
mode in form of neutral 4一EBAH.
2.1 Crystal structure of【La(EBA)3(EBAH)(H2o)】
The repI。esentative structure of the complex
Each La(皿ion is coordinated with nine oxygen
atoms,in which four oxygen atoms from four bridging-
bidentate 4-EBA ligands,three oxygen atoms from two
including the atomic numbering scheme is described in
Fig.1.The prominent characteristic is the 1 D chain.in
which the center La3 ions act as nodes and are conn—
ected through 4一EBA ligands.Carboxyls fO 1-C 1—02
chelating—bridging 4一EBA ligands,one oxygen atom
rom one neutralf 4-EBAH ligand and one from the
and 07一C28—08)adopt bidentate-bridging coordination
fashion,namely,the two oxygen atoms coordinate to two
coordinated water molecule.So each La0 ion lies in a
distorted tricapped trigonal—prismatic coordination
different La ions.Carboxyl f05.C 19—061 adopts the
chelating—bridging coordination mode,in which 05 and
06 coordinate to one La ion by chelating fashion and
environment(Fig.2).Atoms 02 ,08 and 05 construct
the upper plane of the distorted trigonal prism and
atoms 01,06i and 07i form the below one,with the
dihedral angle of 5.744。between them.The 09.03 and
06 atoms are at the vertices of each square pyramid.
06 simultaneously hridges with another La ion.While
Symmety codesr used to generate equivalent atoms: I q
1 ;”2-x,-y,l-z
,
_y
Symmetry codes:‘1 ,-y,1-z; 。2 ,-y,l
Fig.1 Molecular structure of the complex
Fig.2 Coordination polyhedron of the title complex
无机化学学报 第26卷
And the mean distance from the upper and lower plane
is 0.322 8 nm.
bonds are all intramoleculy.ia.e.stabilize the one—
dimensional chain structure of the polymer,as
indicated in Fig.3.Additionally.at the same side of 1D
chain,the benzene rings of 4-EBA ligands or 4-EBAH
ligand parallel each other and the shortest ve ̄ical
The adjacent LaⅢions aye linked by the cayboxy.
1ate groups of 4-EBA ligands in the bridging-bidentate
or chelating—bridging coordination mode,resulting in an
infinite chain structure Mong the b axis.The distance
distance of the corresponding adjacent benzene tings
are 0.560 8.0.680 3.0.578 l and 0.43l 4 nm for the
between two adjacent La3 ions is 0.426 05(3)nm for
Lali…Lal and O.545 10(31 nm for Lal…Lal .And the
angle of Lal …Lal…Lal i is 157.753(6)。.The bond
lengths of Lal-O,except for Lal一06,range from
0.244 7(2)to 0.267 2(2)nm,with a mean value of 0.252 2
nm.which aye rational as literatures reposed【 .
Whereas,the rather long Lal一06 distance of 0.298 9(2)
nm oversteps the average length of La—O bond【 埘.
And the bond angles of O—Lal—O(carboxy1)range from
45.65(7)。to 154.20(7)。.
As shown in Table 3,the coordinating water,
cayboxylate oxygen atoms of 4-EBA ligands and
carboxylic H atom of 4-EBAH ligand are involved in
7
9
7
8
3
7
7
8
2
2
8
3
3
8
1 0
8
8 8
8
4 5
8
O 2
7
5
7
0 2
8
7 9
8
O-H…O hydrogen-bonding interactions r09-H9B…
Fig.3 Intramolecular hydrogen bonds of extended
chain—like stuctrure along the b axis
02,04-H4A…05).Furthermore,these hydrogen
Table 2 Selected bond lengths(nn1)and angles(。)for the complex
La1—07
0.244 7(2)
0.245 2(2)
Lal—O8
La1.05
0.247 9(21
Lal一09
La1.03
La1.06
0.262 4(2)
0.267 2(2)
0.298 9(2)
Lal—O1
Lal一02
0.258 1(2)
0.246 6(2)
0.245 7(2)
Lal—O6
O7i-Lal—O1
O7 .La1.02
85.28(8)
138.38(8)
88.76(7)
72.12(8)
06 .La1.O8
O7i-Lal一05
01.La1.05
O2ii_La1.05
06’.La1.O9
08.La1。O9
O5.La1一O9
O7 一Lal一03
75.51(8)
65.78(8)
141.11(8)
70.76(8)
67.79(8)
O1.La1.02
O7l-La1.O6
0l-La】.O6
O2 一La1 06—
07LLa1.O8
O1.I丑1—08
88.38(8)
148.91(8)
O6 一La1。O5
O1.Lal—O3
O8.Lal一05
OT-Lal—O9
O1.Im1一O9
02ii_Lal一09
O8一La1.06
05.La1.O6
O9.La1一O6
O2ii—La1.03
O6j-Lal一03
08一Lal一03
05.La1.03
68.89(8)
137.01(8)
142.87(8)
69.82(7)
129.47(8)
134.89(8)
81.26(8)
122.91(7)
69.86(7)
O2ii.La1—08
O9一La1—03
07 一La1—06
O6i.La1.06
02 .La1.06
O3一Lal一06
77.73(7)
1 14.27(7)
108.39(7)
O1.La1.O6
154.20(7)
Symmetry codes used to generate equivalent atoms: 1-x,-y,l-z; 2 ,一Y,1-z
Table 3 Hydrogen bond lengths and angles
第9期 杨娟等:一维链状4-乙基苯甲酸镧配合物[La(EBA)3(EBAH)(H 0)] 的合成、晶体结构和性质研究
nm,0=0.233。,in which Cg is the ring centroid,dc.c is
the centroid-centroid distance,dp P is the vertical
distance,and 0 is the dihedral angle of two neighboring
C2-C4-C6,C1 1一C13-C15,C20-C22-C24 and C29-C31一
C33,respectively.Therefore,there is no obvious 7r…7r
packing effect within the one—dimensional polymer
although the benzene rings parallel highly each other.
To some extent,the structure of the title complex
7r—planes【l8】.Similarly,the benzene ring(C20,C2 1,
C22,C23,C24,C25)and the neighboring B ring are
also parallel highly with dc ̄c=0.394 1 2 nm,dP_P=0.356 02
nm.0:O。.The weak 7『…7r stacking interactions
is similar to that of complex[Eu(2・IBA)3・H20] (2-IBA=
2-iodobenzoate) .The latter complex is also 1 D polymer
chain structure,in which Eu ions are connected
through two carboxyl groups of two 2・IBA ligands via
the bridging--chelating・-bridging tetradentate coordina・・
tion mode.In the structure of 1 D chain polymer
[Eu(2,4-DC1BA)3・(CH3CH2OH)2] (2,4-DC1BA=2,4一
dichlorobenzoate)t .each Eu ion is eight.coordinated
with four oxygen atoms of four bidentate--bridging 2,4--
DC1BA anions,two oxygen atoms of one bidentate—
chelating 2,4一DC1BA anion and two atoms of two
ethanol molecules.Unlike the title complex,in the 1 D
polymeric chain of[Tb(3-IBA)3(H20)2・0.5(4,4 bipy)]
(3-IBA=3一iodobenzoate;4,4 一bipy=4,4 bipyridine),
each Tb ion is connected through four bidentate
bridging 3-IBA ligands and lies in a distorted square-
antiprism geometry.The 4,4 一bipy molecule in the
crystal lattice does not coordinate to Tb ion【垌.In the
dinuclear complex of{La[o—C6H4(NO2)(CO2)]3・(DMF)2}2
o-nitro-benzoic acid),two La㈣ions are bridged by
four 0一nitro-benzoic acid ligands with their carboxyls
and occupy the nine coordination sites,in which two
carboxyl groups adopt bidentate—bridging coordination
mode and the other two take monodentate—bridging
mode【l7】.Obviously.the distinct difference from the ifnal
sturctures of these coordination complexes may be
caused by the different ligands,for example,the
different substituent groups or the different position
locating in the benzene rings.
In addition,each unit cell is packed by six 1 D
polymeric chains along a axis.These 1D chains parallel
each other with the shortest distance between the
adjacent La of 1.474 63(6)nm and 1.498 47(6)nm.
Moreover,there are two kinds of inter.molecular 7r…7r
interactions between the benzene rings of neighboring
polymeric chains.As shown in Fig.4,the benzene ring
(C1 1,C12,C13,C14,C15,C16)and the adjacent A
irng are parallel with dc-c=0.377 35 nm,dp
.
p=O.306 32
assemble the neighboring 1D chains into the two—
dimensional layer structure paralleling to bc plane for
the title complex.
Fig.4 Arrangement of the仃…仃stacking interactions
paralleling to bc plane of the title compound
2.2 IR and UV spectrum of the title complex
The IR specturm of the complex was determined in
the range of 4 000-400 cm—as KBr pellets.Compared
with the 4一EBAH ligand,the IR spectral intensity of the
complex around l 7 10 cm~is significantly weakened,
which is observed for the—COOH【捌.It demonstrates
that there are several different coordinating fashions of
the carboxylate groups in the complex,including the
deprotonated anions and the neutral molecule.Another
feature of the IR data of the complexes iS the separation
between v ̄(COO)and vs(coo-),which have often been
used to discuss the coordination mode of carboxylate
group in the carboxylate complexes.Two strong
peaks at 1 532 and l 383 em一 could be assigned to the
(C00一)and/Ys(coo一)stretching vibration of carboxyl
1610 无机化学学报 第26卷
in 4-EBA ligand.The Av[v (COO一)-v (COO一)]of 149
am一 suggests that the coordination of the carboxylate
groups is most probably of the bridging type ,which is
also supported by the results from single-・crystal X・-ray
diffraction data.Peaks observed at 2 985~2 846 cm-1
are in good agreement with C-H vibrations.and the
wide absorption peak at about 3 405 cm一 is assigned to
the vibrations of water molecules.The weak band at
435 am—may be assigned to the vibrations of La—O
bond{2tJ.
The UV spectra of the free ligand and the complex
were recorded in DMF solvent with the concentration of
1 mmol・IJ_ .Both of the spectra have one strong absorp—
tion peak at 272 nm attributing to 7r 7r transition.
however,the intensities are different.The absorption
intensity of the complex =1.51 xl0。)is evidently
stronger than that of free 4-EBAH ligand(e=0.72x 103),
which is attributed to the coordination between the
ligands and the center La3 ions.Owing to the formation
of complex,the degree of conjugation and intensities of
UV absorption obviously increased.
2.3 Luminescent properties
The solid state fluorescence spectrum of the
complex was measured at room temperature.The
excitation specturm was recorded in the range of 250-
400 am,setting 449 nm as the emission wavelength,in
which there is a strong peak at 335 nm.In contrast to
the weak luminescence of the free ligand,the complex
exhibits one strong band centered at 449 nm excited at
335 nm in the solid state(Fig.5).Since there are no 4f
electrons and the energy level of excited states below
the tirplet levels of the ligand for La㈣ions the energy
Wavelength/ilm
Fig.5 Excitation(a)and emission(b)spectra of the
complex in the solid state
absorbed by the 4-EBA ligand cannot transfer to La㈣
ions.The absorbed energy can only relax through its
own eneryg levels.The intense blue fluorescence
emission of the complex is attributed to the enhanced
7r electron transition of the ligand.Therefore.the
complex emits the ligand.centered lfuorescence.
2.4 Thermogravimetric analysis
The TG—DSC analysis was performed in air
atmosphere with a heating rate of 10 oC・min in tlle
temperature range from 30 to 700℃.The results indic.
ate that the complex involve two steps of weight losses.
The first weight loss of 2.26%from 30 to 246℃
corresponds to the coordinated water molecule fcalcul—
ated 2.39%1.The next mass reduction of 74.79%occurs
in the range 246-625 oC and shows two apparent
exothermie peaks,corresponding to the removal of
organic ligands.The weight of the residue is 22.95%.
Supposing La203 as final residue,calculated residue
weight of the complex is 21.59%,which is in coincide-
nce with experimental value.Results indicate that the
complex is degraded to oxide,completely.
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