摘要
采用低温固相反应合成了4种苯乙酸稀土配合物:RE(L)3.nH2O(n=0.5～1.5;RE=La,Nd,Eu,Tb;L=C6H5CH2COO-),经元素分析、稀土络合滴定、摩尔电导及热重分析确定了配合物的组成,测定了配体及配合物的IR谱、1HNMR及配体的磷光光谱和铕、铽配合物荧光激发和发射光谱。根据磷光发射光谱数据计算了配体的三重态平均能级值。铕(Ⅲ)、铽(Ⅲ)配合物的荧光光谱和配体的磷光光谱表明,配体仅对铽(Ⅲ)的荧光具有一定的敏化作用。对镧配合物进行了扫描电镜形貌分析,发现苯乙酸镧为球状空穴结构,粒径在十几微米到几十微米。
The most characteristic of solid state reaction at low temperature is that reaction is in progress at room temperature or near room temperature. Compare with liquid state reaction, solid state reaction is high selection and high yield. Because solid state reaction don＇t need solvent, and this is environtly friendly, so it is a green synthesis method. A lot of people are interested in it recently.
We have synthesized four solid complexes of rare earth with phenylacetic acid （L） by method of solid state reaction at low temperature. Elemental analysis, rare earth coordination titration, Molar conductivity studies suggest that the composition of the complexes is RE （ L ） 3 · nH2O （ n = 0. 5 - 1.5 ;RE = La, Nd, Eu, Tb L = C6H5CH2COO^-）.
TGA curve of La^3＋ complex began to lose weight at 65.41 -86.03℃ and weight loss was 1. 835%,which was good accordance with the theoretical data 1. 628% when complex had 0.5 water molecular. The temperature of losing water was lower, so water is induced to be crystal water. At 345.78 - 376.52 ℃ there is a great lose weight which was caused by the decomposition of La^3＋ complex.
The IR spectra of sodium salt of the ligand show bands at 1 571 cm^-1（s） and 1 386 cm^-1（s） ,assigned to carboxyl group＇s antisymmerty stretch vibration vas （COO^-） and symmetry stretch vibration vs （COO^-）. In addition, the band at 3 026,1 491,706 cm^-1 are individaully assigned to phenyl＇s vC-H ,vC-C ,δC-H vibration.
The IR spectra of complexes shows bands at nearby 1 546 - 1 553 cm^-1（s） assigned to vas（COO^- ） with a shift of 18 -25 cm^-1 to the lower frequency region ,which compared with sodium salt of ligand; The band at nearby 1 393 - 1 403 cm^-1 （s） is assigned to vs （ COO^- ） with a shift of 7 - 17 cm^-1 to the higher frequency region, which still compared with sodium salt of ligand. These results indicate that the carboxyl group is bonded to the metal ions through two oxygen atoms as a symmetrical chelating bidentate group.
The ^1H NMR of the ligand in DMSO shows the proton of phenyl resonance is multiplet peaks at （7.22 - 7.33 ） × 10^-6, and integral intensity shows it has five protons; The proton of methylene group resonance peak is at 3.56 × 10^-6, and integral intensity shows it has two protons. The proton resonance of the -COOH is at 12.33 × 10^-6.
The ^1H NMR spectra of the complexes are similar. The proton of phenyl and methylene group resonance peaks are all clearly, and all shift to high field at different degree. The result indicated the carboxyl group＇s oxygen of ligand coordinated with metal ions, which produced the shielded effect, it led to the proton resonance peaks shifting to high field. The absence of the --COOH proton resonance indicates that the carboxyl group is bonded to the metal ions through COO^- group.
Fluorescence spectra of Eu^3＋ complex show main emission peaks at 592.2 nm and 614.0 nm, which correspond to magnetic dipole transition ^5D0→^7F1 and ^5D0→^7F2 electric dipole transition of Eu^3＋ ion, respectively. The intensity ratio of the latter to the former is 2.1. It indicates that there is no inversion symmetry at site of Eu^3＋ ion. Fluorescence of complexes of Eu^3＋ with phenylacetic acid is part of M→M and L→M mixed luminescence.
Fluorescence spectra of Tb^3＋ complex show main emission peaks at 546.0 nm, which correspond to ^5D4→^7F5 transition, respectively. The emission intensity is 459.5 a.u. Fluorescence of complexes of Tb^3＋ with phenylacetic acid is part of L→M luminescence, and emission intensity is stronger than Eu^3＋ complex. The ligand has sensitized Tb^3＋ ion in fluorescence intensity.
出处
《发光学报》
EI
CAS
CSCD
北大核心
2007年第2期207-213,共7页
Chinese Journal of Luminescence
基金
国家自然科学基金(20461002)
内蒙古大学"513"二层次人才基金(ND205150)
内蒙古教育厅科研基金(NJ06047)资助项目
关键词
稀土配合物
苯乙酸
低温固相反应
发光
形貌分析
rare earth complex
phenylacetic acid
solid state reaction at low temperature
luminescence
shape analysis
