Acta Phys. -Chim. Sin. ›› 1993, Vol. 9 ›› Issue (02): 148-154.doi: 10.3866/PKU.WHXB19930202

• Communication • Previous Articles     Next Articles

Studies on Langmuir-Blodgett Films of Luminescent Rare-Earth Chelates (I)

Qian Dong-Jin; Yang Kong-Zhang   

  1. Institute of Colloid and Interface Chemistry, Shandong University, Jinan 250100
  • Received:1992-08-21 Revised:1992-11-05 Published:1993-04-15
  • Contact: Yang Kong-Zhang

Abstract: Two series of luminescent rare-earth chelates have been studied spectroscopically, one is(TOPO)_2Eu(β-dik)_3(TOPO=tri-n-octyl-phosphine oxide; β-dik=trifluoroace-tylacetone(TFA), hexafluoroacetylacetone(HFA), thenoyltrifluoroacetone(TTA)), the other is (Phen)_2RE(NO_3)_3 (Phen=1,10-phenanthroline; RE=Eu,Tb,Sm). By using British NIMA LB system 2000 round trough, the pressure area (π-A) isotherms for (TOPO)_2Eu(β-dik)_3, (Phen)_2RE(NO_3)_3 monolayers at the air-water interface were investigated, then the monolayers were transfered on hydrophobic glass slides. The alternate-layer LB films were deposited by arachidic acid (AA, odd layers) and (TOPO)_2Eu (β-dik)_3 (even layers). The mixed LB films were deposited by (Phen)_2Eu(NO_3)_3 and AA (in molar ratio 1:4). Low angle X-ray diffraction results showed that the LB films mentioned above all have a periodic structure. The lattice spacing, for alternate-layer LB films are 5.32—5.52 nm, for mixed LB films are 5.23—5.32 nm. FTIR results indicated that hydrogen bond established between —CF_3 of (TOPO)_2Eu(β-dik)_3 and —COOH of AA in alternate-layer LB films. It was found that the fluorescent emission from the LB films mentioned above is strong and the fluorescent emission strength increases with the increasing of the number of layers. that the fluorescent emission from the LB films mentioned above is strong and the fluorescent emission strength increases with the increasing of the number of layers. Especially, even with only two alternate layers of AA and (TOPO)_2Eu(β-dik)_3, the characteristic fluorescent emission of Eu(III)(~5D_0→F_1 and ~5D_0→~7F_2) could be detected also. The fluorescent emission spectra of these rare-earth chelates in multilayers are much similar to those in solution, but the fluorescent excitation spectra are a little different. The characteristic fluorescent emission for each rare-earth chelate appeared in the spectra provided that the mixed LB film of (Phen)_2Eu(NO_3)_3, (Phen)_2Tb(NO_3)_3, (Phen)_2Sm(NO_3)_2 and arachidic acid (in molar ratio 1:1:1:12) was excited by optimum excitation wavelength corresponding to each rare-earth.

Key words: Rare-earth chelate, LB films, Fluorescence, Mixed LB films, Alternatelayer LB films