[Synthesis, characterization and luminescence properties of novel beta-diketone and Eu(III) ternary complex].

The novel beta-diketone 1-(4-bromophenyl)-3-phenylpropane-1, 3-dione (L) was synthesized at room temperature by classical Claisen condensation reaction. With the beta-diketone L as the first ligand and phen as the secondary ligand, and a new rare-earth Eu (III) ternary complex was prepared. The ligand L and ternary complex were characterized by elemental analysis, IR spectra, UV spectra and fluorescence spectra. IR spectra indicated that: the novel ligand L contained the structure of beta-diketone, where the content of enol was high; the Eu3+ ion in the ternary complex was coordinated with six oxygen atoms of three L ligands and two nitrogen atoms of the second ligand phen. UV spectra showed that the main absorption was from the first ligand L in the Eu (III) ternary complex. The excitation and emission spectra of the ternary complex were measured and investigated. Fluorescence spectra demonstrated that the ternary complex could emit characteristic fluorescence of rare earth Eu3+ ion and the strongest emission band was narrow which was attributed to the 5 D0 --> 7 F2 transitions of the 4f electrons of the central Eu3+ ions. So, the new Eu(III) ternary complex is an excellent red-emitter which would be regarded as a valuable material with bright red fluorescence because it presents good monochromaticity.

[Synthesis and photoluminescence of novel terbium(III) ternary complexes with carboxylic acid].

In the present paper, imidazo[5,6-f] phenanthroline(IP), 2-aniline carbonyl benzoic acid (HAB) and 2-diphenylamine carbonyl benzoic acid (HDPAB) were synthesized at room temperature. Under the same condition, with HAB and HDPAB as the first ligand and IP as the secondary ligand, two novel ternary organic terbium complexes were prepared in ethanol solution. Elemental analysis demonstrated that the chemical formula of the two ternary complexes were Tb(HAB)3IP and Tb(HDPAB)3IP. The spectroscopic properties of the ligands and complexes were also discussed. IR spectra indicated that rare earth Tb3+ ion was coordinated with oxygen atoms of the first ligand HAB and HDPAB and two nitrogen atoms of the secondary ligand IP. The UV spectra showed that the main absorption was from the first ligand in the ternary complexes, the secondary ligand was bonded to rare earth Tb3+ ion and the energy transfer efficiency of HAB was higher than that of HDPAB. The excitation and emission spectra of the two terbium complexes were measured and investigated, especially by comparing their fluorescence intensities. Fluorescence spectra demonstrated that the two kinds of ternary organic terbium complexes could emit characteristic fluorescence of rare earth Tb3+ ion. But the fluorescence intensity of Tb(HAB) IP was obviously higher than that of Tb(HDPAB)3 IP. Compared with two first ligands HDPAB and HAB, the fluorescence intensities of the two ternary organic terbium complexes were found to be influenced by the molecule structure, and the benzene ring which was coordinated with nitrogen atom increased in HDPAB. In the system of ternary complexes, due to the different coordinated number of benzene ring, the mobility of electron and the distribution of electron cloud were changed. The variation affected the transition of the pi electrons, which can take in the energy in ternary complexes. So, the energy transfer efficiency from the first ligand to rare earth Tb3+ ion decreased and Antenna effect achieved inefficiency in Tb(HDPAB)3IP.

[Synthesis and fluorescence property of novel rare earth europium, terbium complexes with beta-diketone].

A novel beta-diketone 1-(4-aminophenyl)-4,4,4-trifluorobutane-1, 3-dione(p-NBFA) was synthesized by Classical claisen condensation reaction. With p-NBFA as the first ligand and 1,10-phenanthroline(phen) as the secondary ligand, two new rare earth Eu(III), Tb(III) ternary complexes were prepared. Elemental analysis demonstrated that the compositions of the complexes were Eu(p-NBFA)3 phen and Tb(p-NBFA)3 phen. IR spectra indicated that rare earth ions were coordinated with oxygen atoms of the first ligand and two nitrogen atoms of the secondary ligand. UV spectra showed that the main absorption was from the first ligand in the complexes, the secondary ligand was acted as the synergistic coordination. Fluorescence spectra demonstrated that the emission intensity of Eu(p-NBFA)3 phen was obviously stronger than that of Tb(p-NBFA)3 phen. Further investigation showed that the emission intensity was influenced by the matching situation of energy level between the triplet state of ligand and the emission energy of rare earth ion. In Tb(p-NBFA)3phen, due to that the triplet state energy level of p-NBFA was too near to the energy level of 5D4, then the energy transfered back to the ligand, most of the excitation energy was consumed, so the terbium complex showed lower luminescence intensity and competitive luminescence of p-NBFA also appeared. In Eu(p-NB-FA)3phen, the energy level difference was well matched and the emission of europium complex was characteristic and high.

[Effect of inorganic host MCM-41 doped with Yb3+ on the photoluminescence properties of guest Tb(aspirin) 3phen].

Assembly system with MCM-41 doped with Yb3+ as a host, and Tb(aspirin) 3phen, which had been heat treated, as an active optical guest, was synthesized at room temperature. The structure and physical properties of the composites were characterized by a combination of different techniques such as XRD, N2 adsorption-desorption and IR, while the photoluminescence properties of the composites were analyzed by PL. Excitation and emission spectra were examined to explore the PL properties of the prepared samples and the relationship between the optical guest and the inorganic host. The present paper reports a new synthesis method called "Direct-Calcination" to avoid the loss of rare earth ions in the process of synthesis. Strong reflections at 2theta = 2.6 attributed to (100) reflection were presented in XRD patterns of both Yb/MCM-41 and Tb(aspirin) 3phen-Yb/MCM-41, which always can be observed for regular, spherical structure of MCM-41 materials, and the inorganic framework order increased after Tb(aspirin) 3phen being incorporated into the channels of Yb/MCM-41. The intensity of the band at 963 cm(-1) decreased in IR spectrum of Yb/MCM-41, relative to that in IR spectrum of MCM-41, implying that Yb3+ had been banded with the framwork. And a sharp band at 1 384 cm(-1) in IR spectrum of Tb(aspirin) 3phen-Yb/MCM-41 also gives the characteristic information about the bands in Tb(aspirin) 3phen-MCM-41. The results from the characterization of PL show that the wide excitation band over 240-375 nm of Tb(aspirin) 3phen is assigned to the carbonyl group n --> pi* transition absorption, benzene ring pi --> pi* transition absorption of aspirin, and phenanthrene absorption of phen. The luminescence intensity of Tb(aspirin) 3phen incorporated into the channels of MCM-41 can be enhanced by heat treating in the synthesis process of Tb(aspirin) 3phen, while the intensity also can further increases by doping Yb3+ in the silicon framework of MCM-41. The luminescence intensity of the assembly system gets to maximum when Yb/Si ratio is 7.579 x 10(-3).

[Effect of host MCM-41 on the luminescence properties of Tb(aspirin)3phen].

Highly ordered mesoporous material MCM-41A(after calcination) and MCM-41B (before calcination) were synthesized in ethylenediamine (EDA) medium at room temperature, and the rare earth complexes Tb(aspirin)3phen which had been heat treated as an active optical guest was incorporated into the one-dimensional channels of MCM-41A(B). The photoluminescence properties of the organic/inorganic composites Tb(aspirin)3phen-MCM-41A(B) were investigated based on the analyses of excitation and emission spectra to provide information about the relationship between the organic host and the inorganic optical guest. The results from the characterization of PL show that the wide excitation band in the range of 240-375 nm of Tb(aspirin)3 phen is assigned to the carbonyl group n --> pi* transition absorption, benzene ring pi --> pi* transition absorption of aspirin, and phenanthrene absorption of phen. As no excitation band appears in ultraviolet ranges, the characteristic emission peaks of Tb3+ in the emission spectra are related to antenna effect Relative to the excitation band of Tb(aspirin)3phen, the excitation band of Tb(aspirin)3phen-MCM-41B and Tb(aspirin)3phen/MCM-41A splits obviously, and only one narrow excitation peak at 353 nm appears in the excitation spectrum of Tb(aspirin)3 phen-MCM-41A. The excitation bands of Tb(aspirin)3 phen-MCM-41B and Tb (aspirin)3 phen/MCM-41A at short wavelength weakens and disappears gradually, while excitation peaks at long wavelengths is enhanced gradually, and the IL/ILn ratio I, where IL is the emission intensity at 405 nm under 335 nm excitation, and I(Ln) is the emission intensity at 544 nm under 335 nm excitation, also decreases correspondingly. It is suggested that the triplet states and single states of aspirin and phen reduce with different degree after Tb(aspirin)3phen is banded with MCM-41 framework, and the effect of silicon framework on the states of phen is more than that of aspirin. The degree of the effect on the states of organic ligands is in the order of: MCM-41B external surface > MCM-41A external surface > MCM-41A inside surface. In addition, the ratio I also could indicates the degree of the effect of MCM-41 surface lattice field on the ligand energy level and the content of Tb (aspirin)3phen on the MCM-41 surface.