Lan Yan

Synthesis, characterization and fluorescent properties of lanthanide complexes with two aryl amide ligands

Two aryl amide ligands, N-(p-tolyl)-2-(quinolin-8-yloxy)acetamide (L1 ) and N-(4-chlorophenyl)-2-(quinolin-8-yloxy)acetamide (L2 ), were synthesized. With these ligands, two series of lanthanide(III) complexes were prepared, Ln(L n )2(NO3)3 (n = 1, 2; Ln = La, Sm, Eu, Gd, Dy), and characterized by the elemental analyses, molar conductivity, 1H NMR spectra, IR spectra and TG-DTA. The fluorescence properties of the complexes and the triplet state energies of the ligands were studied in detail. In addition, the quantum yields of both Eu(III) complexes and Eu(L0)2(NO3)3 [where L0 is N-(phenyl)-2-(quinolin-8-yloxy)acetamide] 1 were calculated. The results indicate that among the lowest triplet energies (T) of the three ligands, that of L2 is most suitable to the resonance level (5D1) of Eu(III) ion. Furthermore, Eu(L2)2(NO3)3 has the highest fluorescence intensity and quantum yield of the three Eu(III) complexes.

Rare earth complexes with a novel ligand N-(naphthalen-2-yl)-N-phenyl-2-(quinolin-8-yloxy)acetamide: preparation and spectroscopic studies.

Six complexes of rare earth nitrates (Ln=La, Sm, Eu, Gd, Tb, Dy) with a new amide type ligand, N-(naphthalen-2-yl)-N-phenyl-2-(quinolin-8-yloxy)acetamide (L) have been prepared and characterized by elemental analysis, conductivity measurements, IR and and 1H NMR spectra. Under excitation, Eu(III) and Sm(III) complexes exhibited strong red emissions. And the luminescence intensity of Sm(III) complex is higher than that of Eu(III) complex. Thus the Eu(III) and Sm(III) complexes are the potential light conversion agent. However, the Tb(III) and Dy(III) complexes cannot exhibit characteristic emissions of terbium and dysprosium ions, respectively. The results of phosphorescence spectrum show that the triplet-state energy level of the ligand matches better to the resonance level of Eu(III) than Tb(III) ion. In addition, the luminescence of the Eu(III) complex is also relatively strong in highly diluted tetrahydrofuran solution (2 x 10(-4)mol/L) compared with the powder. This is not only due to the solvate effects but also to the changes of the structure of the Eu(III) complex after being dissolved into the solvents. Furthermore, owing to the co-luminescence effect, the proper La(III) or Gd(III) doped Eu(III) complexes show stronger luminescence than the pure Eu(III) complex.

Synthesis, Characterization, and Fluorescence Studies of a Novel Schiff Base Ligand and Its Zn(II), Ni(II), Co(II), Cu(II) Complexes

A novel ligand, N,N′‐bis(2‐hydroxy‐1‐naphthylidene)‐3‐oxa‐1,5‐diaminopentane (H2L), and its Zn(II), Ni(II), Co(II), Cu(II) complex were synthesized. The structures of the ligand and its complexes were characterized by elemental analyses, MS (Fab), IR spectra and DTA‐TG. The results show that the molecular composition of these complexes is ML · 1/2H2O and they are tetradentate complexes, in which the metal ions are coordinated by two nitrogen atoms (‐C=N) and two oxygen atoms (Ar–OH). The fluorescence of the ligand and its complexes in different solvents and pH conditions have also been studied in detail. An enhancement of the fluorescence intensity of the ligand can be observed clearly in the presence of Zn(II), but quenching occurs for the other metal ions.

TERNARY COMPLEXES OF SM(III), EU(III), TB(III), AND DY(III) WITH 6-METHYLPICOLINIC ACID N-OXIDE AND DIBENZOYLMETHANE

Abstract A series of new ternary complexes of 6-methyl-2-picolinic acid N-oxide (HL) and dibenzoylmethane (HDBM) with Ln(III) (Ln = Sm, Eu, Tb, Dy) have been synthesized and characterized in detail. The composition of the ternary complexes was determined as NaLnL3 DBM·3H2O. They are 1:1 electrolytes in methanol. Compared with LnL3·nH2O, NaLnL4·nH2O and LnL3phen·nH2O, the order of fluorescence intensity as determined by fluorescence spectra is: LnL3phen·nH2O > NaLnL4·nH20>LnL3·nH2O > LnL3DBM·3H2O.

Synthesis, Characterization and Fluorescence of N,N′‐Bis(6‐methyl‐2‐pyridinecarboxylamide‐N‐oxide)‐1,2‐ethane and Corresponding Rare Earth(III) Complexes

A new ligand, N,N′‐bis(6‐methyl‐2‐pyridinecarboxylamide‐N‐oxide)‐1,2‐ethane (L), and its six lanthanide(III) complexes (RE=La, Sm, Eu, Tb, Gd, Yb) were synthesized and characterized in detail. The results indicate that the composition of the binary complexes was determined as [REL(H2O)2(NO3)2] NO3 · nH2O (n=0–2), that the six complexes are 1∶1 electrolytes in DMF, and that the Eu3+ complex has bright red fluorescence in a solid state. At the same time, we synthesized three complexes of Eu3+, Tb3+, and Gd3+ with 6‐methylpicolinic acid N‐oxide (L,). The intensity of sensitized luminescence for Eu3+ increases in the following order: L>L′. The energies of an excited triplet state for the ligands are 20704 cm−1 (L) and 20408 cm−1 (L′), respectively. The fact that the ligands strongly sensitized Eu3+ and the order of the emission intensity for the Eu3+ complexes were explained by the relative energy gap between the lowest triplet energy level of the ligands (T) and 5D of Eu3+ or Tb3+. This means that the triplet energy level of the ligand is the chief factor, which dominates RE3+ luminescence.