Five solid complexes of rare earth Eu

3+

doped La

3+

Gd

3+

Y

3+

Er

3+

and five different proportion co-doped complexes(Eu

3+

:La

3+

) with 2-thiopheneacetic acid and o-phenanthroline have been synthesized and characterized.Elemental analysis

rare earth coordination titration and TG-DTA studies show that the complexes have the composition of Eu(TPAC)

3

Phen.The different dinuclear complexes are composed of Eu

0.5

RE

0.5

(TPAC)

3

Phen(

RE

3+

=La

3+

Gd

3+

Y

3+

Er

3+

);(Eu

x

La

y

)(TPAC)

3

Phen(x:y=0.10:0.90;0.30:0.70;0.40:0.60;0.70:0.30;0.90:0.10).The molar conductivity indicates that all the complexes are nonelectrolyte;IR spectra and

1

H NMR spectra show that 2-thiopheneacetic acid combined as the form of bridging dissymmetrical bidentate ligand

and the two nitrogen atoms in phen are also involved in the rare earth ion coordination for europium complex and its doped with La

3+

Gd

3+

Er

3+

and Y

3+

complexes.There are strong fluorescence intensity for all these complexes

it shows that the lowest excitation state energy level of Eu

3+

ion with the triplet state energy level of the ligands match well each other.Its fluorescence intensity is enhanced after doping with La

3+

Gd

3+

Y

3+

.The sensitization actions from La

3+

Gd

3+

and Y

3+

to Eu

3+

ion are Y

3+

<

Gd

3+

<

La

3+

.But Er

3+

make the fluorescence intensity of the europium complex weaken.We also find that as n(Eu):n(La)=1:1

the fluorescence intensity is the strongest in the complexes of(Eu

x

La

1-x

)(TPAC)

3

Phen.

5

D

0

energy level of Eu

3+

is 17 250 cm

-1

the triplet state energy of 2-thiopheneacetic acid and o-phenanthroline are 25 000 cm

-1

and 22 123 cm

-1

respectively.The triplet state energy of the two ligands are higher than the excitation energy of Eu

3+

ion

thus it is possible that energy transfer from 2-thiopheneacetic acid and o-phenanthroline to Eu

3+

through —COO—Eu—OOC— and —N—Eu—N— bonds.The absorbing energy of the ligands are effectively transferred to europium ion in the luminescence center

and producing a characterization spectrum.Some complexes of non-fluorescence rare earth can absorb the triplet energies of the ligands too

and then transfer them to Eu

3+

in this way the fluorescence intensity was enhanced.If the transition energy of non-fluorescence rare earth complexes is lower than the

5

D

0

energy of Eu

3+

the luminescence will be quenched.