A series of dinuclear complexes with different Eu

3+

to Tb

3+

ratios with

p

-phthalic acid (L') and ligand of 18 crown 6(L) have been synthesized.Elemental analysis

IR absorption spectra and fluorescence spectra have been studied respectively.The compositions of the complexes were confirmed to be(Eu

1-x

Tb

x

)

2

L

2

L'(ClO

4

)

4

·H

2

O

(6+3x)

.Smaller Tb

3+

coordinated with water molecules

which were hydrogen bonded with crown ether while Eu

3+

coordinated with crown ether directly may be concluded. Shimadzu FR-5301PC fluorescence spectrophotometer was employed to measure the luminescence spectra at room temperature.As results showed the excitation wavelength changed with the molar ratios of Eu

3+

to Tb

3+

.The optimum excited wavelength is at the same position(298 nm) when contents of Tb

3+

is 100% and 90%

respectively.It changes to 254 nm when Tb

3+

content decrease to 70% and Eu

3+

content rise to 30%.The measurement results of the emission spectra of the complexes indicated that the emission peaks of Tb

2

L

2

L'(ClO

4

)

4

·12H

2

O consisted of four groups of emission peaks and Eu

2

L

2

L'(ClO

4

)

4

·6H

2

O has three

while (Eu

1-x

Tb

x

)

2

L

2

L'(ClO

4

)

4

·H

2

O

(6+3x)

has five.The previous are as following:peaks at 490.0

545.8

585.6 and 621.0 nm are as the Tb

3+

ions

5

D

4

→

7

F

J

(

J

=6

5

4

3) transitions correspondingly

among them the emission from

5

D

4

→

7

F

5

is the strongest belonging to hypersensitive transition(Δ

J

=2).The latter are following:first group

578.6 nm belongs to

5

D

0

→

7

F

0

transitions of Eu

3+

the second group

588.2 nm and 592.2 nm

both belong to

5

D

0

→

7

F

1

transitions of Eu

3+

the third group

613.6nm and 618.2 nm both belong to

5

D

0

→

7

F

2

transitions of Eu

3+

.The last one:they appear at about 490

545

579

585 and 620 nm.The first and second fluorescence bands centered around 490 nm and 545 nm corresponding to

5

D

4

→

7

F

6

and

5

D

4

→

7

F

5

transitions of Tb

3+

ions.Overlapped peaks at 585 nm and 620 nm were found caused by interaction between

5

D

0

→

7

F

1

5

D

0

→

7

F

2

transitions of Eu

3+

and

5

D

0

→

7

F

4

5

D

4

→

7

F

3

transitions of Tb

3+

.Variance of fluorescence spectra emission peaks showed that there are interaction between Eu

3+

ions and Tb

3+

ions in (Eu

1-x

Tb

x

)

2

L

2

L'(ClO

4

)

4

·H

2

O

(6+3x)

. The fluorescence emission intensity of Tb

3+

(

5

D

4

→

7

F

5

) in Tb

2

L

2

L'(ClO

4

)

4

·12H

2

O was 1 313.6 comparing with 29.8 of Eu

3+

(

5

D

0

→

7

F

2

) transitions in Eu

2

L

2

L'(ClO

4

)

4

·6H

2

O.Concluded from R=

I

d

/

I

c

(

I

d

=values of the fluorescence emission intensity determined

I

c

=calculated values) is below 1.0 at 490 nm and 545 nm (corresponding to Tb

3+

5

D

4

→

7

F

6

and

5

D

4

→

7

F

5

transitions) even at 585 nm.However when ratio of Eu

3+

and Tb

3+

is 0.9:0.1～0.7:0.3

the R values for peaks at 579 nm and 620 nm are higher than 1.0 collectively

Eu

3+

will quench Tb

3+

fluorescence while Tb

3+

will sensitize Eu

3+

.