To study the emission dynamics for the Ru(Ⅱ) complexes bond to DNA

and show the effects of the molecular structure of complexes on bonding to DNA

three kinds of Ru(Ⅱ) complexes [Ru(bpy)

2

(7-CH

3

-dppz)]

2+

[Ru(bpy)

2

(7-F-dppz)]

2+

and [Ru(phen)

2

(7-F-dppz)]

2+

[bpy=2

2′-bipyridine

dppz=dipyrido[3

2-a:2′

3′-c]phenazine

phen=1

10-phenanthroline]

have been synthesized.Their electronic absorption spectras and steady-state fluorescence spectra have been investigated.The electronic absorption spectra show that the wavelength of metal-to-ligand charge transfer(MLCT) peaks of the three kinds of Ru complexes are all at about 400 nm.Under the same power of photoexcitation at the wavelength of the MLCT peaks

the binding of [Ru(bpy)

2

(7-CH

3

-dppz)]

2+

to calf thymus DNA has the strongest fluorescence

and [Ru(bpy)

2

(7-F-dppz)]

2+

to calf thymus DNA has the feeblest one.On the base of the study for the absorption spectra and steady-state fluorescence spectra

the transient luminescence in three kinds of Ru(Ⅱ) complexes bond to DNA have been studied by using picosecond time resolved spectroscopy.The results show that the fluorescence decay for the Ru(Ⅱ) complexes bond to DNA exhibits as a biexponential form.Among the three kinds of Ru(Ⅱ) complexes

[Ru(bpy)

2

(7-CH

3

-dppz)]

2+

bonds to DNA has the longest luminescence lifetime(about 382 ns and 108 ns)

[Ru(bpy)

2

(7-F-dppz)]

2+

bonds to DNA has the shortest lifetime(about 65 ns and 16 ns)

and [Ru(phen)

2

(7-F-dppz)]

2+

bonds to DNA has the lifetime(about 326 ns and 37 ns) shorter then [Ru(bpy)

2

(7-CH

3

-dppz)]

2+

and longer then [Ru(bpy)

2

(7-F-dppz)]

2+

.The possible origin of the luminescence dynamics has been discussed.The luminescence is attribute to radiative decay from the MLCT excited state to the ground state.Through the interaction with the DNA

the radiativeless rate of the photoexcited Ru(Ⅱ) complex molecules is decreased

which results in the increase of luminescence lifetime and efficiency.The more stronger for the interaction

the more longer for the luminescence lifetime and higher for luminescence efficiency.The molecular structure of the Ru(Ⅱ) complex has an important impact on the interaction with DNA.