SUNY at Albany
June 19-23, 2001
DNA mediated energy transfer from 4',6-diamidino-2-phenylindole to [Ru(1,10-phenanthroline)2L]2+: Ligand size effect
It was found in our laboratory that excited energy of a minor groove binder 4',6-diamidino-2-phenylindole(DAPI) transfers to intercalated [Ru(phen)2dipyrido-[3,2-a:2',3'-c]phenazine(DPPZ)]2+ complex across the DNA stem when they are bound to poly[d(A-T)2], simultaneously. Since the efficiency of energy transfer has been known to depend on the distance and orientation of the donor and acceptor, these effect were examined by replacing the DPPZ ligand by larger benzodipyrido-[3,2-a:2',3'-c]phenazine(BDPPZ) and dipyrido-[3,2-a:2',3'-c]phenazinecyclopentane-imidazolidine (DPPZ-CPI) ligand. Similarly to DPPZ case, circular and linear dichroism results indicate that expanded ligand of the metal complex is intercalated from the major groove of poly[d(A-T)2] when minor groove is blocked by DAPI. The extent of decreasing in the DAPI fluorescence intensity by ruthenium complexes was almost the same for all expanded ligands, indicating the distance effect is negligible. When the F(l )/F410nm(l) ratios were plotted with respect to wavelength, the shapes of the resulting plots were similar to absorption spectrum of DAPI. It indicates that excited energy of DAPI was transferred to the ruthenium complexes.
Jungho Yoon(1), Chang-Beom Cho(1), Seog K. Kim(1), and Maeng-Joon Jung(2*)
Department of Chemistry(1) , Yeungnam University, Republic of Korea
Department of Chemical Engineering(2) , Sangju National University, Republic of Korea