Sequential arrangement of chromophores and energy transfer behavior on oligonucleotides assemblies

A sequential arrangement of chromophores using non‐covalent interaction in aqueous media provides a good model for an artificial photosynthetic system. In order to construct sequential arrangements of chromophores having regulated distances and geometry on non‐covalent molecular assembly systems in aqueous media, we designed chromophore/oligo‐DNA conjugates having complementary sequences. Three different chromophores, fluorescamine (Fla), rhodamine B (Rho) and fluorescein (Flu) were employed as an energy donor, an acceptor and a mediator, respectively, and were attached to 5 or 10 residues of oligo‐DNAs at their 5′‐terminals via aminolinkers. Single‐step photo‐induced energy transfer from Fla to Flu or from Flu to Rho on the molecular assembly of the chromophore/oligo‐DNA conjugates was confirmed. Then, the three kinds of conjugates having different chromophores were mixed with 15 or 25 residues of matrix oligo‐DNA consisted of complementary sequences for the conjugates, or mixed in “alternative–complementary” combinations to form sequential array of three kinds of chromophores, Fla‐(Flu) n‐Rho (n = 1–3) having five residues distances. The multi‐steps photo‐induced energy transfer from Fla to Rho through Flu mediator(s) on the molecular assemblies were observed. Copyright © 2000 John Wiley & Sons, Ltd.