Enantiodifferentiating Z-E photoisomerization of cyclooctene sensitized by DNA and RNA.

DNA and RNA have been shown for the first time to function as chiral photosensitizers in aqueous solution, to effect the enantiodifferentiating photoisomerization of (Z)-cyclooctene (1Z), giving the chiral (E)-isomer in enantiomeric excesses (ee's) of up to 15%. In order to elucidate the effect of nucleotide sequence, enantiodifferentiating photoisomerization of 1Z was also performed using oligo and homopolynucleotides as chiral sensitizer. The -18.8% ee was observed by using d(T)15.d(A)15 as sensitizer, whereas sensitization by the poly(U).poly(A) duplex gave only racemic (E)-cyclooctene. From these results, oligothymidine sequence is essential for efficient enantioselective photoisomerization of 1Z.