title: Assembling multiporphyrin stacks inside the DNA double helix.
abstract: Double stranded DNA hybrids containing up to four consecutive, face-to-face stacked porphyrins are described. Non-nucleosidic, 5,15-bisphenyl-substituted porphyrin building blocks were incorporated into complementary oligonucleotide strands. Upon hybridization multiple porphyrins are well accommodated inside the DNA scaffold without disturbing the overall B-DNA structure. The formation of double strands containing up to four free base porphyrins is enabled without compromising duplex stability. UV/vis, fluorescence, and CD spectroscopy demonstrate the formation of porphyrins H-aggregates inside the DNA double helix and provide evidence for the existence of strong excitonic coupling between interstrand stacked porphyrins. H-aggregation results in considerable fluorescence quenching. Most intense CD effects are observed in stacks containing four porphyrins. The findings demonstrate the value of DNA for the controlled formation of molecularly defined porphyrin aggregates.
authors.affiliation: Department of Chemistry and Biochemistry, University of Bern , Freiestrasse 3, CH-3012 Bern, Switzerland.
authors.forename: Mykhailo
authors.initials: M
authors.lastname: Vybornyi
authors.forename: Alina L
authors.initials: AL
authors.lastname: Nussbaumer
authors.forename: Simon M
authors.initials: SM
authors.lastname: Langenegger
authors.forename: Robert
authors.initials: R
authors.lastname: Häner
mesh_terms: D002942:Circular Dichroism; D004247:DNA / Q000737:chemistry*; D005453:Fluorescence; D008958:Models, Molecular; D009690:Nucleic Acid Conformation; D009693:Nucleic Acid Hybridization; D011166:Porphyrins / Q000737:chemistry*
chemical_list: D011166:Porphyrins; D004247:DNA