title: DNA-Based Assemblies for Photochemical Upconversion.
abstract: In the present study DNA was used as a scaffold for the supramolecular assembly of organic chromophores for photochemical upconversion (PUC). Initially, a green-to-blue PUC was observed using free chromophores in solution: tris(2,2'-bipyridine)ruthenium(II), [Ru(bpy)3](2+), which acts as a long-wavelength absorber (λex = 500 nm), and an in situ energy donor to an acceptor (R)-1-O-[4-(1-pyrenylethynyl)phenylmethyl]glycerol (PEPy or TINA monomer), which acts as an annihilator and short-wavelength photoemitter (λem = 420 nm). Then, DNA duplexes possessing TINA monomers were synthesized, and complexes with [Ru(bpy)3](2+) were investigated. In contrast to the dynamic interactions of [Ru(bpy)3](2+) with TINA monomer free in solution, ground-state complex formation was the predominant mechanism of interaction between [Ru(bpy)3](2+) and DNA duplexes bearing two TINA monomers at the 5' ends as shown by fluorescence, circular dichroism (CD), and UV-vis spectroscopy studies. The use of TINA-modified DNAs led to PUC occurring at concentrations significantly lower than that for free chromophores in solution: 2.5 μM [Ru(bpy)3](2+) and 5.0 μM TINA-modified duplex in the DNA-based systems in aqueous buffer versus 46 μM [Ru(bpy)3](2+) and 4.6 mM TINA monomer for the free donor and acceptor in DCM, respectively. Providing vast capabilities of DNA in the development of novel photonic systems as a result of the controllable organization of various chromophores, this study opens a new perspective for the development of DNA-based light-harvesting systems using PUC.
authors.affiliation: Institute of Fundamental Sciences, Massey University , Private Bag 11-222, Palmerston North 4442, New Zealand.
authors.forename: Saymore
authors.initials: S
authors.lastname: Mutsamwira
authors.affiliation: Institute of Fundamental Sciences, Massey University , Private Bag 11-222, Palmerston North 4442, New Zealand.
authors.forename: Eric W
authors.initials: EW
authors.lastname: Ainscough
authors.affiliation: Institute of Fundamental Sciences, Massey University , Private Bag 11-222, Palmerston North 4442, New Zealand.|Department of Physics and School of Engineering, The University of Auckland , 20 Symonds Street, Auckland 1010, New Zealand.
authors.forename: Ashton C
authors.initials: AC
authors.lastname: Partridge
authors.affiliation: Institute of Fundamental Sciences, Massey University , Private Bag 11-222, Palmerston North 4442, New Zealand.|Department of Physics and School of Engineering, The University of Auckland , 20 Symonds Street, Auckland 1010, New Zealand.
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Derrick
authors.affiliation: Institute of Fundamental Sciences, Massey University , Private Bag 11-222, Palmerston North 4442, New Zealand.
authors.forename: Vyacheslav V
authors.initials: VV
authors.lastname: Filichev
mesh_terms: D015082:2,2'-Dipyridyl / Q000031:analogs & derivatives / Q000737:chemistry; D056831:Coordination Complexes; D004247:DNA / Q000737:chemistry*; D015394:Molecular Structure; D009691:Nucleic Acid Denaturation; D055668:Photochemical Processes; D013696:Temperature; D017975:Ruthenium Compounds
chemical_list: D015082:2,2'-Dipyridyl; D056831:Coordination Complexes; D004247:DNA; C547232:tris(2,2-bipyridine)-ruthenium(II); D017975:Ruthenium Compounds