Two-photon absorption of metal-organic DNA-probes
ABSTRACT We report remarkable multiphoton absorption properties of DNA intercalating ruthenium complexes: (1) [Ru(phen)(2)dppz](2+); (2) [(11,11'-bidppz)(phen)(4)Ru(2)](4+); (3) [11,11'-bipb(phen)(4)Ru(2)](4+). Two-photon spectra in the range from 460 to 1100 nm were measured using the Z-scan technique. In particular, complex 2 was found to exhibit very strong two- and three-photon absorption properties, which could be an effect of symmetric charge transfer from the ends towards the middle of the conjugated dimeric orbital system. We propose that these molecules could provide a new generation of DNA binding nonlinear chromophores for wide applications in biology and material science. The combination of a large two-photon cross section and strong luminescence quantum yields for the molecules when intercalated makes the compounds uniquely bright and photo-stable probes for two-photon luminescence imaging and also promising as enhanced photosensitizers in two-photon sensitizing applications.
- SourceAvailable from: Changhee Lee[Show abstract] [Hide abstract]
ABSTRACT: Light‐emitting electrochemical cells (LECs) with a simple device structure were prepared by using heteroleptic bis(tridentate) ruthenium(II) complexes (PF6)2–(PF6)2 as emitters. The push‐pull substitution shifts the emission energy to low energy, into the NIR region. The devices emit deep red light up to a maximum emission wavelength of 755 nm [CIE (International Commission on Illumination) coordinates: x = 0.731, y = 0.269 for (PF6)2], which, to the best of our knowledge, is the lowest emission energy for LECs containing bis(tridentate) ruthenium(II) complexes. A device structure of ITO/PEDOT:PSS/ruthenium(II) complex/Ag was used, and the thickness of the emitting layer was measured by AFM [ITO: indium tin oxide, PEDOT: poly(3,4‐ethylenedioxythiophene), PSS: poly(styrenesulfonate), AFM: atomic force microscopy]. To enhance the external quantum efficiency (EQE), cells were fabricated with and without poly(methyl methacrylate) (PMMA) as additive in the emitting layer.European Journal of Inorganic Chemistry 01/2014; 2014(2). DOI:10.1002/ejic.201301226 · 2.97 Impact Factor
- [Show abstract] [Hide abstract]
ABSTRACT: Interaction of zinc(II) and cadmium(II) sulfates with pyridine-4-aldoxime (4-pyao) and pyridine-4-amidoxime (4-pyamo) ligands resulted in four 1D metal–organic materials (MOMs) with identical composition, [M(SO4)A2(H2O)2]n, where M = Zn(II), A = 4-pyao for 1, M = Cd(II), A = 4-pyao for 2, M = Zn(II), A = 4-pyamo for 3, M = Cd(II), A = 4-pyamo for 4, and mononuclear [Zn(SO4)(4-pyamo)2(H2O)3] 5. New coordination polymers represent the mixed-ligand supramolecular isomers different by the twisting of two pyridine-4-oxime ligands in the metal coordination environments, and crystallizing in the different space groups. Conformational preferences and nonlinear optical properties of the 4-pyao and 4-pyamo complexes were investigated using density functional theory. Spectral properties of 1–3 have been also evaluated. The solid-state emission of 1D polymers 1–3 appears to be ligand-based, as the positions of the emission maxima remain practically unchanged from free ligand to complexes. The enhancement of luminescence and two-photon absorption in polymers in comparison with the pure ligands is attributed to the chelation of the ligand to the metal center. The detailed mechanism of this enhancement upon complex formation is analyzed and can be used in future design of metal–organic nonlinear optical materials.The Journal of Physical Chemistry C 04/2014; 118(17):9217–9227. DOI:10.1021/jp5007395 · 4.84 Impact Factor
- [Show abstract] [Hide abstract]
ABSTRACT: The push-pull-substituted bis(terpyridine)ruthenium(II) amino acid [Ru(4′-tpy-COOH)(4′-tpy-NH2)]2+ (2+; tpy = 2,2′;6′,2″-terpyridine) with carboxylic acid and amino substituents features exceptional chemical and photophysical properties. Its interaction with photons, electrons, and/or protons results in room-temperature phosphorescence, reversible oxidative and reductive redox chemistry, reversible acid/base chemistry, proton-coupled electron transfer, photoinduced reductive and oxidative electron transfer, excited-state proton transfer and energy transfer reactions. These properties can be fine-tuned by variations of the bis(terpyridine) amino acid motif, namely extension of the π system and expansion of the chelate ring. Furthermore, the chemically orthogonal functional groups enable the incorporation of this metallo amino acid into peptide architectures in a highly selective manner, even by solid-phase peptide synthesis protocols. Amide-linked conjugates with other metal complexes [(terpyridine)ruthenium(II), ferrocene, (bipyridine)rhenium(I), (bipyridine)platinum(II)], organic chromophores, or ZnO nanoparticles underscore the versatile synthetic, redox, and photochemistry of this building block. First real-world applications of 2+ and its derivatives include light-emitting electrochemical cells (LECs) and dye-sensitized solar cells (DSSCs).Berichte der deutschen chemischen Gesellschaft 11/2014; 2014(32). DOI:10.1002/ejic.201402466