0000000000939413
AUTHOR
Carlos Lodeiro
Switching from intramolecular energy transfer to intramolecular electron transfer by the action of pH and Zn2+ co-ordination
Abstract Intramolecular electron (eT) and energy transfer (ET) have shown to occur in a covalently linked donor–acceptor (CLDA) system consisting of a naphthalene donor covalently linked through a polyamine chain connector to an anthracene acceptor; the connector has been chosen in order to switch ON or OFF the energy flux as a function of its protonation state as well as by co-ordination to Zn 2+ . The largest energy transfer efficiency ( η =0.61) occurs for the fully protonated form (pH 9 (eT) from the lone pairs of the nitrogens to the excited fluorophore takes place, leading to complete quenching of the emission. On the other hand at neutral and basic pH values, co-ordination of Zn 2+ p…
Energetics and Dynamics of Naphthalene Polyaminic Derivatives. Influence of Structural Design in the Balance Static vs Dynamic Excimer Formation
Two new fluorescent macrocyclic structures bearing two naphthalene (Np) units at both ends of a cyclic polyaminic chain were investigated with potentiometric, fluorescence (steady-state and time-resolved) and laser flash photolysis techniques. The fluorescence emission studies show the presence of an excimer species whose formation depends on the protonation state of the polyamine chains implying the existence of a bending movement (occurring in both the ground and in the first singlet excited state), which allows the two naphthalene units to approach and interact. For comparison purposes, one bis-chromophoric compound containing a rigid chain (piperazine unit) was also investigated. Its em…
Switching from intramolecular energy transfer to intramolecular electron transfer by the action of pH and Zn2+ co-ordination
http://www.sciencedirect.com/science/article/B6TFN-44SKJK4-4/1/7cd5958d3acd1757d2b3a88517f1d557
Fluorescent Type II Materials from Naphthylmethyl Polyamine Precursors
Speciation studies in aqueous solution on the interaction of Cu2+ and Zn2+ with a series of polyaminic ligands N-naphthalen-1-ylmethyl-N′-{2-[(naphthalen-1-ylmethyl)-amino]-ethyl}-ethane-1,2-diamine (Ll), N-naphthalen-1-ylmethyl-N′-(2-{2-[(naphthalen-1-ylmethyl)-amino]-ethylamino}-ethyl)-ethane-1,2-diamine (L2) and N-naphthalen-1-ylmethyl-N′-[2-(2-{2-[(naphthalen-1-ylmethyl)-amino]-ethylamino}-ethylamino)-ethyl]-ethane-1,2-diamine (L3) containing two naphthylmethyl groups at their termini and N 1-(2-{2-[(naphthalen-1-ylmethyl)-amino]-ethylamino}-ethyl)-ethane-1,2-diamine (L4) containing just one naphthylmethyl group have been carried out at 298.1 K in 0.15 mol dm−3 NaCl. In the case of the …
Spectroscopy and Coordination Chemistry of a New Bisnaphthalene−Bisphenanthroline Ligand Displaying a Sensing Ability for Metal Cations
A new fluorescent macrocyclic structure (L1) bearing two naphthalene units at both ends of a cyclic polyaminic chain containing two phenanthroline units was investigated with potentiometric and fluorescence (steady-state and time-resolved) techniques. The fluorescence emission spectra show the simultaneous presence of three bands: a short wavelength emission band (naphthalene monomer), a middle emission band (phenanthroline emission), and a long-wavelength band. All three bands were found to be dependent on the protonation state of the macrocyclic unit (including the polyaminic and phenanthroline structures). The existence of the long-wavelength emission band is discussed and is shown to im…
Potentiometric, NMR, and Fluorescence-Emission Studies on the Binding of Adenosine 5′-Triphosphate (ATP) by Open-Chain Polyamine Receptors Containing Naphthylmethyl and/or Anthrylmethyl Groups
The interaction in aqueous solution of adenosine 5′-triphosphate (ATP) with a series of open-chain polyamines linked at one or both ends to anthrylmethyl or naphthylmethyl fragments was followed by potentiometric titration, 1H-, 13C-, and 31P-NMR spectroscopy, and by steady-state fluorescence measurements. The results revealed greater stabilities for the compounds containing one anthracene moiety than for those with one naphthalene moiety, the stabilities of the compounds with both ends N-substituted with naphthylmethyl groups being close to those containing just one anthrylmethyl unit. The 1H-NMR spectra showed that in all systems, there is involvement of π-π stacking interactions in the s…
Ground and excited state properties of polyamine chains bearing two terminal naphthalene units
A series of compounds bearing two naphthalene units linked through methylene groups to both ends of different open-chain polyamines has been investigated. The fluorescence emission studies show the presence of an excimer species whose formation depends on the protonation state and length of the polyamine chains and implies the existence of a bending movement in the excited state allowing the two naphthalene units to approach and interact. This interpretation was clearly proven by time-resolved fluorescence with the appearance of double exponential decays with a rise time observed at the excimer emission wavelength. For comparison purposes one bis-chromophoric compound containing a rigid cha…
Energy transfer between polyamine chains bearing naphthalene terminal units and k3[Co(CN)6]: An example of a molecular photoreactor
Molecular photoreactors consisting of polyamine chains (receptors) bearing terminal naphthalene units (antennae) are described. The receptors are used to bind the substrate hexacyanocobaltate(III) and the antennae to transfer energy to the complex and thus promote a photoaquation reaction.
A New ZnIITweezer Pyridine-Naphthalene System - An Off-On-Off System Working in a Biological pH Window
Their basic idea consisted of the connec-tion of an amine to a fluorophoric anthracene unit on oneside and to a pyridine moiety on the other. At acidic pHvalues the amino and the pyridine groups are protonatedand a photoinduced electron transfer (PET) occurs fromthe π-π* excited state of the anthracene to the protonatedpyridinium unit, leading to quenching of the fluorescence.However, at high pH values, where the amino group is notprotonated, PET alternatively takes place from the aminelone pair to the same excited state of the fluorophore, yield-ing the same inhibitory effect on the fluorescence. Betweenthese two pH values, there is a pH window where PET doesnot take place and fluorescence…
Specific interaction of citrate with bis(fluorophoric) bibrachial lariat aza-crown in comparison with the other components of the Krebs cycle
Clares Garcia, M. Paz, M.Paz.Clares@uv.es ; Garcia-España Monsonis, Enrique, Enrique.Garcia-Es@uv.es ; Soriano Soto, Concepcion, Concepcion.Soriano@uv.es ; Tejero Toquero, Roberto, Roberto.Tejero@uv.es