0000000001304513
AUTHOR
A. Jorge Parola
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…
Supramolecular interactions of hexacyanocobaltate(III) with polyamine receptors containing a terminal anthracene sensor
Abstract The fluorescence emission properties of a series of chemosensors containing a polyamine receptor bearing an anthracene signaling unit were studied. The fluorescence emission intensity is dependent on the protonation degree of the receptor, the fully protonated form exhibiting the highest emission intensity. By removing protons from the nitrogens a quenching effect can be observed, due to an electron-transfer from the amine to the excited fluorophore. The rate constant of the quenching process is exponentially dependent on the distance of the nitrogen from which the electron is transferred (β=0.6 A−1). The ability of the chemosensors for signaling anions was tested through the model…
Protonation, coordination chemistry, cyanometallate "supercomplex" formation and fluorescence chemosensing properties of a bis(2,2'-bipyridino)cyclophane receptor.
A new polyazamacrocycle (L) containing two 2,2'-bipyridino (bpy) units, where the heteroaromatic nitrogen atoms point outwards from the macrocyclic cavity, was synthesized and characterized by elemental analysis, ESI-MS, (1)H and (13)C NMR, FTIR and TGA. Five protonation constants involving aliphatic nitrogens with log K in the range 9.39-3.07 were determined by potentiometry and NMR and a sixth protonation (log K = 2.2) involving a bipyridine moiety could be detected by UV-Vis and NMR titrations. The interaction of L with the cyanometallate anions [Pt(CN)4](2-) and [Co(CN)6](3-) was studied by potentiometry yielding respectively log K values in the ranges 4.0-6.4 and 5.2-10.5, covering pro…
Steady-state fluorescence emission studies on polyazacyclophane macrocyclic receptors and on their adducts with hexacyanocobaltate(III)
The steady-state fluorescence emission spectra of the azacyclophanes 2,5,8,11-tetraaza[12] paracyclophane (L1), 2,6,9,13-tetraaza[14]paracyclophane (L2), 14,15,17,18-tetramethyl-2,5,8,11-tetraaza[12]paracyclophane (L3) and 16,17,19,20-tetramethyl-2,6,9,13-tetraaza[14]paracyclophane (L4) as a function of pH have been measured. The fully protonated species of each cyclophane gives the highest fluorescence-emission quantum yield. The shapes of the titration curves have been explained by the existence of an electron-transfer quenching effect from a non-protonated amine to the benzene chromophore. This effect is greater for macrocycles in which the first deprotonated amine group is closer to the…
Synthesis and photophysical properties of dansyl-based polyamine ligands and their Zn(II) complexes
The synthesis, potentiometric studies and photophysical properties of two new polyamine ligands (L1 and L2) possessing the dansyl chromophore were studied in aqueous 0.15 M NaCl. The compounds show the absorption and emissions bands characteristic of the dansylamide fluorophore and both present intramolecular excited state proton transfer at intermediate pH ranges. One of the ligands (L2) strongly coordinates Zn(II) leading to fluorescence quenching. A model compound (L3) of the dansyl moiety was also investigated. http://www.sciencedirect.com/science/article/B6TG5-4MB4DV1-2/1/45cafbcee9a8df7daddd765512437ca3
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…
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.
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
CCDC 953539: Experimental Crystal Structure Determination
Related Article: Sandra Gago, Jorge González, Salvador Blasco, A. Jorge Parola, M. T. Albelda, Enrique García-España, Fernando Pina|2014|Dalton Trans.|43|2437|doi:10.1039/C3DT52061G
CCDC 953540: Experimental Crystal Structure Determination
Related Article: Sandra Gago, Jorge González, Salvador Blasco, A. Jorge Parola, M. T. Albelda, Enrique García-España, Fernando Pina|2014|Dalton Trans.|43|2437|doi:10.1039/C3DT52061G