Albelda, MT, Garcia-Espana E, Gil L, Lima JC, Lodeiro C, de Melo JS, Melo MJ, Parola AJ, Pina F, Soriano C.
2003.
Intramolecular excimer formation in a tripodal polyamine receptor containing three naphthalene fluorophores, 2003. Journal of Physical Chemistry B. 107:6573-6578.
Abstractcomprehensive investigation on the energetics and dynamics of a new fluorescent sensor constituted by a tripodal polyamine receptor containing three naphthalene fluorophores, compound L, is reported. The influence of external factors such as the solvent, hydrogen ion concentration, and temperature in the photophysics of the sensor is discussed. The temperature dependence of monomer/excimer interconversion of L revealed an average percentage relative sensitivity of 4.5%/degreesC thus portending its use as a temperature sensor. The activation energy for excimer formation (E-1 = 12 kJ mol(-1)) and dissociation (E-1 = 57 kJ mol(-1)), entropy change (DeltaS = -128 J K-1 mol(-1)), and the binding energy of the excimer (DeltaH = 45 kJ mol(-1)) were obtained in water at acidic pH values and ethanol (E-1 = 15 kJ mol(-1), E-1 = 40 kJ mol(-1), DeltaS = -61 J K-1 mol(-1), and DeltaH = 25 kJ mol(-1)). The dependence of the kinetic and thermodynamic parameters on the dielectric constant of the medium and on the degree of protonation of the polyamine chain was interpreted in terms of the excimer destabilization provoked by the electrostatic repulsion between the positively charged chains.
Rodriguez, L, Alves S, Lima JC, Parola AJ, Pina F, Soriano C, Albelda T, Garcia-Espana E.
2003.
Supramolecular interactions of hexacyanocobaltate(III) with polyamine receptors containing a terminal anthracene sensor, 2003. Journal of Photochemistry and Photobiology a-Chemistry. 159:253-258.
AbstractThe 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 (beta = 0.6Angstrom(-1)). The ability of the chemosensors for signaling anions was tested through the model anion hexacyanocobaltate(III). The temperature dependence of the association constants shows that at least for this compound, the change in solvation entropy is probably the controlling parameter to account for the binding. (C) 2003 Elsevier Science B.V. All rights reserved.
Albelda, MT, Aguilar J, Alves S, Aucejo R, Diaz P, Lodeiro C, Lima JC, Garcia-Espana E, Pina F, Soriano C.
2003.
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. Helvetica Chimica Acta. 86:3118-3135., Number 9
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