Intramolecular excimer formation in a tripodal polyamine receptor containing three naphthalene fluorophores

M. Teresa Albelda, Enrique García-España, Laura Gil, João C. Lima, Carlos Lodeiro, J. Seixas de Melo, M. João Melo, A. Jorge Parola, Fernando Pina, Concepción Soriano

Research output: Contribution to journalArticlepeer-review

59 Citations (Scopus)

Abstract

A comprehensive 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%/°C thus portending its use as a temperature sensor. The activation energy for excimer formation (E1 = 12 kJ mol-1) and dissociation (E-1 = 57 kJ mol-1), entropy change (ΔS = -128 J K-1 mol-1), and the binding energy of the excimer (ΔH = 45 kJ mol-1) were obtained in water at acidic pH values and ethanol (E1 = 15 kJ mol-1, E-1 = 40 kJ mol-1, ΔS = -61 J K-1 mol-1, and ΔH = 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.

Original languageEnglish
Pages (from-to)6573-6578
Number of pages6
JournalJournal of Physical Chemistry B
Volume107
Issue number27
DOIs
Publication statusPublished - 10 Jul 2003

Keywords

  • Pyrene
  • Fluorescence
  • Pyrene excimer

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