New dual emission fluorescent sensor for pH and Pb(II) based on bis(napfthalimide) derivative

Georgina Pina-Luis*, Marisela Martínez-Quiroz, Adrián Ochoa-Terán, Hisila Santacruz-Ortega, Eduardo Mendez-Valenzuela

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

38 Scopus citations

Abstract

This paper describes a novel dual emission bis-1,8-naphthalimide sensor for selective determination of pH and Pb2+ ions. The influence of the variability in the backbone that links the two fluorophores (naphthalimides) as a function of pH and metal ions was studied by UV-visible and fluorescence spectroscopy. Compounds 1(a-d) with different length alkyl linkers (CH 2)n (n=1, 2, 4 and 6) showed no excimer formation in aqueous solution. Fluorescence emission of these derivatives varied in a narrow range of pH (5-8) and was only slightly influenced by the addition of metal ions in CH3CN solutions. However, derivative 1e with amino-containing spacer (CH2-NH-CH2) showed excimer emission in aqueous solution, a wide response to pH (2.5-9.5) and fluorescence enhancement with selective behavior towards metal ions. The pH sensor based in derivative 1e has a sufficient selectivity for practical pH monitoring in the presence of Li +, Na+, K+, Cs+, Ca2+, Mg2+, Ba2+, Cu2+, Pb2+, Ni 2+, Zn2+ and Cd2+. The coordination chemistry of these complexes was studied by UV-Vis, fluorescence and 1H NMR. This chemosensor displayed high selectivity fluorescence enhancement toward Pb2+ ions in the presence of the metals ions mentioned in CH 3CN solutions. Competitive assays show that a 1-fold of metal cations in each case, compared with Pb2+ ions, results in less than ±5% fluorescence intensity changes. Linear calibration up to 1×10-5 M for Pb(II) ions (R=0.9968) was obtained and detection limit resulted of 5.0×10-8 M.

Original languageEnglish
Pages (from-to)729-738
Number of pages10
JournalJournal of Luminescence
Volume134
DOIs
StatePublished - Feb 2013

Keywords

  • Bis(naphtalimides)
  • Dual emission
  • Excimer
  • PET
  • Pb sensor
  • pH sensor

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