Luminescent fluorene-based bis-pyrazolyl aniline ligand for aluminum detection

Andrew Frazer, Alma R. Morales, Adam W. Woodward, Paul Tongwa, Tatiana Timofeeva, Kevin D. Belfield

Research output: Contribution to journalArticlepeer-review

8 Scopus citations


The design, synthesis, and photophysical properties of a new fluorene-based fluorescent chemosensor, 4-((E)-2-(2-(benzo[d]thiazol-2-yl)-9,9-diethyl-9H- fluoren-7-yl)vinyl)-N,N-bis((3,5-dimethyl-1H-pyrazol-1-yl)methyl)benzenamine (AXF-Al), is described for the detection of Al3+. AXF-Al exhibited absorption at 382 nm and strong fluorescence emission at 542 nm (fluorescence quantum yield, Φ F, of 0.80). The capture of Al3+ by the pyrazolyl aniline receptor resulted in nominal change in the linear absorption (372 nm) but a large hypsochromic shift of 161 nm in the fluorescence spectrum (542 to 433 nm, Φ F = 0.88), from which Al3+ was detected both ratiometrically and colorimetrically. The addition of other metal ions, namely Mg2+, Ca2+, Mn2+, Fe 2+, Co2+, Ni2+, Cu2+, Zn 2+, Cd2+, Hg 2+ and Pb2+, produced only minimal changes in the optical properties of this probe. The emission band of this probe was also accessed by two-photon excitation in the near-IR, as two-photon absorption (2PA) is important for potential applications in two-photon fluorescence microscopy (2PFM) imaging. The 2PA cross section of the free fluorenyl ligand AXF-Al was 220 GM at 810 nm and 235 GM at 810 nm for the Al-ligand complex, practically useful properties for 2PFM.

Original languageEnglish (US)
Pages (from-to)239-250
Number of pages12
JournalJournal of Fluorescence
Issue number1
StatePublished - Jan 2014
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Biochemistry
  • Spectroscopy
  • Clinical Biochemistry


  • Aluminum
  • Chemosensor
  • Fluorescence
  • Probe
  • Ratiometric
  • Two-photon absorption


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