Structural characterization of new Cd2+ fluorescent sensor based on lumazine ligand: AM1 and ab initio studies

Na'il Saleh, Abdel Monem M. Rawashdeh, Yaser A. Yousef, Yaseen A. Al-Soud

Research output: Contribution to journalArticlepeer-review

27 Citations (Scopus)


6-Thienyllumazine (TLM) is synthesized as a new fluorescent sensor that is capable of indicating selectively the presence of Cd2+ ion via a fluorescence signal. Experiment has been performed in the presence of Ni2+, Co2+, Cu2+, Ag+, Mn2+, Hg2+, Zn2+, Pb2+, and Mg2+ metal ions in aqueous solutions. The product was characterized by elemental analysis, mass, and NMR spectra. The spectral characteristics (maxima, quantum yields, Stokes shift, and lifetimes) of TLM in organic and aqueous solvents have been studied with the help of absorption and fluorescence spectroscopy, as well as, using time dependent spectrofluorimetry (single photon counting technique). The fluorescence dependence of TLM on the pH has also been investigated. The experimental results indicate that TLM exists in two ionic forms: neutral (acid) and anion (base). Electronic structure calculations of TLM were carried out using Semiempirical Austin Model 1 (AM1) and ab initio Hartree-Fock (HF) with 6-31G* basis set and using Gaussian 03 program. Absorption energies for TLM have been calculated using ZINDO method. The theoretical results confirm the presence of the thiophene and pteridine rings in two conformations: twisted at angle of about 35° in the excited state and coplanar in the ground state.

Original languageEnglish
Pages (from-to)728-733
Number of pages6
JournalSpectrochimica Acta - Part A: Molecular and Biomolecular Spectroscopy
Issue number3
Publication statusPublished - Nov 2007
Externally publishedYes


  • Fluorescence spectra
  • Fluorescent sensor
  • Lumazine
  • Solvent effects
  • Theoretical calculations
  • Time-resolved fluorescence spectra

ASJC Scopus subject areas

  • Analytical Chemistry
  • Atomic and Molecular Physics, and Optics
  • Instrumentation
  • Spectroscopy


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