Abstract: 2', 3' and 4'-borono-benzaldehyde-7-(8-hydroxy-5-sulfoacid) quinoline hydrazone derivatives(1-3) were synthesized. The influences of host molecules with boric acid at different replace positions on the recognition of metal ions was investigated. The combining ability of host compounds with lead ion was compared. Research results showed that 2'-borono benzaldehyde-7-(8-hydroxy-5-sulfoacid) quinoline hydrazone(1) possessed highly selective binding and recognition to Pb²⁺in the KH₂PO₄-NaOH buffer solution with a pH value of 7.0. The 1∶1 complexes between host 1 and lead ion formed and they emitted strong fluorescence. The binding ability of host 1 with Pb²⁺ was the strongest among hosts 1-3. The emission wavelength of complex 1-Pb²⁺ was 477 nm and the binding constant was 1.1×10³ L/mol. The presence of the other metal ions led fluorescent spectra of hosts 1-3 little change, for example Mn²⁺, Cu²⁺, Mg²⁺, Fe²⁺, Ca²⁺, Co²⁺, Hg²⁺, Ni²⁺, Cd²⁺, Ag⁺ and so on. Fluorescence intensity and the concentration of Pb²⁺ presented good linear relationship from 0.36 μmol/L to 10 μmol/L with a correlation coefficient of 0.9976(n=16), the detection limit of method was 0.23 μmol/L. The method was used to detect Pb²⁺in water sample from environment with the recovery of 92%-108%.

Key words: Borono-benzaldehyde-7-(8-hydroxy-5-sulfoacid) quinoline hydrazone derivative, Lead ion, Fluorescence enhancement