Highly selective sensing of lead ion based on α-, β-, γ-, and δ-tetrakis(3,5-dibromo-2-hydroxylphenyl)porphyrin β-CD inclusion complex

alpha, beta, gamma, delta-Tetrakis(3,5-dibromo-2-hydroxylphenyl)porphyrin (TDBHPP) was synthesized and used for the fluorimetric determination of trace amount of lead ion in aqueous solution based on the inclusion interaction of the porphyrin with beta-cyclodextrin (beta-CD). In aqueous solution, the interaction of beta-CD with TDBHPP caused a large enhancement of the porphyrin fluorescence intensity. In addition, the increased fluorescence of TDBHPP by beta-CD was sensitive to metal ion following the fluorescence quenching of TDBHPP at its maximum emission wavelength. The quenching of TDBHPP fluorescence at room temperature was fast and nearly complete upon lead ion interaction. The organizing ability of the beta-CD medium and the protection of the ligand from the micro-environment conferred in increased sensitivity, selectivity and detection limit, and allowed the determination of 2.8 x 10(-7) to 7.4 x 10(-5) mol/L lead compared with those obtained in the absence of beta-CD. The method was applied in the analysis of synthetically biological samples with satisfactory results. (c) 2005 Elsevier B.V. All rights reserved.