Jump to main content
Jump to site search

Issue 5, 2003
Previous Article Next Article

Potentiometric, FTIR and NMR studies of the complexation of metals with theaflavin

Author affiliations

Abstract

Aluminium(III) complexes of theaflavin (LH) were studied by potentiometric, UV-Vis, NMR and FTIR spectroscopic methods. The stoichiometries of the main species formed in the aluminium(III)–theaflavin systems are [AlL], [AlL2], [AlL3], [AlL3H−1] and [AlL3H−2]. AlL, AlL2 and AlL3 correspond to complexes formed between Al(III) and the benzotropolone ring of one, two and three theaflavins, respectively. The species [AlL3H−1] and [AlL3H−2] could be accounted for by deprotonation of free phenol groups in the complexed theaflavin. 1H NMR and HMQC experiments provided structural information on the complexes and allowed the determination of the metal coordination site. FTIR analysis of model aluminium complexes together with the aluminium theaflavin complexation corroborated the coordination site and allowed further spectral analysis of the aluminium–theaflavin system. The following complex stability constants have been evaluated from potentiometric analysis; log βAlL= 7.80 (± 0.07), log βAlL2= 15.00 (± 0.12), log βAlL3 = 22.46 (± 0.13), log βAlL3H−1 = 16.98 (± 0.1), log βAlLH−2 = 10.19 (± 0.1). UV-Vis spectroscopy confirmed in part the stoichiometric coordination of the aluminium theaflavin complex. The complexation of Mn(II) with theaflavin was also investigated potentiometrically. The stoichiometry of the major complex formed in the manganese(II)–theaflavin system is [MnLH−1] and the equilibrium constant has been evaluated as log βMnL = 4.80 (± 0.03).

Graphical abstract: Potentiometric, FTIR and NMR studies of the complexation of metals with theaflavin

Back to tab navigation

Publication details

The article was received on 11 Nov 2002, accepted on 16 Jan 2003 and first published on 04 Feb 2003


Article type: Paper
DOI: 10.1039/B211102K
Citation: Dalton Trans., 2003,0, 801-807
  •   Request permissions

    Potentiometric, FTIR and NMR studies of the complexation of metals with theaflavin

    M. Ó′Coinceanainn, C. Astill and S. Schumm, Dalton Trans., 2003, 0, 801
    DOI: 10.1039/B211102K

Search articles by author

Spotlight

Advertisements