Monoprotonated Sapphyrin-Pertechnetate Anion Interactions in Aqueous Media

Author: Anne E. V. Gorden†  

Publisher: Taylor & Francis Ltd

ISSN: 1061-0278

Source: Supramolecular Chemistry, Vol.16, Iss.2, 2004-03, pp. : 91-100

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Abstract

The addition of aqueous pH 7 solutions of 7.2×10

-3
M pertechnetate to dilute aqueous 2.5% MeOH solutions containing a water-solubilized sapphyrin, 3,12,13,22-tetraethyl-8,17-bis[bis(hydroxyethyl)-amino)carbonylethyl]-2,7,18,23-tetramethylsapphyrin (1), gives rise to spectroscopic changes in the UV-Vis spectrum of 1 that are consistent with anion-binding and sapphyrin deaggregation. The spectroscopic changes induced by pertechnetate were found to differ dramatically from those induced by the addition of either pure water or dilute nitric acid; however, they were found to parallel those seen when sodium phosphate was added to solutions of 1 under analogous experimental conditions. Fits of the spectroscopic titration data to a 1:1 binding profile revealed that the effective K describing the interaction of pertechnetate anion with 1 was ca. 3900±300 M
-1
; this value compares to the effective K of 23000±3000 M
-1
that describes the corresponding interaction of sodium phosphate with 1.

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