Transport of Alkali Metal Ions through a Liquid Membrane System Containing Monofurano 18-Crown-6. X-Ray Crystal Structure of Potassium Picrate Complex

Abstract

The variation of cation transport rate through a bulk chloroform liquid membrane containing a neutral macrocyclic carrier, monofurano 18-crown-6 (MF18C6) with anion type (2-nitrophenolate, 2,4-dinitrophenolate and 2,4,6-trinitrophenolate (picrate)) is reported. The rates of transport of Na⁺, K⁺ and Cs⁺ salts by MF18C6 were found to be strongly dependent on the anion present and on size of cation. The structure of the complex formed by potassium picrate and monofurano 18-crown-6, [K(MF18C6)](picrate) was determined by X-ray crystallography and showed that each potassium ion is eight-coordinate; each K⁺ ion is coordinated to the six oxygen atoms of the crown, to the phenolate oxygen atom and to one of the oxygen atoms of an ortho nitro group of the picrate anion.

Keywords: monofurano 18-crown-6, transport studies, X-ray crystal structure, potassium picrate.