Scripps Institution of Oceanography in La Jolla, CA
Preferential Uptake of Ammonium Ions by Zinc Ferrocyanide
P.S. Braterman,* G. Arrhenius, S.Hui, and W. Paplawsky
*Department of Chemistry and Center for Materials Characterization, University of North Texas, Denton, TX76203, USA.
ABSTRACT
The concentration of ammonia from dilute solution could have facilitated many prebiotic reactions. This may be especially true if this concentration involves incorporation into an organized medium. We have shown that (unlike iron(III) ferrocyanide) zinc ferrocyanide, Zn2Fe(cn)6.x H2O, preferentially takes up ammonium ions from 0.01 MNH4CI to give the known material Zn3(NH4)2[Fe(cn)6]2.x H2O, even in the presence of 0.01M KCI. KCI alone gave Zn3(NH4)2[Fe(cn)6]2.x H2O. Products were characterized by elemental (CHN) analysis and powder X-ray diffraction (XRD). We attribute the remarkable specificity for the ammonium ion to the open framework of the product, which offers enough space for hydrogen0bonded ammonium ions, and infer that other inorganic materials with internal spaces rich in water may show a similar preference.
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