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Heavy‐Metal‐Ion Capture, Ion‐Exchange, and Exceptional Acid Stability of the Open‐Framework Chalcogenide (NH 4 ) 4 In 12 Se 20
Author(s) -
Manos Manolis J.,
Malliakas Christos D.,
Kanatzidis Mercouri G.
Publication year - 2006
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.200600892
Subject(s) - ion exchange , chemistry , hydrochloric acid , aqueous solution , inorganic chemistry , metal , ion , chalcogenide , hydrothermal circulation , chemical engineering , organic chemistry , engineering
The hydrothermal synthesis of the purely inorganic open‐framework indium selenide (NH 4 ) 4 In 12 Se 20 ( 1 ) is reported. Compound 1 exhibits a unique three‐dimensional open‐framework structure. The framework of 1 shows an unusual, for a chalcogenide compound, rigidity arising from the unprecedented connection mode of its building blocks. Compound 1 possesses ion exchange capacity for Cs + , Rb + , NH 4 + , but it has selectivity against Na + and Li + . It also showed exceptional stability in relatively concentrated hydrochloric acid. Ion exchange of 1 with hydrochloric water solutions can produce its solid acid analogue H 2 (NH 4 ) 2 In 12 Se 20 . The maximum cation‐exchange capacity of 1 was found equal to two equivalents per mol, which is consistent with an exchange mechanism taking place in the 1D‐channels formed by the largest cavities. In addition, 1 can do ion‐exchange with heavy‐metal ions like Hg 2+ , Pb 2+ , and Ag + . The capacity of 1 to clean water solutions from heavy‐metal ions was preliminarily investigated and found very high. Specifically, 1 can remove 99.9 % of Hg 2+ , 99.8 % of Ag + , and 94.9 % of Pb 2+ from aqueous solutions of each of these ions. Using different synthetic conditions, we isolated compound (NH 4 ) 2 In 12 Se 19 ( 2 ), which also has as good an acid stability as 1 , but no ion‐exchange properties. Overall, this work provides new hydrothermal synthetic approaches for isolation of all‐inorganic open‐framework chalcogenides.