Solution and solid-state preparation of 18-crown[6] complexes with M[HSO4]n Salts (M = NH4+, K +, Sr2+ and n = 1, 2) and an investigation of solvation/desolvation processes and crystal polymorphism

Dario Braga, Massimo Gandolfi, Matteo Lusi, Demis Paolucci, Marco Polito, Katia Rubini, Fabrizia Grepioni

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Abstract

18-Crown[6] ether has been used to prepare a new class of organic-inorganic complexes of general formula 18-crown[6]·M[HSO4]n (where M = NH4+, K+, Sr2+ and n = 1, 2) by reacting directly in solution or in the solid state the crown ether 18-crown[6] with inorganic salts such as [NH4][HSO4], K[HSO4], and Sr[HSO4]2. The structures of 18-crown[6]·[NH4][HSO4]·2H2O (1·2 H2O), 18-crown[6]·[NH4][HSO 4] (1), 18-crown[6]·K[HSO4]·2H2O (2·2 H2O), 18-crown[6]·K[HSO4] (2), and 18-crown[6]·Sr[HSO4]2 (3) have been characterized by single-crystal X-ray diffraction. The reversible water loss in compounds 1·2 H2O and 2·2 H2O leads to formation of the corresponding anhydrous phases 18-crown[6]·[NH4]-[HSO 4] (1), and 18-crown[6]·K[HSO4] (2), which undergo, on further heating, enantiotropic solid-solid transitions very likely associated with the on-set of a solid state dynamical process. Similar high-temperature behavior is shown by 18-crown[6]·Sr[HSO 4]2 (3). The dehydration and phase-transition processes have been investigated by differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and variable temperature X-ray powder diffraction.

Original languageEnglish
Pages (from-to)5249-5255
Number of pages7
JournalChemistry - A European Journal
Volume13
Issue number18
DOIs
Publication statusPublished - 2007

Keywords

  • Crown compounds
  • Crystal polymorphism
  • Desolvation
  • Phase transitions
  • X-ray diffraction

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