Network self-assembly patterns in Main Group metal chalcogenide-based materials

Abstract

Technological interest in the design of multifunctional microporous materials has stimulated recent research into the development of mild solventothermal techniques for the construction of lamellar and framework Main Group chalcogenidometalates. Reaction pathways from elemental or metal chalcogenide sources can be influenced by a variety of often interdependent factors of which counter cation size and charge, solvent polarity, pH and temperature are of paramount importance. As reviewed in this article, the presence of predominant solution species such as cyclic tripyramidal M₃S₆³⁻ (M = As or Sb) or edge-bridged ditetrahedral Sn₂E₆⁴⁻ anions (E = S or Se) as molecular building units and their participation in columnar substructures is characteristic for M₂S₃- and SnE₂-based anionic networks. Hierarchical topological relationships between individual members of structural families of the type A_xM_yE_z (A = alkali metal or alkylammonium cation) can be established that provide a detailed insight into probable multiple-step cation-directed self-assembly mechanisms. These findings enable the development of rational guidelines for the employment of suitable counter cations in controlling the condensation of small solution species into chains, sheets or frameworks, whose cavities reflect the spatial requirements of the structure-directing agent.