Crystallization of Solid-State Materials via Decomplexation of Soluble Complexes

Abstract

A variety of compounds which are at best sparingly soluble in aqueous media may be readily brought into solution through the formation of soluble coordination complexes. Modification of experimental conditions through, e.g., dilution or slow removal of the complexing agent, leads to supersaturation and, consequently, crystallization of the original solid-state phase. This technique of decomplexation crystallization, both of simple inorganic coordination complexes and of complexes with macrocyclic organic chelating agents, offers the opportunity both to effect the recrystallization of sparingly soluble species and to modify their crystal morphology. Similarly, precursors for solid-state materials may be solubilized in nonaqueous solvents through the formation of soluble complexes and then allowed to undergo reaction crystallization, allowing the examination of both solvent effects and chelation effects on the morphology and phase of the resulting solid-state materials. These effects are often dramatic, and such “complexation-mediated crystallization” approaches offer promise for the facile preparation of metastable phases from simple precursors under ambient conditions.

Polymorph Discrimination of CaCO3 Mineral in an Ethanol/Water Solution: Formation of Complex Vaterite Superstructures and Aragonite Rods

“…In this paper, an environmentally friendly route is reported for effective polymorph discrimination of CaCO 3 mineral in an ethanol/water mixed solution under mild conditions (90 °C) without using any organic additives like previous reports which employed crown ether to produce vaterite. , Complex cakelike vaterite crystals with porous, multilayered structures, as well as aragonite rods can be selectively synthesized. It has been demonstrated that the thermodynamic and kinetic regimes, which contribute to the polymorph discrimination of calcium carbonate mineral, can be well manipulated in ethanol/water mixed solution by simply tuning the composition of this binary solution.…”

“…Self-assembly of a layerlike clay−polyelectrolyte structure with an interesting analogy to the biomineral nacre has also been reported . In contrast, the influence of solvent on the mineralization of CaCO 3 in the absence of organic additives has rarely been studied and the role that simple alcohols play in the polymorph discrimination of CaCO 3 mineral is yet not clear. − …”

Spectroscopy of silver complexes in solutions of inorganic compounds

“…The concentration (C) of impurity Ag + ions was 10 À5 -10 À1 mol/l, and that of aqueous solutions of haloid and oxygen-containing salts 7.6 mol/l. After the solutions had been frozen, transparent glassy samples were obtained [5].…”