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Highlights: [•] ZIF-8 prepared from stoichiometric metal and ligand aqueous solutions. [•] The role of ammonium hydroxide for ZIF-8 preparation was discussed. [•] Concentrated precursor solution was used to prepare ZIF-8. [•] Highly thermally stable ZIF-8 crystals with uniform shapes and high surface areas. [Copyright &y& Elsevier]

Room to breathe: An efficient method for the synthesis of zeolitic imidazolate framework‐7 (ZIF‐7) in ethanol/water at room temperature is reported. The ZIF‐7 undergoes a reverse‐phase transition from large pore (lp)‐phase to narrow pore (np)‐phase under heat treatment and from np‐phase back to lp‐phase in ethanol solution. [ABSTRACT FROM AUTHOR]

Abstract: Zeolitic imidazolate framework-8 (ZIF-8)/chitosan composites were prepared in the chitosan hydrogels. The concentrations of the chitosan and the alkaline solution were varied to the synthesis of the ZIF-8/chitosan composites. In the chitosan hydrogels with the addition of ammonium hydroxide solution, the resulting ZIF-8 crystals exhibited an unusual XRD structure that the XRD peak at about 18o (222) became the strongest. The XRD peak intensity ratio of (222)/(011) increased from 0.68 to 1.5–5.2 in the presence of chitosan hydrogels. ZIF-8/chitosan composites (FC2) were composed of aggregated nanosized particles, and exhibited a higher CO2 adsorption than normal ZIF-8 crystals. After removing chitosan from FC2, XRD pattern of the resulting ZIF-8 crystals returned to the normal state and the morphology kept the same as the composite. [Copyright &y& Elsevier]