Strongly coloured thiocyanate frameworks with perovskite-analogue structures

Area of Science:

• Materials Science
• Inorganic Chemistry
• Crystal Engineering

Background:

• Prussian blue compounds are well-known coordination materials with diverse applications.
• Cyanide ligands in Prussian blue analogues limit their use in certain environments.
• Thiocyanate ligands offer an alternative for designing novel Prussian blue analogues.

Purpose of the Study:

• To synthesize and characterize novel thiocyanate-based analogues of Prussian blue compounds.
• To investigate the structural, optical, and potential functional properties of these new materials.
• To explore their suitability for light-harvesting applications and host-guest chemistry.

Main Methods:

• Synthesis of M^III[Bi(SCN)₆] compounds where M = Fe, Cr, Sc.
• Powder X-ray diffraction to determine crystal structure and topology (pcu).
• Optical absorption spectroscopy to measure band gaps.
• Water uptake experiments for the chromium analogue.

Main Results:

• Successful synthesis of M^III[Bi(SCN)₆] (M = Fe, Cr, Sc) with primitive cubic (pcu) topology.
• Strict cation order observed in the synthesized compounds.
• Band gaps determined to be in the visible and near-infrared regions.
• Cr[Bi(SCN)₆] demonstrated reversible water uptake.

Conclusions:

• The new thiocyanate-based Prussian blue analogues represent a novel class of materials.
• Their optical properties suggest potential for photocatalysis and light-harvesting applications.
• The framework's ability to host guests opens avenues for host-guest chemistry and functional material design.