A five- and six-coordinated two-dimensional metal halide organic-inorganic phase transition material

Area of Science:

• Materials Science
• Solid-State Chemistry
• Crystallography

Background:

• Two-dimensional organic-inorganic hybrid metal halides (2D OIHMHs) are known for their diverse functionalities.
• Most reported 2D OIHMHs feature layered structures with exclusively six-coordinate metal ions.
• The exploration of novel structural motifs and properties in 2D OIHMHs remains an active research area.

Purpose of the Study:

• To synthesize and characterize a novel 2D organic-inorganic hybrid metal halide.
• To investigate the coordination environment of metal ions within the 2D structure.
• To explore the phase transition behavior and optical properties of the new material.

Main Methods:

• Single-crystal X-ray diffraction for structural determination.
• Temperature-dependent powder X-ray diffraction for phase transition analysis.
• UV-Vis spectroscopy for optical bandgap determination.

Main Results:

• A new 2D OIHMH, (N,N'-diisopropylethylammonium) tricadmium heptachloride, was successfully synthesized.
• The crystal structure reveals Cd2+ ions with both five- and six-coordinate geometries, a rare feature in 2D OIHMHs.
• An isostructural phase transition was observed at 263 K.
• A large optical bandgap of 5.53 eV was measured.

Conclusions:

• The discovery of this novel 2D OIHMH expands the structural diversity of this material class.
• The presence of mixed coordination numbers for Cd2+ ions offers new avenues for tuning material properties.
• The observed phase transition and wide bandgap suggest potential applications in areas like temperature-responsive materials and optoelectronics.