From Binary to Ternary Hydrogen-Bonded Solids with Anisotropic Thermal Expansion

Area of Science:

• Materials Science
• Solid-State Chemistry
• Nanotechnology

Background:

• Thermal expansion (TE) is a key property of solids, influenced by bond strength and material dimensionality.
• Covalently bonded materials typically show reduced TE with increased dimensionality, while noncovalently bonded materials exhibit larger TE.
• Controlling TE in molecular solids remains a significant challenge.

Purpose of the Study:

• To synthesize hydrogen-bonded solids with varying dimensionality using identical molecular building blocks.
• To investigate the effect of hydrogen-bonding network dimensionality on anisotropic thermal expansion.
• To explore novel strategies for controlling material properties through structural design.

Main Methods:

• Synthesis of hydrogen-bonded solids by adjusting stoichiometric ratios of molecular building blocks.
• Characterization of thermal expansion behavior across different dimensionalities.
• Utilizing shape-size mimicry for the preparation of a ternary molecular solid.

Main Results:

• All synthesized solids demonstrated anisotropic thermal expansion.
• Systematic increase in dimensionality led to controllable TE.
• A two-dimensional (2D) hydrogen-bonded network exhibited TE comparable to graphite and black phosphorus.
• A ternary molecular solid was successfully prepared via shape-size mimicry.

Conclusions:

• Dimensionality is a critical factor in controlling thermal expansion in hydrogen-bonded solids.
• The presented strategy offers a versatile approach for designing materials with tailored TE properties.
• This work provides new insights into structure-property relationships in molecular solids.