Understanding solid-state reactions of organic crystals with density functional theory-based concepts

Area of Science:

• Solid-state chemistry
• Crystallography
• Computational chemistry

Background:

• Solid-state reactions in organic crystals are anisotropic, affecting initiation and propagation.
• Understanding crystal packing's role is crucial for predicting reaction mechanisms and kinetics.
• Polymorphism significantly impacts the chemical reactivity of organic materials.

Purpose of the Study:

• To investigate the effect of crystal packing on the reaction mechanism and kinetics of organic crystals.
• To elucidate how electronic structures of different polymorphs influence chemical reactivity.
• To explore the role of mechanical differences in solid-state reaction propagation.

Main Methods:

• Density functional theory (DFT) calculations.
• Utilized electron density-based concepts, including nuclear Fukui function.
• Calculated surface energies of reacting faces for two flufenamic acid polymorphs.

Main Results:

• Electronic structures of flufenamic acid polymorphs explain their differing reactivity with ammonia gas.
• Calculated surface energies provide insights into mechanical factors influencing reaction propagation.
• The study supports the hypothesis that crystal packing dictates solid-state reaction behavior.

Conclusions:

• Crystal packing and electronic structure are key determinants of solid-state reaction anisotropy.
• Nuclear Fukui functions and surface energy calculations are valuable tools for predicting reactivity.
• This research offers a framework for understanding and controlling solid-state reactions in organic materials.