Towards Fundamental Understanding and Rational Control of Crystal Growth

1. Towards Fundamental Understanding and Rational Control of Crystal Growth The project focuses on understanding the role played by solvents and additives in affecting growth morphology and polymorphism of organic crystals with density functional theory (DFT) based concepts and Pearson's HSAB (hard and soft acids and bases) Principle. Solvent molecules should match crystal surfaces of a particular polymorph or morphology with respect to their electronic properties. As the sea of electrons on various faces of a crystal couples with or responds to electronic perturbations due to contact of a solvent/additive, the difference in responding sensitivities of the faces may be described by DFT-based softness and hardness. Applying these concepts to establish HSAB type matching principles between solvents/additives and crystals, we will create a new paradigm to clarify the influence of solvents and additives at the electronic level, advancing the rational design of novel crystal materials for chemical, pharmaceutical and biomedical applications. Tonglei Li, University of Kentucky, DMR-0449633 Surface softness calculated by DFT of two major faces of aspirin. There are two different cuts of the (100) face. The inset picture is the (001) face calculated.

2. Towards Fundamental Understanding and Rational Control of Crystal Growth Tonglei Li, University of Kentucky, DMR-0449633 Photos: Left: Shaoxin Feng (1st-year graduate student), Zhan Wang (master student), Stephanie Wendschlag (undergraduate student, chemical engineering) and Clare Aubrey (3rd-year graduate student) Middle: Sakib Motalib (high-school senior) doing visualization of electron density calculated of acetaminophen crystal Right: Ellen Savelli (undergraduate student, pre-pharmacy) doing contact angle measurement of a crystal surface