Spiral Growth Model for Faceted Crystals of Non-Centrosymmetric Organic Molecules Grown from Solution

Abstract

The classical Burton−Cabrera−Frank (BCF) spiral growth model fails to work satisfactorily for many non-centrosymmetric organic molecules such as active pharmaceutical ingredients (APIs), nonlinear optical compounds, etc., due to the inherent assumption of Kossel crystal structure in the solid-state. We develop a more general mechanistic spiral growth model that enables morphology prediction for all kinds of organic molecules. We develop generalized expressions for kink density, kink incorporation rate, and step velocities for such molecules. Stable and unstable edges arising due to the complex bonding pattern are discussed and treated. We demonstrate the applicability of the model by correctly predicting the experimental morphologies of paracetamol and lovastatin grown from solution.

Hydrophobic coating of mica by stearic acid vapor deposition

“…They have been related to steps that terminate at a screw dislocation. Since the step is immobile at the screw dislocation, its growth creates a spiral form, according to the BCF or terrace-step-kink model [28], which has been more recently applied to explain spiral growth from organic molecules [29,30]. We found different spiral structures such as single spirals, oppositely rotating spirals or co-rotating spirals, as predicted from different screw dislocation conformations [31].…”

Measurement, modelling, and closed-loop control of crystal shape distribution: Literature review and future perspectives

“…The modified and extended BCF growth models [148] improved the capability of mechanistic prediction of crystal morphology including the concept of kink rate, in addition to the kink density, the theory of stable and unstable edges to account for both centrosymmetric and noncentrosymmetric growth units. The approach produced excellent agreement between the predicted crystal shapes and the experimental shapes for complex systems such as paracetamol and lovastatin [109,138]. With the advances in molecular modelling, a breakthrough in the field of crystal growth may happen and the faceted growth rates of a crystal could be accurately predicted for real complex crystallisation systems.…”

“…The study demonstrated that polar plots method can be used to obtain the crystal evolution during growth and dissolution, and their rates of individual faces. Doherty and co-workers also developed some theoretical methods to predict crystal growth, dissolution and the effect of additives on crystal habit [76,109,138].…”

In Silico Prediction of Growth and Dissolution Rates for Organic Molecular Crystals: A Multiscale Approach

“…This approach is for instance commonly followed to determine nanoparticle shapes in heterogeneous catalysis [68][69][70]. It has also been used for growth applications from solutions, where also any solvent influences have been neglected [71,72]. This neglect extends over both the solvent influence on the surface vibrational properties and the electrostatic effects on the surface energies due to the solvent dielectric properties.…”