(524e) Morphology prediction for crystals: hybrid force field and COSMO-based solvation free energy model

Crystal morphology plays a significant role in many industrial applications, with different crystal habits possessing different physical and chemical properties. However, due to the large number of crystals, coupled with numerous growth conditions including solvent, additive, temperature, supersaturation, and type of crystallization, it is a challenging task for the industry to obtain desired crystals with particular product functionality and morphology. Therefore, an academic design software aid called ADDICT (Advanced Design and Development of Industrial Crystallization Technology) was developed by our group at UCSB to predict crystal morphology [1].

Recently, we have upgraded ADDICT’s software framework [2] and completely rewritten the code based on Matlab using object-oriented programming in ADDICT3 (the third version of ADDICT) [3]. Based on the new software framework, ADDICT3 can interpret crystallography of varying types of crystals (including organic crystals, organic salts, solvates, and metal organic crystals) with varying Z′. Therefore, theoretically, we can use ADDICT3 to try to predict the morphology of a wide variety of organic crystals.

Force fields are necessary for calculating interaction energies to predict the crystal morphology using mechanistic models. We previously used the Generalized Amber Force Field [4] (GAFF 1.8) to calculate solid-state energy for organic crystals. However, the GAFF force field cannot handle crystals containing metal atoms, such as metal organic crystals. The Universal force field (UFF) [5] is an all-atom potential that has parameters for every element from hydrogen to lawrencium. But the results of UFF are sometimes not so accurate [6].

In this study, based on the advantages of GAFF and UFF, we proposed the Hybrid Force Field (HFF) to predict the morphology for metal and metal-free organic crystals. Three successful cases on the morphology prediction of crystals grown from vapor have been studied. They are (1) olanzapine, (2) metal-free phthalocyanine (H₂Pc), and (3) β-Polymorphs of copper phthalocyanine (CuPc), respectively. The results demonstrate the reliability of the HFF proposed in this paper. In addition, UFF and HFF have been incorporated into the ADDICT software, which can be used to predict the morphology of organic crystals containing any relevant type of atoms.

References

[1] Li, J., Tilbury, C. J., Kim, S. H., & Doherty, M. F. (2016). Prog. Mater. Sci., 82, 1.

[2] Zhao, Y., Tilbury, C. J., Landis, S., Sun, Y., Li, J., Zhu, P., & Doherty, M. F. (2020). Cryst. Growth Des., 20, 2885.

[3] Landis, S., Zhao, Y., & Doherty, M. F. (2020). Comput. Chem. Eng., 133, 106637.

[4] Wang, J., Wolf, R. M., Caldwell, J. W., Kollman, P. A., & Case, D. A. (2004) J. Comp. Chem., 25, 1157.

[5] Rappé, A. K., Casewit, C. J., Colwell, K., Goddard III, W. A., & Skiff, W. M. (1992). J. Am. Chem. Soc., 114, 10024.

[6] Martin, M. G. (2006). Fluid Phase Equilibria, 248, 50.