Use of additives to regulate solute aggregation and direct conformational polymorph nucleation of pimelic acid

Peng Shi; Shijie Xu; Huaiyu Yang; Songgu Wu; Weiwei Tang; Jingkang Wang; Junbo Gong

doi:10.1107/S2052252521000063

Use of additives to regulate solute aggregation and direct conformational polymorph nucleation of pimelic acid

IUCrJ. 2021 Feb 6;8(Pt 2):161-167. doi: 10.1107/S2052252521000063. eCollection 2021 Mar 1.

Authors

Peng Shi^{1

2}, Shijie Xu³, Huaiyu Yang⁴, Songgu Wu^{1

2}, Weiwei Tang^{1

2}, Jingkang Wang^{1

2}, Junbo Gong^{1

2}

Affiliations

¹ School of Chemical Engineering and Technology, State Key Laboratory of Chemical Engineering, Tianjin University, Tianjin 300072, People's Republic of China.
² The Co-Innovation Center of Chemistry and Chemical Engineering of Tianjin, Tianjin 300072, People's Republic of China.
³ Tianjin Key Laboratory of Marine Resources and Chemistry, College of Chemical Engineering and Materials Science, Tianjin University of Science and Technology, Tianjin 300457, People's Republic of China.
⁴ Department of Chemical Engineering, Loughborough University, Loughborough LE11 3TU, United Kingdom.

Abstract

Understanding the nucleation pathway and achieving regulation to produce the desired crystals are mutually beneficial. The authors previously proposed a nucleation pathway of conformational polymorphs in which solvation and solute self-assembly could affect the result of the conformational rearrangement and further nucleation outcomes. Based on this, herein α,ω-alkanedi-carb-oxy-lic acids (DAn, where n represents the number of carbon atoms in the molecule, n = 2-6, 8-11) were designed as homologous additives to interfere with the self-assembly of pimelic acid (DA7) to further induce the form II compound, which differs from form I only in conformation. Interestingly, longer-chain additives (DA6-11) have a stronger form II-inducing ability than short-chain ones (DA2-4). In addition, an apparent gradient of the degree of interference with solute self-assembly, consistent with form II-inducing ability, was detected by infrared and nuclear magnetic resonance spectroscopy. The calculated molecular electrostatic potential charges also clearly indicate that additive-solute electrostatic interactions gradually increase with increasing carbon chain length of the additives, reaching a maximum value with DA6-11. This novel use of additives demonstrates a direct link between solute aggregation and conformational polymorph nucleation.

Keywords: additives; conformational polymorphs; crystal engineering; crystal growth; crystal nucleation; hydrogen bonding; intermolecular interactions; polymorphism; self-assembly.

Grants and funding

This work was funded by National Natural Science Foundation of China grants 21808158 and 21938009. China Postdoctoral Science Foundation grant 2018M641651.