Shi Peng, Xu Shijie, Yang Huaiyu, Wu Songgu, Tang Weiwei, Wang Jingkang, Gong Junbo
School of Chemical Engineering and Technology, State Key Laboratory of Chemical Engineering, Tianjin University, Tianjin 300072, People's Republic of China.
The Co-Innovation Center of Chemistry and Chemical Engineering of Tianjin, Tianjin 300072, People's Republic of China.
IUCrJ. 2021 Feb 6;8(Pt 2):161-167. doi: 10.1107/S2052252521000063. eCollection 2021 Mar 1.
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 (DA, where represents the number of carbon atoms in the molecule, = 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.
理解成核途径并实现调控以产生所需晶体是相辅相成的。作者之前提出了一种构象多晶型物的成核途径，其中溶剂化和溶质自组装可能会影响构象重排的结果以及进一步的成核结果。基于此，本文设计了α,ω-链烷二羧酸（DA，其中 代表分子中的碳原子数， = 2 - 6, 8 - 11）作为同系添加剂，以干扰庚二酸（DA7）的自组装，从而进一步诱导II型化合物，其与I型仅在构象上有所不同。有趣的是，长链添加剂（DA6 - 11）比短链添加剂（DA2 - 4）具有更强的诱导II型的能力。此外，通过红外光谱和核磁共振光谱检测到与诱导II型能力一致的溶质自组装干扰程度的明显梯度。计算得到的分子静电势电荷也清楚地表明，添加剂 - 溶质静电相互作用随着添加剂碳链长度的增加而逐渐增强，在DA6 - 11时达到最大值。这种添加剂的新用途证明了溶质聚集与构象多晶型成核之间的直接联系。
