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Dependence of polymorphism on molecular structure of BPT esters

机译：多态性对BPT酯分子结构的依赖性

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The effect of molecular structure on polymorphic crystallization was investigated by the rapid cooling method in ethanol solutions using BPT methyl ester (Me-est, methyl 2-(3-cyano-4-(2-methylpropoxy)-phenyl)-4-methyl-thiazole-5-carboxylate), BPT propyl ester (Pr-est, propyl 2- (3-cyano-4-(2-methylpropoxy) -phenyl)-4-methyl-thiazole-5-carboxylate), and BPT isobutyl ester (i-But-est, 2-methylpropyl 2-(3-cyano-4-(2- methylpropoxy)-phenyl)-4-methyl-thiazole-5-carboxylate). The crystallization of Meest resulted in only one crystal form at every initial concentration. In the crystallization of Pr-est and i-But-est at a supersaturation ratio lower than 1.85, the stable B form directly crystallized. However, at higher supersaturation, the metastable A form first appeared, and the subsequent transformation to the B form occurred after that (Ostwald step rule is established). The solution-mediated transformation rate appeared to be faster for i-But-est than for Pr-est. The Me-est crystal is constructed by stacking the flat sheet of the molecules that are formed by two hydrogen bonds between a dimer of molecules. Both the stable and metastable forms of Pr-est are also constructed by stacking the sheet structures of the molecules In the metastable form of Pr-est, no hydrogen bonding was observed in the crystal. In the stable form of Pr-est, hydrogen bonding through the nitrite and carbonyl groups is formed. On the other hand, metastable i-But-est crystal is constructed by stacking the zigzag sheets of the molecules, and the stable i-But-est crystal is formed by stacking two types of layers. It appeared that with HI NMR measurement, the conformational difference in solutions could not be detected.
机译：使用BPT甲酯（Me-est，甲基2-（3-氰基-4-（2-甲基丙氧基）-苯基）-4-甲基-甲基）在乙醇溶液中通过快速冷却方法研究了分子结构对多晶型结晶的影响。噻唑-5-羧酸酯），BPT丙酯（Pr-est，2-（3-氰基-4-（2-甲基丙氧基）-苯基）-4-甲基噻唑-5-羧酸丙酯）和BPT异丁酯（最优选的是2-（3-氰基-4-（2-甲基丙氧基）-苯基）-4-甲基-噻唑-5-羧酸2-甲基丙基。 Meest的结晶在每个初始浓度下仅产生一种晶型。在过饱和比低于1.85的Pr-est和i-But-est结晶中，稳定的B形式直接结晶。但是，在较高的过饱和度时，首先出现亚稳态的A形式，随后发生向B形式的后续转变（建立了奥斯特瓦尔德阶梯法则）。 i-But-est的溶液介导转化率似乎快于Pr-est。 Me-est晶体是通过堆叠分子的平板形成的，分子的平板由分子的二聚体之间的两个氢键形成。 Pr-est的稳定形式和亚稳态形式也都通过堆叠分子的片状结构而构建。在Pr-est的亚稳态形式中，在晶体中未观察到氢键。在稳定的Pr-est形式中，通过亚硝酸盐和羰基形成氢键。另一方面，通过堆叠分子的锯齿形薄片来构造亚稳态i-But-est晶体，并且通过堆叠两种类型的层来形成稳定的i-But-est晶体。似乎通过HI NMR测量，不能检测到溶液的构象差异。

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