Polymorphism in a <i>trans</i>-Cinnamic Acid Derivative Exhibiting Two Distinct β-type Phases: Structural Properties, [2 + 2] Photodimerization Reactions, and Polymorphic Phase Transition Behavior
作者:Manal A. Khoj、Colan E. Hughes、Kenneth D. M. Harris、Benson M. Kariuki
DOI:10.1021/cg4009202
日期:2013.9.4
few cases, concomitant crystallization of another polymorph (denoted β2) is also observed. On heating the β1 polymorph, a solid-state phase transition occurs at ca. 119 °C to produce the β2 polymorph. This polymorphic phase transition is irreversible, and the β2 polymorph remains stable on subsequent cooling to ambient temperature. Both the β1 and the β2 polymorphs undergo a topochemical [2 + 2] photodimerization
我们报告发现在反式肉桂酸衍生物之间多态性的罕见情况,其中基于它们的固态结构特性和固态光反应性,两个多晶型物都被归类为β型结构。具体而言,3-氟-反式-肉桂酸,结晶从许多溶剂体系导致形成一种多晶型(表示为β的1),虽然,在一些情况下,多晶型物的另一个(表示为β的伴随结晶2),也观察到。上加热所述β 1多晶型物,固态相转变发生在约 119℃,以产生β 2多晶型物。此多晶型相转变是不可逆的,并且β 2多晶型物在随后冷却至环境温度时保持稳定。无论是β 1和β 2多晶型物经受局部化学[2 + 2]在UV照射光二聚反应,以产生3,3'-二氟-β-truxinic酸作为在几乎100%的收率的光化产物。然而,这些反应与结晶度的完全丧失有关,从而阻止了通过单晶或粉末X射线衍射技术确定直接产生的固体光产物的结构性质。