Naskar Sandip, Moi Rajib, Das Indrajit, Biradha Kumar
Organic and Medicinal Chemistry Division, CSIR-Indian Institute of Chemical Biology, 4, Raja S. C. Mullick Road, Jadavpur, Kolkata, 700032, India.
Department of Chemistry, Indian Institute of Technology (IIT) Kharagpur, Kharagpur, West Bengal 721302, India.
Angew Chem Int Ed Engl. 2022 Jun 7;61(23):e202204141. doi: 10.1002/anie.202204141. Epub 2022 Apr 7.
The synthesis of reversible oligomer/polymers is fascinating both from the perspective of the fundamental understanding as well as their applications, ranging from biomedical to self-healing smart materials. On the other hand, the reactions that occur in single-crystal-to-single-crystal (SCSC) fashion offer great details of the structure, geometry and stereochemistry of the product. However, SCSC [2+2] oligomerization is rather difficult and rare. Further, till date there are no reports for a reversible [2+2] oligomerization in SCSC fashion. In this work, four halogen-substituted acrylic dienone molecules were deliberately designed and their ability to participate in [2+2] cycloaddition reaction in solid state was studied under visible light. Despite of having the required alignment of double bonds of dienes in all four crystal structures, they were found to exhibit variable reactivities given the differences in their weak intermolecular interactions such as halogen⋅⋅⋅halogen, halogen⋅⋅⋅π and C-H⋅⋅⋅O interactions. Notably, one of these materials exhibits reversible oligomerization in a SCSC manner.
可逆低聚物/聚合物的合成，无论是从基础认识的角度，还是从其应用（从生物医学到自愈智能材料）的角度来看，都极具吸引力。另一方面，以单晶到单晶（SCSC）方式发生的反应，能提供有关产物结构、几何形状和立体化学的大量细节。然而，SCSC [2+2] 低聚反应相当困难且罕见。此外，迄今为止，尚无关于以SCSC方式进行可逆 [2+2] 低聚反应的报道。在这项工作中，特意设计了四个卤代丙烯酸二烯酮分子，并研究了它们在可见光下参与固态 [2+2] 环加成反应的能力。尽管在所有四种晶体结构中都具有二烯双键所需的排列，但由于它们在诸如卤素⋅⋅⋅卤素、卤素⋅⋅⋅π和C-H⋅⋅⋅O相互作用等弱分子间相互作用上存在差异，发现它们表现出不同的反应活性。值得注意的是，其中一种材料以SCSC方式表现出可逆低聚反应。
