摘要:
IntroductionPolymorphism is an important phenomenon in solid state chemistry because the chemical and physical properties are dependent on polymorphs.1Commonly, polymorphism is divided into two types(i)packing the same molecules into different arrangements, or(ii)packing conformational isomers into similar or different arrangements, called conformational polymorphism.2–4Most studies of polymorphism have been applied to onecomponent systems. However, more recently, polymorphism of inclusion compounds has been reported for two host compounds, urea and cholic acid1.Polymorphism of host frameworks dependent on the guest species has been observed in many hosts.10These two compounds yield two types of inclusion crystals that have the same host–guest combinations and host–guest ratios.5,6In the crystal structures, the hosts and guests have the same conformations but different molecular arrangements. This indicates that they are classified as the former type polymorphism of a twocomponent system.Table 1summarizes classification of known polymorphs. Here, we describe a rare example of conformational polymorphs of inclusion crystals. Inclusion crystals of1with ethyl acetate give two types of crystal structure that have different host–guest conformations resulting in different hydrogen bond networks.Polymorphism of organic crystalsSystem(i)(ii)One componentKnown1Known2–4Two componentKnown5,6This work
ISSN:1466-8033
DOI:10.1039/b009361k
出版商:RSC
年代:2000
数据来源: RSC