Electron deficient confined spaces within naphthalene diimide cryptophanes

Abstract

In order to enhance the recognition properties of a given substrate, to increase the stability of an intermediate or to sequester a pollutant from its medium, the development of suitable confined spaces is an attractive strategy. However, most of the covalent cages described in the literature are based on electron rich scaffolds, thus limiting access to electron deficient confined spaces. Naphthalene diimides are broadly used as π-acidic surfaces and can additionally serve as recognition units through anion–π interactions thanks to their high quadrupole moments. In order to preorganize the naphthalene diimide units into a well-defined confined space, cryptophanes are well-suited because of the rigidity of the cyclotriveratrylene moieties, their bowl shape and their well-known synthesis. Herein, we describe the synthesis of two diastereoisomers of a cryptophane having three naphthalene diimide spacers, their characterization, the resolution of the racemate and their recognition properties towards selected anions and pyrene.