Three new designs of covalent cages

Abstract

Organic cages provide regularly well-defined cavities, which have the potential for many applications such as catalysis or sensoring. In recent years, dynamic covalent chemistry (DCC) has become an important approach for the synthesis of purely organic cages. This study focuses on three new designs: A, B and C (Figure 1). The designs are heterosequenced and/or contain a functionalized interior to stimulate versatile catalysis. They are analyzed with retrosynthesis and separated in building blocks. The synthesis of building blocks is studied as well as the coupling reactions between building blocks (DCC). Unfortunately, cage A and B could not be synthesized as the coupling reaction(s) failed. Cage C is successfully synthesized with a quantitative yield (C1) as well as the imine analogue (C2). C2 shows luminescence with addition of acid. This property is further studied and quantified. In addition, both cages show the ability to coordinate zinc ions. Other metals have been tested for C2. However, only indirect evidence of coordination is found due to solubility issues. Catalytic testing for a possible C2 with Fe(III) leads to inconclusive results.