Discrete Polyketones: Synthesis, Derivatization, and Potential Applications

The present account reviews recent progress in the synthesis, functionalization, and application of discrete polyketones. Whereas most polyketones are synthesized as polydisperse polymers with various molecular chain lengths and sizes, discrete polyketones are obtained in chemically pure forms. This allows precise structural analysis using NMR and X-ray diffraction. Discrete polyketones have been used to determine the critical chain length that distinguishes the crystallization behaviors of small molecules from those of macromolecules. Calix[3]pyrrole, which is a ring-contracted analogue of porphyrinogen, was first obtained from a cyclic hexaketone. The discovery of the strain-induced ring expansion reaction of calix[3]pyrroles has provided an important insight into solving a long-standing enigma in porphyrin synthesis. Chemical derivatization of discrete polyketones using ketone-derived transformations has resulted in the generation of various functional molecules for potential applications. These molecules have been used to develop several materials, including luminescent chromophores, ion adsorbents, drug–drug conjugates, and microfluidic devices for cancer diagnosis.