Organoplatinum-mediated synthesis of cyclic π-conjugated molecules: towards a new era of three-dimensional aromatic compounds

Abstract

This article describes the most recent developments in the synthesis of three-dimensional π-conjugated molecules and the elucidation of their properties made by our research group. Various cycloparaphenylenes (CPPs) of different sizes and a cage-like 3D molecule were synthesized based on the platinum-mediated assembly of π-units and subsequent reductive elimination of platinum. The assembly of π-units by this method mimics the self-assembly process for the formation of supramolecular ligand-metal complexes with 3D cages and polyhedral structures. Furthermore, reductive elimination of platinum successfully took place with high efficiency, despite the high strain energy of the target molecule. Several size-dependent physical properties of CPPs, namely the photophysical, redox, and host-guest chemistries, were also clarified. These results are of use for a molecular-level understanding of CNT physical properties as well as fullerene peapods. Theoretical and electrochemical studies suggest that small CPPs and their derivatives should be excellent lead compounds for molecular electronics.

Keywords: cycloparaphenylenes; fullerenes; host-guest systems; nanotubes; supramolecular chemistry.