Synthetic methodologies for structurally defined linked-[n]rotaxanes with permethylated cyclodextrins: Platform for functionalized molecular electronics

Abstract

Insulated molecular wires, π-conjugated molecules insulated by nonconductive macrocycles, have been regarded as key components in the field of single-molecule electronics. Their various functionalities were attributed to their π-conjugated systems and enhanced by their macrocyclic insulation. We have recently proposed that the linked-structures resulting from π-conjugation with cyclic molecules, especially with permethy-lated cyclodextrins, were effective for preparing various types of functionalized insulated molecular wires for use in molecular electronics. The unique self-threading supramolecules called linked-[n]rotaxanes, are reported to have the enhanced functional properties of molecular wires. The development of such insulated molecular wires has been strongly supported by precise engineering protocols with fine synthetic techniques for making self-threading supramolecular structures. In this account, we systematically describe and categorize synthetic procedures for making structurally defined linked-[n]rotaxanes via various reaction systems with focus on the threading and fixation systems peculiar to linked-[n]rotaxane structures.