Photoswitching of Intramolecular Magnetic Interaction Using Photochromic Compounds

Abstract

Recent advances in organic material chemistry have helped to realize several novel organic functional materials, including organic conductors, magnets, and nonlinear optical materials. One of the current frontiers in this field is molecular electronics, where a single molecule plays the role of one component in an electric circuit. For the realization of this goal, highly integrated materials with multiple functions are necessary. Photochromism is the light-induced reversible transformation of chemical species between two isomers that have different absorption spectra. The two isomers differ from each other not only in the absorption spectra but also in various physical and chemical properties. These property changes can, in principle, be utilized to control the function of organic materials. Two organic radicals placed at the two edges of a π-conjugative molecule interact magnetically through the framework via the exchange interaction J. Therefore photocontrol of the magnetism of the system is possible when the photochromic moiety is used as a backbone. In this chapter we will describe studies of the photoswitching of the intramolecular magnetism by incorporating two radical moieties into a photochromic diarylethene spin coupler. Photoswitching using a diarylethene dimer, which showed similar electric-circuit behavior, will also be discussed.