ABSTRACT

The design and experimental investigations of high-spin organic systems will be reviewed with focusing π-conjugated organic spin systems. This article deals with ground-state high-spin polycarbenes and photo-excited high-spin states of π-conjugated stable radical systems (anthracene radical or biradical systems etc.). The former is a famous example of the intra-molecular spin alignment in the ground states and the latter is the first example of the spin alignment in the photo-excited states of the π- conjugated organic spin systems. The relationship between the π- topology and spin alignment will be discussed. The mechanism of the intramolecular spin alignment and the role of the spin polarization and spin delocalization are revealed by the molecular orbital calculations. The main part of this article will deal with the recent excited high-spin works on π-conjugated organic spin systems.