The influence of the radicaloid character of polyaromatic hydrocarbon couplers on magnetic exchange interactions

Abstract

The molecular properties of conjugated spacers, such as the π-conjugation, aromaticity, length of the couplers, etc., that couple two localized spin-centers influence the intramolecular magnetic exchange interactions (2J) mediated through them. In recent years, the development and synthesis of highly conjugated polyaromatic hydrocarbons (PAHs) in the context of graphene nano-ribbon carbonaceous materials, prompted us to investigate their role as magnetic couplers. Apart from the highly conjugated nature of various PAHs, the intriguing open-shell characteristic dominates the electronic structures and properties of the PAHs. The extent of the open-shell behaviors of the PAHs could be quantified with the radicaloid character (y) applying density functional theory (DFT) calculations. In this work, we observed a strong correlation between the radicaloid character of the spacer and the strength of the magnetic exchange interactions mediated through it. The larger the radicaloid character the stronger the magnetic exchange interactions within the fixed length of the couplers.