Dendritic Groups Substituted Kekulé‐Benzene‐Bridged Bis(triarylamine) Mixed‐valence Systems: Syntheses, Characterization and Electronic Coupling Properties

Abstract Alkoxy‐substituted phenyl‐bridged triarylamine compounds 1 – 3 of three different sizes were synthesized and characterized by nuclear magnetic resonance, elemental analysis, and X‐ray single diffraction. Their electronic coupling properties were investigated by electrochemistry, UV‐vis‐near‐infrared (NIR) spectroscopy, and density functional theory calculations. Electrochemistry experiment results with small potential difference reveal that unresolved electronic coupling occurred between two NAr 2 termini. Observable electronic coupling of mixed‐valence 1 + – 3 + were exhibited by NIR absorptions, and electronic coupling parameter H ab was calculated by the Hush theory formula from experimental characteristic intervalence charge‐transfer transitions. The results revealed that the electron coupling of 1 + – 3 + gradually increased with the alkoxy size of the substituents (from methoxy to dendritic groups) attached to the central phenyl bridge. These findings are supported by the increasing gradient trend of spin density contributions of bridge linkers (terphenyl) ( 1 + : 23 %; 2 + : 30 %; 3 + : 38 %) and further prove that introducing protected groups, such as large dendritic groups in bridge cores, can effectively enlarge electronic coupling.