Synthesis, Physical Properties, and Reactivity of Stable, π-Conjugated, Carbon-Centered Radicals

Abstract

Recently, long-lived, organic radical species have attracted much attention from chemists and material scientists because of their unique electronic properties derived from their magnetic spin and singly occupied molecular orbitals. Most stable and persistent organic radicals are heteroatom-centered radicals, whereas carbon-centered radicals are generally very reactive and therefore have had limited applications. Because the physical properties of carbon-centered radicals depend predominantly on the topology of the π-electron array, the development of new carbon-centered radicals is key to new basic molecular skeletons that promise novel and diverse applications of spin materials. This account summarizes our recent studies on the development of novel carbon-centered radicals, including phenalenyl, fluorenyl, and triarylmethyl radicals.

Aromatic Nanosandwich Obtained by σ-Dimerization of a Nanographenoid π-Radical

“…Dimerization of π-conjugated radicals is a fundamentally important process providing control over magnetism and reversible covalent bond formation in organic materials. 1 Two π radicals can recombine by formation of a covalent bond to produce a so-called σ-dimer, in which one atom of each π system has been converted into a tetrahedral center. As these bonds often have relatively low dissociation energies, σ-dimerization provides an important mechanism for assembly of complex architectures by dynamic covalent bonding.…”

Persistent, highly localized, and tunable [4]helicene radicals

“…16 In fact, the majority of persistent carbon-centered radicals are highly delocalized, which promotes p-p interactions and spinspin communication. [17][18][19] On the other hand, localization of spin density can increase spin polarization [20][21][22] and foster longer excited state lifetime, 23 faster spin mixing rate, 24,25 and higher reversibility of the cation-radical redox processes under air. 26,27 Thus, the syntheses of persistent carbon-centered radicals with localized, yet exposed, spin are highly desirable.…”

Simultaneous photoadhesion and photopatterning technique for passivation of flexible neural electrodes based on fluoropolymers

“…Although we have fabricated an ECoG electrode array through a SU-8 and FEP composite for demonstration purposes, the proposed simultaneous P&P technique can be applied to a wide range of flexible devices that require chemically robust passivation, such as implantable electrochemical sensors, biosensors, wearable sensing devices, and electronic skin devices. Recently, long-lived organic radical species have attracted much attention owing to their unique electronic and magnetic properties 52 ; therefore, our P&P technique may pave the way for new functional device fabrication by offering a robust adhesive interface with fluoropolymers.…”