Anthracene‐Attached Persistent Tricyclic Aromatic Hydrocarbon Radicals

Abstract

Anthracene-attached tricyclic aromatic hydrocarbon radicals having different central polygons, Ant-5, Ant-6, and Ant-7,w ere synthesized to evaluatet he role of an anthracene substituent group in the stabilitya nd reactivity of tricyclic aromatich ydrocarbon radicals. The bulky anthryl group effectively protects ac arbon atom with high spin density,r esultingi nh igh persistence of the radicals. On the other hand, the combination of the anthrylg roup and the tricyclica romatic scaffold makes the molecular structure drastically change from at wisted form to af olded form and an unpaired electron movesi nto the anthryl moiety,e ventually affordingatail-to-tail s-dimer.[a] Dr.

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

“…We also investigated the effect of ring size of the fluorenyl radical on chemical and physical properties. Three kinds of anthracene-attached tricyclic radicals ( 11 , 12 , and 13 ) were designed and synthesized ( Figure 12 ) [ 31 ]. It is well-known that five- and seven-membered rings have electron-deficient and electron-rich properties, respectively.…”

Bulky Substituent Effect on Reactivity of Localized Singlet Cyclopentane‐1,3‐diyls with π‐Single Bonding (C‐π‐C) Character

“…The results prompted us to investigate the effect of more rigid and bulkier substituents (R′), such as mesityl (Mes) and triisopropylphenyl (Tip) groups, at the meta position of the phenyl ring, on the reactivity of singlet diradicals S‐ DR2 ‐ 4 (Figure ), which have π‐single bonding character between the radical centers . The bulky substituents are well known to kinetically stabilize the low‐valent species and open‐shell molecules .…”

“…Radical-radical couplingr eaction [12][13][14] is an important fundamental reaction, involved in processes such as termination of radicalp olymerization [15][16][17] and deactivation of open-shell species. [18][19][20] Therefore, it is important to understand how the coupling reactionisinfluenced by steric effects in order to develop new organic materials with open-shell characters.…”

“…The results prompted us to investigate the effect of more rigid and bulkier substituents (R'), such as mesityl (Mes) and triisopropylphenyl (Tip) groups, att he meta positiono ft he phenylr ing, on the reactivity of singlet diradicals S-DR2-4 ( Figure 1), which have p-single bondingc haracter between the radicalc enters. [20] The bulky substituents are well knownt ok i-Scheme1.Generation of singlet diradical S-DR1 and the formation of ringclosedp roduct. [a] R. Akisaka, Prof. M. Abe Department of Chemistry Graduate School of Scienece Hiroshima University netically stabilize the low-valent species [9] and open-shell molecules.…”

Structure-Property Correlations in Luminescent Anthracene Derivatives

“…The preparation of 10 and the stability and reactivity of its radicals have been reported recently in 2019 by Tomohiko et al, but the photophysical properties were not investigated and will therefore be evaluated during this work. [187] From the previous works on the disubstituted [9,10-…”