Stable 2D anti-ferromagnetically coupled fluorenyl radical dendrons

• Published in: Chemical science (Cambridge) Vol. 9; no. 13; pp. 3395 - 3400
• Main Authors: Wang, Jian, Kim, Gakhyun, Sandoval-Salinas, María Eugenia, Phan, Hoa, Gopalakrishna, Tullimilli Y., Lu, Xuefeng, Casanova, David, Kim, Dongho, Wu, Jishan
• Format: Journal Article
• Language: English
• Published: CAMBRIDGE Royal Soc Chemistry 2018; Royal Society of Chemistry
• Subjects: Chemistry; Chemistry, Multidisciplinary; Conjugation; Dimensional stability; Energy gap; Ferromagnetism; Photon absorption; Physical Sciences; Science & Technology; GROUND-STATE; HYDROCARBONS; UNPAIRED ELECTRONS; POLYRADICALS; 2ND HYPERPOLARIZABILITIES; OPEN-SHELL; CLOSED-SHELL; PHENYLACETYLENE DENDRIMERS; DIRADICAL CHARACTER; MOLECULES
• ISSN: 2041-6520; 2041-6539
• DOI: 10.1039/C7SC05493A

We report the first class of stable, two-dimensional (2D) anti-ferromagnetically coupled dendritic polyradicaloids. A kinetically blocked fluorenyl radical was used to build up the first and second generation dendrons FR-G1 and FR-G2 containing three and seven fluorenyl units, respectively. The neighboring fluorenyl radicals in FR-G1 and FR-G2 show moderate anti-ferromagnetic exchange interaction, resulting in a doublet and quartet ground state, respectively, with a small doublet–quartet energy gap. From FR-G1 to FR-G2 , the energy gap decreased and the two-photon absorption was enhanced owing to more extended 2D π-conjugation. Both compounds showed multiple redox waves due to their polyradical character.