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Reversible Dimerization and Polymerization of a Janus Diradical To Produce Labile C−C Bonds and Large Chromic Effects |
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| Authors: | Dr. José L. Zafra Lili Qiu Naoyuki Yanai Takamichi Mori Dr. Masahiro Nakano Dr. Miriam Peña Alvarez Prof. Juan T. López Navarrete Prof. Carlos J. Gómez‐García Prof. Miklos Kertesz Prof. Kazuo Takimiya Prof. Juan Casado |
| Affiliation: | 1. Department of Physical Chemistry, University of Málaga, Málaga, Spain;2. Department of Chemistry and Institute of Soft Matter, Georgetown University, Washington, D.C., USA;3. Department of Applied Chemistry, Graduate School of Engineering, Hiroshima University Kagamiyama, Higashi-Hiroshima, Japan;4. Emergent Molecular Function Research Group, RIKEN Center for Emergent Matter Science (CEMS), Saitama, Japan;5. Department of Physical Chemistry, Complutense University of Madrid, Madrid, Spain;6. Instituto de Ciencia Molecular, Universidad de Valencia, Valencia, Spain |
| Abstract: | Conducting polymers can be synthesized by irreversible diradical monomer polymerization. A reversible version of this reaction consisting of the formation/dissociation of σ‐dimers and σ‐polymers from a stable quinonoidal diradical precursor is described. The reaction reversibility is made by a quinonoidal molecule which changes its structure to an aromatic species by forming weak and long intermolecular C?C single bonds. The reaction provokes a giant chromic effect of about 2.5 eV. The two opposite but complementary quinonoidal and aromatic tautomers provide the Janus faces of the reactants and products which produces the observed chromic effect. A reaction mechanism is proposed to explain the variety of final products starting with structurally very similar reactants. These reversible reactions, covering an unusual regime of weak covalent supramolecular bonding, yield products which might be envisaged as novel molecular and polymeric soft matter phases. |
| Keywords: | cyclophanes density functional calculations radicals reaction mechanisms solvatochromism |