Using wave function and density functional methodologies, we investigated the optical propertiesof 1.4-phenylenedinitrene and 4,4'-stilbenedinitrene biraradical molecules. In the process, weestablished a relationship between the absorption features and the electronic structures of ourtarget systems. The spin splitting is shown to be inversely proportional to the separation betweenthe two spin carrying centers and is driven by the Coulombic interaction. The intense peaks on theabsorption spectra (of the singlet) are the result of the mixing of transitions from the spin carryingcenters with those of p (pi) origin. Our calculations reveal distinctive and persistent absorptionfeatures that are integrative with our simple two states model. The absorption features are at theorigine of the optical contrast between the singlet and the triplet of both 1,4-phenylenedinitreneand 4,4'-stilbenedinitrene biraradicals. The optical contrast increases as the spacer group isadded to 1,4-phenylenedinitrene, and the spin splitting is reduced

Investigating absorption features and biradical character in open-shell organic compounds

247th National Meeting (2014)

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