Tuning the Biradicaloid Nature of Polycyclic Aromatic Hydrocarbons: The Effect of Graphitic Nitrogen Doping in Zethrenes

Author(s)

Das, Anita ^[1] ; Pinheiro, Jr., Max ^[2] ; Machado, Francisco B. C. ^[2] ; Aquino, Adelia J. A. ^{[1, 3]} ; Lischka, Hans ^{[4, 1]}

Affiliation

^[1] Tianjin Univ, Sch Pharmaceut Sci & Technol, Tianjin 300072 - Peoples R China

^[2] Inst Tecnol Aeronaut, Dept Quim, BR-12228900 Sao Paulo - Brazil

^[3] Univ Nat Resources & Life Sci Vienna, Inst Soil Res, Peter Jordan Str 82, A-1190 Vienna - Austria

^[4] Univ Vienna, Inst Theoret Chem, A-1090 Vienna - Austria

• Document type: Journal article
• Source: ChemPhysChem; v. 19, n. 19, p. 2492-2499, OCT 5 2018.
• Web of Science Citations: 3

Abstract

Zethrenes are interesting polycyclic aromatic hydrocarbons (PAHs), which possess unique optoelectronic and magnetic properties because of their singlet open-shell biradicaloid character, making them promising candidates for application in organic electronics. Tuning their properties is a key task in order to develop efficient compounds for practical use by balancing the desired biradicaloid character against its chemical instability. In this work, high-level theoretical multireference methods appropriate for the correct description of polyradicaloid systems are used to develop rules for doping of zethrenes by means of nitrogen taking heptazethrene (HZ) as a benchmark example. The results of the quantum chemical calculations have been concentrated on a series of quantitative descriptors such as unpaired densities and singlet-triplet (S-T) splittings. They clearly indicate different regions in the HZ where N-doping can either lead to strong enhancement of the biradicaloid character or to strong quenching towards a closed shell state. A wide scale of varying open-shell character is accessible from the different doping positions. It is shown that the S-T splittings correlate well with the total number of unpaired electrons in the medium range of biradicaloid character. For pronounced biradical character the S-T splitting decays to about zero with a margin of +/- 0.15eV. In the opposite closed-shell limit, much larger S-T splittings of up to 3eV are computed. (AU)

• FAPESP's process: 17/50157-4 - The development of biradicaloid systems and functionalized materials for organic semiconductors: accurate molecular information from multireference quantum theory
• Grantee: Francisco Bolivar Correto Machado
• Support Opportunities: Regular Research Grants
• FAPESP's process: 17/07707-3 - Excited states and biradicalar nature of poliacenes and periacenes
• Grantee: Francisco Bolivar Correto Machado
• Support Opportunities: Regular Research Grants