Magnetism‐Tunable Oligoacene Dioxide Diradicals: Promising Magnetic Oligoacene‐Like Molecules

Abstract

Graphene oxide has attracted intense research interest recently because the graphene oxide synthesis route, as a promising alternative for cost-effective mass production of graphene, has been explored. To further study the oxidation process and possible mechanism and to explore applicability of the oxidized products, we have performed a computational study on three series of oligoacene dioxides, focusing on their structures and electronic properties. Taking 1,5-dioxidized naphthalene as a starting point, three series of oligoacene dioxides are considered as follows: 1) middle insertion by 1-2 benzene rings; 2) single-side expansion using 1-2 benzene rings; 3) double-side expansion using two benzene rings. On the basis of density functional theory and complete active space self-consistent field (CASSCF) calculations, we reveal that oligoacene dioxides in the middle insertion series have a triplet ground state, whereas those in the single-side expansion series and the double-side expansion series have open-shell broken-symmetry singlet diradical ground states except for their common origin naphthalene-1,5-dioxide whose ground state is triplet and which is also viewed as the origin of the middle insertion series. Magnetic coupling interactions of these oligoacene dioxides are also determined. This work should help people toward an atomistic understanding of the electronic structures and properties of possible intermediates or products and even the oxidation mechanism of graphene sheets, and provides a reasonable strategy of designing novel graphene-oxide-based magnetic materials.

Molecular Vibrations Induced Potential Diradical Character in Hexazapentacene

“…In view of the successful and a vast number of applications of B3LYP functional in optimizing molecular geometries and examining diradical character, ,,− herein, we perform a B3LYP functional calculational analysis to obtain a basic understanding of potential diradical character in HAP that appears due to molecular thermal vibrations. Thus, the geometries of CS and T states of static HAP were fully optimized by using the UB3LYP/6-311++G­(d, p) method. , The optimized geometries were further verified to be local minima through vibrational analyses, which show no imaginary frequency vibrational mode.…”

Remarkable Magnetic Coupling Interactions in Multi-Beryllium-Expanded Small Graphene-like Molecules with Well-Defined Polyradical Characters

“…Clearly, it has been a formidable but meaningful task to seek or design new magnetic materials through modifying oligoacenes, graphene patches, or other graphene-like molecules. In recent years, our group is devoted continuously to the studies of graphene and graphene-like molecules. − In particular, we theoretically designed multi-Zn-expanded oligoacenes (from benzene to pentacene, m Zn- n A, n = 1–5, m and n denote the number of Zn atoms and acenes, respectively) and multi-Zn-expanded graphene patches ( m Zn-GP) by introducing Zn arrays into oligoacenes and specific benzenoid rings of simple graphene patches in different ways, respectively, and explored their relevant electronic/magnetic properties. Our results indicate that these multi-Zn-expanded graphene-like molecules have open-shell singlet diradical ground states with well-defined diradical characters and AFM characteristics and that one of the m Zn-GPs possesses a quintet ground state as a tetraradical. , …”