Multi-zinc-expanded graphene patches: tetraradical versus diradical character

Three classes of multi-Zn-expanded graphene patches in different shapes are computationally designed through introducing a Zn chain into the corresponding middle benzenoid chain. Both density functional theory and complete active space self-consistent field calculations predict that molecules of nnn-quasi-linear and nnn-slightly bent series have the open-shell broken-symmetry (BS) singlet diradical ground states, whereas those of n(n+1)n species possess quintet tetraradical as their ground state and become open-shell BS singlet tetraradicals when they are in a higher energy state. These results offer the first theoretical attempt to introduce multi-Zn into the small graphene patches to form Zn-expanded graphene patches, leading them to polyradical structures. This work provides an executable strategy to yield molecules which have stable polyradicaloid character and enhanced electronic properties of multi-Zn-expanded graphene patches.