Graphene oxide and reduced graphene oxide hybrids with spin crossover iron(III) complexes

Graphene (rGO) based hybrid materials exhibiting electrical conductivity and spin crossover (SCO) behavior are reported. The non-conductive [Fe(qnal)(2)](n)GO (1.GO) and [Fe(qsal)(2)](n)GO (2.GO) hybrids have been prepared by employing the electrostatic interaction between the negatively charged graphene oxide (GO) nanosheet and the respective iron(III) complex cations in [Fe(qnal)(2)]Cl-+(-) and [Fe(qsal)(2)]Cl-+(-). The conductive [Fe(qnal)(2)](n)rGO (1.rGO) and [Fe(qsal)(2)](n)rGO (2.rGO) hybrids were obtained by thermal reduction of 1.GO and 2.GO. 1.GO and 1.rGO exhibit SCO behavior, and 1.rGO also shows a light-induced excited spin state trapping (LIESST) effect. Thus, in 1.rGO the electrical conductivity of rGO and the SCO behavior of [Fe(qnal)(2)](+) coexist in a single structure. We propose that the observed cooperativity for the rGO nanosheet-bound iron(III) [Fe(qnal)(2)](+) SCO material occurs through formation of large domains via pi-pi stacking between the graphene skeleton and the [Fe(qnal)(2)](+) cations.