Room temperature organic magnets derived from sp3 functionalized graphene

Abstract

Materials based on metallic elements that have d orbitals and exhibit room temperature magnetism have been known for centuries and applied in a huge range of technologies. Development of room temperature carbon magnets containing exclusively sp orbitals is viewed as great challenge in chemistry, physics, spintronics and materials science. Here we describe a series of room temperature organic magnets prepared by a simple and controllable route based on the substitution of fluorine atoms in fluorographene with hydroxyl groups. Depending on the chemical composition (an F/OH ratio) and sp3 coverage, these new graphene derivatives show room temperature antiferromagnetic ordering, which has never been observed for any sp-based materials. Such 2D magnets undergo a transition to a ferromagnetic state at low temperatures, showing an extraordinarily high magnetic moment. The developed theoretical model addresses the origin of the room temperature magnetism in terms of sp2-conjugated diradical motifs embedded in an sp3 matrix and superexchange interactions via –OH functionalization.

Cyanographene and Graphene Acid: Emerging Derivatives Enabling High-Yield and Selective Functionalization of Graphene

“…The emergence of magnetism was recently confirmed for graphene covalently functionalized by −F and −OH groups. 42 The magnetic properties of graphene-based structures were triggered by a sublattice imbalance of the graphene bipartite lattice caused by changes of its sp 2 hybrid states to sp 3 by the covalent functionalization and suitable exchange interaction. The functionalized graphene can be, hence, considered as sp 2 graphene with sp 3 structural defects or vice versa, depending on the functionalization degree.…”

“…Electronic and magnetic properties of the functionalized graphenes are given by the functionalization degree, nature of the functional group, arrangement of functionalities and sublattice symmetry. 42−46 For the sake of completeness it should be noted that lattice imperfections, including impurities, defects, atomic vacancies and structural distortion naturally occur in sheets of functionalized graphenes and they alter the electronic properties of experimental samples. 41,43−45,47 Because the observable electronic structure of G-COOH will be the result of statistical averaging over structures and arrangements having both metallic and semiconducting properties, it should have noticeable conductivity.…”

Functionalized Ultrasmall Fluorinated Graphene with High NIR Absorbance for Controlled Delivery of Mixed Anticancer Drugs

“…[16][17][18][19][20][21][22] Specially, as an ovel biomaterial, FG not only inheritst he good geneso fg raphene,s uch as low cytotoxicity and high drug loading ratio,b ut also distinctly distinguishing itself from other graphene derivativesdepending on its uniquep roperties. [16][17][18][19][20][21][22] Specially, as an ovel biomaterial, FG not only inheritst he good geneso fg raphene,s uch as low cytotoxicity and high drug loading ratio,b ut also distinctly distinguishing itself from other graphene derivativesdepending on its uniquep roperties.…”

Selective Hydrogen Adsorption in Graphene Rotated Bilayers

“…7 Beyond model hamiltonians many first principles calculations been performed and there is a large list of published papers. To mention some of them: hydrogen and vacancies have been studied by Yazyev 5,6 , fluorine has been studied for instance by Sofo et al 27 and Tucek et al 10 and different sp 3 defects by Santos et al 28 Before studying hydrogen chemisorption on rotated bilayers, we have looked at the monolayer case. Hydrogen atoms are known to chemisorb on top of carbon atoms.…”