The described method generates metal-organic frameworks (MOFs) that display semiconducting behavior with tunable electrical properties. These materials have applications in the semiconductor, chemical, and electronics industries. They can act as electrochemical sensors, electrocatalysts, and various electronic devices such as light-emitting diodes, photovoltaic solar cells, and transistors.
2D covalent-organic frameworks (COFs) present exceptional charge mobility and mechanical stability and are considered a more effective replacement for conventional semiconductors such as graphene. A recent class of COFs, described as semiconducting metal-organic graphene analogues (s-MOGs), are assembled from dithiolene and catecholate aromatic organic moieties bridge by square-planar metal ions. The electrical conductivity of these s-MOGs show potential but as of yet has been below 1 S∙cm-1.
This invention replaces s-MOG dithiolene and catecholate groups with ortho-diimine groups, leading to considerable improvement of the materials’ electrical properties and making them more attractive for applications in the semiconductor device industry. These novel s-MOGs are synthesized by reacting organic ligands containing at least two ortho-phenylenediamine groups with metal salts. The organic ligands are oxidized and each ortho-phenylenediamine group is transformed into an ortho-phenylenediimine group, which binds to the metal ion. Oxidation and formation of the ortho-diimine group is essential for electrical conductivity.
The inventors have identified a compound, Ni(isq)2, as a target for the construction of a fully charged-delocalized s-MOG. Ni(isq)2 is fully π-conjugated with its ground state having partial singlet biradical character. The inventors perform a 2D extension of Ni(isq)2 by reacting hexaaminotriphenylene hexahydrochloride (HATP 6HCl) with ammoniacal NiCl2 to produce a new crystalline s-MOG with very high electrical conductivity that is linearly proportion to its temperature. The conductivity of this new material vastly exceeds those of previous s-MOGs and other conductive MOFs and is higher than even some of the best organic conductors.
Method amenable to
chemical functionalization, allowing for tunable electrical properties
sMOGs have greater
electrical conductivity than commonly used materials like graphene
sMOGs using metal ortho-phenylenediimine
groups offer improved electrical conductivity over those using dithiolene and