Related Experiment Video
Updated: Oct 28, 2026

Magnetometric Characterization of Intermediates in the Solid-State Electrochemistry of Redox-Active Metal-Organic Frameworks
Published on: June 9, 2023
Intraligand Charge Transfer in Metal-Organic Frameworks Facilitates Radical Anion-Mediated Hydrogen Evolution
Emmanuel Nyela Musa1, Galen Fritz2, Dylan Pyle1
1Materials Discovery Laboratory (MaD Lab), Department of Chemistry, Oregon State University, 153 Gilbert Hall, Corvallis, Oregon97331, United States.
Abstract:
Metal-organic frameworks (MOFs) offer a structurally tunable platform for photocatalysis, yet their activity for hydrogen evolution is often constrained by inefficient charge separation and reliance on metal cocatalysts. Herein, a family of MOFs, BVR-19-M, constructed from divalent transition metal ions (M = Mg2+, Mn2+, Cu2+, Zn2+, Cd2+) and the aliphatic amino acid l-cystine is reported. Among them, BVR-19-Zn exhibits the highest photocatalytic activity, enabled by the zinc's filled d-orbitals and the redox-active disulfide l-cystine ligand, promoting intraligand charge transfer (ILCT). Uniquely, the disulfide (S-S) bridges within BVR-19-Zn undergo transient homolytic cleavage upon light irradiation, generating a thiyl radical and thiolate anion pair that actively mediate charge separation and drive hydrogen evolution in the absence of a co-catalyst. Open-shell metal ions incorporated into BVR-19-M either introduce a mid-gap state that serves as a recombination center or promote metal-centric charge transfer, both of which diminish photocatalytic efficiency. The radical anion-mediated ILCT mechanism introduces a distinct molecular design strategy for MOFs, demonstrating how disulfide redox chemistry can be harnessed to unlock efficient, sustainable photocatalysis.
Related Concept Videos
Metal-Ligand Bonds
In these complexes, transition metals form coordinate covalent bonds, a kind of Lewis acid-base interaction in which both of the electrons in the bond are contributed by a donor (Lewis base) to an electron acceptor (Lewis acid). The Lewis acid in...
Radical Formation: Abstraction
Even though homolysis produces radicals, it is different from radical...
Radical Formation: Homolysis
π Molecular Orbitals of the Allyl Radical
The allyl systems have identical molecular orbitals but differ in the number of π electrons.
Ionic Bonding and Electron Transfer
Reduction of Alkenes: Asymmetric Catalytic Hydrogenation
The metal catalyst used can be either heterogeneous or homogeneous. When hydrogenation of an alkene generates a chiral center, a pair of enantiomeric products is expected to form. However, an enantiomeric excess of one of the products can be facilitated using an enantioselective reaction or an...
