Chiral two-dimensional conjugated metal-organic-frameworks with high spin polarization
In a recent article published in Nature Communications, researchers from TU Dresden and the Max Planck Institute of Microstructure Physics reported a side chain-induced chirality amplification (SICA) strategy that enables the synthesis of highly crystalline and conductive chiral 2D c-MOFs with tunable chirality and record-high spin polarization of up to 96.9%. This approach represents a significant advancement for designing chiral 2D crystalline materials with high conductivity and high spin polarization, highlighting the significant potential of chiral 2D c-MOFs in chiral electronics and spintronics.
a) Schematic illustration for the strategy of side chain induced chirality. b) Schematic diagram of chiral 2D c-MOF structure. c) CD spectra of 2D c-MOFs, (S)-Ph, (R)-Ph, (S)-Na and (rac)-Ph. d) Schematic illustration of the tunneling current in a parallel configuration for (S)-Ph, (R)-Ph, and (S)-Na. e) Room-temperature I-V curves for chiral 2D c-MOF films at thickness around 100 nm obtained by mc-AFM.
Chiral two-dimensional (2D) crystals have attracted extensive attention for their potential applications in optoelectronics, spintronics, and chirality-induced spin selectivity (CISS). The CISS effect, which enables chiral structures to preferentially transmit electrons with a specific spin orientation, resulting in substantial spin polarization. However, most reported chiral materials still exhibit spin polarization below 90%, mainly restricted by their limited electrical conductivity. Two-dimensional conjugated metal-organic frameworks (2D c-MOFs) have recently emerged as a promising platform to address these limitations. Their unique d-π conjugated architectures, constructed from π-conjugated organic linkers and metal ions, provide strong spin-orbit coupling, thereby enhancing intrinsic spin polarization. Therefore, implanting chirality into 2D c-MOFs represents a promising strategy for constructing spin filter materials with high spin-selectivity and polarization efficiency. Nevertheless, efforts to introduce chirality into inherently achiral 2D materials have primarily focused on chiral molecules intercalation and asymmetric building block incorporation, often lead to issues like interlayer inhomogeneity, weak structural robustness, and incompatibility with the high symmetry required for 2D c-MOF synthesis. Consequently, implanting chirality into 2D c-MOFs remains a significant challenge, largely due to the lack of chiral building blocks compatible with the symmetrical architecture essential for 2D c-MOF construction.
A recent article by researchers from TU Dresden and the Max Planck Institute of Microstructure Physics, published in Nature Communications, proposes a side chain-induced chirality amplification (SICA) strategy to synthesize conjugated ligands with intrinsic molecular chirality, enabling precise chiral control while preserving high framework symmetry in 2D c-MOFs. By grafting chiral side chains onto π-conjugated HATI ligands, molecular distortion is induced, transferring chirality from the side chains to the conjugated backbone. Upon constructing secondary building units (SBUs) with Ni ions, the resulting 2D c-MOFs exhibit high crystallinity and pronounced chirality. The degree of chirality can be tuned by steric hindrance: replacing chiral phenylethyl (PhEt) with chiral naphthylethyl (NaEt) increases the distortion angle from 2.3° to 7.0°, leading to enhanced chirality amplification in the bulk material. This structural chirality amplification results in improved spin polarization, with mc-AFM measurements revealing values up to 96.9%—among the highest reported for chiral materials. The SICA strategy thus provides a robust pathway for designing chiral 2D crystalline materials with high conductivity and spin polarization, highlighting the significant potential of chiral 2D c-MOFs in chiral electronics and spintronics.
The paper entitled “Chiral two-dimensional conjugated metal-organic-frameworks with high spin polarization” by Shiyi Feng, Yang Lu, Chenchen Wang, Morteza Torabi, Xing Huang, Florian Auras, Ran He, Lukas Sporrer, Paul-Alexander Laval-Schmidt, Xizheng Wu, Xia Wang, Li Wan, Dongxu Wang, Bernd Plietker, Mike Hambsch, Markus Löffler, Stefan C. B. Mannsfeld, Claudia Felser, and Xinliang Feng can be found at: https://www.nature.com/articles/s41467-025-64969-9
