Asymmetric Coordination Toward a Photoinduced Single-Chain Magnet Showing High Coercivity Values

The production of photo-switchable molecular nanomagnets with substantial coercivity, which is indispensable for information storage and process applications, is challenging. Introducing photo-responsive spin-crossover units provides a feasible means of controlling the magnetic anisotropy, interactions, and overall nanomagnet properties. Herein, we report a cyanide-bridged chain 1.12H(2)O ({[((Pz)Tp)Fe-III(CN)(3)](2)Fe-II(Pmat)(2)}(n).12 H2O) generated by linking the Fe-II-based spin-crossover unit with the [((Pz)Tp)Fe(CN)(3)](-) ((Pz)Tp: tetrakis(pyrazolyl)borate) building block in the presence of asymmetric ditopic ligand Pmat ((4-pyridine-4-yl)methyleneamino-1,2,4-triazole). Structural characterization revealed that the introduction of this asymmetric ligand led to a distorted coordination environment of Fe-II ions, which were equatorially coordinated by four cyanide N atoms, and apically coordinated by one pyridine N atom and one triazole N atom. Upon 808-nm light irradiation, 1.12H(2)O underwent photoinduced spin-crossover and exhibited single-chain magnet behavior with a coercive field of up to 1.3 T. This represents a 3d-based photoinduced single-chain magnet exhibiting pronounced hysteresis.

Automated summary

The production of photo-switchable molecular nanomagnets with substantial coercivity is challenging but essential for information storage and processing applications. This study demonstrates a cyanide-bridged chain generated by introducing photo-responsive spin-crossover units, leading to a 3d-based photoinduced single-chain magnet exhibiting pronounced hysteresis. Structural characterization revealed a distorted coordination environment of Fe-II ions upon the introduction of an asymmetric ligand, resulting in the observed magnetic properties.