Ligand Modified and Light Switched On/Off Single-Chain Magnets of {fe2co} Coordination Polymers Via Metal-to-Metal Charge Transfer

It is still a formidable challenge to simultaneously switch single-chain magnet (SCM) behavior via ligand modification and light irradiation in the field of molecular spintronics. Herein, we present a ligandbridged layer {[pzTpFe(CN) (3)](4)Co-2(Bib)4}center dot 3H(2)O (1; pzTp, tetra-kis(1-pyrazolyl)borate; Bib, 1,4-bis-(1Himidazol-1-yl)benzene) and a well-isolated double chain {[pzTpFe(CN)(3)](2)Co(Bpi)(2)}center dot CH3CN center dot 4H(2)O (2; Bpi, 1-Biphenyl-4-yl-1H-imidazole) that display reversible metal-to-metal charge transfer (MMCT) between (FeLS)-L-III(mu-CN)(CoHS)-H-II(mu-NC)Fe-III LS (LS, low spin; HS, high spin) and (FeLS)-L-III(mu-CN)(CoLS)-L-III(mu-NC)FeII LS linkages under alternating irradiation with 808 and 532 nm lasers. The bidirectional light irradiations induces significant changes in anisotropy and intrachain magnetic interactions, resulting in the on/off switching of SCM behavior with observable hysteresis loops by 808 and 532 nm light irradiations for both compounds. Because of the ligand modification, the SCM property of 2 with the monodentate ligand is greatly improved with a correlation length increased to 83, which is the largest correlation length among all reported light actuated SCMs. Furthermore, the influence of ligand modification on their thermally induced MMCT is also discussed. This study provides a rational approach for the swift and reversible control of SCM behavior via ligand modified and light induced MMCT, which is crucial to the future technological demand for high-density data storage and processing.