A newly synthesized photomagnet based on a cyanido-bridged Co-W assembly,[{Co(isoquinoline)_(4)}_(3){W(CN)_(8)}_(2)]·_(2)EtOH(CoWisoq),exhibits a controllable photoinduced(PI)phase with a metamagnetic behavior.Th...A newly synthesized photomagnet based on a cyanido-bridged Co-W assembly,[{Co(isoquinoline)_(4)}_(3){W(CN)_(8)}_(2)]·_(2)EtOH(CoWisoq),exhibits a controllable photoinduced(PI)phase with a metamagnetic behavior.The PI phase shows a transition from paramagnetic to ferromagnetic with a coercive field of 550 Oe at 2 K.It has a monoclinic(P21/n)crystal structure and is comprised of two-dimensional cyanido-bridged Co-W coordination layers with two crystallographically independent Co sites(Co1,Co2)and one W site.Both Co sites adopt a pseudo-octahedral six-coordinated geometry involving four isoquinoline and two cyanide ligands.π-πinteractions are induced at half of the isoquinoline ligands in Co1 and all of those in Co2 sites,suggesting that the coordination environment at the Co1 site has structural flexibility.CoWisoq displays a thermal phase transition around 140 K with a small thermal hysteresis due to the charge transfer-induced spin transition between Co^(Ⅱ)-W^(Ⅴ) of the high temperature(HT)phase and Co ^(Ⅲ)-W^(Ⅳ) of the low temperature(LT)phase.This charge transfer,which is also responsible for a drastic color change between purple(HT)and yellow(LT),involves only the structurally flexible Co1 sites.The ligand field,which is composed of four isoquinoline and two cyanide ligands,contributes to a unique metal-to-metal charge transfer absorption band of the LT phase at 1025 nm.Irradiation of the LT phase with near-infrared light produces a PI phase with the CoII-WV state.展开更多
基金supported in part by a Grant-in-Aid for Scientific Research(A)from JSPS KAKENHI(Grant Number 20H00369)Advanced Technologies for Carbon-Neutral(ALCA)-Next from JST(JPMJAN23A2)+2 种基金CNRS-University of Tokyo“Excellence Science”Joint Research Program,Second CNRS–University of Tokyo PhD Joint Program.The Cryogenic Research Center,The University of Tokyo,the Center for Nano Lithography&Analysis,The University of Tokyo,Quantum Leap Flagship Program(Q-LEAP,Grant Number JPMXS0118068681)by MEXT is also acknowledged for supportKazuki Nakamura was supported by the World-Leading Innovative Graduate Study Program for Materials Research,Information,and Technology(MERIT-WINGS)the Fellowship for Integrated Materials Science and Career Development.Koji Nakabayashi acknowledges the Iketani Science and Technology Foundation(Grant Number 0351111-A).
文摘A newly synthesized photomagnet based on a cyanido-bridged Co-W assembly,[{Co(isoquinoline)_(4)}_(3){W(CN)_(8)}_(2)]·_(2)EtOH(CoWisoq),exhibits a controllable photoinduced(PI)phase with a metamagnetic behavior.The PI phase shows a transition from paramagnetic to ferromagnetic with a coercive field of 550 Oe at 2 K.It has a monoclinic(P21/n)crystal structure and is comprised of two-dimensional cyanido-bridged Co-W coordination layers with two crystallographically independent Co sites(Co1,Co2)and one W site.Both Co sites adopt a pseudo-octahedral six-coordinated geometry involving four isoquinoline and two cyanide ligands.π-πinteractions are induced at half of the isoquinoline ligands in Co1 and all of those in Co2 sites,suggesting that the coordination environment at the Co1 site has structural flexibility.CoWisoq displays a thermal phase transition around 140 K with a small thermal hysteresis due to the charge transfer-induced spin transition between Co^(Ⅱ)-W^(Ⅴ) of the high temperature(HT)phase and Co ^(Ⅲ)-W^(Ⅳ) of the low temperature(LT)phase.This charge transfer,which is also responsible for a drastic color change between purple(HT)and yellow(LT),involves only the structurally flexible Co1 sites.The ligand field,which is composed of four isoquinoline and two cyanide ligands,contributes to a unique metal-to-metal charge transfer absorption band of the LT phase at 1025 nm.Irradiation of the LT phase with near-infrared light produces a PI phase with the CoII-WV state.
