ABSTRACT
Molecular materials possessing photo-tunable polarization switching is promising for optical switches, smart sensors, and data storage devices. However, it is challenging to devise a molecular material featuring simultaneous switchable magnetic and dielectric properties with regard to non-invasive and convenient light stimulus. Herein, we report a new Hofmann-type metal-organic framework (MOF) {Fe(bpt)[Pt(CN)4 ]} â 0.5anth (1, bpt=2,5-bis(4-pyridyl)thiophen; anth=anthracene), which displays thermo- and photo-switchable magnetic and dielectric properties. Photo-monitored structural analyses revealed that it was the photo-induced deformation of FeII coordination sphere and relative movement of guest anthracene that resulted in the variation of the local electric dipoles. These findings provide a new strategy to realize polarization switching through the light-induced spin crossover, and would be of fundamental significance for future photo-switchable and multifunctional materials.
ABSTRACT
Extended Goldschmidt tolerance factor t is applied to the hybrid double perovskites (MA)2 [B'B''(CN)6 ] (MA=methylammonium cation) to predict and screen dielectric transitions in 121 compounds through the correlations among t, the radius of the B component rB and the transition temperature Tc , based on experimental results from model compounds. For (MA)2 [B'Co(CN)6 ], it is concluded that: i)â when t>0.873, the cubic phase would be stable below 298â K; ii)â when 0.873>t>0.805, the cubic phase would be stable between 298 and 523â K; iii)â the larger the rB , the higher the Tc of the perovskite (Tc (1/2) ârB ); and iv)â the Tc of the hybrid perovskites can be well tuned by doping the B components.