The synergy between luminescence and SCO has been investigated for less than a decade. In 2017, Guo and co-workers described synergic behavior between Luminescence and SCO in a mononuclear iron(II) complex [Fe(L1)2](BF4)2 (1) (L1 = 2,6-bis(pyrazol-1-yl)pyridine; Scheme 1) , although the structural as well as magnetic properties of 1 were previously reported by Halcrow and co-workers (Fig. ) . Yellow crystal of 1 can be obtained from complexation of Fe(BF4)2•6H2O with ligand L1 in 1:2 ratio in acetone and successive slow diffusion of diethyl ether into the acetonitrile or nitromethane solution of the complex 1. Temperature-dependent single-crystal structure analyses were performed at different temperatures such as 290 and 240 K, which showed that upon lowering the temperature, the average Fe-N bond distance decreases by around 0.215 Å, suggesting the conversion between the HS to LS states in the Fe(II) complex.