In To explore the correlation between SCO and luminescence, PL studies were performed on the free L19 ligand and 25 in the temperature span of 120 -300 K (Fig. ). At room temperature, the free L19 ligand exhibited a strong emission peak situated at around 462 nm while excitation at 365 nm, while a similar emission peak with lower intensity (λem = 460 nm) was noticed for 25, confirming the retention of emission properties of L19 ligand after coordination with the Fe(II) center. Upon increasing temperature, relative intensity (I(T) -I(300K)) was increased with temperature to reach a maximum at around SCO temperature, i.e., 200 K (Fig. ), while a small monotonous decrease in the relative intensity due to thermal quenching was observed for free L19 ligand. The results clearly described a synergic tie-up between luminescence and SCO in 25.