Variable temperature PL studies of 3-d in between 250 and 400 K showed that upon heating from 250 K, the PL intensity maxima of the max = 560 nm typical of rhodamine 6G (Iem) decreases to reach a minimum at 300 K for the thermal quenching effect. Further, with an increase in temperature, Iem showed an increase to attain a maximum value at 350 K, then Iem decreased upon increasing temperature up to 400 K. In contrast, the analogs Zn(II) complex (4) displayed a continuous decrease in emission intensity while increasing temperatures. Moreover, in cooling mode, a similar discontinuous nature in Iem was observed between 300 and 310 K, consistent with the SCO at 303 K (T1/2↓). Overall, all these results concluded that the luminescence emission of 3-d is affected by the SCO process, where the emission of 3-d can be quenched by the LS Fe(II) state (Fig. ).