Modulation of luminescence intensity triggered by light input is demonstrated. The system consists of a Zn-porphyrin and an azopyridine derivative, which axially coordinates to Zn-porphyrin and quenches its fluorescence more efficiently in the trans-form than in the cis-form. Thus, light-induced isomerization of the azopyridine results in the increase/decrease of the porphyrin fluorescence.