Fig. 6.

UV–vis spectra of GdPc-thiof in toluene at 20 mg l⁻¹ upon addition of acetic acid (AcOH). 1: without AcOH; 2: addition of 5 μl AcOH, reaction time 5 min; 3: as 2, but after 30 min; 4: as 2, but after 1 h, 5: as 4—addition of 10 μl Et₃N