[Au24Pt(PET)18] 0 (1). NC 1 was synthesized using a previously reported method with slight modifications. First, 4.80 mmol of HAuCl4 was dissolved in 10 mL of acetone, to which was added 10.6 mmol of PPh3 dissolved in acetone, and the resulting solution was stirred at 0 °C for 15 min and filtered. The solution was then washed with acetone and dried to give AuClPPh3. Resulting AuClPPh3 was dissolved in dichloromethane, to which AgNO3 was added, and the mixture was stirred in the dark for 1 h. The resulting product was purified to give Au(NO3)(PPh3). Next, Pt(PPh3)4 was dissolved in ethanol, refluxed under argon for 2 h, and washed to obtain Pt(PPh3)3. Au(NO3)(PPh3), synthesized earlier, was dissolved in THF and added to the solution, which was stirred under hydrogen for 3 h and allowed to stand for 6 h. The resulting product was quickly washed and dried under vacuum. The dried product was dissolved in dichloromethane, to which triethylamine and Au(NO3)(PPh3) were added, and the mixture was stirred overnight. The resulting product was dried using a rotary evaporator, dissolved in methanol, and crystallized by adding diethyl ether as a poor solvent. The resulting crystals were washed with diethyl ether and n-pentane and solidified to dryness to give [PtAu8(PPh3)8](NO3)2. Then, [PtAu8(PPh3)8](NO3)2 was dissolved in ethanol and 500 µL of 0.1 M NaBH4 ethanol solution. AuCl(S(CH 3 ) 2 ) was obtained by dissolving HAuCl 4 in methanol, to which was added dimethyl sulfide and 900 µmol of PETH in THF, and the mixture was stirred for 30 min. Next, 1.20 mmol of triethylamine dissolved in THF was added, and the mixture was stirred for 30 min. The product was washed and purified on an alumina column (dichloromethane:hexane = 1:1) to give NC 1 (Scheme S1).