Preparation of Pt nanoclusters with different emission wavelengths and their application in Co2+ detection.

Differently colored fluorescent Pt nanoclusters (NCs) are easily prepared using polyethyleneimine as the stabilizing ligand and environmentally friendly L-ascorbic acid as the reducing agent. The quantum yields of the blue- (1:5), green- (1:20), and yellow-emitting (1:25) NCs are 4 %, 11 %, and 7 %, respectively. The fluorescent Pt NCs show excellent photostability and are sensitive to Co(2+) ions (with a detection limit of 500 nM).