Color-tunable ultralong room temperature phosphorescence from EDTA.

Unexpected color-tunable ultralong room-temperature phosphorescence (RTP, τ ∼0.5 s) was observed from EDTA (and also EDTA salts, chelates, and structural analogues). Through both experimental and theoretical investigations, the through-space conjugation of the lone pair n electrons of N/O atoms in EDTA was identified as the origin of RTP. The results here will be important for further developing phosphors with ultralong emission lifetime.