Fig. 4: Photophysical studies.
From: Photoresponsive supramolecular coordination polyelectrolyte as smart anticounterfeiting inks
a Partial emission spectrum (black curve) of Eu3+-L, and absorption spectra of OF-1 (red curve) before and (blue curve) after irradiation with 300 nm UV light for 60 s. b, c Luminescence emission spectral changes of Eu3+-L-OF-1 upon (b) UV light (300 nm) irradiation and c subsequent visible light (>450 nm) irradiation in water. Insets show corresponding emission intensity changes at 615 nm. d Luminescence emission changes of Eu3+-L-OF-1 upon consecutive alternating exposure to UV and visible light. Insets show corresponding intensity changes at 615 nm (upper) and the photographs of the SCP solution under 254 nm UV lamp (lower). [Eu3+] = 1.4 × 10−4 M, [L] = [OF-1] = 2.1 × 10−4 M.
