Solid-state phosphorescence-to-fluorescence switching in a cyclometalated Ir(III) complex containing an acid-labile chromophoric ancillary ligand: implication for multimodal security printing.
In this study, we have demonstrated the reconstruction of encrypted information by employing photoluminescence spectra and lifetimes of a phosphorescent Ir(III) complex (IrHBT). IrHBT was constructed on the basis of a heteroleptic structure comprising a fluorescent N^O ancillary ligand. From the viewpoint of information security, the transformation of the Ir(III) complex between phosphorescent and fluorescent states can be encoded with chemical/photoirradiation methods. Thin polymer films (poly(methylmethacrylate), PMMA) doped with IrHBT display long-lived emission typical of phosphorescence (λ(max) = 586 nm, τ(obs) = 2.90 μs). Meanwhile, exposure to HCl vapor switches the emission to fluorescence (λ(max) = 514 nm, τ(obs) = 1.53 ns) with drastic changes in both the photoluminescence color and lifetime. Security printing on paper impregnated with IrHBT or on a PMMA film containing IrHBT and photoacid generator (triphenylsulfonium triflate) enables the bimodal readout of photoluminescence color and lifetime.
Center for Supramolecular Optoelectronic Materials, WCU Hybrid Materials Program, Department of Materials Science and Engineering, Seoul National University, Korea.
Dong Ryeol
DR
Whang
Youngmin
Y
You
Weon-Sik
WS
Chae
Jeongyun
J
Heo
Sehoon
S
Kim
Soo Young
SY
Park
D005453:Fluorescence; D006851:Hydrochloric Acid / Q000737:chemistry*; D007495:Iridium / Q000737:chemistry*; D008024:Ligands; D008163:Luminescent Measurements; D015394:Molecular Structure; D009942:Organometallic Compounds / Q000138:chemical synthesis / Q000737:chemistry*; D019904:Polymethyl Methacrylate / Q000737:chemistry; D011327:Printing / Q000379:methods*; D012637:Security Measures; D013499:Surface Properties
D008024:Ligands; D009942:Organometallic Compounds; D007495:Iridium; D019904:Polymethyl Methacrylate; D006851:Hydrochloric Acid