TADF and X-ray Radioluminescence of New Cu(I) Halide Complexes: Different Halide Effects on These Processes

• Published in: International journal of molecular sciences 2023-03, Vol.24 (6), p.5145
• Main Authors: Artem'ev, Alexander V, Baranov, Andrey Yu, Berezin, Alexey S, Stass, Dmitry V, Hettstedt, Christina, Kuzmina, Ul'yana A, Karaghiosoff, Konstantin, Bagryanskaya, Irina Yu
• Format: Article
• Language: English
• Subjects: Cu(I) complexes; Emitters; Fluorescence; halide effect; Inorganic Chemicals; Ligands; Oxides; phosphorescence; Quantum efficiency; Radiography; thermally activated delayed fluorescence; X ray irradiation; X-ray radioluminescence; X-Rays
• ISSN: 1422-0067; 1661-6596; 1422-0067
• DOI: 10.3390/ijms24065145

A series of complexes [Cu X (Pic PO) ] (X = Cl, Br, I) based on tris(pyridin-2-ylmethyl)phosphine oxide (Pic PO) has been synthesized. At 298 K, these compounds exhibit thermally activated delayed fluorescence (TADF) of (M+X)LCT type with λ varying from 485 to 545 nm, and quantum efficiency up to 54%. In the TADF process, the halide effect appears as the emission intensification and bathochromic shift of λ in the following order X = I < Br < Cl. Upon X-ray irradiation, the title compounds emit radioluminescence, the emission bands of which have the same shape as those at TADF, thereby meaning a similar radiative excited state. By contrast to TADF, the halide effect in the radioluminescence is reversed: its intensity grows in the order X = Cl < Br < I, since heavier atoms absorb X-rays more efficiently. These findings essentially contribute to our knowledge about the halide effect in the photo- and radioluminescent Cu(I) halide emitters.