Metal-free pyridinium salts with strong room-temperature phosphorescence and microsecond radiative lifetime

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A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä

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en

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7

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Chemical Science, Volume 16, issue 37, pp. 17261-17267

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Easily processed metal-free phosphorescent luminophores with a fast rate of phosphorescence are emerging as promising materials for advanced optoelectronics. Alkylation of a modified vitamin B6 vitamer (pyridoxine) affords a family of pyridinium-derived ionic pairs 1-7 exhibiting variable anion-π interactions in the solid state. Such a noncovalent cation-anion network promotes tunable room-temperature phosphorescence (RTP, λem = 510-565 nm) in crystalline materials stemming from anion(I−)-π(pyridinium+) charge transfer. Systematic X-ray structural and computational studies manifest the key role of the anion(I−)-π(pyridinium+) distance in the spin-orbit coupling, hence the observed RTP. For the studied pyridinium salts with RTP, the radiative rate constants (kr) reach up to 0.9-1.3 × 105 s−1 which are competitive with those of many noble metal emitters. Ion pair 2 reached an RTP with a quantum yield of 93% and was successfully demonstrated as an excellent X-ray scintillating dye in neat films. The demonstrated strategy of attaining intense RTP in small metal-free accessible molecules, i.e., atom-photon economy, represents a new twist in designing efficient and sustainable photofunctional molecular materials.

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Publisher Copyright: © 2025 The Royal Society of Chemistry.

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Hakkarainen, E, Lin, H-C, Nechaev, A A, Peshkov, V A, Eskelinen, T, Chang, K-H, Liao, T-H, Chen, P-Y, Koshevoy, I O, Lin, H-W, Chou, P-T & Belyaev, A 2025, 'Metal-free pyridinium salts with strong room-temperature phosphorescence and microsecond radiative lifetime', Chemical Science, vol. 16, no. 37, pp. 17261-17267. https://doi.org/10.1039/d5sc03813h