Hakkarainen Eetu, Lin Hao-Cheng, Nechaev Anton A, Peshkov Vsevolod A, Eskelinen Toni, Chang Kai-Hsin, Liao Tzu-Hao, Chen Po-Yu, Koshevoy Igor O, Lin Hao-Wu, Chou Pi-Tai, Belyaev Andrey
Department of Chemistry and Sustainable Technology, University of Eastern Finland Yliopistokatu 7 80101 Joensuu Finland
Department of Materials Science and Engineering, National Tsing-Hua University 101, Sec. 2, Kuang-Fu Road Hsinchu 30013 Taiwan Republic of China
Chem Sci. 2025 Aug 15. doi: 10.1039/d5sc03813h.
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, = 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 ( ) reach up to 0.9-1.3 × 10 s 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, , atom-photon economy, represents a new twist in designing efficient and sustainable photofunctional molecular materials.
具有快速磷光速率且易于加工的无金属磷光发光体正成为先进光电子学领域颇具前景的材料。对一种改性维生素B6维生素原（吡哆醇）进行烷基化反应，可得到一系列吡啶鎓衍生的离子对1 - 7，它们在固态下表现出可变的阴离子-π相互作用。这种非共价阳离子-阴离子网络促进了晶体材料中源自阴离子（I）-π（吡啶鎓）电荷转移的可调室温磷光（RTP，λem = 510 - 565 nm）。系统的X射线结构和计算研究表明，阴离子（I）-π（吡啶鎓）距离在自旋-轨道耦合中起关键作用，从而导致了所观察到的RTP。对于所研究的具有RTP的吡啶鎓盐，辐射速率常数（kr）高达0.9 - 1.3×10⁵ s⁻¹，与许多贵金属发光体的辐射速率常数相当。离子对2实现了量子产率为93%的RTP，并在纯薄膜中成功证明是一种优异的X射线闪烁染料。在小型无金属可及分子中实现强RTP的策略，即原子-光子经济性，代表了设计高效且可持续的光功能分子材料的新方向。
