近日，陕西师范大学苗荣团队实现了颠覆罗丹明范式：280纳米斯托克斯位移的闭式荧光驱动可塑圆周性。相关论文于2025年9月10日发表在《德国应用化学》杂志上。

罗丹明衍生物具有反开闭形式的荧光行为，重新定义了传统的光化学范式，同时阐明了新的结构-性质关系和迷人的应用潜力。

研究组报告了一种供体-受体工程策略，该策略激活罗丹明的闭合形式发射，实现了前所未有的斯托克斯位移（>280 nm），同时克服了聚集-管状淬火。通过吲哚（给体）取代N，N-二乙基和螺内酰胺转化为苯磺酰胺（受体），得到了具有反开合形式发射行为的新一类罗丹明。单晶x射线衍射证实了封闭结构，吲哚取代后分子内空间位阻增加，避免了激子耦合，在固态下产生明亮的荧光（绝对量子产率>；25%）。

密度泛函理论计算证实了合成的染料相对于罗丹明B具有反分子内电荷转移（ICT）特性，其中中等ICT具有较高的荧光，而强ICT猝灭荧光。利用新型罗丹明独特的光物理性质，研究组提出了一种闭环塑料回收方案，将封闭状态下的染料进行荧光示踪，将标记的不可回收塑料在酸处理（开状态）后用作加密油墨。这一发现为罗丹明染料的工程荧光研究提供了新的思路，有助于提高塑料的可持续性。

附：英文原文

Title: Inverting the Rhodamine Paradigm: Closed-Form Fluorescence with 280 nm Stokes Shift Drives Plastic Circularity

Author: Qiuping Wang, Yalei Ma, Yutong Shang, Taihong Liu, Xiaoyan Liu, Jing Liu, Liping Ding, Rong Miao, Yu Fang

Issue&Volume: 2025-09-10

Abstract: Rhodamine derivatives exhibiting inverted open-closed form fluorescence behavior redefines conventional photochemical paradigms while illuminating new structure–property relationships and fascinating application potentials. Herein, we report a donor–acceptor engineering strategy that activates closed form emission in rhodamines, achieving unprecedented Stokes shifts (>280 nm) while overcoming aggregation-caused quenching. The new class of rhodamines with inverted open-close form emission behavior are created through simultaneous substitution of N,N-diethyl groups with indole (donor) and conversion of spiro-lactam to benzene sulfonamide (acceptor). The closed structure was verified by single crystal X-ray diffraction and the intramolecular spatial steric hinderance increased after indole substitution, which avoids exciton coupling and leads to bright fluorescence in solid state (absolute quantum yield>25%). Density functional theory calculations confirmed inverted intramolecular charge-transfer (ICT) characteristics of the synthesized dyes versus rhodamine B, where moderate ICT gives higher fluorescence and strong ICT quenches fluorescence. Leveraging the unique photophysical properties of the novel rhodamines, a closed-loop plastic recycling scheme is proposed, where the dye in closed state is used for fluorescence tracing and the labelled unrecyclable plastics are utilized as encryption ink after acid treatment (open state). This finding highlighted a new insight for engineering fluorescence of rhodamine dyes and contributes to plastics sustainability.

DOI: 10.1002/anie.202514295

Source: https://onlinelibrary.wiley.com/doi/10.1002/anie.202514295