Fluolab【Angew.Chem.】华东理工马骧、李大伟、陈斌斌|三个数量级！超两千倍光活化对比度，这种有机室温磷光材料“稳”如泰山
文章标题： Engineering Ultrahigh-Contrast Photoactivated Room-Temperature Phosphorescence With a Robust and Universal Ureido-Functionalized Siloxane Network
通讯作者： Bin Bin Chen, Da Wei Li, Xiang Ma
文章概要
引言
光活化室温磷光（pRTP）材料因其独特的非侵入性响应、高可逆性和颜色可调性，在信息加密、防伪及生物医药领域展现出巨大的潜力。然而，传统的高分子基质（如PVA、PMMA等）面临着严峻的性能瓶颈。首先，这些基质依赖于氧气的被动渗透，导致对发光分子的猝灭效率不足，难以实现完美的“初始关断”状态，从而限制了光活化后的对比度。其次，普通聚合物在水分渗透、有机溶剂侵蚀或强酸环境下极易失效，结构稳定性较差，极大地制约了其在复杂环境及液相场景中的应用。为了解决这些问题，华东理工大学马骧教授团队等合作者提出了一种全新的设计思路，开发出一种具有强主动捕氧能力的脲基功能化硅氧烷网络。这种基质不仅能够提供极高的光活化对比度，还表现出了令人惊叹的化学稳定性和环境耐受性。
Schematic illustration of an efficient pRTP system with ultrahigh photoactivation efficiency and exceptional stability, enabled by a ureido-functionalized siloxane network matrix.
主要实验及结论
研究团队通过简单的水解缩合工艺，利用γ-脲基丙基三乙氧基硅烷（UPTES） 构建了这种独特的宿主基质。该材料的核心优势在于其侧链上的脲基基团能够通过多位点主动捕获并富集氧气，这一特性经密度泛函理论（DFT）计算证实，其吸附能远高于传统的BA、PVA和PMMA基质。由于基质内部氧气浓度高，掺杂其中的磷光客体分子在初始状态下被彻底猝灭。而在302 nm紫外光照射下，捕获的氧气被迅速转化为单线态氧并消耗，从而触发极强的磷光发射。实验数据显示，这种体系实现了最高约2100倍的磷光强度提升，且磷光寿命可延长达65倍，这种高达三个数量级的增强效果是目前传统聚合物基质难以企及的。此外，该体系具有极佳的普适性，能够适配包括苯硼酸衍生物、芘及多种芳香族化合物在内的多种客体分子，覆盖了从蓝色到红色的全色谱发光。
The pRTP properties of the UPTES@PBADs. (a) Schematic of the synthesis route and reversible photoactivation behavior of UPTES@PBADs (i: UPTES@PCBBA, ii: UPTES@BBA, iii: UPTES@NPBA, iv: UPTES@PBA). (b) Phosphorescence photographs of the UPTES@PBADs before and after 302 nm UV photoactivation, corresponding to their respective equilibrium durations: 10 min for UPTES@PCBBA, 8 min for UPTES@BBA, 12 min for UPTES@NPBA, and 12 min for UPTES@PBA. (c) Maximum prompt and delayed PL spectra of the UPTES@PBADs, along with corresponding excitation spectra. Delay time: 2 ms. (d) Chromaticity coordinates of the UPTES@PBADs in the CIE 1931 color space. (e) Frontier molecular orbitals (LUMO and HOMO) of PCBBA, BBA, NPBA, and PBA. (f) Quantified phosphorescence intensity of UPTES@PBADs before and after photoactivation, corresponding to the images shown in (b). Error bars represent standard deviation (n = 10). (g) Phosphorescence lifetimes of UPTES@PBADs before and after photoactivation.
Mechanistic investigation of the pRTP effect in UPTES-based systems. (a) XRD patterns and (b) FT-IR spectra of UPTES@PBA before and after photoactivation. (c) 13C NMR spectra of UPTES@PBA before and after photoactivation, along with the heat UPTES sample. (d) Locally magnified 13C NMR spectra from (c). (e) Phosphorescence spectra of UPTES@PBA measured in a nitrogen atmosphere before and after photoactivation (insets: corresponding phosphorescence photographs). Delay time: 2 ms. (f) EPR spectra of UPTES@PBA before and after photoactivation, using 2,2,6,6-tetramethylpiperidine as a probe for 1O2 detection. (g) Phosphorescence photographs of BA@PBADs and PVA@PBADs (without photoactivation), and of PMMA@PBADs before and after 302 nm UV photoactivation. (h) Intensity values derived from the phosphorescence photographs in (g) for PMMA@PBADs (I: PMMA@PCBBA; II: PMMA@BBA; III: PMMA@NPBA; IV: PMMA@PBA). Error bars represent standard deviation (n = 10). (i) Phosphorescence spectra of APTES@NPBA measured in air before and after photoactivation (insets: corresponding phosphorescence photographs). Delay time: 2 ms. (j) Calculated ΔEAds between the ureido group and an oxygen molecule at three sites (1: oxygen-primary amine; 2: oxygen-carbonyl; 3: oxygen-secondary amine), obtained using the DMol3 module in Materials Studio. (k) Calculated Δ_E_Ads between common polymer matrices (BA, PVA, PMMA) and oxygen. (l) Schematic illustration of the proposed pRTP mechanism.
Universality of the UPTES matrix as a photoactive host. Phosphorescence spectra of (a) UPTES@PBzH, (b) UPTES@PBSA, (c) UPTES@ABP, (d) UPTES@BPBA, (e) UPTES@HBP, (f) UPTES@BPCA, and (g) UPTES@DPPBA, measured before and after photoactivation under 302 nm UV light (insets: corresponding phosphorescence photographs). Delay time: 2 ms. (h) Intensity values quantified from the phosphorescence photographs shown in (a–g). I: UPTES@PBzH, II: UPTES@PBSA, III: UPTES@ABP, IV: UPTES@BPBA, V: UPTES@HBP, VI: UPTES@BPCA, and VII: UPTES@DPPBA. (i) Phosphorescence lifetimes of these systems before and after photoactivation.
在稳定性测试中，UPTES基质展现了“坚不可摧”的一面。得益于其高度交联且致密的硅氧烷网络结构，该材料在水中浸泡、有机溶剂浸泡、甚至在浓盐酸中存放90天后，依然能够保持高效的光活化性能，且完全没有客体分子泄露。相比之下，传统的PMMA体系在有机溶剂中瞬间溶解或失效。这种超强的稳定性不仅保证了材料的长效使用，也为其在水相环境或严苛工业条件下的应用铺平了道路。基于这些优异特性，研究团队进一步开发了多级信息加密应用。通过将UPTES基质与非光活化材料组合，设计了复杂的二维码和图案加密系统。该系统利用光活化时间、延迟观察时间以及溶剂处理作为多重密钥，只有在特定光照时长和读取规则下才能获取真实信息，极大提升了防伪的安全等级。
Multi-level information encryption. (a) Design and workflow of an encrypted pattern: (I) Phosphorescence images captured after different photoactivation times under 302 nm UV irradiation; (II) fluorescence and phosphorescence images of the EtOH-treated pattern after 12 min of photoactivation; (III) phosphorescence images of the EtOH-treated pattern captured before and after photoactivation over three cycles of 302 nm UV irradiation. (b) Design of an encrypted QR code: (I) Decoding flowchart of the QR code; (II) material composition and binary code definition for each grid in the QR code; (III) pattern evolution of the QR code with increasing photoactivation time; (IV) decoding of the correct encrypted message ('SKY') by reading even-numbered grids; (V) phosphorescence images of the QR code after different photoactivation times (left) and after different delay times once photoactivated for 6 min (right).
总结及展望
这项研究成功报道了一种基于脲基功能化硅氧烷网络的通用型光活化平台，打破了光活化对比度与环境稳定性之间的矛盾。该基质凭借其主动“捕氧”的化学结构特性，实现了极高的光信号开关比，并凭借其稳固的无机-有机杂化网络提供了卓越的化学耐受力。这不仅为设计高性能智能发光材料提供了新的化学模型，也预示着pRTP材料将从实验室的干燥保存环境走向更广阔的实际应用场景，特别是在高端防伪、多级动态加密以及复杂环境下的光探测领域。未来，这种设计理念有望进一步拓展至其他刺激响应型材料体系，推动柔性光电器件的创新发展。