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Organic ultralong room-temperature phosphorescence (RTP) materials have promising applications in anti-counterfeiting. To improve the encryption level, the exploration of organic materials with tunable solid-state long persistent luminescence is in urgent need. Herein, a series of organic ultralong RTP polymeric systems are prepared by doping versatile indolocarbazole isomers into the poly(vinyl alcohol) (PVA) matrix. Notably, the doping film 11,12-ICz@PVA exhibits excellent RTP property with an ultralong lifetime of 2.04 s and a high phosphorescence quantum yield of 44.1%. Theoretical calculations reveal that this excellent RTP property can be attributed to the strong electrostatic attraction resulting from the synergistic double hydrogen-bond between the isomer 11,12-ICz and PVA matrix. More impressively, color-tunable and time-dependent long persistent luminescence is successfully achieved through efficient phosphorescence energy transfer between the indolocarbazole isomers with ultralong blue RTP emissions and commercially available fluorescent dyes with emission colors ranging from green to red doped into the PVA matrix. Besides, diversified encryption patterns are fabricated to demonstrate the promising applications of these water-soluble doping PVA systems with tunable solid-state persistent luminescence in advanced anti-counterfeiting technology. © 2022 Wiley-VCH GmbH.

Organic phosphors exhibiting room-temperature phosphorescence (RTP) in the amorphous phase are promising candidates for optoelectronic and biomedical applications. In particular, noncovalently embedding organic phosphors into a poly(vinyl alcohol) (PVA) matrix has emerged as the most commonly used yet effective approach to obtain amorphous organic RTP materials. While the role of intermolecular hydrogen-bonding interactions in determining the RTP properties of doping PVA systems has been well documented, we show that electrostatic and dispersion interactions contribute crucially to the ultralong RTP properties of doping PVA films. This impressive outcome reveals the nature of non-covalent interactions existing in doping PVA systems for the first time. We demonstrate this through detailed experimental and computational studies for a series of hydrogen-bond crosslinked PVA films where star-shaped organic phosphors containing active groups of carboxy, hydroxy, and amino act as multisite crosslinkers for the construction of extensive hydrogen-bonding networks. More importantly, we successfully obtain an ultralong RTP lifetime of up to 1.74 s by tuning the electrostatic and dispersion interactions between organic phosphors and the PVA matrix through simply modifying active groups of organic phosphors. This instructive work will provide new guiding principles for the exploration of amorphous organic RTP systems.

Organic emitters with multiple emissions such as aggregation-induced emission (AIE), thermally activated delayed fluorescence (TADF), room-temperature phosphorescence (RTP), and mechanoluminescence (ML) are promising candidates for various high-tech applications but are still very rare. Here, for the first time, an effective strategy of positional isomerism is applied to obtain simple organic isomers featuring diversified emissive behaviors of AIE, TADF, RTP, dual-RTP, and ML. In particular, AIE, TADF, and ML are successfully realized simultaneously in the ortho-isomer o-ClTPA while typical AIE and unique dual-RTP coexist in the para-isomer p-ClTPA. Crystal structure analysis shows that the subtle variation in the substitution position can significantly alter intermolecular interactions and molecular packings, which in turn exerts remarkable effects on the crystal-state emissive properties. Therefore, diversified emissive behaviors of TADF, RTP, dual-RTP, and ML are consequently observed from these positional isomers. Furthermore, theoretical calculations not only afford deep insight into the mechanism of different luminescence properties but also elaborate the relationship between positional isomers and luminescence properties from molecular and crystalline perspectives. These simple isomers featuring diversified emissive behaviors of AIE, TADF, RTP, dual-RTP, and ML are reported for the first time, which will deepen the understanding of the relationship between molecule structures and multiple emissions.

Photodynamic therapy (PDT) has long been recognized to be a promising approach for cancer treatment. However, the high oxygen dependency of conventional PDT dramatically impairs its overall therapeutic efficacy, especially in hypoxic solid tumors. Exploration of distinctive PDT strategy involving both high-performance less-oxygen-dependent photosensitizers (PSs) and prominent drug delivery system is an appealing yet significantly challenging task. Herein, a precise nuclear targeting PDT protocol based on type-I PSs with aggregation-induced emission (AIE) characteristics is fabricated for the first time. Of the two synthesized AIE PSs, TTFMN is demonstrated to exhibit superior AIE property and stronger type-I reactive oxygen species (ROS) generation efficiency owing to the introduction of tetraphenylethylene and smaller singlet–triplet energy gap, respectively. With the aid of a lysosomal acid-activated TAT-peptide-modified amphiphilic polymer poly(lactic acid)12k–poly(ethylene glycol)5k–succinic anhydride-modified TAT, the corresponding TTFMN-loaded nanoparticles accompanied with acid-triggered nuclear targeting peculiarity can quickly accumulate in the tumor site, effectively generate type-I ROS in the nuclear region and significantly suppress the tumor growth under white light irradiation with minimized systematic toxicity. This delicate “Good Steel Used in the Blade” tactic significantly maximizes the PDT efficacy and offers a conceptual while practical paradigm for optimized cancer treatment in further translational medicine. © 2021 The Authors. Advanced Science published by Wiley-VCH GmbH

Organic phosphors exhibiting room-temperature phosphorescence (RTP) in amorphous phase are good candidates for optoelectronic and biomedical applications. In this proof-of-concept work, a rational strategy to activate wide-color ranged and persistent RTP from amorphous films by embedding electron-rich organic phosphor into electron-deficient matrix polyacrylonitrile (PAN) is presented. Through tailoring noncovalent interactions between the electron-deficient PAN matrix and electron-rich organic phosphors, an ultralong lifetime of 968.1 ms is obtained for doped film TBB-6OMe@PAN. Control experiments conducted on the polymers polymethyl methacrylate (PMMA) and polystyrene (PS) without electron-withdrawing groups, and organic phosphors containing electron-withdrawing groups indicate that the persistent RTP of doped films may be triggered by strong electrostatic interactions between electron-deficient PAN and electron-rich organic phosphor. Further theoretical calculations including electrostatic potential distributions, binding energies, and energy decomposing analysis demonstrate that both electrostatic and dispersion interactions between electron-deficient PAN and electron-rich organic phosphor are responsible for the activation of persistent RTP of doped films. In addition, the doped film TBB-6OMe@PAN still maintains brightness even after soaking in water for 12 weeks. This excellent water resistance not only is favorable for future applications but also demonstrates an advantage of electrostatic and dispersion interactions over hydrogen bonding interactions. © 2021 Wiley-VCH GmbH