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Achieving high-performance circularly polarized organic room temperature phosphorescence (CPRTP) holds significant academic and industrial importance. Herein, a series of near-infrared, color-tunable, and long-lived CPRTP materials have been successfully constructed by doping achiral luminescent guests into chiral crystallizable hosts. Naphthalimide derivatives are chosen as the guest molecules owing to the large conjugation and good structure tunability. (−)-Di-p-toluoyl- L - and (+)-di-p-toluoyl- D -tartaric acid are selected as the host molecules on account of the outstanding chirality and crystallinity. Through doping naphthalimide into tartaric acid derivatives, the resultant materials show the desirable CPRTP with a luminescence dissymmetry factor equal to 1.14 × 10−2. The host stabilizes and protects triplet excitons generated from the guest and induces the chirality of phosphorescence. Impressively, the doping material is emissive in the near-infrared region of 720 nm, which has hardly been achieved before. By modifying the chemical structure of the guest, the phosphorescent color of doping materials can be well-modulated from green to yellow and red. Moreover, the doping material displays a lifetime of up to 2.14 s. It is highly anticipated that this work will provide a new design strategy for high-performance CPRTP materials. [ABSTRACT FROM AUTHOR]

A general approach to constructing room temperature phosphorescence (RTP) materials involves the incorporation of a phosphorescent emitter into a rigid host or polymers with high glass transition temperature. However, these materials often suffer from poor processability and suboptimal mechanical properties, limiting their practical applications. In this work, we developed benzothiadiazole‐based dialkene (BTD‐HEA), a multifunctional phosphorescent emitter with a remarkable yield of intersystem crossing (ΦISC, 99.83 %). Its high triplet exciton generation ability and dialkene structure enable BTD‐HEA to act as a photoinitiator and crosslinker, efficiently initiating the polymerization of various monomers within 120 seconds. A range of flexible phosphorescence gels, including hydrogels, organogels, ionogels, and aerogels were fabricated, which exhibit outstanding stretchability and recoverability. Furthermore, the unique fluorescent‐phosphorescent colorimetric properties of the gels provide a more sensitive method for the visual determination of the polymerization process. Notably, the phosphorescent emission intensity of the hydrogel can be increased by the formation of ice, allowing for the precise detection of hydrogel freezing. The versatility of this emitter paves the way for fabricating various flexible phosphorescence gels with diverse morphologies using microfluidics, film‐shearing, roll coating process, and two/three‐dimensional printing, showcasing its potential applications in the fields of bioimaging and bioengineering. [ABSTRACT FROM AUTHOR]

Organic near‐infrared room temperature phosphorescence (RTP) materials offer remarkable advantages in bioimaging due to their characteristic time scales and background noise elimination. However, developing near‐infrared RTP materials for deep tissue imaging still faces challenges since the small band gap may increase the non‐radiative decay, resulting in weak emission and short phosphorescence lifetime. In this study, fused‐ring pyrrole‐based structures were employed as the guest molecules for the construction of long wavelength emissive RTP materials. Compared to the decrease of the singlet energy level, the triplet energy level showed a more effectively decrease with the increase of the conjugation of the substituent groups. Moreover, the sufficient conjugation of fused ring structures in the guest molecule suppresses the non‐radiative decay of triplet excitons. Therefore, a near‐infrared RTP material (764 nm) was achieved for deep penetration bioimaging. Tumor cell membrane is used to coat RTP nanoparticles (NPs) to avoid decreasing the RTP performance compared to traditional coating by amphiphilic surfactants. RTP NPs with tumor‐targeting properties show favorable phosphorescent properties, superior stability, and excellent biocompatibility. These NPs are applied for time‐resolved luminescence imaging to eliminate background interference with excellent tissue penetration. This study provides a practical solution to prepare long‐wavelength and long‐lifetime organic RTP materials and their applications in bioimaging. [ABSTRACT FROM AUTHOR]

Comprehensive Summary: Organic room‐temperature phosphorescence (RTP) materials have attracted immense attention in bioimaging due to their long emission lifetime and large Stokes shift. RTP materials with long emission wavelength can improve the penetration depth for bioimaging. However, the design of red persistent RTP materials is still challenging. In this study, a fused‐ring structure has been proposed to effectively decrease the triplet energy level, thus extending the emission wavelength of phosphorescence. In addition, the fused‐ring structure exhibits a high molar extinction coefficient (ɛ) and high luminescence efficiency due to the rigid structure. A new class of crystalline hosts (iminodibenzyl, IDB) are developed to stabilize the triplet excitons that are generated from the fused‐ring molecules. The maximum RTP wavelength of doping materials can reach 635 nm with a lifetime of 9.35 ms. Water‐disperse nanoparticles are successfully prepared for in vivo time‐resolved bioimaging, which eliminates the background fluorescence interference from biological tissues. These reveal a delicate design strategy for the construction of long‐wavelength emissive RTP materials for high‐resolution bioimaging. [ABSTRACT FROM AUTHOR]

A series of nine 2,3,4,5‐tetraphenyl pyrrole derivatives presenting benzonitrile substitution at different positions was designed and synthesized for this work. Their structure–emission property relationships were investigated in depth through a joint advanced experimental and computational effort. Our ultrafast and non‐linear spectroscopic results showed more efficient intramolecular charge transfer and enhanced two‐photon absorption cross sections when the benzonitrile substitution is at position 3 of the central pyrrole. On the other hand, an intriguing dual‐state emission behaviour was found to be activated by substitution at position 2, with exceptionally large photoluminescence quantum yields exhibited both in solution and in the solid state. Indeed, the quantum chemical simulations revealed for the derivatives functionalized at position 2 that the distorted geometry of the benzonitrile substituent with respect to the phenyl ring prevents emission quenching in the aggregate species by π‐π stacking interactions. Our findings shed new light on optimized design strategies of highly emitting materials for efficient optoelectronic devices. [ABSTRACT FROM AUTHOR]

The host–guest doping strategy has become one of the most effective approaches to realize pure organic room temperature phosphorescence (RTP). Crystalline small molecules can provide a rigid environment that restricts the molecular motion of luminescent guests, thus enhancing phosphorescence emission. Triphenylamine (TPA) is a classic crystalline small molecule matrix that, when doped with designed guest molecules, enables tunable RTP properties and diverse functionalities. These properties afford TPA‐based doping systems with numerous applications in anticounterfeiting, bio‐imaging, and multiple responsive sensing. In this concept, design strategies, luminescence mechanisms, and applications of TPA‐based host‐guest doping systems are summarized. Moreover, the future prospects of TPA‐based RTP materials are proposed. [ABSTRACT FROM AUTHOR]

Dynamically tunable room‐temperature phosphorescence (RTP) organic materials have attracted considerable attention in recent years due to their great potential over a wide variety of advanced applications. However, the precise regulation of the intersystem crossing (ISC) process for efficient RTP materials with dynamically modulated properties in a rigid environment is challenging. Herein, an effective strategy for RTP material preparation with controllably regulated properties is developed via the construction of dynamic metal‐ligand coordination in a host‐guest doped system. The coordination interaction promotes ISC and phosphorescence emission of the guest, thus allowing the modulation of the photophysical properties of doped materials by changing the doping ratio and Zn2+ counterions. By taking advantage of the reversible metal‐ligand coordination interaction, the coordination‐activated, and dissociation‐deactivated RTP is dynamically manipulated. With the unique Zn2+‐responsible RTP enhancement materials, the anti‐counterfeiting applications of thermal development, and color inversion have been constructed for inkjet printing of high‐resolution patterns with high reversibility for many write/erase cycles. The results show that dynamic metal‐ligand coordination strategy is a promising approach for achieving efficient RTP materials with controllably modulated properties. [ABSTRACT FROM AUTHOR]