Organic Supramolecular Zippers with Ultralong Organic Phosphorescence by a Dexter Energy Transfer Mechanism

A novel ratiometric fluorescent probe for the detection of co-existing Fe3+ and Ag+ ions: characterization and mechanism exploration

A novel white-light-emitting Ln-MOF composite, g-C3N4@TbEu(cpioa), was developed as a ratiometric fluorescent probe for the qualitative and quantitative analysis of metal ions. Among the tested ions, only Fe3+ and Ag+ exhibited distinct quenching behaviors. Mechanistic studies revealed that Fe3+ and Ag+ quench luminescence via dynamic and static processes, respectively, involving energy competitive absorption (ECA), photoinduced electron transfer (PET), Förster resonance energy transfer (FRET), and intramolecular weak interactions. The probe demonstrated high sensitivity with limits of detection (LODs) of 0.117 μM for Fe3+ and 0.383 μM for Ag+. Notably, the observable chromaticity variations enabled differentiation of co-existing Fe3+ and Ag+ in solutions-a pioneering achievement. Empirical equations derived from orthogonal experiments and multiple regression analysis validated the probe's capability for dual-ion detection. This work pioneers the application of Ln-MOF-based probes in analyzing mixed analytes, offering significant potential for environmental monitoring, clinical diagnostics, and industrial applications.

Frontier in Advanced Luminescent Biomass Nanocomposites for Surface Anticounterfeiting

Biomass-based luminescent nanocomposites have garnered significant attention due to their renewable, biocompatible, and environmentally sustainable characteristics for ensuring information encryption and security. Nanomaterials are central to this development, as their high surface area, tunable optical properties, and nanoscale structural advantages enable enhanced luminescent efficiency, stability, and adaptability in diverse conditions. This review delves into the principles of luminescence, focusing on the inherent bioluminescent properties of natural materials, the utilization of biomass as precursors for carbon dots (CDs) and aggregation-induced emission (AIE)-enhanced substances, and the structural and functional optimization of luminescent materials. The role of cellulose nanocrystals (CNC), lignin, and chitosan as key biomass-derived nanomaterials will be highlighted, alongside surface and interfacial engineering strategies that further improve material performance. Recent advancements in the synthesis of biomass carbon dots and their integration into luminescent anticounterfeiting systems are discussed in detail. Furthermore, the integration of advanced artificial intelligence (AI) technologies is explored, emphasizing their potential to revolutionize luminescent anticounterfeiting. Current challenges, including scalability, waste minimization, and performance optimization, are critically examined. Finally, the review outlines future research directions, including the application of AI-driven methodologies and the exploration of unconventional luminescent biomass materials, to accelerate the development of high-performance, eco-friendly anticounterfeiting solutions.

Lone Pairs-Mediated Multiple Through-Space Interactions for Efficient Room-Temperature Phosphorescence

The simultaneous generation and stabilization of triplet excitons are the key to realizing efficient organic room temperature phosphorescence (RTP), which is challenging owing to the obscure mechanism and structure-property relationships. Herein, a strategy of lone-pair-mediated multiple through-space interactions (TSIs) is proposed to availably induce RTP. By incorporating heteroatoms to facilitate through-space n-n and n-π interactions, the lone pairs are delocalized throughout the structure, resulting in the dense splitting of the excited-state energy levels. Thus, more matched energy levels with a small energy gap between singlet and triplet states (ΔEST) emerge, resulting in multiple intersystem crossing (ISC) transition channels that assist triplet excitons generation. The strong TSIs also effectively rigidify the molecular structures and thus stabilize triplet excitons for radiation. Furthermore, the manipulation of TSI intensity allows efficiency enhancement, persistent time prolongation, and tolerance to high temperatures of RTP. This work not only explores the fundamental principle of the RTP mechanism from a new view but also provides a universal strategy for ISC promotion and triple excitons stabilization.

Triggering anti-Kasha organic room temperature phosphorescence of clusteroluminescent materials

Clusterization-triggered emission (CTE) from organic materials without π-conjugated structures for room temperature phosphorescence (RTP) is fascinating with extraordinary photophysical properties and diversified applications, but rather challenging in material design owing to the limited mechanism understanding. Here, we demonstrate a facile strategy to construct CTE polymers with stimuli-responsive emission, anti-Kasha RTP and organic ultralong RTP (OURTP) by introducing ions into the hydrolyzed nonconjugated maleic anhydride and acrylamide copolymers. Thanks to the synergistic effects of hydrogen and ionic bonding with the ion-triggered electrostatic and coordinate interactions to suppress non-radiative decays and promote intersystem crossing, the amorphous copolymers show efficient photoluminescence with quantum efficiencies up to 13.5%, anti-Kasha RTP blue-shift of 29 nm, and OURTP lifetime up to 420 ms. Moreover, the temperature-dependent and water-sensitive anti-Kasha RTP and OURTP are also observed due to the formation of highly emissive CTE structure regulated by ionization. With the excellent processability and flexibility of the copolymer, lifetime-, temperature- and color-encrypted information anti-counterfeiting is designed and explored. The anti-Kasha RTP in CTE materials realized for the first time demonstrates impressive potential for multi-level encryption/anti-counterfeiting applications and more importantly, providing fundamental mechanism understanding for the rational modulation and design of CTE materials with extraordinary photophysical properties.

Achieving Tunable Monomeric TADF and Aggregated RTP via Molecular Stacking

Organic emitters with both thermally activated delayed fluorescence (TADF) and room-temperature phosphorescence (RTP) have attracted widespread interest for their intriguing luminescent properties. Herein, a series of triphenylamine-substituted isoquinoline derivatives possessing monomeric TADF and aggregated RTP properties are reported. As the molecules exhibited various forms of π-π and charge transfer (CT) stacking with different intensities, inter/intramolecular CT can be meticulously modulated to achieve tunable TADF-RTP. Aggregated phosphorescence originates from intermolecular CT initiated by CT dimers, whereas monomeric TADF is facilitated by intramolecular CT enhanced by π-π dimers. Leveraging the properties of these molecules, luminescent materials with tunable TADF-RTP properties in multistates are obtained by molecular substitution position alignment, dealing with different solvents, grinding, adjusting concentration, changing polymer matrix, photoactivation, and heat treatment. This work is critical for a deeper understanding of construction and regulation of the TADF-RTP dual-channel emission, enabling the development of advanced optoelectronic devices with tailored emission properties.

Enhancing Purely Organic Room Temperature Phosphorescence via Supramolecular Self-Assembly

Long-lived and highly efficient room temperature phosphorescence (RTP) materials are in high demand for practical applications in lighting and display, security signboards, and anti-counterfeiting. Achieving RTP in aqueous solutions, near-infrared (NIR) phosphorescence emission, and NIR-excited RTP are crucial for applications in bio-imaging, but these goals pose significant challenges. Supramolecular self-assembly provides an effective strategy to address the above problems. This review focuses on the recent advances in the enhancement of RTP via supramolecular self-assembly, covering four key aspects: small molecular self-assembly, cocrystals, the self-assembly of macrocyclic hosts and guests, and multi-stage supramolecular self-assembly. This review not only highlights progress in these areas but also underscores the prominent challenges associated with developing supramolecular RTP materials. The resulting strategies for the development of high-performance supramolecular RTP materials are discussed, aiming to satisfy the practical applications of RTP materials in biomedical science.

Long lifetimes white afterglow in slightly crosslinked polymer systems

Intrinsic polymer room-temperature phosphorescence (IPRTP) materials have attracted considerable attention for application in flexible electronics, information encryption, lighting displays, and other fields due to their excellent processabilities and luminescence properties. However, achieving multicolor long-lived luminescence, particularly white afterglow, in undoped polymers is challenging. Herein, we propose a strategy of covalently coupling different conjugated chromophores with poly(acrylic acid (AA)-AA-N-succinimide ester) (PAA-NHS) by a simple and rapid one-pot reaction to obtain pure polymers with long-lived RTPs of various colors. Among these polymers, the highest phosphorescence quantum yield of PAPHE reaches 14.7%. Furthermore, the afterglow colors of polymers can be modulated from blue to red by introducing three chromophores into them. Importantly, the acquired polymer TPAP-514 exhibits a white afterglow at room temperature with the chromaticity coordinates (0.33, 0.33) when the ratio of chromophores reaches a suitable value owing to the three-primary-color mechanism. Systematic studies prove that the emission comes from the superposition of different triplet excited states of the three components. Moreover, the potential applications of the obtained polymers in light-emitting diodes and dynamic anti-counterfeiting are explored. The proposed strategy provides a new idea for constructing intrinsic polymers with diverse white-light emission RTPs.

Eu3+-Doped Anionic Zinc-Based Organic Framework Ratio Fluorescence Sensing Platform: Supersensitive Visual Identification of Prescription Drugs

Advanced techniques for both environmental and biological prescription drug monitoring are of ongoing interest. In this work, a fluorescent sensor based on an Eu3+-doped anionic zinc-based metal-organic framework (Eu3+@Zn-MOF) was constructed for rapid visual analysis of the prescription drug molecule demecycline (DEM), achieving both high sensitivity and selectivity. The ligand 2-amino-[1,1'-biphenyl]-4,4'-dicarboxylic acid (bpdc-NH2) not only provides stable cyan fluorescence (467 nm) for the framework through intramolecular charge transfer of bpdc-NH2 infinitesimal disturbanced by Zn2+ but also chelates Eu3+, resulting in red (617 nm) fluorescence. Through the synergy of photoinduced electron transfer and the antenna effect, a bidirectional response to DEM is achieved, enabling concentration quantification. The Eu3+@Zn-MOF platform exhibits a wide linear range (0.25-2.5 μM) to DEM and a detection limit (LOD) of 10.9 nM. Further, we integrated the DEM sensing platform into a paper-based system and utilized a smartphone for the visual detection of DEM in water samples and milk products, demonstrating the potential for large-scale, low-cost utilization of the technology.

Management of triplet excitons transition: fine regulation of Förster and dexter energy transfer simultaneously

Understanding and management of triplet excitons transition in the same molecule remain a great challenge. Hence, for the first time, by host engineering, manageable transitions of triplet excitons in a naphthalimide derivative NDOH were achieved, and monitored through the intensity ratio (ITADF/IRTP) between thermally activated delayed fluorescence (TADF) and room-temperature phosphorescence (RTP). Energy differences between lowest triplet excited states of host and guest were changed from 0.03 to 0.17 eV, and ITADF/IRTP of NDOH decreased by 200 times, thus red shifting the afterglow color. It was proposed that shorter conjugation length led to larger band gaps of host materials, thus contributing to efficient Dexter and inefficient Förster energy transfer. Interestingly, no transition to singlet state and only strongest RTP with quantum yield of 13.9% could be observed, when PBNC with loosest stacking and largest band gap acted as host. This work provides novel insight for the management and prediction of triplet exciton transitions and the development of smart afterglow materials.

Aromatic Hydrocarbon Based and Space Interactions Induced Color-tunable Single-component Organic Phosphorescence

Construction of new system and exploration of new approach are of great importance for the improvement of their photophysical properties to meet the growing various uses of phosphorescent materials. Triphenylmethane (TPM), composed only of carbon and hydrogen, exhibits excellent color tunable phosphorescence in air, with ultralong lifetime (836 ms), and wide color-tunable range (from cyan to green, then to yellow and finally to orange, 525 nm-616 nm). Through careful comparison with the single crystal diffraction structure of tetraphenylmethane (TTPM) and theoretical calculation analysis, we believe that various clusters formed through space interactions are crucial for color-tunable phosphorescence.

Phosphorescence resonance energy transfer from purely organic supramolecular assembly

Phosphorescence energy transfer systems have been applied in encryption, biomedical imaging and chemical sensing. These systems exhibit ultra-large Stokes shifts, high quantum yields and are colour-tuneable with long-wavelength afterglow fluorescence (particularly in the near-infrared) under ambient conditions. This review discusses triplet-to-singlet PRET or triplet-to-singlet-to-singlet cascaded PRET systems based on macrocyclic or assembly-confined purely organic phosphorescence introducing the critical toles of supramolecular noncovalent interactions in the process. These interactions promote intersystem crossing, restricting the motion of phosphors, minimizing non-radiative decay and organizing donor-acceptor pairs in close proximity. We discuss the applications of these systems and focus on the challenges ahead in facilitating their further development.

The Effect of Molecular Conformations and Simulated "Self-Doping" in Phenothiazine Derivatives on Room-Temperature Phosphorescence

The research of purely organic room-temperature phosphorescence (RTP) materials has drawn great attention for their wide potential applications. Besides single-component and host-guest doping systems, the self-doping with same molecule but different conformations in one state is also a possible way to construct RTP materials, regardless of its rare investigation. In this work, twenty-four phenothiazine derivatives with two distinct molecular conformations were designed and their RTP behaviors in different states were systematically studied, with the aim to deeply understand the self-doping effect on the corresponding RTP property. While the phenothiazine derivatives with quasi-axial (ax) conformation presented better RTP performance in aggregated state, the quasi-equatorial (eq) ones were better in isolated state. Accordingly, the much promoted RTP performance was achieved in the stimulated self-doping state with ax-conformer as host and eq-one as guest, demonstrating the significant influence of self-doping on RTP effect.