Phosphorescence Lifetime Research Articles

A biomimetic phosphor that can build a rigid microenvironment for its long-lived afterglow in aqueous medium.

Organic phosphorescent materials have great prospects for application, whose performance particularly depends on the preparation method. Inspired by nature's wisdom, we report a phosphor that can utilize monomers in its environment by polymerization to construct a rigid microenvironment under light illumination, leading to a glow-in-the-dark emulsion with a phosphorescence lifetime of 1 s in water. This phosphor can achieve active growth of the aqueous emulsion with the introduction of more monomers. In the presence of trace amounts of oxygen (which has adverse effects on both polymerization and afterglow), this phosphor can still undergo photo-induced polymerization, removing the influence of oxygen and obtaining afterglow emulsion, demonstrating its adaptability to the environment. This phosphor can also catalyze the polymerization of monomers containing yellow fluorophore, obtaining long-lifetime yellow afterglow emulsion through excited state energy transfer. We have also conducted in-depth studies on the photo-catalytic and phosphorescent properties of this phosphor in model systems. This biomimetic intelligent manufacturing provides a new approach for organic phosphorescent materials and is significant for future applications.

Cyclometalated N-Difluoromethylbenzimidazolylidene Platinum(II) Complexes with Built-in Secondary Coordination Spheres: Photophysical Properties and Bioimaging.

Bidentate Pt(II) complexes with cyclometalated N-heteroarene or N-heterocyclic carbene (NHC) ligands have been extensively studied as phosphorescent emitters over the past two decades. Herein, we introduce a difluoromethyl group (CF2H) into the wingtip of NHCs, where CF2H acts as a lipophilic hydrogen bond (HB) donor. Their cyclometalated Pt(II) complexes show excellent PLQYs (up to 93%) and phosphorescence lifetimes mainly due to the rigid structure with hydrogen bonding between the CF2H group and the adjacent O atom at the β-diketonate ligand. Bioimaging studies demonstrate high cellular uptake efficiency and deep tumor penetration capability of complex 7 in HeLa cells and multicellular tumor spheroids, highlighting their potential as bioimaging probes.

Photoinduced On and Off Polymeric Room Temperature Phosphorescence Based On Polycyclic Aromatic Hydrocarbon Isomers.

As family members of polycyclic aromatic hydrocarbons, compound anthracene (Ant) and phenanthrene (Phe) as isomers are widely used in organic optical materials and electronic materials. But their photochemical and physical properties are very different. In this work, the room temperature phosphorescence (RTP) properties of PVA-B-Ant and PVA-B-Phe are discussed carefully which are prepared by B-O click reaction through polyvinyl alcohol (PVA) with 9-anthraceneboronic acid (B-Ant) and 9-phenanthrenylboronic acid (B-Phe), respectively. PVA-B-Phe 1 % film exhibits excellent fluorescence (FL) emission at 374 nm and RTP emission at 523 nm with green afterglow and around 1.9 s phosphorescence lifetime. However, PVA-B-Ant 1 % film only shows strong blue FL emission at 414 nm, and the emission intensity decreases seriously with the extension of irradiation time. Experimental and theoretical calculations results suggest that the photodimer of Ant which is formed in PVA matrix under the UV light irradiation would be competitive with the process of RTP emission. This work demonstrates that the RTP properties of organic molecules might be probably affected by the photostability of the organic phosphor under UV irradiation.

Luminous Fish‐Inspired Hydrogels with Underwater Long‐Lived Room Temperature Phosphorescence

AbstractSome marine animals form long‐lived luminescence for predation, communication, camouflage, and anti‐predation. These marine animals demonstrate soft nature, sustainable glowing, and underwater emission, which are difficult to achieve in synthetic room temperature phosphorescence (RTP) materials. Inspired by these marine animals, here the study reports RTP hydrogels that show long‐lived phosphorescence (lifetime >500 ms and afterglow >10 s) in water. Exceptional underwater mechanical properties are simultaneously achieved, including tensile strength of 5.1 MPa, tensile strain of 452%, and toughness of 19.3 MJ m−3. The key to this achievement lies in the in situ phase separation microarchitecture formed between polyacrylamide (PAM) and its partial hydrolysates, which confines the motions of polymer chains and protects vulnerable triplet excitons from quenching of water. Such a strategy shows the merits of facile fabrication without laborious synthesis. In addition, these RTP hydrogels offer repeatable photoprinting and highly stability in water, providing a versatile platform for underwater applications of RTP materials, including information encryption and camouflage of marine animals.

Insertable Biomaterial-Based Multianalyte Barcode Sensor toward Continuous Monitoring of Glucose and Oxygen.

Chronic diseases, including diabetes, cardiovascular diseases, and microvascular complications, contribute significantly to global morbidity and mortality. Current monitoring tools such as glucometers and continuous glucose monitors only measure one analyte; multiplexing technologies offer a promising approach for monitoring multiple biomarkers, enabling the management of comorbidities and providing more comprehensive disease insights. In this work, we describe a miniaturized optical "barcode" sensor with high biocompatibility for the continuous monitoring of glucose and oxygen. This enzymatic sensor relies on oxygen consumption in proportion to local glucose levels and the phosphorescence reporting of tissue oxygen with a lifetime-based probe. The sensor was specifically designed to operate in a tissue environment with low levels of dissolved oxygen. The barcode sensor consists of a poly(ethylene glycol) diacrylate (PEGDA) hydrogel with four discrete compartments separately filled with glucose- or oxygen-sensing phosphorescent microparticles. We evaluated the response of the barcode hydrogels to fluctuating glucose levels over the physiological range under low oxygen conditions, demonstrating the controlled tuning of dynamic range and sensitivity. Moreover, the barcode sensor exhibited remarkable storage stability over 12 weeks, along with full reversibility and excellent reproducibility (∼6% variability in the phosphorescence lifetime) over nearly 50 devices. Electron beam sterilization had a negligible effect on the glucose response of the barcode sensors. Furthermore, our investigation revealed minimal phosphorescence lifetime changes in oxygen compartments while exhibiting increased lifetime in glucose-responsive compartments when subjected to alternating glucose concentrations (0 and 200 mg/dL), showcasing the sensor's multianalyte sensing capabilities without crosstalk between compartments. Additionally, the evaluation of chronic tissue response to sensors inserted in pigs revealed the appropriate biocompatibility of the barcodes as well as excellent material stability over many months. These findings support further development of similar technologies for introducing optical assays for multiple biomarkers that can provide continuous or on-demand feedback to individuals to manage chronic conditions.

Polymer microparticles with ultralong room-temperature phosphorescence for visual and quantitative detection of oxygen through phosphorescence image and lifetime analysis

Room-temperature phosphorescence (RTP) materials exhibiting long emission lifetimes have gained increasing attention owing to their potential applications in encryption, anti-counterfeiting, and sensing. However, most polymers exhibit a short RTP lifetime (<1 s) because of their unstable triplet excitons. Herein, a new strategy of polymer chain stabilized phosphorescence (PCSP), which yields a new kind of RTP polymers with an ultralong lifetime and a sensitive oxygen response, has been reported. The rigid polymer chains of poly(methyl mathacrylate) (PMMA) immobilize the emitter molecules through multiple interactions between them, giving rise to efficient RTP. Meanwhile, the loosely-packed amorphous polymer chains allow oxygen to diffuse inside, endowing the doped polymers with oxygen sensitivity. Flexible and transparent polymer films exhibited an impressive ultralong RTP lifetime of 2.57 s at room temperature in vacuum, which was among the best performance of PMMA. Intriguingly, their RTP was rapidly quenched in the presence of oxygen. Furthermore, RTP microparticles with a diameter of 1.63 μm were synthesized using in situ dispersion polymerization technique. Finally, oxygen sensors for quick, visual, and quantitative oxygen detection were developed based on the RTP microparticles through phosphorescence lifetime and image analysis. With distinctive advantages such as an ultralong lifetime, oxygen sensitivity, ease of fabrication, and cost-effectiveness, PCSP opens a new avenue to sensitive materials for oxygen detection.

Activatable red/near-infrared aqueous organic phosphorescence probes for improved time-resolved bioimaging

Abstract Organic red/near-infrared (NIR) room-temperature phosphorescence (RTP) holds significant potential for autofluorescence-free bioimaging and biosensing due to its prolonged persistent luminescence and exceptional penetrability. However, achieving activatable red/NIR organic RTP probes with tunable emission in aqueous solution remains a formidable challenge. Here we report on aqueous organic RTP probes with red/NIR phosphorescence intensity and lifetime amplification. These probes consist of supramolecular assemblies comprising macrocyclic cucurbit[8]uril and amine-containing alkyl-bridged pyridiniums, exhibiting viscosity-activatable phosphorescence with enhanced quantum yield (up to 20%) and lifetime. Notably, by utilizing this activatable organic RTP probe, we successfully achieve two-photon imaging of lysosomal viscosity and millisecond scale time-resolved cell imaging. Moreover, intravital phosphorescence imaging using RTP probe enable the monitoring of viscosity variations in inflammatory mice, demonstrating a significantly improved signal-to-background ratio compared to fluorescence imaging. This activatable red/NIR supramolecular platform facilitates versatile high-resolution phosphorescence imaging for in vivo tracking of specific biomarkers and physiological events.

Excitation wavelength and time dependent colour tunable room temperature phosphorescence from boron doped carbon nanodots.

Developing metal free room temperature phosphorescence (RTP) materials have received tremendous attention due its potential application in various fields such as sensing, optoelectronics and anticounterfeiting. Herein, we have synthesized an excitation wavelength and time dependent phosphorescent boron doped carbon nanodots (BCNDs) by thermal treatment of ethanolamine and boric acid at 240°C, where boric acid act as both doping and host agents. The obtained BCNDs display blue to orange fluorescence in both aqueous medium and solid state. In addition, the BCNDs display tunable orange-yellow-green phosphorescence in solid state under UV and visible light, lasting upto 10s, visible to naked eye. The boron and nitrogen doping regulates the band gap of the BCNDs, resulting the phosphorescence colour tunability. The average phosphorescence lifetime and quantum yield of BCNDs are found to be 1.27s and 8.61% respectively. Based on the optical properties, the BCNDs are applied as security ink in information encryption and security marking. Hence, this work can promote the development of metal free phosphorescent carbon based materials which may find application in various emerging fields.

Ultralong Room-Temperature Phosphorescence in Ca(II) Metal-Organic Frameworks Based on Nicotinic Acid Ligands.

In recent years, metal-organic framework (MOF) materials with long persistent luminescence (LPL) have inspired extensive attention and presented various applications in security systems, information anticounterfeiting, and biological imaging fields. However, obtaining LPL materials with ultralong lifetime remains challenging. Halogen atoms, as nonmetallic elements existing in the frameworks, can not only induce the heavy-atom effect, effectively enhancing spin-orbit coupling and promoting intersystem crossing (ISC) processes, but also suppress non-radiative transition of the triplet states through the intra- and intermolecular interactions. Specifically, fluorine atoms with the strongest electronegativity may form intermolecular aggregate interlockings through halogen-bonding interactions that restrict molecular motions and vibrations, thereby improving phosphorescent lifetime. With the aforementioned considerations, two distinct types of MOFs with/without fluorine atoms (namely, Ca-MOF and 5FCa-MOF) were synthesized. Notably, by introducing fluorine atoms into MOFs, fluorine-induced intermolecular aggregate interlockings effectively enhanced the phosphorescent lifetime of 5FCa-MOF exceeding 264 ms compared to that of Ca-MOF (103.94 ms). Remarkably, both MOFs displayed bright LPL to the naked eye after removal of the irradiation source, especially 5FCa-MOF which can last for about 2 s. By introducing fluorine atoms, 5FCa-MOF exhibits greatly enhanced ISC with a rate constant up to 4.1 × 106 s-1 and suppressed non-radiative decay down to 3.73 s-1, thereby extending the LPL time. The thus obtained LPL provides potential in information encryption, security systems, optical anticounterfeiting, and so on.

Dynamic Phosphorescence/Fluorescence Switching in Hybrid Metal Halides Toward Time‐Resolved Multi‐Level Anti‐Counterfeiting

AbstractHybrid metal halides (HMHs) with time‐resolved luminescence behavior promise to be a breakthrough in multi‐level anti‐counterfeiting, but controlling the dynamic switching between phosphorescence and fluorescence is extremely challenging. Herein, an array of 0D HMHs is constructed by screening the π‐conjugated ligand with room‐temperature phosphorescence (RTP). Compared to the organic chromophore, (ETPP)2ZrCl6 possesses a misaligned stacking and rigid structure, contributing to an improved phosphorescence quantum yield (ΦP = 27.50%) and an extended phosphorescence lifetime (τ = 0.6234 s), as the intervening of inorganic unit [ZrCl6]2− suppresses the energy losses caused by nonradiative relaxation and prompts the intersystem crossover (ISC) process. Not only that, the interplay of phosphorescence‐fluorescence dual‐mode emission can be intelligently controlled by doping the active metal Te4+, resulting in a dynamic switching between RTP phosphorescence and self‐trapped exciton (STE) fluorescence. DFT calculations reveal the governing origins of RTP‐STE from the intermolecular ISC channels and spin‐orbit coupling (SOC) coefficients. These precise images into periodic pixelated arrays enable the multi‐level anti‐counterfeiting and information encryption. This work proposes a fluorescence‐phosphorescence co‐modulating strategy under the premise of dissecting the structural origins for optimizing RTP phosphorescence, which paves the way for designing high‐security‐level anti‐counterfeiting materials.

Organic doped red room-temperature afterglow materials based on 2,3,5-triarylfuro[3,2-b]pyridines through Förster-resonance energy transfer

A series of novel 2,3,5-triarylfuro[3,2-b]pyridines are designed and acquired to be used as the guest molecules in organic doped room-temperature phosphorescence (RTP) system. Phenyl(pyridin-2-yl)methanone which can provide the rigid and tight microenvironment is chosen as the host molecule, which enables the two-component doped materials to emit RTP emissions of 0.5–8 s with 41–565 ms phosphorescence lifetimes and 2.9–19.4 % phosphorescence quantum efficiencies through constricting the non-radiative decay of triplet excitons. Furthermore, using commercial dyes Erythrosin B sodium salt and Eosin Y sodium salt as the third component and energy acceptor, the three-component materials emit bright red afterglows of 2 s with delayed lifetimes of 252–286 ms and emission quantum yields of 5.1–5.6 %, which are demonstrated to come from the triplet-to-singlet Förster-resonance energy transfer (FRET) from phosphorescence emission of 2,3,5-triarylfuro[3,2-b]pyridine derivative to fluorescence emission of commercial dye. This work not only provides valuable reference for the development of furo[3,2-b]pyridine-based afterglow materials, but also proves that the strategy of the FRET process provides new possibilities for molecules that can only emit fluorescence to participate in constructing afterglow materials.

Multi-confinement structured carbon dots with long room temperature phosphorescence lifetime and efficiency for sensing thiram residues assisted by copper ions.

Room temperature phosphorescent carbon dots(NCCDs@SiO2) were obtained by encapsulating hydrothermally synthesized CDs in a dense Si-O network structure after high-temperature calcination using silica as the matrix. Thiscan avoid the quenching effect of dissolved oxygen in water and has a phosphorescence lifetime of up to 2.41 s. Using the phosphorescence property of NCCDs@SiO2, a phosphorescence quenching sensor was developed for the sensitive and selective detection of thiram with the assistance of Cu2+. Cu2+-thiram complexesled to a rapid phosphorescence quenching of NCCDs@SiO2 within 30 s through the inner filter effect. The linear range of phosphorescence for thiram was 0.5-100 µM with a detection limit of 0.121 µM. Theproposed method was able to detect thiram in real samples and was validated by high-performance liquid chromatography (HPLC) confirmingthe potential of this phosphorescence sensing method for thiram detection. This work opens up a new avenue for the detection of thiram residues in fruits and vegetables and also provides a new idea for the design of a rapid detection platform using other room temperature phosphorescent materials.

Room-temperature phosphorescence and aggregation behavior in chiral heavy-atom-free organic molecules

Purely organic room temperature phosphorescence materials (RTP) have attracted much attention recently, but most of them are substituted with heavy atoms to enhance the intersystem crossing (ISC), which requires complicated design and synthesis. Herein, we report four chiral heavy-atom-free small molecules which integrate properties of aggregation and long-lifetime room temperature phosphorescence. The phosphorescence lifetime of synthesized chiral molecules is measured to be 150 ms, and the phosphorescence quantum yield reaches 15 % at room temperature. The twisted chiral conformation of four molecules not only affect aggregation photoluminescence properties but also can synergistically stabilize triplet exciton in the triplet excited states for excellent ISC efficiency. This strategy enriches the application fields of chiral aggregated long-lifetime room temperature phosphorescent materials.

Design and Preparation of Lifetime-Based Dual Fluorescent/Phosphorescent Sensor of pH and Oxygen and its Exploration in Model Physiological Solutions and Cells.

In the present report, a novel dual pH-O2 sensor based on covalent conjugate of rhodamine 6G and cyclometalated iridium complex with poly(vinylpyrrolidone-block-vinyltetrazole) copolymer is reported. In model physiological solutions the sensor chromophores display independent phosphorescent and fluorescent lifetime responses onto variations in oxygen concentration and pH, respectively. Colocalization studies on Chinese hamster ovary cells demonstrate the preferential localization in endosomes and lysosomes. The fluorescent lifetime imaging microscopy-phosphorescent lifetime imaging microscopy (FLIM-PLIM) experiments show that the phosphorescent O2 sensor provides unambiguous information onto hypoxia versus normoxia cell status as well as semi-quantitative data on the oxygen concentration in cells in between these two states. However, the results of FLIM measurements indicate that dynamic lifetime interval of the sensor (≈0.5ns between pH values 5.0 and 8.0) is insufficient even for qualitative estimation of pH in living cells because half-width of lifetime distribution in the studied samples is higher than the sensor dynamic interval. Nevertheless, the variations in rhodamine emission intensity are much higher and allow rough discrimination of acidic and neutral cell conditions. Thus, the results of this study indicate that the suggested approach to the design of dual pH-O2 sensors makes possible to prepare the biocompatible and water-soluble conjugate with fast cellular uptake.

Effect of ionic bonding on luminescence properties of histidine maleic anhydride derivatives

Polymeric materials exhibiting room-temperature phosphorescent (RTP) have attracted wide attention for their easy synthesis, low toxicity, and applications in various fields such as data encryption, cell imaging, information security and other fields. Nevertheless, the conventional ways of preparing such materials are mainly focused on doping, which may suffer from phase separation, poor compatibility, and lack of effective methods to promote intersystem crossing and suppress the nonradiative deactivation rates. Herein, a series of polymers with fluorescence and phosphorescence dual emission were prepared by simple radical solution copolymerization. Through rigid ion-bonded cross-linked networks and cross-linked hydrogen-bonded networks between the polymer chains, the non-radiative jumps and achieve ultra-long phosphorescence lifetimes were able to suppress. By suppressing non-radiative transitions through rigid ion-bonded cross-linked networks and intermolecular hydrogen-bonding networks between polymer chains, ultra-long phosphorescence is achieved. Impressively, a LRTP lifetime of up to 815.38 ms in polymers under ambientconditions is set up. Moreover, in this study, phosphorescence emission can be easily tuned by balancing ion radius and charge states. These results outline the construction of polymeric materials, endowing traditional polymers with new characteristics and promising potential applications.

Star-shaped multifunctional organic emitters based on N-(2-cyanophenyl) carbazole frameworks: Effects of steric hindrance fluorene and heavy-atom bromine

To investigate the effects of steric hindrance fluorene and heavy-atom bromine on the general optoelectronic properties of star-shaped organic emitters based on 9-(2-cyanophenyl) carbazole (OCzPhCN) frameworks, heavy element of bromine and steric hindrance fluorene were introduced into OCzPhCN to produce four derivatives of 2-(3-bromo-9H-carbazol-9-yl)benzonitrile (BrCzPhCN), 2-(3-bromo-6-(9-(4-ethoxyphenyl)-9H-fluoren-9-yl)-9H-carbazol-9-yl)benzonitrile (BrFCzPhCN), 2-(3-(9-(4-ethoxyphenyl)-9H-fluoren-9-yl)-9H-carbazol-9-yl)benzonitrile (FCzPhCN) and 2-(3,6-bis(9-(4-ethoxyphenyl)-9H-fluoren-9-yl)-9H-carbazol-9-yl)benzonitrile (2FCzPhCN). The fluorene units obviously improve the thermal stability of the obtained compounds, and 2FCzPhCN has the highest thermal stability with 5 % mass heat loss temperature reaching 447 °C. In different polar solvents, the absorption peaks wavelength of OCzPhCN, FCzPhCN and 2FCzPhCN are basically unchanged, and the redshifted emission peaks are positively correlated with solvent polarity. The photoluminescence quantum yields (PLQYs) of OCzPhCN, BrCzPhCN, FCzPhCN, BrFCzPhCN and 2FCzPhCN powders were 20.17 %, 5.43 %, 30.75 %, 3.27 % and 23.56 %. The fluorescence and phosphorescent quantum efficiencies of OCzPhCN, BrCzPhCN, FCzPhCN, BrFCzPhCN and 2FCzPhCN powders are 9.76 % and 10.41 %, 1.2 % and 3.23 %, 28.45 % and 2.3 %, 3.27 % and 0 %, 23.56 % and 0 %. OCzPhCN, BrCzPhCN and FCzPhCN powders show obvious room temperature phosphorescent emission, and the phosphorescent emission lifetime of OCzPhCN, BrCzPhCN and FCzPhCN powders at 561 nm, 576 nm and 568 nm are 193.17 ms, 18.65 ms and 7.25 ms. Compared with OCzPhCN, the introduction of bromine decreases the PLQY and the phosphorescent lifetime of BrCzPhCN powder, while the fluorescence quantum efficiency of the compound FCzPhCN powder has been improved. The corresponding single-triplet energy splitting (ΔEST) of OCzPhCN, FCzPhCN and 2FCzPhCN in solutions are 0.49 eV, 0.63 eV and 0.63 eV, and the corresponding ΔEST values of OCzPhCN, BrCzPhCN FCzPhCN powders are 1.19 eV, 0.74 eV and 0.55 eV. The steric hindrance fluorene units result in smaller and stabilized ΔEST in the solid powder states, and the same situation is opposite in the unimolecular solutions. The maximum external quantum efficiency of organic light-emitting diode based on 10,10′-(4,4′-sulfonylbis (4,1-phenylene)) bis (9,9-dimethyl-9,10-dihydroacridine) hosted by OCzPhCN reaches 12.7 %, and the external quantum efficiency at 100 cd/m2 rolls down to 11 %. OCzPhCN is the best emitters in terms of room temperature phosphorescent emission and host applications.

Accumulated in-situ spectral information analysis of room-temperature phosphorescence with time-gated bioimaging

This study introduces the time-gated analysis of room-temperature phosphorescence (RTP) for the in-situ analysis of the visible and spectral information of photons. Time-gated analysis is performed using a microscopic system consisting of a spectrometer, which is advantageous for in-situ analysis since it facilitates the real-time measurement of luminescence signal changes. An RTP material hybridized with a DNA aptamer that targets a specific protein enhances the intensity and lifetime of phosphorescence after selective recognition with the target protein. In addition, time-gated analysis allows for the millisecond-scale imaging of phosphorescence signals, excluding autofluorescence, and improves the signal-to-background ratio (SBR) through the accumulation of signals. While collecting the time-gated images and spectra of RTP and autofluorescent materials simultaneously, we develop a method for obtaining phosphorescence signals by means of selective exclusion of autofluorescence signals in simulated or real cell conditions. It is confirmed that the accumulated time-gated analysis can provide ample information about luminescence signals for bioimaging and biosensing applications.

Out-of-focus signal rejection for in vivo pO₂ measurements using two-photon phosphorescence lifetime microscopy

Out-of-focus signal rejection for in vivo pO₂ measurements using two-photon phosphorescence lifetime microscopy

Ultralong room temperature phosphorescence with multicolor afterglow achieved in a harsh polymeric viscous flow state.

Polymer-based ultralong room temperature phosphorescence (RTP) is more attractive than that of organic small molecules. However, the intrinsic contradictions between the motion of the chain and the stability of phosphors' triplet excitons make achieving ultralong lifetime in polymeric systems a big challenge. Herein, we have achieved ultralong RTP emission in a polymeric viscous flow state with free chain motion through a facile B-O click reaction among boric acid, polyvinyl alcohol, and hydroxyl silicone oil. The yielded RTP putties (RTPPs) exhibited long lifetimes under ambient conditions (up to 2.39 s), surpassing those of all reported elastic RTP polymers and most glassy RTP polymers. Furthermore, multi-color afterglow can be achieved in RTPPs using the triplet-to-singlet Förster resonance energy transfer strategy. Impressively, utilizing viscous liquid features combined with RTP performance, RTPPs can be easily applied in complex models, handiwork, and anti-counterfeiting. Therefore, this progress, achieving a long phosphorescence lifetime in a viscous flow state, greatly expands the application scope of polymeric RTP materials and further compels a conceptual advance of polymeric RTP.

Stable Persistent Room-Temperature Phosphorescent Hydrogels Based on Ionically Crosslinked Nonaromatic Carboxylate Polymers.

Developing pure organic room-temperature phosphorescent (RTP) hydrogels is important for expanding the practical applications of phosphorescent materials. However, most of the reported RTP hydrogels containing aromatic phosphors suffer from short phosphorescent lifetimes, unstable underwater RTP emissions, and complex preparation processes. Herein, novel nonaromatic RTP hydrogels are prepared by using two types of non-traditional luminescent polymers, sodium alginate and a polymeric carboxylate, which are not RTP emissive or very weakly emissive in aqueous environments. The prepared hydrogels exhibit the following features: I) color-tunable RTP emissions with ultra-long lifetimes up to 451.1ms, II) excellent anti-swelling properties and stable persistent RTP emission even after being immersed in deionized water for months, III) efficient and large-scale preparation of hydrogel fibers by wet spinning technique. Experiment results and theoretical calculations show that the stable and long-lifetime RTP emissions of the hydrogels originate from the introduction of more nonconventional chromophores which are strongly crosslinked with ionic bonding between carboxylate groups and calcium ions and enhanced through-space interactions between them. This work provides a reliable strategy for designing nonaromatic hydrogels with stable and persistent RTP.