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Organelle-targeted imaging can provide information on cellular functions and intracellular interactions, being significant for disease diagnosis. The use of room-temperature phosphorescence (RTP) in organelle-targeted imaging can fully utilize its unique characteristics of long wavelength and deep penetration. However, this technology has long been plagued by insufficient probe targeting and limited luminous intensity. In this work, we prepared a series of complexes composed of multicationic persulfurated arenes and biomacromolecules via electrostatic interactions in 1:1 stoichiometry for high-contrast mitochondrial-targeted RTP imaging. Such an electrostatic interaction design effectively prevented the self-aggregation of the probes, which is not conducive to mitochondrial targeting. Simultaneously, it suppressed the non-radiative decay to the maximum extent, enabling the probes to exhibit strong RTP signals both in aqueous solution and at the cellular level. Furthermore, the biomacromolecules can serve as carriers for an electrostatic interaction transfer of the persulfurated arenes to mitochondria. This leads to high mitochondrial targeting Pearson's correlation coefficients of the probes and high-contrast RTP imaging effects, as well as the independence of the co-incubated probe concentration. These results provide new insights for the development of targeted imaging technologies. [ABSTRACT FROM AUTHOR]

Organic room-temperature phosphorescence (RTP) materials have garnered considerable attention in the fields of biosensing, optoelectronic devices, and anticounterfeiting because of their substantial Stokes shifts, tunable emission wavelengths, and prolonged lifetimes. These materials offer remarkable advantages for biological imaging applications by effectively reducing environmental autofluorescence and enhancing imaging resolution. Recently, host–guest systems have been employed as efficient approaches to fabricate pure-organic RTP materials for bioimaging, providing benefits such as controllable preparation and flexible modulation. Consequently, an increasing number of corresponding studies are being reported; however, a comprehensive systematic review is still lacking. Therefore, we summarize recent advances in the development of pure-organic RTP materials using host–guest systems with regard to bioimaging, including rigid matrices and sensitization. The challenge and potential of RTP for biological imaging are also proposed to promote the biomedical applications of organic RTP materials with excellent optical properties. [ABSTRACT FROM AUTHOR]

Responsive luminescence materials with prolonged lifetime and multicolor emission have drawn great attention due to their attractive optical property and potential applications. Herein, two responsive carbon dots (CDs) based composites: CD1@MCM-22P and CD2@ZSM-12 were achieved by a one-step hydrothermal method. By adjusting the hydrothermal condition, CD1@MCM-22P owns temperature-dependent afterglow, while CD2@ZSM-12 is equipped with excitation-dependent room-temperature phosphorescence. The photoluminescence mechanisms of CD1@MCM-22P and CD2@ZSM-12 were investigated and proposed, and the composites were applied in multi-mode anti-counterfeiting. This work provides an insight as well as a feasible method for the development of multi-emissive CDs@zeolite composite. [ABSTRACT FROM AUTHOR]

Metal-free room-temperature phosphorescence (RTP) materials have the characteristics of large Stokes shift, long lifetime, and triplet state transition. They exhibit application potential in various fields, such as bioimaging, computer display, sensor, and anti-counterfeiting and have drawn much research interest. Recent work showed that manipulating intermolecular interactions (e.g., crystallization, polymerization, and rigid matrix) and host-guest assembly to restrain nonradiative transitions and isolate phosphor from oxygen as much as possible is a feasible way to obtain various types of efficient RTP materials. In some cases, intermolecular interactions also facilitated RTP emission by regulating the triplet state. On the other hand, heavy atoms (Br, I, etc.), heteroatoms (N, O, S, etc.), or carbonyls were introduced to the molecular skeleton through molecular engineering to enhance intersystem crossing, which is important for populating the triplet exciton. By comprehensively using the aforesaid strategies, great progress has been made for RTP materials. In this mini-review, we summarized recent advances in organic RTP materials based on manipulating intermolecular interactions. Typical host-guest assembly, hydrogen-bond assembly, energy transfer process, and exciplex emission system-based RTP materials were well illustrated. In summary, the current challenges and prospects for development in this field were presented. [ABSTRACT FROM AUTHOR]

Room-temperature phosphorescence (RTP) with a dynamic feature endows organic luminescent materials with promising application in optoelectronic fields. However, it remains a formidable challenge to obtain dynamic RTP materials. Herein, we reported a strategy for dynamic RTP via reversible transformation of radicals under external stimuli. RTP gradually disappeared with continuous UV-light irradiation owing to the conversion of NDIA to NDIA·− in NDIA/PVA film, which can be recovered by oxidation with oxygen. Regarding the excellent reversibility and repeatability, the potential applications for round-the-clock anti-counterfeiting and tag were first demonstrated. This finding not only outlines a principle to synthesize new RTP materials with dynamic behavior, but also expands the scope of applications of dynamic RTP materials. [ABSTRACT FROM AUTHOR]

A bromophenylpyridine derivative (BH-PY) was designed and synthesized as the guest molecule included in the cavity of cucurbit[8]uril (CB[8]) to form a 2:1 host–guest complex, which displays good room-temperature phosphorescence (RTP) in aqueous solutions. The interaction and optical properties of CB[8] with a guest in aqueous solution were investigated using 1H NMR spectroscopy, UV–Vis absorbance spectra, fluorescence and phosphorescence spectra and X-ray diffraction analysis in detail. The result showed that the bromophenyl moieties of the two guest molecules are included in the cavity of the CB[8] in a 'head-to-tail' stacking way, whereas the other part of BH-PY remains outside the portal to form a 2:1 supramolecular structurce, and supramolecular assemblies were applied for targeted phosphorescent imaging of mitochondria. [ABSTRACT FROM AUTHOR]

Seeking pure organic functional luminescent materials that are processed from green, low-cost, and sustainable resources remains a challenging but beneficial task. As an abundant natural polymer composed of crosslinked phenol ether units, lignin is a potential source of organic luminescent material because of the presence of extensive aromatic fragments. In the present work, a remarkable afterglow involving room-temperature phosphorescence (RTP) was achieved via simply embedding alkalized lignin into polyvinyl alcohol (PVA) matrix, and an ultralong luminescence lifetime of more than 160 ms was observed. More importantly, our study revealed that small fragments of hydrolyzed lignin (named LA-H) bearing extensive phenolic oxygen anions were the effective luminescent species. When embedded into a PVA matrix, LA-H showed remarkably high luminescence quantum yield and long lifetime of RTP emission compared with those of unprocessed lignin. Additionally, the various phenol oxygen anion moieties endowed LA-H with an excitation-dependent characteristic: the color-tunable RTP could be simply tuned from a maximum emission wavelength of 434–532 nm via altering the excitation wavelength. Thus, the color-tunable afterglow of emissive LA-H could be facilely obtained with a yield up to 38.4% using simple acid hydrolysis of lignin without other complex synthesis procedures. This work opens new avenues in the large-scale preparation of low-cost and sustainable pure organic RTP materials. [ABSTRACT FROM AUTHOR]

Supramolecular polymers with different functionalities have been continuously developed in the past decade because of their indispensable role in soft materials. However, pure organic supramolecular polymers with stable room temperature phosphorescence (RTP) emission were very rarely reported for the difficulties of synthesis and achieving RTP in solution. Herein, soluble helical supramolecular polymers with circularly polarized room-temperature phosphorescence were developed via a facile host-guest strategy. Through assembly, a transition from pure fluorescence to almost pure RTP emission was achieved. Adjusting the asymmetry of guest could easily control the chiroptical property of supramolecular polymers. This work provides new opportunities for the design and development of intelligent soft functional soft materials. [ABSTRACT FROM AUTHOR]

Pure organic room-temperature phosphorescent (RTP) materials have been attracting widespread attention due to the unique properties and broad applications. However, RTP materials with the adjustable photochromic property are still a challenge. Based on this, two polymers containing hexaarylbiimidazole are strategically designed with dual emission of both fluorescence and phosphorescence. Furthermore, both polymers show sensitive photochromic responses from faint yellow to brown upon exposure to ultraviolet light. This study can enrich pure organic luminescent systems and provide new ideas for functional RTP materials. [ABSTRACT FROM AUTHOR]

Room-temperature phosphorescence (RTP) of arenes, naphthalene-d8 and phenanthrene, in complexes with β-cyclodextrin (βCD) in the presence of a third component, tert-butylbenzene or p-tert-butyltoluene, providing the appearance of long-lived arene RTP, has been studied. The RTP lifetimes τph of naphthalene-d8 in the naphthalene-d8–βCD–tert-butylbenzene and naphthalene-d8–βCD–p-tert-butyltoluene complexes in the presence of oxygen are 14 and 4.8 s, respectively, and increase up to 16.4 and 6.6 s after oxygen removal. The rate constants of the phosphorescence quenching in these complexes are 34.4 and 76 L mol−1 s−1, respectively, indicating a high degree of naphthalene-d8 isolation from oxygen in the supramolecular system based on βCD. The highest value of τph for phenanthrene in the phenanthrene–βCD–tert-butylbenzene complex in the presence of oxygen is 2.4 s. The RTP decay in the presence of oxygen is always the superposition of two exponents, which is the general property of such three-component complexes, and indicates the presence of two types of phosphorescing complexes. The proposed structures of the complexes have been calculated by the quantum-chemistry method. The mechanism of the arene RTP quenching by oxygen is discussed with the use of the calculated structures of the complexes. [ABSTRACT FROM AUTHOR]

Ultralong organic room-temperature phosphorescence (RTP) materials have attracted tremendous attention recently due to their diverse applications. Several ultralong organic RTP materials mimicking the host-guest architecture of inorganic systems have been exploited successfully. However, complicated synthesis and high expenditure are still inevitable in these studies. Herein, we develop a series of novel host-guest organic phosphorescence systems, in which all luminophores are electron-rich, commercially available and halogen-atom-free. The maximum phosphorescence efficiency and the longest lifetime could reach 23.6% and 362 ms, respectively. Experimental results and theoretical calculation indicate that the host molecules not only play a vital role in providing a rigid environment to suppress non-radiative decay of the guest, but also show a synergistic effect to the guest through Förster resonance energy transfer (FRET). The commercial availability, facile preparation and unique properties also make these new host-guest materials an excellent candidate for the anti-counterfeiting application. This work will inspire researchers to develop new RTP systems with different wavelengths from commercially available luminophores. [ABSTRACT FROM AUTHOR]

Developing metal-free and long lifetime room-temperature phosphorescence (RTP) materials has received tremendous interest due to their numerous potential applications, of which stable triplet-excited state is the core challenge. Here, boron carbon oxynitride (BCNO) dots, emitting stable blue fluorescence and green RTP, are reported for the first time. The obtained BCNO dots exhibit an unexpected ultralong RTP lifetime of 1.57 s, lasting over 8 s to naked eyes. The effective doping of carbon and oxygen elements in boron nitride (BN) actually provides a small energy gap between singlet and triplet states, facilitating the intersystem crossing (ISC) and populating of triplet excitons. The formation of compact cores via crystallization and effective inter-/intra-dot hydrogen bonds further stabilizes the excited triplet states and reduces quenching of RTP by oxygen at room temperature. Based on the water-soluble feature of BCNO dots, a novel advanced security ink is developed toward anti-counterfeiting tag and confidential information encryption. This study extends BCNO dots to rarely exploited phosphorescence fields and also provides a facile strategy to prepare ultralong lifetime metal-free RTP materials. [ABSTRACT FROM AUTHOR]

Optical silicon (Si)-based materials are highly attractive due to their widespread applications ranging from electronics to biomedicine. It is worth noting that while extensive efforts have been devoted to developing fluorescent Si-based structures, there currently exist no examples of Si-based materials featuring phosphorescence emission, severely limiting Si-based wide-ranging optical applications. To address this critical issue, we herein introduce a kind of Si-based material, in which metal-organic frameworks (MOFs) are in-situ growing on the surface of Si nanoparticles (SiNPs) assisted by microwave irradiation. Of particular significance, the resultant materials, i.e., MOFs-encapsulated SiNPs (MOFs@SiNPs) could exhibit pH-responsive fluorescence, whose maximum emission wavelength is red-shifted from 442 to 592 nm when the pH increases from 2 to 13. More importantly, distinct room-temperature phosphorescence (maximum emission wavelength: 505 nm) could be observed in this system, with long lifetime of 215 ms. Taking advantages of above-mentioned unique optical properties, the MOFs@SiNPs are further employed as high-quality anti-counterfeiting inks for advanced encryption. In comparison to conventional fluorescence anti-counterfeiting techniques (static fluorescence outputs are generally used, thus being easily duplicated and leading to counterfeiting risk), pH-responsive fluorescence and room-temperature phosphorescence of the resultant MOFs@SiNPs-based ink could offer advanced multi-modal security, which is therefore capable of realizing higher-level information security against counterfeiting. [ABSTRACT FROM AUTHOR]

Room-temperature phosphorescence (RTP) has attracted much attention due to its potential applications in the fields of biological imaging, chemical sensors and so forth. Particularly, amorphous metal-free RTP materials show special advantages of low cost and good processability. In addition, non-conjugated polymers have seldom been reported as phosphorescent materials. In this work, a novel non-conjugated amorphous metal-free copolymer composed of brominated olefins and acrylamide was prepared in a facile way, which could engender blue-purple RTP emission. Polymers with different kinds of brominated olefins and different ratios of two monomers have been investigated with the purpose of researching the composition/property relationship that may affect the RTP properties. This unique phenomenon could be due to the clustering of carbonyl and amino units caused molecular interaction, and the heavy-atom effect enhanced intersystem crossing. Meantime, the hydrogen bonding in the system enhanced the conformation rigidification to reduce the non-radiative decay. This work provided a delicate way to construct non-conjugated metal-free RTP materials and supplied a new insight into the development of RTP materials. [ABSTRACT FROM AUTHOR]

Sensitized phosphorescence of naphthalene-d8 with a lifetime of 14.7 s at 22°C has been obtained in the supramolecular complex "naphthalene-d8–β-cyclodextrin–cyclohexane–benzophenone" and attributed to T–T energy transfer upon excitation of benzophenone at 365 nm. The geometric structure of this complex, energies of singlet transitions, and oscillator strengths have been calculated by quantum-chemistry methods. [ABSTRACT FROM AUTHOR]

A sensitive phosphorescent sensor based on riboflavin (RF)-modulated mercaptopropionic acid (MPA)-capped Mn-doped ZnS quantum dots (QDs) was developed and utilized as room-temperature phosphorescence (RTP) sensor for DNA detection. The RTP of the MPA-capped Mn-doped ZnS QDs was stored via photoinduced electron transfer by RF, and formed an electrochemically nonactive QDs/RF nanohybrids through electrostatic attraction. In the presence of DNA, RF could bind with DNA, which has a double helical structure, via electrostatic interaction and intercalation. RF can be removed from the surface of the QDs, thus releasing the RTP of the QDs. On the basis of this principle, an RTP sensor for DNA detection was developed. Under optimal conditions, the detection limit for DNA was 15 μg mL, the relative standard deviation was 1.9 %, and the method recovery ranged from 97 % to 103 %. The proposed method was applied to biological fluids, in which satisfactory results were obtained. [ABSTRACT FROM AUTHOR]

We evaluated the potential of tryptophan (Trp) phosphorescence spectroscopy for investigating conformational states of proteins involved in interaction with nanoparticles. Characterization of protein-nanoparticle interaction is crucial in assessing biological hazards related to use of nanoparticles. We synthesized glutathione-coated CdS quantum dots (GSH-CdS), which exhibited an absorption peak at 366 nm, indicative of 2.4 nm core size. Chemical analysis of purified GSH-CdS suggested an average molecular formula of GSHSCd. Investigations were conducted on model proteins varying in terms of isoelectric point, degree of burial of the Trp probe, and quaternary structure. GSH-CdS fluorescence measurements showed improvement in nanoparticle quantum yield induced by protein interaction. Trp phosphorescence was used to examine the possible perturbations in the protein native fold induced by GSH-CdS. Phosphorescence lifetime measurements highlighted significant conformational changes in some proteins. Despite their small size, GSH-CdS appeared to interact with more than one protein molecule. Rough determination of the affinity of GSH-CdS for proteins was derived from the change in phosphorescence lifetime at increasing nanoparticle concentrations. The estimated affinities were comparable to those observed for specific protein-ligand interactions and suggest that protein-nanoparticle interaction may have a biological impact. [ABSTRACT FROM AUTHOR]

A highly selective molecularly imprinted polymer (MIP) for the recognition of the pesticide carbaryl in water has been synthesized using halogenated bisphenol A compounds as one of the polymeric precursors and carbaryl as the template molecule. On the basis of the heavy-atom effect, both the brominated and the iodinated MIPs allowed analyte detection by room-temperature-phosphorescence measurements. In the presence of an oxygen scavenger (sodium sulphite) the halide, included in the polymeric structure, induced efficient room-temperature phosphorescence of the analyte (once it had been selectively retained by the MIP). The MIP cavity can be easily regenerated for subsequent sample injections with 2 mL methanol. The optosensing system developed has demonstrated high selectivity for carbaryl, even in the presence of other luminophores that could be unspecifically adsorbed onto the MIP surface. Under optimal experimental conditions, the detection limit for the target molecule was 4 µg/L (3-mL sample injection volume), and the linear range extended up to 1 mg/L of the analyte. Good reproducibility was achieved (a relative standard deviation of 3% was obtained for ten replicates of 150 µg/L carbaryl). The synthesized sensing material showed good stability for at least 3 months after preparation. Finally, the applicability to carbaryl determination in real samples was evaluated through the successful determination of the pesticide in spiked mineral and tap water samples. [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

It is already recognised that heavy-atom-induced, room-temperature phosphorescence can be used to determine pindolol in pharmaceutical samples and biological fluids. We describe here a new, simple, rapid and selective development of this technique. The phosphorescence signals derive from the interaction of pindolol with a relatively high concentration of heavy-atom salts in the presence of sodium sulphite as oxygen scavenger. Phosphorescence was registered in the presence of 1.2 M potassium iodide, 15 mM sodium sulphite and 30% v/v methanol at 450 nm, exciting at 285 nm. The detection limit was 21.1 ng mL−1. The method has been successfully applied to the determination of pindolol in commercial pharmaceutical tablets, urine and blood serum. [ABSTRACT FROM AUTHOR]

A detailed analysis of luminescence properties of humic substances and fulvic acids extracted from peat soil is carried out for the first time. Their fluorescence excitation and emission spectra, fluorescence lifetimes, phosphorescence excitation and emission spectra, and phosphorescence lifetimes at room temperature are investigated. The nature of chromophores of humic substances is discussed. [ABSTRACT FROM AUTHOR]

An optosensing method for gadolinium based on the room-temperature phosphorescence behavior in aqueous solution induced by the transient adsorption of the complex formed by 1,4- bis (1′-phenyl-3′-methyl-5′-pyrazolone-4′-)butanedione (1,4) with Gd (III) on the chelating resin Chelex 100 (packed in a flow cell) is proposed. The proposed optosensing is satisfactory for the determination of the gadolinium ion in the range 8 × 10–7−5 × 10−5 M with a correlation coefficient of 0.995. The relative standard deviation was 2.0% for determination of 5× 10−6 M gadolinium ion ( n = 10). The response mechanism of the optosensing and the interferences of other lanthanide ions were also investigated. The method has been used to determine gadolinium ion in synthetic sample. [ABSTRACT FROM AUTHOR]

The Ga(III)-7-iodo-8-hydroxyquinoline-5-sulfonic acid complex in the presence of suitable micelles and with sodium sulfite as oxygen scavenger exhibited strong phosphorescence at room temperature in aqueous solutions. This micellar reaction provides the basis for a convenient phosphorimetric determination of traces of gallium. Different types of micelles showed their maximum enhancing effects at different pH ranges, affording greater convenience for various analytical purposes. A phosphorimetric procedure with surfactant cetyltrimethylammonium bromide as enhancing agent is proposed. The detection limit for gallium was 5 ng/ml and the calibration graph was rectilinear in the range of 5 to 600 ng/ml. The relative standard deviation was 4% at 50 ng/ml level. The applicability of this room-temperature phosphorimetric procedure to multi-component analyses for the group III elements, Al(III), Ga(III), and In(III), was demonstrated. Kalman filtering was used to deconvolute the phosphorescence spectra of mixtures of aluminium and gallium allowing the simultaneous determination of both metals with satisfactory results. [ABSTRACT FROM AUTHOR]

The characteristics of the decay of the triplet state of metal chelates have been investigated in micellar media using room temperature phosphorescence (RTP) measurements of the Al-ferron (7-iodo-8-hydroxyquinoline-5-sulfonic acid) complex in cetyltrimethylammonium bromide (CTAB) micelles. Applications of such decay measurements include discrimination between metal complex species and evaluation of the stoichiometry of phosphorescent metal chelates. A thorough study of the effect of foreign ions (interferences) on the photochemical characteristics of RTP of the aluminum complex leads to a tentative classification of foreign cations. Results are compared with those for the Nb(V)-ferron phosphorescent complex in CTAB micelles and possible reaction mechanisms in the presence of micellar media are outlined in an effort to contribute to basic knowledge of micelle stabilized RTP of such inorganic ions. [ABSTRACT FROM AUTHOR]

An original and very strong long-lived emission of 2,2′-biquinoline is observed in hydrogen-bonded polymeric matrices only. This long-lived emission (Τ = 1 s) is ascribed to room-temperature phosphorescence (RTP) because of the large value of the decay time, the temperature-dependence, and the polarization results. The existence of hydrogen-bonded complexes in the ground state is assumed to be the origin of the RTP. They involve changes in the conformation of the 2,2′-biquinoline. [ABSTRACT FROM AUTHOR]

The luminescence properties of inclusion complexes of naphthalene-d with γ-cyclodextrin (γ-CD) in the presence of adamantane or o-carborane added as third parties were studied in aqueous solutions. It was found that the structure of the cage compound added to the aqueous solution of the naphthalene-d@γ-CD complex completely determines the luminescence type of the ternary complex. For instance, the intensity of excimer fluorescence (EF) band increases considerably at the expense of reduction of the intensity of monomer fluorescence (MF) band on adding adamantane. On the contrary, adding o-carborane causes a decrease in the intensity of the EF band of naphthalene-d and simultaneous appearance of MF in addition to long-lived room-temperature phosphorescence (RTP) whose lifetime increases from 1.5 s to 9.1 s after deoxygenation of the solution. Structural differences between the complexes affecting their behavior under the action of the third parties were explained using the results of semiempirical quantum chemical calculations. [ABSTRACT FROM AUTHOR]

Mesoporous molecularly imprinted polymers (MIPs) containing mangnanese-doped ZnS quantum dots (Mn-ZnS QDs) were prepared for specific recognition and detection of 4-nitrophenol (4-NP). The Mn-ZnS QDs display orange room-temperature phosphorescence with excitation/emission peaks at 295/590 nm and a decay time of 2.0 ms. In the presence of 4-NP, the orange phosphorescence is strongly reduced. Phosphorescence drops linearly in the 0.1–100 μM 4-NP concentration range, and the detection limit is 60 nM. The detection limit is far lower than the maximally allowed 4-NP concentrations in surface water and drinking water as specified by the U.S. Environmental Protection Agency. The intraday (n = 5) and interday (n = 6) spiked recovery rates were 96.0–104.5% and 97.9–107.9%, respectively, with relative standard deviations of 0.7–4.8% and 1.8–7.5% respectively. These MIPs integrated the characteristic features of phosphorimetry and molecular imprinting. Potential interference by competitive substances, background fluorescence or scattered light are widely reduced. Graphical abstract Schematic presentation of the synthesis of phosphorescent molecularly-imprinted polymers. A novel probe with manganese-doped ZnS quantum dots (Mn-ZnS QDs) and 3-aminopropyl-triethoxysilane (APTES) as functional monomers and tetraethoxysilane (TEOS) as crosslinking agent was prepared for selective phosphorescence detection of 4-nitrophenol (4-NP). [ABSTRACT FROM AUTHOR]

Spectral and photochemical properties of three aromatic thioketones, 4 H-1-benzopyran-4-thione and its two alkyl derivatives, in their second excited singlet and two lowest triplet states have been a subject of stationary and time-resolved studies. Quantum yields of emissions from the above-mentioned states as well as lifetimes of these states have been measured. The results indicate an important role of intermolecular solvent-induced processes in deactivation of the excited states of the thioketones studied. The possible mechanism of these processes involves hydrogen atom abstraction and/or formation of exciplex. For relatively high thione concentrations, the contribution of self-quenching in deactivation of the triplet states becomes significant. The effect of the alkyl chain in a thione molecule on deactivation parameters is discussed. [ABSTRACT FROM AUTHOR]