Detection of Oxygen Based on Host-Guest Doped Room-Temperature Phosphorescence Material

Quantitative oxygen detection,especially at low concentrations,holds significant importance in the realms of biology,complex environments,and chemical process engineering.Due to the high sensitivity and rapid response of the triplet excitons of phosphorescence to oxygen,pure organic room-temperature phosphorescence(RTP)materials have garnered widespread attention in recent years for oxygen detection.However,simultaneously achieving ultralong phosphorescence at room temperature and quantitative oxygen detection from pure organic host-guest doped materials poses challenges.The d ensely packed materials may decrease non-radiative decay to increase the phosphorescence,but are unsuitable for oxygen diffusion in oxygen detection.Herein,the oxygen sensitivity of host-guest doped RTP materials using 4-bromo-N,N-bis(4-(tertbutyl)phenyl)aniline(TPABuBr)as the host and 6-bromo-2-butyl-1H-benzo[de]isoquinoline-1,3(2H)-dione(NIBr)as the guest was developed.The doped material exhibits fluorescence-phosphorescence dual-emission behavior at room temperature.The tert-butyl groups in TPABuBr facilitate appropriate intermolecular spacing in the crystal state,enhancing oxygen permeability.Therefore,oxygen penetration can quench the phosphorescence emission.The observed linear relationship between the phosphorescence intensity of the doped material and the oxygen volume fraction conforms to the Stern-Volmer equation,suggesting its potential for quantitative analysis of oxygen concentration.The calculated limit of detection is 0.015%(φ),enabling the analysis of oxygen with a volume fraction of less than 2.5%(φ).Moreover,the doped materials demonstrate rapid response and excellent photostability,indicating their potential utility as oxygen sensors.This study elucidates the design and characteristics of NIBr/TPABuBr doped materials,highlighting their potential application in oxygen concentration detection and offering insights for the design of oxygen sensors.

Photoinduced Room-Temperature Phosphorescence of Triphenylamine-Phenothiazine Derivative-Doped Polymers

Photo-responsive room-temperature phosphorescent(RTP)materials have garnered significant interest due to the advantages of rapid response,spatiotemporal control,and contactless precision manipulation.However,the development of such materials remains in its infancy,underscoring the importance of exploiting novel and efficient light-responsive RTP molecules.In this work,three phenothiazine derivatives of TPA-PTZ,TPA-2PTZ,and TPA-3PTZ were successfully synthesized via the Buchwald-Hartwig C—N coupling reaction.By embedding these molecules as RTP guests into polymethyl methacrylate(PMMA)matrix,photo-induced RTP properties were realized.Upon sustained UV irradiation,there was an enhancement of 19 times in the quantum yield to reach a value of 5.68%.Remarkably,these materials exhibit superior alongside robust light and thermal stability,maintaining high phosphorescence intensity even after prolonged UV exposure(irradiation for>200 s by a 365 nm UV lamp with the power of 500μW·cm-2)or at higher temperature up to 75℃.The outstanding properties of these photo-induced RTP materials make them promising candidates for applications in information encryption,anti-counterfeiting,and advanced optical materials.

Recent Advances in Pure-Organic Host-Guest Room-Temperature Phosphorescence Systems Toward Bioimaging

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 pureorganic 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.

Room-Temperature Phosphorescence and Lifetime of Fossil Resins (Amber) from Dominican Republic, Mexico, Baltic Sea, Myanmar, and Fushun, China

Amber can emit room temperature phosphorescence(RTP)under the well-known 365 nm fluorescence ultraviolet light.This paper is devoted to the phosphorescence study of 20 pieces of amber materials from the Dominican Republic,Mexico,Baltic sea,Myanmar,and Fushun,China.The results show that amber from the same geographic origin has similar shape in phosphorescence spectra.However,the shape of the amber phosphorescence spectra varies depending on their different localities.Burmite(amber from Myanmar)and Fushun amber have a bright yellow phosphorescence with a long lifetime,while the Dominican and Mexican ones are weaker and last shorter.The irradiation of Baltic amber becomes faint or even inert.Phosphorescence spectral Gaussian fitting results suggest an emission maximum near 550 nm in most amber samples.Their phosphorescence lifetime,analyzed through the exponential function fitting,is up to 1 second in Burmite and Fushun samples,shorter in the Dominican and Mexican ones,about 0.230 s,and the shortest in Baltic amber,close to 0.151 s.These variations of phosphorescence lifetime and intensity are related to the relative geological ages of these amber.It indicated that the phosphorescence agent was probably formed during the long geological time.While the anomaly occurred in Baltic amber,the only one found in a sea secondary deposit form,it demonstrated that the terrestrial geological environment these amber preserved has prevented the phosphorescence agent to be deactivated.

Study on Room-Temperature Phosphorescence of 1-Bromonaphthalene in Media of Surfactant and β-Cyclodextrin

Sdrictants(S) induced room-ternperature phorphorescence(RTP) frorn l-bromonaplithalene(l-BrN) in aerated aqueous solutions of o-cyclodextha(β-CD) hasbeco mvestigated m detail. lt has been fotmd that the partial incIu5ion and coil ofhydIocarbon chain of edctans at the mouth of the 6-CD ca\4ty' is reSPoedle foTbright RTP

The Current Progress and Challenges of Carbonized Polymer Dot-Based Room-Temperature Phosphorescent Materials

Carbonized polymer dots(CPDs)as one type of carbon dots have attracted widespread attention in recent years.The proposal of the“shell–core”structure of CPDs leads to further thinking about the association between their special structures and luminescent properties.In recent years,great progress has been made in the field of CPD-based room-temperature phosphorescent materials.This review pays particular attention to how the special“core–shell”structure of CPDs influences the activation of roomtemperature phosphorescence(RTP).The strategies and vital factors to activate RTP for CPD-based materials in both solid state and water were reviewed in detail to elaborate on the effect of the special structure on RTP generation.Furthermore,some perspectives on the current challenges were also provided to guide the further development of CPD-based room-temperature phosphorescent materials.

Organic Host-Guest Materials with Bright Red Room-Temperature Phosphorescence for Persistent Bioimaging

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.

Recent Advances in Organic Room-Temperature Phosphorescence of Heteroatom(B/S/P)-Containing Chromophores

Purely organic room-temperature phosphors,which have received extensive attention as emerging stateof-the-art luminescent materials in various fields,have a longer lifetime than fluorophores.The energy gap law and El-Sayed’s rule provide clear design principles for the development of organic room-temperature phosphorescence.Therefore,the incorporation of heteroatoms(such as sulfur and phosphorus)usually promotes the intersystem crossing rate and increases the 3(π,π*)configuration to realize long lifetimes.Furthermore,boron-containing phosphors not only display excellent phosphorescence properties but also expand El-Sayed’s rule without(n,π*)transitions.This review summarizes recent work on organic phosphorescence of heterocycles with boron,sulfur,and phosphorus heteroatoms and highlights the significance of the guidelines for constructing efficient phosphorescence molecules.This work is instrumental in further diversifying the pool of phosphorescent molecules and developing new and effective design strategies.

Generation of color-controllable room-temperature phosphorescence via luminescent center engineering and in-situ immobilization

Materials with controllable luminescence colors are highly desirable for numerous promising applications, however, the preparation of such materials, particularly with color-controllable room-temperature phosphorescence(RTP), remains a formidable challenge. In this work, we reported on a facile strategy to prepare color-controllable RTP materials via the pyrolysis of a mixture containing 1-(2-hydroxyethyl)-urea(H-urea) and boric acid(BA). By controlling the pyrolysis temperatures, the as-prepared materials exhibited ultralong RTP with emission colors ranging from cyan, green, to yellow. Further studies revealed that multiple luminescent centers formed from H-urea, which were in-situ embedded in the B2O3matrix(produced from BA) during the pyrolysis process. The contents of the different luminescent centers could be regulated by the pyrolysis temperatures, resulting in color-tunable RTP. Significantly, the luminescent center engineering and in-situ immobilization strategy not only provided a facile method for conveniently preparing color-controllable RTP materials, but also endowed the materials prepared at relatively lower temperatures with color-changeable RTP features under thermal stimulus. Considering their unique properties, the potential applications of the as-obtained materials for advanced anti-counterfeiting and information encryption were preliminarily demonstrated.

A gated strategy stabilizes room-temperature phosphorescence

Room-temperature phosphorescence(RTP)of purely organic materials is easily quenched with unexpected purposes because the excited triplet state is extremely susceptible to external stimuli.How to stabilize the RTP property of purely organic luminogens is still challenging and considered as the bottleneck in the further advancement of the bottom-up approach.Here,we describe a gated strategy that can effectively harness RTP by employing complexation/dissociation with proton.Due to the order-disorder transition orientation of intermolecular packing,the RTP of organic molecules 2,4,6-tris(4′-bromo-[1,1′-biphenyl]-4-yl)-1,3,5-triazine(Br-TRZ)will easily vanish upon mechanical force.Impressively,by enhancing its intramolec-ular charge transfer effect,the protonated Br-TRZ stubbornly possesses an obvious RTP under external grinding,whatever in the ordered or disordered intermolec-ular arrangement state.Consequently,the“Lock”gate of RTP was achieved in the protonated Br-TRZ molecule.Combined with theoretical calculation analy-sis,the enhanced charge transfer effect can narrow the energy gap singlet-tripletsignificantly,and stabilize the RTP property of triazine derivative sequentially.Fur-thermore,the locked RTP can be tuned via proton and counterions repeatedly and show excellent reversibility.This gated RTP concept provides an effective strategy for stabilizing the RTP emission of purely organic systems.

Effect of stereoregularity on excitation-dependent fluorescence and room-temperature phosphorescence of poly(2-vinylpyridine)

Preparation of non-conjugated luminescent polymers(NCLPs)with excellent cluster luminescence(CL)performance is of great significance for scientific and industrious applications,and yet improving the performance of NCLPs through proper structural design is still a huge challenge.Herein,we report a non-conjugated ionized polymeric system consisting of(−)-camphorsulfonic acid((−)-CSA)and poly(2-vinylpyridine)(P2VP).These acid-base complexes exhibit typical excitationdependent fluorescence and room-temperature phosphorescence(RTP)with a lifetime up to 364 ms.We discover that changing the stereoregularity from atactic to isotactic significantly improves the CL performance of the complex.It(1)broadens the fluorescence emission spectra to cover the entire visible region,(2)enhances the fluorescence emission intensity at long wavelength beyond 500 nm,(3)enhances the phosphorescence intensity,and(4)extends the phosphorescence lifetime.Systematical experimental characterization and molecular dynamics simulation unravel the key role of stereoregularity in determining the formation of different pyridine aggregates that strongly influence the CL performance.Moreover,the different luminescence shows great potential in excitation divided information display and time-resolved encrypted display.This work not only points to a new direction for developing NCLPs with excellent performance,but also broadens the applications of NCLPs materials.

Ratiometric hypoxia detection by bright organic room temperature phosphorescence of uniformed silica nanoparticles in water

Organic room temperature phosphorescence(RTP)in water has attracted much attention recently for its potential biological applications.However,it remains a formidable challenge to achieve efficient RTP from pure organic compounds in aqueous phase due to the dramatic deactivation of triplet excited states in water and the poor water dispersibility of large organic particles/crystals.Represented herein is covalent incorporation of a pure organic monochromophore in silica nanoparticles(SiNPs)featuring fluorescence and bright phosphorescence in aqueous solution.The covalent bonding of organic phosphors in polysiloxane framework was found to show excellent water dispersibility,at the same time suppress the nonradiative deactivation of triplet excited states especially from water,thus leading to high phosphorescence quantum yields(up to 22%)and long lifetimes(up to 3.5 ms)in aqueous phase.More strikingly,oxygen-insensitive fluorescence as internal reference and oxygen-dependent phosphorescence as oxygen indicator from the organic chromophore in the porous SiNPs realized ratiometric hypoxia detection with ultrasensitivity(K_(SV)=449.3 bar^(-1)).

木质素/丙烯酰胺构建室温磷光气凝胶

木质素是自然界中芳环含量最高的天然高分子,关于其光致发光特性的研究仍较少。本研究以制浆造纸行业中常见副产物木质素磺酸钠为发色团,丙烯酰胺为聚合单体,采用一步聚合法在60℃、1 h下制备了磷光/聚丙烯酰胺(LS@PAM)水凝胶,再经冻干制得气凝胶。借助丙烯酰胺刚性且多氢键的基质环境限域木质素,制得了高强度的磷光气凝胶材料。结合傅里叶变换红外光谱(FT-IR)、X射线衍射(XRD)、扫描电镜(SEM)和稳态/瞬态荧光光谱仪等手段对气凝胶的结构性质和光物理性能进行分析。实验结果表明,采用320 nm作为激发波长时,在510 nm(绿光)处检测到最长的磷光寿命287.43 ms;SEM揭示出气凝胶具有有序多孔的网状结构,经过力学测试发现其拉伸强度为24.24 MPa,当压缩应变为10%时,其压缩强度为9.39 MPa。借助丙烯酰胺基质对铁离子的灵敏响应,可对铁离子进行有效检测。而磷光气凝胶与现有的电阻式/电容式湿度传感器相比,也能达到对湿度的可视化传感,在相对湿度由30%增加到50%时,气凝胶余辉颜色发生显著变化。本研究通过简单的一步共聚法,借助刚性的丙烯酰胺基质对木质素磺酸钠的限域作用,有效构建了高力学强度的磷光材料,为开发利用木质素提供了更多手段,拓展了以林木生物质为原料的余辉发射材料的制备策略和应用领域。

Electrostatic interaction-mediated 1:1 complexes for high-contrast mitochondrial-targeted phosphorescence bioimaging

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.

Recent advances in room-temperature phosphorescent materials by manipulating intermolecular interactions

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 anticounterfeiting 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.

Multi-modal anti-counterfeiting and encryption enabled through silicon-based materials featuring pH-responsive fluorescence and room-temperature phosphorescence

Nano Research volume 13,pages1614–1619(2020)Cite this article 236 Accesses Metrics details Abstract 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.

A facile and green strategy to obtain organic room-temperature phosphorescence from natural lignin

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.

Photo-controllable room-temperature phosphorescence of organic photochromic polymers based on hexaarylbiimidazole

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.

Color-tunable ultralong organic phosphorescence materials for visual UV-light detection

Ultralong organic phosphorescence(UOP)materials have roused considerable attention in the field of photonics and optoelectronics owing to the feature of long-lived emission lifetimes.However,to develop UOP materials with color-tunability is still a formidable challenge.Here,we report a class of UOP materials containing carbonyl,amino or amide groups,exhibiting colortunable persistent luminescence ranging from blue(458 nm)to yellow-green(508 nm)under different UV wavelength excitation.Taken theoretical and experimental results together,we conclude that the excitation dependent color-tunable UOP emission is ascribed to multiple emission centers from single molecular and aggregated states in crystal.Given color-tunable UOP feature,these materials are used to successfully realize visual UV-light detection.This finding not only provides a strategy to design new organic phosphorescent molecules with colorful emission,but also extends the scope of the applications of purely organic phosphorescent materials.

Tunable room-temperature phosphorescence and circularly polarized luminescence encoding helical supramolecular polymer

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 hostguest 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.