Developing organic room-temperature phosphorescence(RTP)materials with a wide range of tunable-emission is significant in expanding the applications of RTP materials.Herein,we rationally designed amphiphilic alternating copolymers poly(1,2-bis(4-alkoxyphenyl)ethane-1,2-dione-alt-(ethylene glycol)x)(P(Bz-alt-EGx))that combined the advantage of alternating benzil and EGxskeleton,and tunable mainchain conformation.Through a mainchain conformation ordering assembly(COA)process,P(Bz-alt-EGx)self-assembled into well-defined platelets,and such assemblies emitted blue RTP at ca.425 nm due to the ordered folded-chain conformation and confined microenvironment.In contrast,traditional self-assembly(TA)of P(Bz-alt-EGx)obtained less ordered aggregates,such as asymmetric worms,vesicles,and rod-like micelles.The resultant less ordered aggregates exhibited yellow-green RTP at ca.550 nm.The wide-tuning RTP emission in solution(between blue and yellow-green,over125 nm)is realized using the P(Bz-alt-EG_(x))alternating copolymers under the treatment of different self-assembly conditions.This study uncovers a new strategy to tailor the RTP emission through different self-assembly pathways and holds great promise for the fabrication of advanced optical materials.
Despite great achievements obtained for polymer-based room-temperature phosphorescence(RTP)materials,the limited efficiencies of persistent RTP still hinder their development.Herein,a simple and universal strategy of using the dual-functional additive of Cs+was presented,which could simultaneously enhance the efficiency(Φp)and maintain the long lifetime(τp)of RTP in existing polymer-based systems with various phosphors and polymers.Among them,the commercial emitter(TpB)-doped polyvinyl alcohol(PVA)/Cs_(2)CO_(3) system possessed an extremely high Φp up to 75.5% and still maintained a longτp of 2.13 s,by introducing the heavy-atom effect and an extra network of ionic bonding through the Cs+additive.Additionally,the temperature resistance of RTP in TpB@PVA/Cs+film could also be improved to 85℃.More satisfactorily,the efficiency of Förster resonance energy transfer(FRET)from RTP to near-infrared(NIR)was also remarkably enhanced in the multi-component systems.This work provides a simple and universal strategy for developing polymer systems with high RTP performance.
Yao LiuJinzheng ChenYiling MiaoKaimin ZhangFaxu LinHuahua HuangLina ZhangZhan YangYi ZhangZhenguo ChiZhiyong Yang
Achieving color-tunable room-temperature phosphorescence(RTP),especially including blue RTP from a single-component polymer still faces a formidable challenge.Herein,we wisely choose conformation-dependent phenothiazine with trifluoromethyl substituent as the side group of the phosphor monomer(Cz PT)and then copolymerize it with N-isopropylacrylamide(NIPAM)through photopolymerization to obtain polymers PPCz PTs.Time-dependent color-tunable phosphorescence from unusual quasi-equatorial(eq)to quasi-axial(ax)conformers are obtained,and the RTP color changes from orange(550 nm)to blue(470 nm)with phosphorescence lifetime up to 0.96 s.The theoretical calculations confirm that the quasi-axial conformer is the preferred structure that facilitates the formation of intramolecular hydrogen bonds on the trifluoromethyl group.The EPR spectra illustrate that the persistent UV irradiation generates radical cations to induce the conformational transitions first,followed by photopolymerization immobilizing the ax conformation in PPCz PTs.Applications of data encryption and anti-counterfeiting are fabricated to show prompt and delayed multicolor information.This work affords a simple and feasible avenue for two-dimensional color tunable room temperature phosphorescence from a single-component polymer.
Jiwen LuYifan NiuChanjuan JinChengheng WuHanyu WangYan GuanPing WangXinghe Fan
Development of new anti-counterfeiting technology with dynamic optical signals has drawn great attention,but the use of multiple external stimulus or long-time light irradiation inevitably increases the operation complexity and limits the practical application.In this work,we report the design of new fluorescence-phosphorescence dual-emission materials based on carbon dots(CDs)-engineered gold nanoclusters(AuNCs)in silica for advanced luminescent anti-counterfeiting.In particular,co-encapsulation of phosphorescent CDs and fluorescent AuNCs by rigid silica matrix enables the construction of a dual-emission system(AuNCs/CDs@SiO_(2))in aqueous phase.The AuNCs/CDs@SiO_(2) composite displayed significant fluorescence color change based on inner filter effect,as confirmed by in-depth spectral and photophysical characterization.Highly reversible and dynamic color switching between magenta fluorescence and green phosphorescence was easily achieved by simply switching on/off the ultraviolet(UV)irradiation.Potential utility of dual-emitting AuNCs/CDs@SiO_(2) as novel dynamic anti-counterfeiting materials has been successfully demonstrated,including anti-counterfeiting ink,ink-free optical printing film,and information encryption.The present aqueous-phase fluorescence-phosphorescence dual-emission system exhibits two types of anti-counterfeiting mode without introducing external stimulus,increasing the difficulty of imitation and duplication.This work provides a straightforward and generable strategy to design advanced optical anti-counterfeiting materials by combining phosphorescent materials with other fluorophores via reasonable engineering strategy.
The unusual room-temperature phosphorescence(RTP)from the n electron-rich systems(without regular conjugated structure)has aroused great attention for structural designing and application development of RTP materials.Such emission has been ascribed to clusterization-triggered emission(CTE)via weak through-space conjugation of n electrons in the heteroatoms.However,there was suspicion on such RTP as impurity-induced result.Therefore,in-depth photophysical investigation and effective proof methods are needed to trace the origin of such RTP.Here,using the recently reported CTE phosphor boric acid as the example,a Jablonski diagram-based verification protocol was proposed to confirm the intrinsic luminescence of the n electrons-rich systems.Meanwhile,some other types of luminophores,that is,traditional phosphors,already reported impurity-induced and host-guest doping luminophores,were included for comparison.Overall,this work provides a basic paradigm for differentiating between the impurity-involved and the n electron-rich phosphors and will further deepen the understanding of nonconventional luminescence.
D-A charge transfer, including through-bond charge transfer and through-space charge transfer between two different electron donors(D) and electron acceptors(A), is a fundamental and powerful tool to tune the optical properties of organic dyes. Herein,we demonstrate a unique strategy to tune phosphorescence and circularly polarized luminescence properties of axially chiral binuclear Pt(Ⅱ) complexes through long-range charge transfer, even though these molecules have two totally identical segments on either side of the chiral core. The presence of axial chirality would break not only the symmetry of molecular structure and π-conjugation system but also the symmetry of charge distribution for long-range charge transfer. These binaphthyl-based Pt(Ⅱ)complexes bearing coordinated atoms far away from chiral axis exhibit no Pt-Pt interactions but colorful concentrationdependent phosphorescence with quantum yield up to 86.4% and could be applied as emitters in highly efficient solutionprocessed organic light-emitting diodes to achieve luminance, luminance efficiency, power efficiency, external quantum efficiency, and asymmetry factor up to 8.94 × 10^(3)cd m^(-2), 41.9 cd A-1, 18.8 lm W^(-1), 12.6% and 2.98 × 10^(-3), respectively. Therefore,the present work affords a new and simple way to utilize the inherently asymmetric advantage of chirality for the design of D-Abased organic dyes.
Hydrogen bonding has been employed to suppressnonradiative decay in organic compounds that showroom-temperature phosphorescence (RTP);however, the small number of structurally diverse examplesmakes it unclear how general this strategy is to turnon RTP. In this study, we report highly efficient blueRTP from 4,4′,4′′-nitrilotribenzoic acid (TPA-CO_(2)H)in five structurally and chemically distinct hydrogenbonded supramolecular networks. In doped films inpoly(vinyl alcohol) (PVA), the phosphorescencequantum yield and lifetime (ΦPh and τPh) reach 52%and 275 ms. Boric acid can also be used to turn onRTP, and the performance changes significantlywhen the sample is heated beyond the dehydrationtemperature of this host where there is a 14-foldenhancement in the ΦPh after heat treatment. BlueRTP similar to that observed in PVA was also observed using granulated sugar, gelatine, and paper ashost matrices. This work elucidates for the first timethe role and the generality of hydrogen bonding inactivating efficient blue RTP and examines how thechoice of hydrogen bonding host influences RTPperformance. We further demonstrate how the emission color can be tuned by codoping the films withRhodamine 6G.
Polymeric ultralong organic phosphorescence(UOP)with persistent emission is of great importance in practical applications.However,achieving good water-resistance for long-term environmental stability is a formidable challenge.In this contribution,through tailoring the alkyl-chain length of the hardeners and emitters,polymeric UOPs with varying crosslinking density and hydrophobic effect were obtained.Notably,all the polymers show no obvious decrease in UOP emission after high temperature-humidity test(85℃/85%relative humidity for 7 days).Detailed investigations demonstrate that the rigid covalent crosslinking networks suppress the quenching of triplet excitons while the hydrophobic microenvironment affords good water/moisture-resistance ability.Moreover,the polymers with superior processability are successfully applied as optical coatings,prepreg,and afterglow displays.With this work,we provide a new strategy to promote the long-term stability of polymeric UOP materials in high-temperature-humidity conditions.
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.
As an interdisciplinary product,water-soluble gold nanoclusters(AuNCs)stabilized by ligands containing carboxyl(-COOH)group have garnered significant attention from synthetic chemists and biologists due to their immense potential for biomedical applications.However,revealing the crystallographic structures of-COOH-functionalized AuNCs remains a bottleneck.Herein,we successfully applied the salting-out method to obtain a series of high-quality single crystals of-COOH-functionalized Au_(25)nanoclusters and revealed their crystallographic structures.Particularly,K_(3)Au_(25)(2-Hmna)_9(mna)_6]^(-)(Au25a)protected by 2-mercaptonicotinic acid features an unprecedented tetrameric Au_(4)(SR^(S))_(3)(SR^(S,N))_(2)staple motifs surrounding the icosahedral Au_(13)kernel,breaking the traditional perception on the structure of Au_(25)(SR)_(18).Au25a exhibits a distinct near-infrared emission at 970 nm with long lifetime of 8690 ns,which have been studied by transient absorption spectroscopy and time-dependent density functional theory.This work compensates for the research gap in the experimental structure of-COOHfunctionalized AuNCs and opens up a new avenue to explore their structure-property correlations.
