| Room temperature phosphorescence(RTP)has aroused wide-ranging interest owning to their long lifetimes,large Stokes shifts,and widely potentials in various areas.Nonetheless,achieving RTP emission in pure organic systems is commonly a tough project for that obtaining affluent triplet excitons and shielding the exctions from outsider quenchers are both hard to meet.Traditional RTP materials usually focus on novel metals,eg,Pt and Ir complexes,for the strong spin-orbit coupling(SOC)will accelerate the inter-system crossing(ISC)process effectively.However,their distinct drawbacks,involving high cost and serious biological toxicity,make them less competitive with non-metal materials in materials science.Compared with traditional fluorescent materials,pure organic RTP materials were rarely reported for the spinforbidden transition process between singlet state and triplet state,as well as the quenching resulted from oxygen and moister outsider.Although the crystallization of phosphors has been proven effective in restricting nonradiative decay such as molecular vibration,rotation and collision.However,general growth conditions of organic crystals are stringent,exhibiting poor repeatability and machinability.To further develop environment-friendly chemistry and make materials more applicable,the cost,biocompatibility and preparation simplicity of materials should be all considered.In addition to designing phosphorescent molecules based on molecular engineering to obtain as many triplet excitons as possible,many methods have been applied to immobilize phosphorescent molecules and minimize the quenching of triplet excitons at room temperature,realizing improved RTP emission successfully.Among them,fixing luminescent molecules into rigid polymer matrices by intermolecular interaction(covalent and non-covalent interaction)as a simple but promising method has aroused considerable attention due to those cross-linked matrices enable to inhibit the movement and intermolecular collision of luminescent molecules,realizing effective and persistent RTP emission.Phosphorescent systems with color tunability show a very broad application prospect in sensing,flexible electronics,biological detection,anti-counterfeiting and data encryption,which have attracted extensive attention of researchers.As an emerging novel subject in stimulating phosphorescence signals,multicolor polymerbased pure organic RTP materials are still developing in mechanisms and methods compared to developed fluorescent systems.Developing new efficient phosphorescent systems with wide color-tunable range is absolutely an urgent issue today.This paper was conducted around polymer-based RTP materials,focusing on simplifying the preparation process of the system,enriching the types of phosphorescent molecules,and developing stimulus-responding RTP in combination with p H-responsive polymers.Wide color-adjustable ranges from purple to orange,including white light have been collected along with the prolonged lifetimes and increased quantum yields in three different RTP systems.It is worth noting that the relationships between the structures and phosphorescence properties have been explored after introducing theoretical calculations to feedback the development of polymer-based pure organic phosphorescent materials in the near future.The details are as follows:(1)The construction of polyacrylamide-based binary luminescent copolymer materials exhibiting color-tunable and efficient long-lived RTP emission.A lifetime reaching to 1.9 s and a phosphorescence quantum yield up to 40.1% were observed in the binary copolymers obtained through simple radical polymerization of dye monomers and acrylamide monomer.Concentration-dependent and excitationdependent phosphorescence signals were both detected in doped luminescent copolymer systems.The underlying mechanisms of this effective and persistent color-tunable RTP system have been discussed in detail based on the experimental data and theoretical calculations.In addition,the application in dynamic information encryption under ambient conditions was proved available.(2)The building of multicolor phosphorescent supramolecular polymer system based on the host-guest interaction between the host macrocycle CB[8] and the guest polymers.Herein,in order to enrich the RTP systems based on supramolecular polymers,we have designed and synthesized three kinds of phenylpyridine cationic dyes with different substituents(hydrogen atom,bromine atom and bromobenzene group)according to molecular engineering.The RTP emission colors from blue to yellow have been acquired from the copolymers of three kinds of acrylamidephenylpyridium with different feed ratios.With the inclusion of cucurbit[8]uril(CB[8]),unnecessary nonradiation processes of chromophore on the side chains of polymers have been further diminished,leading to prolonged and effective RTP emission.Notably,interesting red-shifted emission was witnessed under UV irradiation in those newly obtained supramolecular polymers,which is ascribed to the ?-? stacking of light-emitting fragments induced by the binding of host CB[8]with large and electron-rich cavity.We verified the design principles of phosphors through theoretical calculations incorporating with experimental data,achieving deeper understanding of the relationships between structures and photophysics performance.Moreover,considering the multiple properties of polymer phosphorescence emission in the system,we confined the application possibility of copolymers and supramolecular polymers in the field of information encryption as well.(3)Color-tunable RTP mediated by host-guest chemistry and stimuli-responsive polymer matrices.we have obtained the extended red-shifted multicolor RTP afterglow from blue to orange,including white light,by constructing a series of supramolecular polymers from one single kind of phosphor 1-((2-methylallyl)oxy)pyrene containing guest polymers and host ?-cyclodextrin(?-CD)molecules.Benefiting from the strong restriction on the dimeric pyrene units induced by the effective inclusion of CD and multiple interactions amongst polymer matrices and phosphorescent moieties,RTP enhancement was realized.Additionally,a blue-shifted color-tuning range was also enabled after introducing p H-sensitive fragments into P-pyr-1,which is attributed to the self-assembly behaviors of the ternary polymer caused by ionic bonding.Notably,optimized intelligent multicolor RTP systems induced by altered external stimuli,including concentration,irradiation,and p H,have been established,showing great potentials in developing stimuli-responsive luminescent materials for practical applications.In addition,theoretical calculations have been conducted to elucidate diverse emission mechanisms of pyrene units in different assembly states. |
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