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Impact of bidentate N,C-Chelate ligands on the performance of phosphorescent Pt(II) complexes as oxygen sensors
摘要： A library of 1,2- cyclometalated Pt(II) complexes based on various bidentate N,C-chelate chromophores have been studied for their uses as luminescent oxygen sensing probes (OSPs). The bidentate chelate ligands have been found to have a distinct impact on the performance of the Pt(II) compounds as OSPs. For some of the complexes, attachment of a dimesityl boron group (BMes2) to the chelate ligands enhances their oxygen sensitivity. For phenyl-1,2,3-triazole (Phtrz) based Pt(II) complexes, the attachment of a diphenyl amino moiety to the N,C-chelate ligand substantially enhances phosphorescence quenching and the performance of the OSP. A high (cid:1)(cid:2)(cid:3) (cid:4)(cid:5)(cid:5) value (0.0667 Torr-1) for the OSP based on the diphenyl amino functionalized Pt(II) complex was achieved, which is the highest value reported to date for OSPs based on bidentate Pt(II) complexes.
关键词： C-chelate ligands,N,phosphorescence,Pt(II) complexes,oxygen sensors
更新于2025-09-09 09:28:46
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Controlling the white phosphorescence ZnGa2O4 phosphors by surface defects
摘要： White phosphorescence that lasted ≈ 212 seconds, being the longest phosphorescence time reported so far for any Ga based material, has been observed in undoped ZnGa2O4 (ZGO) phosphors. The samples were synthesized by a simple combustion method by using two different Gallium precursors (Gallium nitrate and Gallium Acetylacetonate). According to the X-ray diffraction analysis, the samples prepared with the two different precursors presented the same single cubic phase. TEM images demonstrated that the ZGO phosphors made with both precursors are formed by nanoparticles with quasi-spherical shape, and they have nanoparticle sizes in the range of 17-43 nm. When excited with UV light (400 nm), these phosphors produced a broad blue-green-yellow luminescence. The blue band was associated to transitions from the Ga-O levels, while that of green-yellow band was attributed to radiative transitions from oxygen vacancies. Particularly, the sample synthesized with Gallium acetylacetone precursor presented the highest phosphorescent emission intensity and had a CIE coordinates of (x= 0.27, y= 0.33), which is close to that for pure white light (x=0.33, y=0.33). Since the ZGO presented a white phosphorescent emission without doping with rare earths, they could be good candidates for lighting or signaling applications.
关键词： White emission,Zinc-gallate,phosphorescence,Oxygen-vacancies,luminescence
更新于2025-09-09 09:28:46
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Achieving Amorphous Ultralong Room Temperature Phosphorescence by Coassembling Planar Small Organic Molecules with Polyvinyl Alcohol
摘要： Development of novel strategies for achieving amorphous ultralong organic phosphorescence (UOP) at room temperature is highly desired. Herein, a simple approach is reported by coassembling small organic molecules with polyvinyl alcohol (PVA) to afford amorphous UOP. These small organic molecules with planar conformation present quenched triplet state emission in an excessive stacking solid state. When coassembling these molecules with PVA, their planar structures are well confined in coassembly films. Such a confined environment leads to restricted molecular rotation and vibration, permitting these molecules to show stable triplet state and generate UOP. In control studies, corresponding structurally distorted molecules are also coassembled with PVA. However, they exhibit very weak or quenched UOP, since distorted structures with molecular rotation and vibration could easily dissipate the excitation energy in dilute film state. By employing this polymer confinement strategy, multicomponent luminescence dyes are further coassembled with PVA for multicolor luminescence displays, providing multicolor, uniform, and flexible luminescence films. This work demonstrates a general strategy of employing small organic molecules to coassemble with PVA to obtain amorphous UOP, which greatly expands the scope of organic molecules for developing simple but useful UOP films.
关键词： ultralong organic phosphorescence,distorted molecules,coassembly,planar molecules,flexible luminescence films
更新于2025-09-09 09:28:46
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Sr2MgWO6:Cr3+ phosphors with effective near-infrared fluorescence and long-lasting phosphorescence
摘要： Cr3+-doped near-infrared (NIR) long-lasting phosphorescence (LLP) phosphors have drawn great attention for the promising application in unique bio-labels. Most of the studies are focused on gallate materials. Here we report a novel non-gallates NIR LLP phosphor Sr2MgWO6:Cr3+ that exhibit broadband emission at 700–1000 nm. X-ray powder diffraction, photoluminescence spectra, photoluminescence excitation spectra, LLP decay curves and thermoluminescence glow curves were determined to study the NIR LLP property and mechanism of Sr2MgWO6:Cr3+. Although Sr2MgWO6:0.4%Cr3+ gives the strongest NIR emission, the optimum content of Cr3+ in Sr2MgWO6 phosphor for LLP was 0.1%. Trap type and depth in Sr2MgWO6:Cr3+ were also discussed according to the thermoluminescence glow curves. Sr2MgWO6:Cr3+ phosphor is promising in optical information storage, night-vision surveillence, and in vivo bio-imaging.
关键词： long-lasting phosphorescence,Cr3+,Sr2MgWO6,near-infrared
更新于2025-09-09 09:28:46
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Modeling and Assessment of Long Afterglow Decay Curves
摘要： Multiple exponential equations have been successfully fitted to experimental long afterglow decay curve data for some phosphor materials by previous researchers. The calculated decay constants in such equations are used to assess the phosphorescence characteristics of an object. This study generates decay constants from experimental test data and from existing literature for comparison. It shows that the decay constants of an object may not be invariant and that they are dependent on phosphor material, temperature, irradiation intensity, sample thickness, and phosphor density for samples. In addition, the use of different numbers of exponential components in interpretation leads to different numerical results for decay constants. The relationship between the calculated decay constants and the afterglow characteristics of an object is studied and discussed in this paper. The appearance of the luminescence intensity is less correlated to the decay constants than to the time-invariant constants in an equation.
关键词： decay curves,exponential equations,long afterglow,phosphorescence,decay constants
更新于2025-09-09 09:28:46
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Intrinsic and Extrinsic Heavy Atom Effect on the Multifaceted Emissive Behavior of Cyclic Triimidazole
摘要： Since heavy halogen atoms can be used to tune the emissive properties of organic luminogens, the understanding of their role in the photophysics is fundamental for materials engineering. Here, the extrinsic and intrinsic heavy atom effects on the photophysics of organic crystals are separately evaluated by comparing cyclic triimidazole (TT) with its mono-iodo derivative (TTI) and its cocrystal with diiodotetrafluorobenzene (TTCo). Crystals of TT show room temperature ultralong phosphorescence (RTUP) originated from H-aggregation. TTI and TTCo display two additional long lived components whose origin is elucidated through single crystal X-ray and DFT-TDDFT studies. The results highlight the different effects of the I atom on the three phosphorescent emissions. Intrinsic heavy atom effects play a major role on molecular phosphorescence which is displayed at RT only for TTI. H-aggregate RTUP and the I···N XB induced phosphorescences on the other side depend only on packing features.
关键词： photophysics,co-crystal,room temperature phosphorescence,halogen bonding,time resolved spectroscopy
更新于2025-09-04 15:30:14
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Efficient and Long-lived Room Temperature Organic Phosphorescence: Theoretical Descriptors for Molecular Designs
摘要： Room-temperature phosphorescence (RTP) with long afterglow from pure organic materials has attracted great attentions for their potential applications in biological imaging, digital encryption and optoelectronic device and so on. Organic materials have been long considered to be non-phosphorescence owing to the weak molecular spin-orbit coupling and highly sensitive to temperature. However, recently, some purely organic compounds can demonstrate highly efficient RTP with long afterglow upon aggregation while others fail. Namely, it remains a challenge to expound the underline mechanisms. In this study, we present the molecular descriptors to character the phosphorescence efficiency and lifetime. For prototypical RTP system consists of carbonyl group and π-conjugated segments, the excited states can be regarded as admixture of n→π* (with portion α) and π→π* (portion β). Starting from phosphorescent process and El-Sayed rule, we deduced that (i) the intersystem crossing (ISC) rate of S1→Tn is mostly governed by the modification of the product of α and β, and (ii) the ISC rate of T1→S0 is determined by the β value of T1. Thus, the descriptors (γ=α×β, β) can be employed to describe the RTP character of organic molecules. From hybrid quantum mechanics and molecular mechanics (QM/MM) calculations, we illustrated the relationships amongst the descriptors (γ, β), phosphorescent efficiency and lifetime, as well as spin-orbit coupling constants. We stressed that the large γ and β values are favorable to the strong and long-lived RTP in organic materials. Experiments have reported confirmations of these molecular design rules.
关键词： Organic materials,Molecular descriptors,Room-temperature phosphorescence,QM/MM calculations,Spin-orbit coupling
更新于2025-09-04 15:30:14
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Paintable Room Temperature Phosphorescent Liquid Formulations of Alkylated Bromonaphthalimide
摘要： Organic phosphors have been widely explored with an understanding that crystalline molecular ordering is a requisite for enhanced intersystem crossing. In this context, we explore the room temperature phosphorescence features of a solvent-free organic liquid phosphor in air. Given alkyl chain substitution varied the physical states of bromonaphthalimides, phosphorescence remained unaltered for the solvent-free liquid in air. As the first report, a solvent-free liquid of a long swallow tailed bromonaphthalimide exhibits room temperature phosphorescence in air. Doping of the phosphor with carbonyl guests resulted in enhanced phosphorescence and hence a large area paintable phosphorescent liquid composite with improved lifetime and quantum yield is developed.
关键词： luminescent thermometer,excimer,organic liquids,liquid phosphor,phosphorescence
更新于2025-09-04 15:30:14
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Luminescent silica based nanostructures from <i>in vivo</i> Iridium-doped diatoms microalgae.
摘要： A novel biotechnological approach to the preparation of Ir-doped luminescent silica based nanostructures is proposed availing of diatoms microalgae which generate highly nanostructured biosilica shells (frustules) by in vivo biomineralization of orthosilicic acid. After the in vivo incorporation of a phosphorescent organometallic complex (Ir-1) in Thalassiosira weissflogii diatom frustules (DFs), bulk functionalized phosphorescent silica based nanostructures are obtained by isolation and proper ultrafine processing of Ir-1 doped DFs. High-resolution characterization reveals the presence of phosphorescent hybrid organic/inorganic clusters (HCs) composed of biogenic silica NPs intimately trapped within the diatom organic residual matter. The bio-factory strategy investigated herein can be a sustainable, cost-effective and scalable route to transition metal doped silica nanomaterials, and can pave the way to a great variety of heavy-metal and rare-earth metal doped silica nanostructures, whose applications range from photonics to imaging, sensing and biomedicine.
关键词： micro-bioreactors,diatoms microalgae,iridium,extraction method,nanoparticles,nanostructures,Biosilica,phosphorescence
更新于2025-09-04 15:30:14
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Deep blue emitting Cu( <scp>i</scp> ) tripod complexes. Design of high quantum yield materials showing TADF-assisted phosphorescence
摘要： In a previous investigation, it was shown that [Cu(tpym)(PPh3)]PF6 1 with tpym = tris(2-pyridyl)methane represents a deep blue emitter (λmax = 466 nm) though with a low emission quantum yield ΦPL if doped in a polymer (7%) or dissolved in a ?uid solvent (?1%). In this study, we present new tripod compounds with [Cu(tpym)(P(o-tol)3)]PF6 2 and [Cu(tpym)(P(o-butyl-ph)3)]PF6 3 with sterically demanding ligands: P(o-tol)3 = tris(ortho-tolyl)phosphine and P(o-butyl-ph)3 = tris(ortho-n-butylphenyl)phosphine. These compounds show high emission quantum yields even in a ?uid solution (dichloromethane) reaching a benchmark value for 3 of ΦPL = 76%. This becomes possible due to the speci?c design of rigidifying the complexes. Importantly, the deep blue emission color is maintained or even further blue shifted to λmax = 452 nm (compound 3 powder). Compound 2 is characterized photophysically in detail. In particular, it is shown that the lowest excited triplet state T1 experiences very e?cient spin–orbit coupling (SOC). Accordingly, the phosphorescence decay rate is as large as 5 × 104 s?1 (20 μs) belonging to the fastest T1 → S0 transition values (shortest decay times) reported so far. Investigations down to T = 1.5 K reveal a large total zero-?eld splitting (ZFS) of 7 cm?1 (0.9 meV). Although thermally activated delayed ?uorescence (TADF) grows in at T ≥ 160 K, the phosphorescence of 2 still dominates (60%) over TADF (40%) at ambient temperature. Thus, the compound represents a singlet harvesting-plus-triplet harvesting material, if applied in an OLED.
关键词： TADF-assisted phosphorescence,Deep blue emitting,Cu(I) tripod complexes,high quantum yield
更新于2025-09-04 15:30:14