Ultrafast Visual Detection of a Trace Amount of Water by Highly Efficient Hybrid Manganese Halides.

A quantitative water detection method is urgently needed in storage facilities, space exploration, and the chemical industry. Although numerous physical techniques have been widely utilized to determine the water content, they still suffer from many disadvantages such as highly expensive special instruments, complicated analysis processes, etc. Hence, a convenient, rapid, and sensitive water analysis method is highly desirable. Herein, we developed a visual fluorescence sensing technology for water detection based on reversible PL off-on switching of organic-inorganic hybrid zero-dimensional (0D) manganese halides. In this work, a family of hybrid manganese halides were synthesized through a facile solution method, namely, [NH4(18-Crown-6)]2MnBr4, [Ca(18-Crown-6)·3H2O](18-Crown-6)MnBr4, [NH4(dibenzo-18-Crown-6)]2MnBr4, and [Ca(dibenzo-18-Crown-6)·2H2O]MnBr4. Excited by UV light, these highly crystalline manganese halides exhibit strong green light emissions from the d-d electron transition of Mn2+ with near-unity photoluminescence quantum yield and submillisecond lifetime. Benefiting from the dynamic and weak ionic bonding interactions, these 0D manganese halides display reversible water-response on/off luminescence switching but fail in any other aprotic solvents. Therefore, these 0D hybrid manganese halides can be explored as ultrafast visual fluorescence probes to detect the trace amount of water in organic solvents with multiple superiorities of rapid response time (< 2 s), ultralow detection limit (9.71 ppm), excellent repeatability, etc. The reversible water-response luminescent on/off switching also provides a binary optical gate with advanced applications in anticounterfeiting and information security, etc.

Nylons with Highly-Bright and Ultralong Organic Room-Temperature Phosphorescence.

Endowing the widely-used synthetic polymer nylon with high-performance organic room-temperature phosphorescence would produce advanced materials with a great potential for applications in daily life and industry. One key to achieving this goal is to find a suitable organic luminophore that can access the triplet excited state with the aid of the nylon matrix by controlling the matrix-luminophore interaction. Herein we report highly-efficient room-temperature phosphorescence nylons by doping cyano-substituted benzimidazole derivatives into the nylon 6 matrix. These homogeneously doped materials show ultralong phosphorescence lifetimes of up to 1.5 s and high phosphorescence quantum efficiency of up to 48.3% at the same time. The synergistic effect of the homogeneous dopant distribution via hydrogen bonding interaction, the rigid environment of the matrix polymer, and the potential energy transfer between doped luminophores and nylon is important for achieving the high-performance room-temperature phosphorescence, as supported by combined experimental and theoretical results with control compounds and various polymeric matrices. One-dimensional optical fibers are prepared from these doped room-temperature phosphorescence nylons that can transport both blue fluorescent and green afterglow photonic signals across the millimeter distance without significant optical attenuation. The potential applications of these phosphorescent materials in dual information encryption and rewritable recording are illustrated.

Boost the Circularly Polarized Phosphorescence of Chiral Organometallic Platinum Complexes by Hierarchical Assembly into Fibrillar Networks.

Circularly polarized luminescence (CPL)-active molecular materials have drawn increasing attention due to their promising applications for next-generation display and optoelectronic technologies. Currently, it is challenging to obtain CPL materials with both large luminescence dissymmetry factor (glum) and high quantum yield (Φ). A pair of enantiomeric N N C-type Pt(II) complexes (L/D)-1 modified with chiral Leucine methyl ester are presented herein. Though the solutions of these complexes are CPL-inactive, the spin-coated thin films of (L/D)-1 exhibit giantly-amplified circularly polarized phosphorescences with |glum| of 0.53 at 560 nm and Φair of ~50 %, as well as appealing circular dichroism (CD) signals with the maximum absorption dissymmetry factor |gabs| of 0.37-0.43 at 480 nm. This superior CPL performance benefits from the hierarchical formation of crystalline fibrillar networks upon spin coating. Comparative studies of another pair of chiral Pt(II) complexes (L/D)-2 with a symmetric N C N coordination mode suggest that the asymmetric N N C coordination of (L/D)-1 are favorable for the efficient exciton delocalization to amplify the CPL performance. Optical applications of the thin films of (L/D)-1 in CPL-contrast imaging and inducing CP light generation from achiral emitters and common light-emitting diode lamps have been successfully realized.

Endowing Metal-Organic Coordination Materials with Chiroptical Activity by a Chiral Anion Strategy.

Recently, chiral metal-organic coordination materials have emerged as promising candidates for a wide range of applications in chiroptoelectronics, chiral catalysis, and information encryption, etc. Notably, the chiroptical effect of coordination chromophores makes them appealing for applications such as photodetectors, OLEDs, 3D displays, and bioimaging. The direct synthesis of chiral coordination materials using chiral organic ligands or complexes with metal-centered chirality is very often tedious and costly. In the case of ionic coordination materials, the combination of chiral anions with cationic, achiral coordination compounds through noncovalent interactions may endow molecular materials with desirable chiroptical properties. The use of such a simple chiral strategy has been proven effective in inducing promising circular dichroism and/or circularly polarized luminescence signals. This concept article mainly delves into the latest advances in exploring the efficacy of such a chiral anion strategy for transforming achiral coordination materials into chromophores with superb photo- or electro-chiroptical properties. In particular, ionic small-molecular metal complexes, metal clusters, coordination supramolecular assemblies, and metal-organic frameworks containing chiral anions are discussed. A perspective on the future opportunities on the preparation of chiroptical materials with the chiral anion strategy is also presented.

Near-Unity Green Luminescent Hybrid Manganese Halides as X-ray Scintillators.

The increasing demands in optoelectronic applications have driven the advancement of organic-inorganic hybrid metal halides (OIMHs), owing to their exceptional optical and scintillation properties. Among them, zero-dimensional (0D) low-toxic manganese-based scintillators have garnered significant interest due to their exceptional optical transparency and elevated photoluminescence quantum yields (PLQYs), making them promising for colorful light-emitting diodes and X-ray imaging applications. In this study, two OIMH single crystals of (Br-PrTPP)2MnBr4 (Br-PrTPP = (3-bromopropyl) triphenylphosphonium) and (Br-BuTPP)2MnBr4 (Br-BuTPP = (4-bromobutyl) triphenylphosphonium) were prepared via a facile saturated crystallization method. Benefiting from the tetrahedrally coordinated [MnBr4]2- polyhedron, both of them exhibited strong green emissions peaked at 517 nm owing to the d-d electron transition of Mn2+ with near-unity PLQYs of 99.33 and 86.85%, respectively. Moreover, benefiting from the high optical transparencies and remarkable luminescence properties, these manganese halides also exhibit excellent radioluminescent performance with the highest light yield of up to 68,000 photons MeV-1, negligible afterglow (0.4 ms), and linear response to X-ray dose rate with the lowest detection limit of 45 nGyair s-1. In X-ray imaging, the flexible film made by the composite of (Br-PrTPP)2MnBr4 and PDMS shows an ultrahigh spatial resolution of 12.78 lp mm-1, which provides a potential visualization tool for X-ray radiography.

Dual-Emissive Monoruthenium Complexes of N(CH3)-Bridged Ligand: Synthesis, Characterization, and Substituent Effect.

Three monoruthenium complexes 1(PF6)2-3(PF6)2 bearing an N(CH3)-bridged ligand have been synthesized and characterized. These complexes have a general formula of [Ru(bpy)2(L)](PF6)2, where L is a 2,5-di(N-methyl-N'-(pyrid-2-yl)amino)pyrazine (dapz) derivative with various substituents, and bpy is 2,2'-bipyridine. The photophysical and electrochemical properties of these compounds have been examined. The solid-state structure of complex 3(PF6)2 is studied by single-crystal X-ray analysis. These complexes show two well-separated emission bands centered at 451 and 646 nm (Δλmax = 195 nm) for 1(PF6)2, 465 and 627 nm (Δλmax = 162 nm) for 2(PF6)2, and 455 and 608 nm (Δλmax = 153 nm) for 3(PF6)2 in dilute acetonitrile solution, respectively. The emission maxima of the higher-energy emission bands of these complexes are similar, while the lower-energy emission bands are dependent on the electronic nature of substituents. These complexes display two consecutive redox couples owing to the stepwise oxidation of the N(CH3)-bridged ligand and ruthenium component. Moreover, these experimental observations are analyzed by computational investigation.

Rapid and Low-Cost Quantification of Adulteration Content in Camellia Oil Utilizing UV-Vis-NIR Spectroscopy Combined with Feature Selection Methods.

This study aims to explore the potential use of low-cost ultraviolet-visible-near infrared (UV-Vis-NIR) spectroscopy to quantify adulteration content of soybean, rapeseed, corn and peanut oils in Camellia oil. To attain this aim, test oil samples were firstly prepared with different adulterant ratios ranging from 1% to 90% at varying intervals, and their spectra were collected by an in-house built experimental platform. Next, the spectra were preprocessed using Savitzky-Golay (SG)-Continuous Wavelet Transform (CWT) and the feature wavelengths were extracted using four different algorithms. Finally, Support Vector Regression (SVR) and Random Forest (RF) models were developed to rapidly predict adulteration content. The results indicated that SG-CWT with decomposition scale of 25 and the Iterative Variable Subset Optimization (IVSO) algorithm can effectively improve the accuracy of the models. Furthermore, the SVR model performed best for predicting adulteration of camellia oil with soybean oil, while the RF models were optimal for camellia oil adulterated with rapeseed, corn, or peanut oil. Additionally, we verified the models' robustness by examining the correlation between the absorbance and adulteration content at certain feature wavelengths screened by IVSO. This study demonstrates the feasibility of using low-cost UV-Vis-NIR spectroscopy for the authentication of Camellia oil.

Electrically Amplified Circularly Polarized Luminescence by a Chiral Anion Strategy.

The development of circularly polarized electroluminescence (CPEL) is currently hampered by the high difficulty and cost in the syntheses of suitable chiral materials and the notorious chirality diminishment issue in electrical devices. Herein, diastereomeric IrIII and RuII complexes with chiral (±)-camphorsulfonate counteranions are readily synthesized and used as the active materials in circularly polarized light-emitting electrochemical cells to generate promising CPELs. The addition of the chiral ionic liquid (±)-1-butyl-3-methylimidazole camphorsulfonate into the active layer significantly improves the device performance and the electroluminescence dissymmetry factors (≈10-3 ), in stark contrast to the very weak circularly polarized photoluminescence of the spin-coated films of these diastereomeric complexes. Control experiments with enantiopure IrIII complexes suggest that the chiral anions play a dominant role in the electrically-induced amplification of CPELs.

Molecular Cocrystals with Hydrogen-Bonded Polymeric Structures and Polarized Luminescence.

Crystalline materials with appealing luminescent properties are attractive materials for various optoelectronic applications. The in situ bicomponent reaction of 1,2-ethylenedisulfonic acid with 1,4-di(pyrid-2-yl)benzene, 1,4-di(pyrid-3-yl)benzene, or 1,4-di(pyrid-4-yl)benzene affords luminescent crystals with hydrogen-bonded polymeric structures. Variations in the positions of the pyridine nitrogen atoms lead to alternating polymeric structures with either a ladder- or zigzag-type of molecular arrangement. By using a nanoprecipitation method, microcrystals of these polymeric structures are prepared, showing polarized luminescence with a moderate degree of polarization.

Unveiling Local Electronic Structure of Lanthanide-Doped Cs2 NaInCl6 Double Perovskites for Realizing Efficient Near-Infrared Luminescence.

Lanthanide ion (Ln3+ )-doped halide double perovskites (DPs) have evoked tremendous interest due to their unique optical properties. However, Ln3+ ions in these DPs still suffer from weak emissions due to their parity-forbidden 4f-4f electronic transitions. Herein, the local electronic structure of Ln3+ -doped Cs2 NaInCl6 DPs is unveiled. Benefiting from the localized electrons of [YbCl6 ]3- octahedron in Cs2 NaInCl6 DPs, an efficient strategy of Cl- -Yb3+ charge transfer sensitization is proposed to obtain intense near-infrared (NIR) luminescence of Ln3+ . NIR photoluminescence (PL) quantum yield (QY) up to 39.4% of Yb3+ in Cs2 NaInCl6 is achieved, which is more than three orders of magnitude higher than that (0.1%) in the well-established Cs2 AgInCl6 via conventional self-trapped excitons sensitization. Density functional theory calculation and Bader charge analysis indicate that the [YbCl6 ]3- octahedron is strongly localized in Cs2 NaInCl6 :Yb3+ , which facilitates the Cl- -Yb3+ charge transfer process. The Cl- -Yb3+ charge transfer sensitization mechanism in Cs2 NaInCl6 :Yb3+ is further verified by temperature-dependent steady-state and transient PL spectra. Furthermore, efficient NIR emission of Er3+ with the NIR PLQY of 7.9% via the Cl- -Yb3+ charge transfer sensitization is realized. These findings provide fundamental insights into the optical manipulation of Ln3+ -doped halide DPs, thus laying a foundation for the future design of efficient NIR-emitting DPs.

Selective, Anisotropic, or Consistent Polarized-Photon Out-Coupling of 2D Organic Microcrystals.

Nano- and micromaterials with anisotropic photoluminescence and photon transport have widespread application prospects in quantum optics, optoelectronics, and displays. But the nature of the polarization information of the out-coupled light, with respect to that of the source luminescence, has never been explored in active optical-waveguiding organic crystals. Herein, three different modes (selective, anisotropic, and consistent) of polarized-photon out-coupling are proposed and successfully implemented in a set of 2D organic microcrystals with highly linearly-polarized luminescence. It is found that the polarization direction and degree of the luminescence out-coupled through different waveguiding channels can either be essentially retained or distinctly changed with respect to those of the original luminescence, depending on the molecular arrangement and the orientation of transition dipole moments of the crystal. This work demonstrates the promising potential of 2D emissive microcrystals in multi-channel polarized photon transport.

Organoplatinum(II) Cruciform: A Versatile Building Block to Fabricate 2D Microcrystals with Full-Color and White Phosphorescence and Anisotropic Photon Transport.

Conventional square-planar platinum complexes typically form one-dimensional assemblies as a result of unidirectional metallophilic and/or π⋅⋅⋅π intermolecular interactions. Organoplatinum(II) complexes with a cruciform shape are presented herein to construct two-dimensional (2D) microcrystals with full-color and white phosphorescence. These 2D crystals show unique monocomponent π⋅⋅⋅π stacking, from either the cyclometalating or noncyclometalating ligand, and the bicomponent alternate π⋅⋅⋅π stacking from both ligands along different facet directions. Anisotropic tri-directional waveguiding is further implemented on a single hexagonal microcrystal. These results demonstrate the great capability of the organoplatinum(II) cruciform as a general platform to fabricate 2D phosphorescent micro-/nanocrystals for advanced photonic applications.

Boosting the Self-Trapped Exciton Emission in Alloyed Cs2 (Ag/Na)InCl6 Double Perovskite via Cu+ Doping.

Fundamental understanding of the effect of doping on the optical properties of 3D double perovskites (DPs) especially the dynamics of self-trapped excitons (STEs) is of vital importance for their optoelectronic applications. Herein, a unique strategy via Cu+ doping to achieve efficient STE emission in the alloyed lead-free Cs2 (Ag/Na)InCl6 DPs is reported. A small amount (1.0 mol%) of Cu+ doping results in boosted STE emission in the crystals, with photoluminescence (PL) quantum yield increasing from 19.0% to 62.6% and excitation band shifting from 310 to 365 nm. Temperature-dependent PL and femtosecond transient absorption spectroscopies reveal that the remarkable PL enhancement originates from the increased radiative recombination rate and density of STEs, as a result of symmetry breakdown of the STE wavefunction at the octahedral Ag+ site. These findings provide deep insights into the STE dynamics in Cu+ -doped Cs2 (Ag/Na)InCl6 , thereby laying a foundation for the future design of new lead-free DPs with efficient STE emission.

Dual-Band-Tunable White-Light Emission from Bi3+ /Te4+ Emitters in Perovskite-Derivative Cs2 SnCl6 Microcrystals.

Luminescent metal halides have attracted considerable attention in next-generation solid-state lighting because of their superior optical properties and easy solution processibility. Herein, we report a new class of highly efficient and dual-band-tunable white-light emitters based on Bi3+ /Te4+ co-doped perovskite derivative Cs2 SnCl6 microcrystals. Owing to the strong electron-phonon coupling and efficient energy transfer from Bi3+ to Te4+ , the microcrystals exhibited broad dual-band white-light emission originating from the inter-configurational 3 P0,1 →1 S0 transitions of Bi3+ and Te4+ , with good stability and a high photoluminescence (PL) quantum yield of up to 68.3 %. Specifically, a remarkable transition in Bi3+ -PL lifetime from milliseconds at 10 K to microseconds at 300 K was observed, as solid evidence for the isolated Bi3+ emission. These findings provide not only new insights into the excited-state dynamics of Bi3+ and Te4+ in Cs2 SnCl6 , but also a general approach to achieve single-composition white-light emitters based on lead-free metal halides through ns2 -metal ion co-doping.

Dual-Emissive Tris-Heteroleptic Ruthenium Complexes: Tuning the DNA-Triggered Ratiometric Emission Response by Ancillary Ligands.

Three tris-heteroleptic mononuclear Ru(II) complexes with dual fluorescence and phosphorescence-[Ru(dpma)(bpy)(phen)]2+ (12+), [Ru(dpma)(bpy)(dppz)]2+ (22+), and [Ru(dpma)(phen)(dppz)]2+ (32+)-have been designed and used as ratiometric light-response probes for DNA, where dpma is di(pyrid-2-yl)(methyl)-amine, bpy is 2,2'-bipyridine, phen is 1,10-phenanthroline, and dppz is dipyridophenazine, respectively. Single crystals of complex 2(PF6)2 have been obtained and studied by X-ray analysis. The interactions of these complexes with different DNAs are investigated by means of spectroscopic methods, viscosity measurements, and molecular modeling. In the presence of calf thymus DNA, complexes 2(PF6)2 and 3(PF6)2 show the emergence of a new lower-energy phosphorescence emission band; meanwhile, the higher-energy fluorescence emission band is essentially unchanged, functioning as an intrinsic internal reference. These two complexes exhibit stronger preference for calf thymus DNA over single-strand DNA (d(A)16 and d(C)16). In contrast, no binding interaction between 1(PF6)2 and calf thymus DNA is observed. The intrinsic binding constants (Kb) of 2(PF6)2 and 3(PF6)2 with calf thymus DNA are determined to be (1.4 ± 0.4) × 105 and (9.5 ± 0.15) × 104 M-1, respectively. In addition, these spectroscopic results are compared with those of the prototype complex [Ru(bpy)2(dppz)]2+ (42+), and density functional theory and time-dependent density functional theory calculations are employed to elucidate these experimental findings.

Full-Color and White Circularly Polarized Luminescence of Hydrogen-Bonded Ionic Organic Microcrystals.

A simple and general method is presented herein for the in situ preparations of circularly polarized luminescence (CPL)-active microcrystals with a large luminescence dissymmetry factor glum , high fluorescence quantum efficiency (ΦFL ), wide emission color tenability, and well-ordered morphology. The reactions of pyridine-containing achiral molecules 1-7 with chiral camphor sulfonic acid ((±)-CSA) gave crystalline microplates formed by hydrogen bonding interactions between the protonated pyridinium units and the sulfonic anions. The chiral information of CSA are effectively transferred to the microcrystals by hydrogen bonding to afford full-color CPL from deep-blue to red with glum in the order of 10-2 and ΦFL up to 80 %. Moreover, organic microcrystals with high-performance white CPL (ΦFL =46 %; |glum |=0.025) are achieved via the light-harvesting energy transfer between blue and yellow emitters.

A Carbazole-Bridged Biscyclometalated Diplatinum Complex: Synthesis, Characterization, and Dual-Mode Aggregation-Enhanced Phosphorescence.

A cationic carbazole-bridged biscyclometalated diplatinum complex 4 has been synthesized and characterized. Single-crystal X-ray analysis demonstrates that complex 4 displays a dimeric structure with noncovalent π-π stacking and unique double Pt-Pt interactions. In aerated dilute CH3CN, complex 4 is characterized by a very weak monomeric yellow emission (λemi = 547 nm; Φ = 0.51%), which is attributed to the triplet intraligand (3LC) excited state mixing with some charge transfer characters. In contrast, under aerated conditions, the dispersion of 4 in a mixed solvent of CH3CN/Et2O (1/9, v/v) or CH3CN/H2O (1/9, v/v) displays intense yellow (λemi = 550 nm; Φ = 35.5%; τ = 11.10 µs) and red emission (λemi = 635 nm; Φ = 14.1%; τ = 7.00 µs), respectively. These aggregation-induced phosphorescent emission enhancements are considered being caused by the oxygen-shielding effect and the molecular rigidification-induced decrease of nonradiative decays in the aggregate state. The morphology and size of the aggregates under these two conditions are examined by scanning electron microscope and dynamic light scattering analysis. The absorption and emission properties of 4 are further rationalized by time-dependent density functional theory calculations on a model compound.

Engineering the Bandgap and Surface Structure of CsPbCl3 Nanocrystals to Achieve Efficient Ultraviolet Luminescence.

Herein, we report the design of novel ultraviolet luminescent CsPbCl3 nanocrystals (NCs) with the emission peak at 381 nm through doping of cadmium ions. Subsequently, a surface passivation strategy with CdCl2 is adopted to improve their photoluminescence quantum yield (PLQY) with the maximum value of 60.5 %, which is 67 times higher than that of the pristine counterparts. The PLQY of the surface passivated NCs remains over 50 % after one week while the pristine NCs show negligible emission. By virtue of density functional theory calculations, we reveal that the higher PLQY and better stability after surface passivation may result from the significant elimination of surface chloride vacancy (VCl ) defects. These findings provide fundamental insights into the optical manipulation of metal ion-doped CsPbCl3 NCs.

Unveiling the Excited-State Dynamics of Mn2+ in 0D Cs4PbCl6 Perovskite Nanocrystals.

Doping is an effective strategy for tailoring the optical properties of 0D Cs4PbX6 (X = Cl, Br, and I) perovskite nanocrystals (NCs) and expanding their applications. Herein, a unique approach is reported for the controlled synthesis of pure-phase Mn2+-doped Cs4PbCl6 perovskite NCs and the excited-state dynamics of Mn2+ is unveiled through temperature-dependent steady-state and transient photoluminescence (PL) spectroscopy. Because of the spatially confined 0D structure of Cs4PbCl6 perovskite, the NCs exhibit drastically different PL properties of Mn2+ in comparison with their 3D CsPbCl3 analogues, including significantly improved PL quantum yield in solid form (25.8%), unusually long PL lifetime (26.2 ms), large exciton binding energy, strong electron-phonon coupling strength, and an anomalous temperature evolution of Mn2+-PL decay from a dominant slow decay (in tens of ms scale) at 300 K to a fast decay (in 1 ms scale) at 10 K. These findings provide fundamental insights into the excited-state dynamics of Mn2+ in 0D Cs4PbCl6 NCs, thus laying a foundation for future design of 0D perovskite NCs through metal ion doping toward versatile applications.