Emission Spectra Research Articles

Predicting Emission of Heteroleptic Iridium Complexes using Artificial Chemical Intelligence.

We report a deep learning-based approach to accurately predict the emission spectraof phosphorescent heteroleptic [Ir(C^N)2(NN)]+complexes, enabling the rapid discovery of novel Ir(III) chromophores for diverse applications including organic light-emitting diodes and solar fuel cells. The deep learning models utilize graph neural networks and other chemical features in architectures that reflect the inherent structure of the heteroleptic complexes, composed of C^Nand N^Nligands, and are thus geared towards efficient training over the dataset. By leveraging experimental emission data, our models reliably predict the full emission spectra of these complexes across various emission profiles, surpassing the accuracy of conventional DFT and correlated wavefunction methods, while simultaneously achieving robustness to the presence of imperfect (noisy, low-quality) training spectra. We showcase the potential applications for these and related models for \insilico\ prediction of complexes with tailored emission properties, as well as in "design of experiment'' contexts to reduce the synthetic burden of high-throughput screening. In the latter case, we demonstrate that the models allow to exploit a limited amount of experimental data to explore a wide range of chemical space, thus leveraging a modest synthetic effort.

Influence of O-H···Pt interactions on photoluminescent response in the (Bu4N)2{[Pt(bph)(CN)2][phenylene-1,4-diresorcinol]} framework.

Tunable photoluminescence (PL) is one of the hot topics in current materials science, and research performed on the molecular phases is at the forefront of this field. We present the new (Et4N)2[PtII(bph)(CN)2]·rez3·1/3H2O (Pt2rez3) (bph = biphenyl-2,2'-diyl; rez3 = 3,3",5,5"-tetrahydroxy-1,1':4',1"-terphenyl,phenylene-1,4-diresorcinol coformer, a linear quaternary hydrogen bond donor) co-crystal salt based on the recently appointed promising [PtII(bph)(CN)2]2- luminophore. Within the extended hydrogen-bonded subnetwork [PtII(bph)(CN)2]2- complexes and rez3 coformer molecules form two types of contacts: the rez3O-H···Ncomplex ones in the equatorial plane of the complex and non-typical rez3O-H···Pt ones along its axial direction. The combined structural, PL, and DFT approach distinguished the rez3O-H···Pt synthons to promote the noticeable uniform redshift of bph ligand centered (LC) emission compared to the LC emission of (Et4N)2[PtII(bph)(CN)2]·H2O (Pt2) precursor owing to the direct interference of the phenol group into the PtII-bph orbital system via altering the CT processes. The high-resolution emission spectra for Pt2 and Pt2rez3 were successfully reproduced at 77 K by using the Franck-Cordon expressions. The possibility to tune PL properties along the plausible continuum of rez3O-H···Pt synthons is indicated, considering various scenarios of molecular occupation of the space above and below the complex plane.

Fiber optic-based integrated system for in vivo multiscale pharmacokinetic monitoring

This paper presents the development of a fiber-optic-based fluorescence detection system for multi-scale monitoring of drug distribution in living animals. The integrated system utilized dual laser sources at the wavelengths of 488 nm and 650 nm and three photomultiplier channels for multi-color fluorescence detection. The emission spectra of fluorescent substances were tracked using the time-resolved fluorescence spectroscopy module to continuously monitor their blood kinetics. The fiber bundle, consisting of 30,000 optic filaments, was designed for wide-field mesoscopic imaging of the drug’s interactions within organs. The inclusion of a gradient refractive index (GRIN) lens within the setup enabled fluorescence confocal laser scanning microscopy to visualize the drug distribution at the cellular level. The system performance was verified by imaging hepatic and renal tissues in mice using cadmium telluride quantum dots (CdTe QDs) and R3. By acquiring multi-level images and real-time data, our integrated system underscores its potential as a potent tool for drug assessment, specifically within the realms of pharmacokinetic and pharmacodynamic investigations.

The quantification of southern corn leaf blight disease using deep UV fluorescence spectroscopy and autoencoder anomaly detection techniques.

Southern leaf blight (SLB) is a foliar disease caused by the fungus Cochliobolus heterostrophus infecting maize plants in humid, warm weather conditions. SLB causes production losses to corn producers in different regions of the world such as Latin America, Europe, India, and Africa. In this paper, we demonstrate a non-destructive method to quantify the signs of fungal infection in SLB-infected corn plants using a deep UV (DUV) fluorescence spectrometer, with a 248.6 nm excitation wavelength, to acquire the emission spectra of healthy and SLB-infected corn leaves. Fluorescence emission spectra of healthy and diseased leaves were used to train an Autoencoder (AE) anomaly detection algorithm-an unsupervised machine learning model-to quantify the phenotype associated with SLB-infected leaves. For all samples, the signature of corn leaves consisted of two prominent peaks around 450 nm and 325 nm. However, SLB-infected leaves showed a higher response at 325 nm compared to healthy leaves, which was correlated to the presence of C. heterostrophus based on disease severity ratings from Visual Scores (VS). Specifically, we observed a linear inverse relationship between the AE error and the VS (R2 = 0.94 and RMSE = 0.935). With improved hardware, this method may enable improved quantification of SLB infection versus visual scoring based on e.g., fungal spore concentration per unit area and spatial localization.

References for Small Fluorescence Quantum Yields.

Three compounds with fluorescence quantum yields in the range of 10- 5 to 10- 4 and emission spectra covering the UV/Vis spectral range are suggested as new references for the determination of small fluorescence quantum yields. The compounds are thymidine (dT) in water, dibenzoylmethane (DBM) in ethanol, and malachite green chloride (MG) in water, representing the blue, green, and red regions of the spectrum, respectively. All compounds are easily handled, photostable, and commercially available. Furthermore, these compounds exhibit a mirror-image symmetry between their absorption and fluorescence spectra. This symmetry, along with closely aligned fluorescence excitation and absorption spectra, confirms that the observed emissions originate from the compounds themselves. The fluorescence quantum yields were determined via a relative approach as well as Strickler-Berg analysis in conjunction with time resolved fluorescence spectroscopy. Within the respective error margins, the two approaches yielded identical results.

Deciphering the chemical language of inbred and wild mouse conspecific scents.

In most mammals, conspecific chemosensory communication relies on semiochemical release within complex bodily secretions and subsequent stimulus detection by the vomeronasal organ (VNO). Urine, a rich source of ethologically relevant chemosignals, conveys detailed information about sex, social hierarchy, health, and reproductive state, which becomes accessible to a conspecific via vomeronasal sampling. So far, however, numerous aspects of social chemosignaling along the vomeronasal pathway remain unclear. Moreover, since virtually all research on vomeronasal physiology is based on secretions derived from inbred laboratory mice, it remains uncertain whether such stimuli provide a true representation of potentially more relevant cues found in the wild. Here, we combine a robust low-noise VNO activity assay with comparative molecular profiling of sex- and strain-specific mouse urine samples from two inbred laboratory strains as well as from wild mice. With comprehensive molecular portraits of these secretions, VNO activity analysis now enables us to (i) assess whether and, if so, how much sex/strain-selective 'raw' chemical information in urine is accessible via vomeronasal sampling; (ii) identify which chemicals exhibit sufficient discriminatory power to signal an animal's sex, strain, or both; (iii) determine the extent to which wild mouse secretions are unique; and (iv) analyze whether vomeronasal response profiles differ between strains. We report both sex- and, in particular, strain-selective VNO representations of chemical information. Within the urinary 'secretome', both volatile compounds and proteins exhibit sufficient discriminative power to provide sex- and strain-specific molecular fingerprints. While total protein amount is substantially enriched in male urine, females secrete a larger variety at overall comparatively low concentrations. Surprisingly, the molecular spectrum of wild mouse urine does not dramatically exceed that of inbred strains. Finally, vomeronasal response profiles differ between C57BL/6 and BALB/c animals, with particularly disparate representations of female semiochemicals.

Deciphering the chemical language of inbred and wild mouse conspecific scents

In most mammals, conspecific chemosensory communication relies on semiochemical release within complex bodily secretions and subsequent stimulus detection by the vomeronasal organ (VNO). Urine, a rich source of ethologically relevant chemosignals, conveys detailed information about sex, social hierarchy, health, and reproductive state, which becomes accessible to a conspecific via vomeronasal sampling. So far, however, numerous aspects of social chemosignaling along the vomeronasal pathway remain unclear. Moreover, since virtually all research on vomeronasal physiology is based on secretions derived from inbred laboratory mice, it remains uncertain whether such stimuli provide a true representation of potentially more relevant cues found in the wild. Here, we combine a robust low-noise VNO activity assay with comparative molecular profiling of sex- and strain-specific mouse urine samples from two inbred laboratory strains as well as from wild mice. With comprehensive molecular portraits of these secretions, VNO activity analysis now enables us to (i) assess whether and, if so, how much sex/strain-selective ‘raw’ chemical information in urine is accessible via vomeronasal sampling; (ii) identify which chemicals exhibit sufficient discriminatory power to signal an animal’s sex, strain, or both; (iii) determine the extent to which wild mouse secretions are unique; and (iv) analyze whether vomeronasal response profiles differ between strains. We report both sex- and, in particular, strain-selective VNO representations of chemical information. Within the urinary ‘secretome’, both volatile compounds and proteins exhibit sufficient discriminative power to provide sex- and strain-specific molecular fingerprints. While total protein amount is substantially enriched in male urine, females secrete a larger variety at overall comparatively low concentrations. Surprisingly, the molecular spectrum of wild mouse urine does not dramatically exceed that of inbred strains. Finally, vomeronasal response profiles differ between C57BL/6 and BALB/c animals, with particularly disparate representations of female semiochemicals.

Primordial black hole superradiance and evaporation in the string axiverse

In the string axiverse scenario, light primordial black holes may spin up due to the Hawking emission of a large number of light (sub-MeV) axions. We show that this may trigger superradiant instabilities associated with a heavier axion during the black holes’ evolution, and study the coupled dynamics of superradiance and evaporation. We find, in particular, that the present black hole mass-spin distribution should follow the superradiance threshold condition for black hole masses below the value at which the superradiant cloud forms, for a given heavy axion mass. Furthermore, we show that the decay of the heavy axions within the superradiant cloud into photon pairs may lead to a distinctive line in the black hole’s emission spectrum, superimposed on its electromagnetic Hawking emission.

Optical properties and passive self Q-switching of floating zone grown Cr–Nd co-doped YVO4 crystal

Single crystals of Cr (0.7, 1.0, 1.4 and 2.0 at%) and Nd (0.7 at%) co-doped yttrium vanadate (YVO4) were grown by optical floating zone method. [100]-oriented elements were fabricated from the grown crystals for optical and lasing studies. The refractive index analysis revealed that the values of ordinary refractive indices (no) for 0.7, 1.0, 1.4 and 2.0 at% Cr doped samples were found to be almost constant except for a slight increase corresponding to 532 nm. But the extraordinary refractive indices (ne) was found to increase with Cr doping concentration and it is maximum at 1.4 at% for all the wavelengths. The thermal coefficient of ne and no increases slightly and becomes constant beynd 1.4 at% of Cr. The band gap of the crystal is polarization sensitive with the values in the range of 3.51–3.55 eV and 3.59–3.62 eV for electric field parallel and perpendicular to c axis, respectively. The band gap does not exhibit any significant change on Cr doping. The emission spectrum with excitation at 808 nm is characterized by three broad asymmetric bands centered at 896, 1064 and 1341 nm. The emission intensity for the peak around 1064 nm decreases with an increase in Cr due to a broad absorption around 1100 nm of Cr5+ ion and, therefore, this band is exploited for passive Q-switching in the crystal. Further, excitation at 400 nm of Cr band revealed that there is strong emission at 1064 nm, which may be explored for pumping the gain medium with solar radiation. Finally, a stable passive Q-switching at 1064 nm was demonstrated in [100] element fabricated from the gown crystal having 1.4 at% Cr. An output power of ∼108 mW having pulse-width ∼220 ns and repetition rate ∼239 kHz was achieved for a pumping of ∼14.6 W at 808 nm.

Anthocyanins of Delonix Regia Floral Petals: A Novel Approach on Fluorescence Enhancement, Forster Resonance Energy Transfer Mechanism and Photostability Studies for Optoelectronic Applications.

In this work, we focused on extracting the anthocyanin dye in acetone, butanol, ethanol, and water solvents from Delonix regia flowers by a simple maceration extraction process. The identification of functional group analysis, vibrational studies, energy transfer mechanisms, optoelectronic properties, photostability studies, FRET-assisted potential light emissions and photometric properties of the anthocyanin dyes are successively investigated. FTIR spectroscopy and vibrational studies have confirmed the existence of polyphenolic groups in 2-phenyl chromenylium (anthocyanin) dyes. The optoelectronic results show the least direct bandgap (2.04eV), indirect bandgap (1.55eV), Urbach energy (0.380eV), high refractive index (1.20), dielectric constant (2.794), and high optical conductivity (1.954 × 103 S/m) for the anthocyanin dye extracted found in water solvent. The photoluminescence properties such as Stoke's shift, high quantum yield, and lifetime results show that anthocyanin dyes are promising candidates for red-LEDs and optical materials. The absorption and emission spectra of the anthocyanin dyes follow the mirror image rule and the Franck-Condon factor exists between vibrational energy levels corresponding to all the electronic transitions. The excellent correspondence between the absorption and emission spectra reinforces that the anthocyanins are efficient (46%) FRET probes. Further, photometric properties such as CIE, CRI, CCT and colour purity results of anthocyanins in all studied solvents revealed that this material exhibits orange to red shades (x = 0.48 → 0.54 and y = 0.36 →0.45) and is well suitable for have great potential in the manufacturing of Organic-LEDs and other optoelectronic device applications.

IMK–IAA MIPAS retrieval version 8: CH4 and N2O

Abstract. Using the IMK–IAA data processor, methane and nitrous oxide distributions were retrieved from version-8 limb emission spectra recorded with the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS). The dataset includes measurements from the nominal, upper troposphere–lower stratosphere, middle-atmosphere, upper-atmosphere and noctilucent-cloud observation modes. The processing differs from the previous version-5 data with respect to the atmospheric state variables that are jointly retrieved along with the target gases CH4 and N2O, the treatment of the radiance offset, the selection of microwindows, the regularization, the spectroscopic data used and the treatment of horizontal variability of the atmospheric state. Besides the regular data product, a coarse-grid representation of the profiles with unity averaging kernels is available, as well as a specific research product for middle-atmosphere measurements resulting from a slightly different retrieval approach. The CH4 errors are dominated by the large spectroscopic uncertainty for line intensities, which probably is too pessimistic, and estimated to be 21 %–34 % in the altitude range 6–68 km for northern midlatitude summer day conditions. The N2O errors are 7 %–17 % below 45 km. At higher altitudes they increase strongly due to nearly vanishing N2O amounts. Analysis of the horizontal averaging kernels reveals that for both gases the horizontal resolution is sampling-limited; i.e., information is not smeared over consecutive limb scans. Zonal-mean seasonal composites of both CH4 and N2O exhibit the typical distribution of source gases with strong upwelling in the tropics and subsidence above the winter poles. Comparison with the previous data version shows several improvements: first, the vertical resolution of the retrieved CH4 (N2O) profiles has generally been significantly enhanced and varies between 2.5 (2.5) and 4 (5) km at altitudes between 10 and 60 km, with the best resolution around 30 km for both species. Secondly, the number of non-converged retrievals has been clearly reduced, and thirdly, formerly strongly oscillating profiles are now considerably smoother.

Polyvinylalcohol Composite Filled with Carbon Dots Produced by Laser Ablation in Liquids.

Carbon dots (CDs), owing to their excellent photoluminescent features, have been extensively studied for physics preparation methods and for biomedical and optoelectronic device applications. The assessment of the applicability of CDs in the production of luminescent polymeric composites used in LEDs, displays, sensors, and wearable devices is being pursued. The present study reports on an original, environmentally friendly, and low-cost route for the production of carbon dots with an average size of 4 nm by laser ablation in liquid. Jointly, to prove the significance of the study for a wide range of applications, a free-standing flexible polyvinyl alcohol (PVA) composite containing photoluminescent carbon dots was manufactured. CDs were prepared using targets of porose charcoal with a density of 0.271 g/cm3 placed in phosphate-buffered saline (PBS) liquid solution and irradiated for 30 min by pulsed IR diode laser. The optical properties of the obtained suspension containing carbon dots were studied with UV-ViS and FTIR spectroscopies. The photoluminescence of the produced carbon dots was confirmed by the emission peak at 480 nm in the luminescence spectrum. A narrow luminescence band with a full width at half-maximum (FWHM) of less than 40 nm could be an asset in spectral emission analysis in different applications. Atomic force microscopy confirms the feasibility of manufacturing CDs in clean and biocompatible environments, paving the way for an easier and faster production route, crucial for their wider applicability.

Multi-channel decentralized decoupling FxLMS algorithm and active vibration control experiment

When vibrations generated by marine machinery propagate through a ship’s hull into the ocean, they produce low-frequency radiated noise with distinct “acoustic fingerprint” characteristics. This noise, characterized by stable and concentrated energy, long transmission distances, and difficulty in elimination, becomes the primary target for enemy sonar detection. Active vibration isolation serves as a critical method for reducing low-frequency vibrations in ships and enhancing their acoustic stealth performance. However, control challenges persist, including multi-frequency excitation, frequency fluctuation, multi-channel coupling, and slow convergence speed. To address these issues, this paper introduced an innovative multi-channel decentralized decoupling filtered-x least mean square (DMFxLMS) algorithm. Firstly, a recursive least squares identification algorithm with a forgetting factor was proposed, taking into account the characteristics of single-input, multi-output and multi-input, and multi-output control systems, effectively enhancing the algorithm’s convergence speed and control accuracy. Secondly, based on the decentralized decoupling control concept, the multi-channel control system was simplified into parallel single-channel control loops. The control weight coefficient updates were only related to adjacent error signals, significantly reducing the algorithm’s computational complexity. Thirdly, an anti-impact link was designed to improve the algorithm’s robustness, considering the interference caused by other mechanical equipment during the control process. The influence of abnormal error signals in the control weight coefficient correction term was suppressed, and a percentage function was introduced to limit the output signal. Finally, the feasibility and effectiveness of the DMFxLMS algorithm were verified through simulations and experiments. The results demonstrated that the DMFxLMS algorithm achieved significant control effects for both constant frequency line spectrum excitation and frequency fluctuating line spectrum excitation, fulfilling the objective of reducing base vibration. The DMFxLMS algorithm exhibited fast convergence and excellent robustness, making it suitable for practical engineering applications.

Spatiotemporal differentiation of carbon budget and balance zoning: Insights from the middle reaches of the Yangtze River Urban Agglomeration, China

Urbanization has substantially changed land use and led to local growth and an overall imbalance in carbon emissions. Scientific analysis of carbon emissions from land use (CELU) and exploration of carbon balance zoning can provide useful references for regional low-carbon land use management in urban agglomerations. This study analyzed the spatiotemporal dynamics of CELU based on land use and socioeconomic data, and utilizing the emission coefficient method. The economic contribution coefficient of carbon emissions (ECC) and Ecological Support Coefficient of carbon emissions (ESC) was used as the basis for developing carbon balance zoning, and the main function positioning of counties was used to combine with carbon balance zoning. Subsequently carbon balance partitions with determinants across 190 counties in the Middle Reaches of the Yangtze River Urban Agglomeration (MRYRUA) was obtained. We found that the net carbon emissions from land use in MRYRUA increased from 1.242 to 4.049 million tons, showing a clear upward trend. Notably, the Gini coefficients of carbon emissions and sinks of the MRYRUA were both higher than 0.4, and the pressure on the regional carbon balance intensified. In addition, based on the carbon balance analysis, MRYRUA was divided into five types: low-carbon economic zones, low-carbon optimization zones, carbon intensity control zones and high-carbon optimization zones. These zones were used to combine with the main function positioning, and finally got 11 types of zoning results. In response, this study proposes different low-carbon land-use optimization strategies based on the carbon budget and comprehensive development characteristics of different zones.

Electronic analysis of n-propyl xanthate complexes with group 12 metals: a theoretical-experimental study.

Xanthates are organic compounds of great interest in coordination chemistry due to their different basic sites, which allow them to form complexes with different coordination modes and geometries. These compounds are relevant in the environment and act as heavy metal collectors in aqueous environments. In this theoretical-experimental work, electronic spectroscopy studies of n-propyl xanthate complexes with group 12 metals were performed. This study verified structural differences in these systems, depending on the environment in which they are inserted. In addition, structural differences were observed when the solid was changed to an n-hexane solution. Thus, it was observed that the complexes assume a mononuclear structure in solution, while they present a polymeric form in the solid phase. The electronic spectra obtained through TD-DFT calculations were compared to those of the previously synthesized complexes. In the final theoretical analysis, the main orbitals involved in these transitions were assigned using population analysis calculations. The synthesis of the complexes was confirmed through infrared (MID and FAR), UV‒Vis, Raman, and NMR-1H spectroscopic analyses. The structures of the mononuclear and polymeric complexes were optimized in vacuum and n-hexane. Under vacuum, DFT levels M06L/6-311 + + G** + LANL2TZ and M06L/def2-TZVP were used for the mononuclear complexes, and M06L/LANL2DZ + LANL2 were used for the polymer complexes. For the calculations of the mononuclear complexes in n-hexane, the same level of theory was used for the solid state. TD-DFT calculations for 300 excited states were performed with the same levels of theory and used the optimized structures of the complexes. Furthermore, population analysis was carried out on all the systems studied. Gaussian 09 software was used for the structure optimization, TD-DFT, and population analysis calculations. GaussSum software was used to evaluate the molecular orbitals and electronic spectra.

Thickness‐Dependent Formation Capacity and Mechanism of Planar (β)‐Conformation in Polydiarylfluorenes for Stable Deep‐Blue Polymer Light‐Emitting Diodes

AbstractConjugated polymers with p‐orbital overlap show intramolecular‐conformation‐dependent photophysical and electrical properties. Compared to the non‐planar segments, the planar conformation segments have a relatively long effective conjugated length and rigid backbone structure, which are beneficial for the enhancement of optoelectronic properties. Herein, the effect of film thickness on the formation capacity of planar (β) conformations in polyfluorene (poly[4‐(octyloxy)‐9,9‐diphenylfluorene‐2,7‐diyl]‐co‐[5‐(octyloxy)‐9,9‐diphenylfluorene‐2,7‐diyl], PODPF) for the fabrication of stable deep‐blue polymer light‐emitting diodes (PLEDs) is explored. Thickness‐tunable films with thicknesses ranging from 15 to 270 nm by controlling the concentration of precursor solution are prepared. The main observations are as follows. The PODPF chains in thin films are less likely to adopt the β conformations associated with the loose interchain packing in nano‐aggregates than those in thick films. Red‐shifted and well‐resolved emission spectra are observed for the annealed film with a high thickness, indicating the greater presence of β‐conformation segments. More interestingly, interchain aggregation is a necessary but not sufficient condition for the formation of β conformations. Finally, PLEDs based on β‐conformation segments have outstanding brightness, low turn‐on voltage, and stable deep‐blue electroluminescent behavior, confirming the unique advantage of planar conformation for optoelectronic applications.

High efficiency and high color purity deep‐blue organic light‐emitting diodes with blue index >500

AbstractThermally activated delayed fluorescent (TADF) and phosphorescent blue organic light‐emitting diodes (OLEDs) have been developed to overcome the relatively low triplet exciton utilization of traditional fluorescent OLEDs. However, broad emission spectra originating from charge transfer process limit the commercial application of such blue OLEDs. Herein, an effective phosphor‐sensitized fluorescent (PSF) OLED device structure was designed. PSF OLED exhibited a maximum blue index (BI) of 508 cd/A/CIEy with CIEy of 0.060, which has been the highest efficiency result reported for PSF deep‐blue OLEDs. A nearly 100% improvement in operational lifetime LT95 (L/L0 = 95%) was achieved successfully by using lower triplet energy (T1) and deuterated host materials. Impressively, the sensitized OLEDs maintained BI of 407 cd/A/CIEy, narrow emission spectra (FWHM = 17 nm), and high color purity (CIEy = 0.046), revealing the attractive technical advantages and commercial application potential.

Enhanced UVB 311 emission in Sb2O3–SiO2 glasses doped with Gd2O3 and tailored Pb3O4 content for potential phototherapy

This study investigates the enhancement of the sharp 311 nm UVB emission from Gd3+ ions in antimony silicate glass system doped with a fixed concentration of Gd2O3 (1.0 mol%) and varying amounts of red lead (40–10 mol%). The emission spectra revealed an intense sharp UVB band at 311 nm, originating from the 6P7/2 → 8S7/2 transition of gadolinium ions upon excitation at 273 nm. Interestingly, the intensity of this band nearly doubles as the Pb3O4 content decreases from 40 to 10 mol%. Such improvement was attributed to the decomposition of Pb3O4 into various phases that include α-PbO2, β-PbO2 polymorphs, and PbO. Out of these decomposition products, PbO acted as modifiers, reduced phonon losses and consequently enhanced the emission intensity. The decrease in Pb3O4 content is also hypothesized to promote de-clustering of Gd3+ ions within the glass matrix. This de-clustering reduced cross-relaxation losses, further contributed to the observed emission enhancement. In summary, this study demonstrated a successful strategy for boosting the UVB emission from Gd3+ ions in antimony silicate glasses by manipulating the content of Pb3O4.

An ESIPT-Based Fluorescent Probe for Wash-Free Cell Membrane Imaging.

The cell membrane tracking is important for studying the membrane function and diagnosing membrane-related diseases, so the development of fluorescent molecule specifically lighting up cell membrane is highly desirable. In this work, we designed and readily prepared a fluorescent dye (BOHI) that can target cell membrane. The pH-dependent emission spectra reveal that BOHI shows fluorescence based on the excited-state intramolecular proton transfer (ESIPT) under acidic and neutral conditions, while the blue-shifted emission from the phenolate anion of BOHI was observed when pH ≥ 9. Among various solvents, the weakest fluorescence emission was observed in H2O, which is favorable to wash-free imaging. The fluorescence intensity of BOHI is greatly affected by surfactants. The anionic surfactant can induce intense green fluorescence, while very weak fluorescence was observed in the solution of cationic surfactant. Hela cells images show that BOHI can specifically targets and lights up cell membrane.

A Ratiometric Green Fluorescent Carbazole-bis(hydrazinobenzothiazole) Probe for the Selective Detection of Toxic Hg2+ Ions in Real Water Samples.

A dyad Carbazolyl-bis(hydrazinobenzothiazole) was designed to form a symmetrical structure that containing two-arm active binding sites facilitates coordination with Hg2+ ion. This sensor has imparted a colorimetric and fluorometric changes in presence of Hg2+ ions. The ligand showed a selective blue shift in presence of Hg2+even in co-existence with heavy metal ions with luminescence change from colorless to blue and colorless to green under day light. Enhanced Intramolecular charge transfer process is responsible for fluorescence transformation when ligand interacts with Hg2+ ion. The emission spectra showed a ratiometric response to increasing addition of Hg2+ ions. The sensor is capable of detecting above the lower concentration of 6.8025 × 10-8 M. The fluorescence efficiency of CBT-2 with Hg2+ ion is quite stable under different co-metal ions and wide range of pH 6 to 9. The sensor CBT-2 forms a 1:1 stoichiometric complex with Hg2+ ions and the binding nature is confirmed from the 1H-NMR, FTIR, and mass spectroscopic studies. The sensor CBT-2 and its Hg2+ complex possess good binding nature to protein in Bovine Serum Albumin which could be good in biological applications. Additionally, wedevelop a practical application in real water sample analysis and electrochemical detection viaoxidation potential discrimination.