Energy Transfer Mechanism Research Articles

Synthesis of the polyethylene polyamine-based flexible covalent organic frameworks and their application for capturing and fluorescence sensing iodine

Effective uptake of radioactive steam waste in the fission process is of great vital for the safe use of nuclear energy. Nitrogen-rich polyethylenepolyamine provides effective adsorption sites for the capture of iodine, but triethylenediamine (TEDA)-impregnated activated carbon has the disadvantages of easy sublimation, poor safety, and poor regeneration capacity. Herein, we report five polyethylene polyamine-based (PEPA-based) flexible COFs for the first time which were synthesized by Schiff base polymerization reactions with the flexible knot [2,4,6-tris(4-formylphenoxy)-1,3,5-triazine (TPT–3–CHO)] and flexible linkers (PEPA). The PEPA-based flexible COFs possess large surface areas and strong iodine adsorption capacity, which can be reused. With the increase of the linker lengths, their BET-surface areas decreases, but their adsorption of iodine increase. When dispersed in polar organic solvents, the PEPA-based flexible COFs can fluorescently sense iodine through the electron transfer mechanism and the energy transfer mechanism.

Bi3+/Eu3+ Co‐Activated Multimode Anti‐Counterfeiting Material with White Light Emission and Orange‐Yellow Persistent Luminescence

AbstractTraditional anti‐counterfeiting luminescent phosphors are usually composed of single‐mode photoluminescence materials, which greatly limits the security of encryption by its static fluorescent pattern. Herein, multi‐mode luminescence properties are achieved including fluorescence and persistent luminescence (PersL) within single host by co‐doping Bi3+ and Eu3+ in CaNaSb2O6F (CNSOF). A tunable emission is observed from blue (Bi3+, 3P1→1S0) to white and then to orange‐yellow (Eu3+, 5D1→7F2 and 5D0→7F0, 1, 2, 3, 4) as the excitation schemes, environment temperatures and doping level are modulated. Impressively, the blue emission attributed to the Bi3+ rapidly disappears after stopping the excitation light irradiation, and only the intense orange‐yellow PersL produced by Eu3+ can be observed. And a possible model for the energy transfer and PersL mechanism is proposed by the investigation crystal structure and photoluminescence/PersL. A schematic of security logo and digital information encryption is demonstrated using the prepared samples, which shows the dynamic evolution of the emission color and PersL brightness. The excellent property of multiple color outputs, different decay processes, and external field stimulation modes (including low energy light, thermal, and mechanical stimuli) present in CNSOF:Bi3+, Eu3+ provides a fast, low‐cost, and effective method for advanced anti‐counterfeiting and information encryption applications.

Deciphering the Nd3+ environment and energy-transfer mechanisms in thermally stable novel calcium aluminate glasses: elucidation of broadband high-gain performance for laser applications

Rare-earth-doped barium calcium aluminate (BCA) glasses, having extended infrared (IR) transmission (6 μm), are attractive materials for near IR (NIR) photonic applications. Nd2O3-doped BCA glasses display broadband emission at 1.07 µm, but they are limited, with poor glass-forming ability (GFA) and low emission cross sections. In the present study, four different barium zinc calcium aluminate (BZCA) glasses are synthesized with varied ZnO concentrations (from 9.5 to 24.5 mol%) and doped with 0.5 mol% Nd2O3 to decipher the effect on GFA and spectroscopic properties. The addition of ZnO enhances the GFA, and the NdBZCA20 glass shows the maximum GFA. Ultraviolet (UV)–visible (Vis)–NIR absorption spectra reveal a decreasing trend in the nephelauxetic effect, while J–O parameters, emission, and gain properties lead to no significant alteration with increasing ZnO, and the structure–properties correlation is established accordingly. However, the emission cross sections for all ZnO concentrations are found ∼4.5 × 10−20 cm2 accompanied by broadband emission (Δλ eff ∼ 40 nm), which ensures the potentiality of these glasses for low-threshold high-gain laser applications as well as ultrashort pulse laser applications. Furthermore, a thorough analysis of 1.06 µm emission as a function of Nd concentration in the BZCA20 glass is reported here. The emission spectra and decay time indicate that 0.5 mol% is the optimized doping concentration. Inokuti–Hirayama and Burshtein equations are adopted to study the decay kinetics and energy-transfer mechanisms, which confirm that the energy-transfer process due to cross-relaxation is dominant up to 0.5 mol% concentration, whereas, beyond that concentration, excitation energy migration via the hopping mechanism supersedes.

Alkali Silicates Codoped with NIR-Emitting RE (Nd3+ and Yb3+) Ions for Thermometry Applications.

In the present study, the synthesis of BaSrSiO4 co-doped Yb3+ and Nd3+ nanophosphors (NPs) was successfully achieved through the conventional sol-gel method, as confirmed by X-ray diffraction and SEM analysis, verifying the formation of pure NPs. The FTIR and Raman spectra analysis confirm the formation of silicates, as different modes and vibrations of Si-O and Si-O-Si were seen at 800-1000cm-1. The energy transfer (ET) mechanism between Nd3+ and Yb3+ ions was seen as the emission spectra showed a rise in intensity of one over another. PLE emission spectra showed transitions at 2F7/2-2F5/2 for Yb3+ and from 4F3/2 to (4I9/2, 4I11/2, and 4I13/2) for Nd3+ when excited at 785nm. All the samples record low activation energy, which shows that the rate of reaction will be higher in all the samples, and it will be highest for 1mol% Nd3+ and 1mol% Yb3+. An increasing value of τ was seen with increasing Yb3+ concentration, which confirms the increase in the population of trap centers. The positron annihilation lifetime (PAL) curve showed that 1mol% Yb3+ and 2mol Nd3+ have single vacancies or shallower positron traps, whereas 3mol% Yb3+ and 2mol% Nd3+ have larger defects like surface oxygen vacancy clusters. The other two samples have balance vacancies, which makes them best for thermometry applications. The fluorescence intensity ratio (FIR) was calculated to get sensitivity for thermometry application. 2.13% K-1 sensitivity achieved at 303-333K temperature.

Study on the photoluminescence performance and thermal sensitivity of (Y,Gd)2O3:Tb3+,Dy3+,Tm3+ phosphors

Using ammonia as a precipitation agent, (Y,Gd)2O3:Tb3+x,Dy3+y,Tm3+z phosphors were synthesized by the co-precipitation method. In order to improve the luminescence performance of the luminescent center Tb3+, Tb3+-Dy3+ co-doping and Tb3+-Dy3+-Tm3+ tri-doping were successively carried out, and the optimal component formulations were determined by the controlled variable method (x = 0.03, y = 0.005, z = 0.001). XRD results showed that the sample has a cubic phase Y2O3 structure with good crystalline properties. SEM results revealed that the samples have a unique micro morphology of small ball aggregation. The effects of doping concentration of Dy3+ and Tm3+ on the luminescence properties of Tb3+ were systematically investigated. The energy transfer mechanism among the three ions of Tb3+-Dy3+-Tm3+ was demonstrated by photoluminescence spectroscopy, and the main interaction modes between ions were elucidated. In addition, the matrix lattice environment can change the thermal stability properties of phosphors. In this paper, the temperature characteristics of Y2O3:Tb3+,Dy3+,Tm3+ phosphors are expected to be changed by microtuning the Y2O3 matrix lattice with the introduction of Gd3+. The fluorescence intensity ratio (FIR) and thermal sensitivity indicated that Gd3+ has good temperature sensitivity, and its introduction can effectively improve the temperature sensing performance of the phosphors, which has a wide range of applications in optical temperature measurement sensors.

Research on structure and optical properties of Tm3+-Tb3+ doped borate glass

In this paper, a series of B2O3–Al2O3–ZnO–BaO–Tm2O3–Tb2O3 glasses were synthesized by high temperature melting method. Under appropriate ultraviolet excitation, Tm3+ ions produce 1D2→3F4 energy level transition and emit blue light. The concentration quenching point is 0.75 % mol, and the color saturation is high. Tb3+ ions produce 5D4→7F5 energy level transition and emit green light, and the concentration quenching point of Tb3+ ions is 0.75 % mol. By characterizing the fluorescence lifetime and luminescence intensity of B2O3–Al2O3–ZnO–BaO–Tm2O3–Tb2O3 glass, the existence of Tm3+→Tb3+ energy transfer in the glass was verified, and the energy transfer efficiency and energy transfer mechanism were studied in detail. It is found that B2O3–Al2O3–ZnO–BaO–Tm2O3–Tb2O3 glass is an ideal material for light-emitting diodes, light-emitting materials and fluorescent display devices.

Spectroscopy and luminescence dynamic of Ce3+ and Sm3+ ions in Na3Y(BO3)2

Ce3+, Sm3+ singly-doped and Ce3+-Sm3+ co-doped sodium yttrium borate Na3Y(BO3)2 phosphors are prepared using a high temperature solid-state reaction route, in order to investigate their spectroscopic properties, luminescence dynamic and energy transfer mechanisms. The weak electron-vibrational interaction (EVI) between Ce3+ ions and their surroundings is demonstrated according to measured spectra and theoretical analysis. The mechanism of the Ce3+ → Sm3+ energy transfer in the host is investigated via luminescence dynamic models. In addition, the potential application of Ce3+-Sm3+ co-doped Na3Y(BO3)2 phosphors in the optical anti-counterfeiting is demonstrated according to the luminescence regulation of excitation wavelength response.

Effects of real gas models on the wave dynamics and refrigeration of gas wave rotor

The gas wave rotor was usually designed and performed on the ideal gas model. However, the real gas effect could not be ignored anymore under high-pressure ratio conditions. In this study, for the first time, a two-dimensional computational model of a double-opening gas wave refrigerator (GWR) using a multi-parameter Benedict–Webb–Rubin equation of state is established and the influence of the real gas effect on gas wave dynamics and energy transfer processes in the GWR with discontinuous boundary conditions is thoroughly investigated. The numerical results show that the wave dynamics of the ideal gas and the real gas are similar under different operating conditions, but compression waves and expansion waves in real gas obviously lag behind the ideal gas. In addition, the low-temperature real gas is completely discharged earlier than the ideal gas and the difference between them gradually increases as the pressure ratio gets higher, which benefits the GWR compact structure design and cost reduction. At the same time, the temperature of the real gas being discharged is lower than that of the ideal gas. Therefore, the refrigeration efficiency of the isentropic expansion of the real gas will be improved compared with the operation in ideal gas. The research results on the real gas effect reveal the mechanism of wave dynamics and energy transfer, providing support for the optimization design of GWR.

Photoluminescence of Sm3+ and Eu3+ co-doped La2O3–Ga2O3 glasses fabricated by an aerodynamic levitation furnace

A series of transparent (1-y)La2O3–Ga2O3-ySm2O3-xEu2O3 (where x = 0, 0.02, 0.04, 0.06, 0.08, 0.10, 0.12, 0.14, and y = 0, 0.04) were successfully synthesized using a containerless solidification process. Co-doping with Sm3+ and Eu3+ enhanced the energy absorption of Eu3+, notably improving the characteristic emission peak 5D0-7F2 of Eu3+. The peak emission intensity for y = 0.04 was observed at x = 0.08, attributable to the concentration quenching of Eu3+ ions. As the concentration of Eu3+ increased, the energy transfer effect on emission intensity diminished. Attributed to the energy transfer between Sm3+ and Eu3+, Sm3+ may primarily serve as the sensitizer, and Eu3+ as the activator. According to the Dexter theory, which suggests that the interaction between activator ions and their adjacent ions is the primary mechanism of energy transfer and quenching among Eu3+ ions and adjacent ions, an increase in Eu3+ concentration leads to a decrease in the distance between Eu3+ and adjacent ions, strengthening their interaction, and potentially inducing concentration quenching. Furthermore, with an increase in Eu3+ concentration, the CIE chromaticity coordinates for the samples co-doped with Sm3+ and Eu3+ shifted significantly, enhancing the color purity of the emitted light and bringing it closer to the NTSC color standard coordinates (0.67, 0.33).

Enhanced photocatalytic degradation of sulfathiazole via dual-ligand Zr-MOFs: A porphyrin and pyrene-based energy transfer

Energy transfer (EnT) has been identified as an effective method to facilitate charge separation and improve photocatalytic performance. However, EnT has rarely been used in the photocatalytic degradation of pollutants. In this study, the arrangement of organic ligands in metal–organic frameworks (MOFs) was precisely engineered to enable efficient EnT among ligands. The compounds TCx-TB10 (X = 3, 4, 5, 6, 7, 8) were synthesized through solvothermal and technique, employing 5,10,15,20-tetrakis(4-carboxyphenyl)porphyrin (TCPP) and 1,3,6,8-tetrakis(p-benzoic acid)pyrene (TBAPy) as ligands for the photocatalytic degradation of sulfathiazole (STZ). Among these, TC4-TB10 achieved the highest degradation efficiency, with a removal rate of 93.09 % for STZ. When similar photocatalytic tests were conducted on ranitidine (RAN), nizatidine (NZT), tetracycline (TC), and gatifloxacin (GAT), TC4-TB10 continued to demonstrate outstanding photocatalytic activity, showing removal efficiencies of 95.85 %, 95.30 %, 86.50 %, and 85.85 %, respectively. The effective EnT mechanism from TBAPy to TCPP in TC4-TB10 was confirmed through fluorescence and photocatalytic oxidation studies. Furthermore, singlet oxygen (1O2) was identified as the main reactive oxygen species involved. Proposed degradation pathways for STZ were outlined based on DFT calculations and UPLC-HRMS analysis. The Toxicity Estimation Software Tool (T.E.S.T.) was used to predict that STZ and its degradation products would largely exhibit low or no toxicity. Notably, 1O2 demonstrated remarkable resistance to interference, not being affected by most inorganic ions and humic acid (HA), which allowed TC4-TB10 to maintain high STZ removal rates even in real water samples. This research extends the potential applications and offers important insights into employing the EnT process for enhancing the photocatalytic capabilities of MOFs.

Click generated photochromic naphthalenediimide-dithienylethene diad: Application in deciphering secret codes

Photochromic molecules with efficient fluorescence switching capability remain a core research interest among the scientific community for the application in security technologies and anti-counterfeiting measures. A dithienylethene-naphthalene diimide diad was designed and synthesized using Cu(I) catalysed click reaction between a fluorescent core substituted naphthalene diimide (cNDI) and photochromic dithienylethene (DTE) molecule, which demonstrated excellent photocyclization (ksolution = 0.0359 s−1, ksolid = 0.0122 s−1) and photocycloreversion (ksolution = 0.01737 s−1, ksolid = 0.00456 s−1) dynamics with high fluorescence quantum yield (5o ΦF = 0.39, PSS ΦF = 0.05). The fluorescence property of the molecule was switched ‘on-off’ by UV and visible light irradiation respectively via Förster resonance energy transfer (FRET) mechanism in solution state as well as in solid state, which was further corroborated with DFT studies. In view of efficient fluorescence switching behaviour and high fatigue resistance properties (25 cycles), the molecule was successfully applied in secret code encryption-decryption purposes using barcode demonstrating real-life applicability of the molecule in security technologies.

A Renal Clearable Nano-Assembly with Förster Resonance Energy Transfer Amplified Superoxide Radical and Heat Generation to Overcome Hypoxia Resistance in Phototherapeutics.

Given that type I photosensitizers (PSs) possess a good hypoxic tolerance, developing an innovative tactic to construct type I PSs is crucially important, but remains a challenge. Herein, we present a smart molecular design strategy based on the Förster resonance energy transfer (FRET) mechanism to develop a type I photodynamic therapy (PDT) agent with an encouraging amplification effect for accurate hypoxic tumor therapy. Of note, benefiting from the FRET effect, the obtained nanostructured type I PDT agent (NanoPcSZ) with boosted light-harvesting ability not only amplifies superoxide radical (O2 •-) production but also promotes heat generation upon near-infrared light irradiation. These features facilitate NanoPcSZ to realize excellent phototherapeutic response under both normal and hypoxic environments. As a result, both in vitro and in vivo experiments achieved a remarkable improvement in therapeutic efficacy via the combined effect of photothermal action and type I photoreaction. Notably, NanoPcSZ can be eliminated from organs (including the liver, lung, spleen, and kidney) apart from the tumor site and excreted through urine within 24 h of its systemic administration. In this way, the potential biotoxicity of drug accumulation can be avoided and the biosafety can be further enhanced.

Enhanced luminescence of Eu3+ in LaAl2B4O10 via energy transfer from Dy3+ doping

In this study, an investigation was conducted on the structural and photoluminescence (PL) characteristics of LaAl2B4O10 (LAB) phosphors initially incorporated with Dy3+ and Eu3+ ions. Subsequently, the impact of varying Eu3+ concentration while maintaining a constant Dy3+ concentration was examined. Structural characterization was performed using X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), and energy-dispersive X-ray spectroscopy (EDS). XRD analysis confirmed the effective embedding of both dopants into the hexagonal framework of the LAB. The PL emission spectra revealed characteristic emissions of Dy3+ (blue and yellow) and Eu3+ (red) ions. The optimized dopant concentrations of both Dy3+ and Eu3+ were observed to be 3 wt%. The dominant mechanism for concentration quenching in doped LAB phosphors was determined to be the electric dipole–dipole interaction. Co-doping with Eu3+ led to a substantial decrease in Dy3+ emission intensity (∼0.18-fold) while enhancing Eu3+ emission intensity (∼3.72-fold). The critical energy transfer distance (RC = 11.64 Å) and the analysis based on the Dexter theory confirmed that the energy transfer mechanism corresponds to dipole–dipole interaction. The color purities and correlated color temperatures (CCT) were estimated, suggesting the potential of these phosphors for warm white and red lighting applications, respectively. The observed energy transfer and luminescence properties, along with the structural and compositional characterization, highlight the promising potential of LAB:Dy3+/Eu3+ co-doped phosphors for advanced lighting and display technologies.

Memory effects in the efficiency control of energy transfer under incoherent light excitation in noisy environments.

Fluctuations in energy gap and coupling constants between chromophores can play an important role in absorption and energy transfer across a collection of two-level systems. In photosynthesis, light-induced quantum coherence can affect the efficiency of energy transfer to the designated "trap" state. Theoretically, the interplay between fluctuations and coherence has been studied often, employing either a Markovian or a perturbative approximation. In this study, we depart from these approaches to incorporate memory effects by using Kubo's quantum stochastic Liouville equation. We introduce the effects of decay of the created excitation (to the ground state) on the desired propagation and trapping that provides a direction of flow of the excitation. In the presence of light-induced pumping, we establish a relation between the efficiency, the mean survival time, and the correlation decay time of the bath-induced fluctuations. A decrease in the steady-state coherence during the transition from the non-Markovian regime to the Markovian limit results in a decrease in efficiency. As in the well-known Haken-Strobl model, the ratio of the square of fluctuation strength to the rate plays a critical role in determining the mechanism of energy transfer and in shaping the characteristics of the efficiency profile. We recover a connection between the transfer flux and the imaginary part of coherences in both equilibrium and excited bath states, in both correlated and uncorrelated bath models. We uncover a non-monotonic dependence of efficiency on site energy heterogeneity for both correlated and uncorrelated bath models.

Photoluminescence and energy transfer studies in the Sm3+ and Eu3+ co-doped Sr2ZnSi2O7 red-emitting phosphors

In this study, we utilized a high-temperature solid-state reaction method to synthesize the red-emitting phosphors, namely Sr2ZnSi2O7:Sm3+ and Sr2ZnSi2O7:Sm3+/Eu3+. Characterization through X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive X-ray analysis (EDX) revealed that the crystal structure of the as synthesized Sr2ZnSi2O7 samples aligned with the standard JCPDS no. 00-039-0235, featuring small irregularly shaped particles having a tetragonal structure with space group P-421m and space group number 113. The band gap values were determined using diffuse reflectance spectral (DRS) data. Photoluminescence (PL) emission spectra indicated efficient excitation of Sr2ZnSi2O7:Sm3+ and Sr2ZnSi2O7:Sm3+/Eu3+ phosphors under near-ultraviolet light (λex = 404 nm). The PL intensity of Eu3+ ions increased with increasing the concentration of Eu3+ ions, leading to a decrease in the PL intensity of Sm3+ ions. The energy transfer mechanism from Sm3+ to Eu3+ ions is mainly driven by dipole-dipole (D-D) interaction, as predicted using Dexter Reisfeld's approximation. As the concentration of Eu3+ ions increased, there was a reduction in the photoluminescence (PL) decay lifetimes. This decline affirmed the presence of the energy transfer (ET) mechanism from Sm3+ to Eu3+ ions, reaching a maximum transfer efficiency of around 23.11 % in the Sr2ZnSi2O7:Smx/Euy (x = 1.5, y = 5 mol%) phosphor. Computed CIE parameters under UV excitation showed a gradual shift towards the deep red region with increase in Eu3+ concentration. For Sr2ZnSi2O7: Smx/Euy (x = 1.5, y = 5 mol%) phosphor, the CIE color coordinates and color purity were (0.60120, 0.39485) and 95.62 %, respectively. These findings highlight the potential of the synthesized phosphors as solid-state emitters for warm white LED applications, featuring a low color-correlated temperature (CCT) value of 1724 K when stimulated with UV chips.

A light/thermal cascaded-driven equipment for machine recognition inspired by water lilies using as multifunctional soft actuator

Inspired by the natural stimulus–response of plants and animals, a range of soft equipment has been extensively developed and used in intelligent human–computer interaction, editable remote drives, and machine learning. Poly(N-isopropyl acrylamide) (PNIPAM) hydrogels have gained popularity thanks to their low phase transition temperature and excellent flexibility. However, the PNIPAM hydrogels suffer from poor mechanical properties, low electrical conductivity, and lack of self-responsiveness. Herein, a bilayer light/thermal cascaded-driven anisotropic poly acrylamide/poly(N-isopropylacrylamide-co-acrylamide)-polyvinyl alcohol-MXene (P/PP-M) actuator was prepared by a simple two-step polymerization method. The unique bionic light/thermal response mechanism enables rapid conversion of energy forms and the construction of remote editable actuators. Concretely, the mechanical properties of hydrogels (strain: 1014 %, stress: 94 KPa) have been greatly improved by copolymerizing MXene nanosheets and multiplex hydrogels through two-by-two interpenetrating molecular chains. MXene nanosheets formed dynamic networks conferring the hydrogel system with high conductivity and light/thermal conversion efficiency. The P/PP-M soft actuator features high sensitivity (Gauge factor = 3.62), fast response time (400 ms), and cycling durability (>500 cycles). Finally, the energy transfer mechanism from light to thermal energy to kinetic energy was corroborated by preparing a series of bionic equipment. Manual clips were prepared on this basis, which enables the transportation of objects and realizes the real-time reflection of the operating status of remotely driven soft manual clips through changes in electrical signals. Thus, the proposed efficient editable remote-driven machine recognition soft equipment provides new insights for developing intelligent flexible robots and wearable smart devices.

Comprehensive investigation of Y2Si2O7:Eu3+ nanophosphors for w-LEDs: Structural, Judd-Ofelt calculation and photoluminescent characteristic with high color purity and thermal stability

In recent decades, numerous red phosphors have been designed and developed. Nevertheless, many of them are unsatisfactory due to their low brightness and poor thermal stability. Look at these shortcomings; present study reports on Eu3+ doped Y2Si2O7 (YPS) phosphors, synthesized through low temperature based urea assisted gel-combustion method. Comprehensive investigations were conducted on phase purity, luminous characteristics, energy transfer mechanism, quantum efficacy, morphology, elemental makeup, band gap and thermal stability. XRD analysis was employed to verify the preparation of Y2Si2O7 matrix with triclinic structure (P-1 space group). Morphology and elemental investigations of the fabricated materials was evaluated via TEM and EDX techniques respectively. Under the illumination at 393 nm, the most strong emission band is shown in PL spectra at 613 nm (electric dipole 5D0→7F2 transition). Additionally, the dipole-quadrupole (d-q) interaction was found to be the predominant route of energy transfer among nearby Eu3+ ions and it was concluded that 3 mol % was the optimal doping concentration of Eu3+ ions. The Judd-Ofelt (J-O) theory was used for current phosphors in order to establish their Ω2 and Ω4 with other radiative parameters. The assessment of thermal stability yielded highly promising results with activation energy of 0.241 eV. Present research indicates that Y2Si2O7:Eu3+ is a promising candidate of red emitting phosphor for white light-emitting diodes.

Eu2+/Eu3+ co-activated Ba2La8(SiO4)6O2 phosphors for optical thermometry

The Eu2+/Eu3+ co-doped Ba2La8(SiO4)6O2 phosphors were synthesized via the high-temperature solid-state reaction method. The crystal structure and electronic properties of Ba2La8(SiO4)6O2 were investigated. Furthermore, a systematic study was conducted on the photoluminescence characteristics of Ba2La8(SiO4)6O2: Eu(2+, 3+) as well as the potential energy transfer mechanism from Eu2+ to Eu3+. Temperature sensing can be achieved through two methods, either monitoring the emission intensity of the phosphor or utilizing the fluorescence intensity ratio technique. The investigation results suggest that the synthesized phosphor exhibits promising potential as a luminescent thermometer.

Two water-stable Cd(II)-based coordination compounds as a fluorescent sensor for selective and sensitive detection of antibiotics

Developing highly stable materials for harmful compound detection in a water environment is of much importance and challenge. we report two cadmium based fluorescent coordination compounds with formula [Cd(HL)(phen)(H2O)3] (1) and [Cd(HL)(2,2′-bipy)(H2O)2] (2) where H3L = 4-(N,N’-bis(4-carbonylbenzyl)amino)-3-methylbenzenesulfonic acid, phen = 1,10-phenanthroline monohydrate and 2, 2′-bipy = 2, 2′-bipyridine. Details structural studies showed that compounds 1 and 2 are mononuclear and binuclear discrete compounds, respectively. Its excellent luminescence stability in aqueous solutions, coupled with outstanding thermal and chemical stabilities, enables it to function as an efficient detector for metamitron (MMT). It boasts a limit of detection of 2.72 ppm and exhibits quenching constant (KSV) values of 0.09, making it an effective luminescent sensor for detecting MMT. The luminescence quenching of the compound 1 by MMT was attributed to competing absorption and photoelectron energy transfer mechanisms.

Transient Chiral Dynamics in the Fenna-Matthews-Olson Complex Revealed by Two-Dimensional Circular Dichroism Spectroscopy.

Chirality plays a pivotal role across scientific disciplines with profound implications spanning light-matter interactions, molecular recognition, and natural evolutionary processes. This study delves into the active influence of molecular chirality on exciton energy transfer within photosynthetic protein complexes, focusing on the Fenna-Matthews-Olson (FMO) complex. Employing two-dimensional circular dichroism (2DCD) spectroscopy, we investigate the transient chiral dynamics of excitons during energy transfer processes within the FMO complex. Our approach, incorporating pulse information into population dynamics based on the third-order response function, facilitates the calculation of 2DCD spectra and dynamics. This enables the extraction of chiral contributions to excitonic energy transfer and the examination of electronic wave functions. We demonstrate that 2DCD spectra offer excitation energies that are better resolved than those from conventional two-dimensional electronic spectroscopy. These findings deepen our understanding of exciton energy transfer mechanisms in natural photosynthesis, emphasizing the potential of 2DCD spectroscopy as a powerful tool for unraveling the chiral contribution to exciton dynamics.