Search

Hydrogen production was carried out in a photochemical device in a Mark-5 cycle. The photolysis of iron sulphate solution was carried out in a close periodic system. The reaction mixture was 8.5 g iron sulphate compound (FeSO4•7 H2O), 2.5 g I2 and 1.0 g HI in 100 mL water. Fifty millilitres of this solution was filled into a quartz reactor and connected to cycle system. The optimisation of hydrogen production was achieved by temperature, flow rate and radiation irradiation. The maximum hydrogen generated was 50.0 × 1016 molecules per minute at 120 °C temperature, 0.08 mL/sec. Pump speed, pressure 0.30 MPas, and Hg-vapour λmax = 365 nm. Eact. = 14.92 kC/mol caused bimolecular reactions to occur at low temperatures by photochemical action. Quantum yield of hydrogen depended on the absorbed of 0.5 × 1015 kvant/s. The energy of the quantum above T ≥ 100°C temperatures was φ ≥ 1. The dependence of the hydrogen generation rate (W) increased from 0.001 to 0.0038 × 1016 molecules/sec at 10-90 minutes, respectively. [ABSTRACT FROM AUTHOR]

White light-emitting diodes (WLEDs) have become essential to various aspects of our daily lives. However, the absence of a strong cyan emission significantly hinders the development of full-spectrum WLEDs that could achieve high-quality applications. Here, a feasible method is introduced to synthesize highly luminescent and stable CsPbBr3 by employing an efficient dual-matrix encapsulation technique. Sodium citrate (SC) is utilized as a matrix to disperse these CsPbBr3 nanomaterials, thereby reducing self-absorption and energy transfer. In addition to functioning as a matrix, SC also passivates the perovskite nanomaterials, resulting in an increased photoluminescence quantum yield (PLQY) and enhanced stability of the perovskite. Notably, the stability of the perovskite, especially its resistance to water, is significantly enhanced after encapsulating the composite within poly-(methyl methacrylate) (PMMA). A series of full-spectrum WLEDs with variable color temperatures ranging from 2763 to 7145 K and high color rendering indices (90–96) were fabricated using SC-CsPbBr3@PMMA in combination with commercially available YAG and red phosphors CaAlSiN3:Eu2+. This research opens up new avenues for the utilization of perovskite nanomaterials in the development of next-generation full-visible-spectrum WLED lighting. [ABSTRACT FROM AUTHOR]

ABSTRACT Luminescent lanthanide‐based coordination polymers (LnCPs) present great potential in low‐temperature detection due to their convenience in contactless readout. High quantum yields and energy transfer efficiency are favored by LnCPs as luminescent thermometer. In this work, based on the thermogravimetric analysis and temperature‐dependent powder x‐ray diffraction, coordinated and isolated molecules of [Ln2(mip)3(H2O)8·4H2O]∞ (abbreviated as Ln2MIP) were removed by dehydration process. Combining luminescent measurement and calculation, both quantum yields and energy transfer efficiency between Tb3+ and Eu3+ have been greatly enhanced. Additionally, the Eu3+ intensity of dehydrated Gd0.2Tb1.08Eu0.72MIP displays excellent temperature sensing ability from 77 to 300 K with enhanced relative sensitivity. These results demonstrate the potential of LnCPs in low‐temperature sensing with high quantum yields and energy transfer efficiency. [ABSTRACT FROM AUTHOR]

Like-caviar molybdenum ferrite nanoparticles (MoFe2O4 NPs) have been successfully synthesized via a hydrothermal route in the presence of the negative surfactant (sodium dodecyl sulfate (SDS)). SDS acts as a template, stabilizer, and stops the aggregating process through storage. The mean crystal size of MoFe2O4 NPs rises with decorating it with Al2O3. Based on SEM analysis, the shapes of MoFe2O4, Al2O3, and their composite demonstrated like-caviar, like-brain cells, and like-grains, respectively. Al2O3 has been chosen to incorporate with spinel MoFe2O4 to make it color more light, this crucial step is necessary to enhance their optical characteristics. FTIR spectra observed the MoFe2O4 NPs are inverse spinel. The photo-decolorization test employs indigo carmine (IC) as a model pollutant. The quantum yields (Φ) of IC dye decolorization with studied photocatalysts are low, which may be created by quencher materials, dimerization of dye molecules, and photophysical deactivation processes (ISC process). Moreover, the photocatalytic activity of using MoFe2O4 raised after being decorated with alumina, which revealed an increase in the surface acidity, hydroxyl group adsorption, size, band gap, pHpzc of MoFe2O4 from 2.9–3.6 to 4.2–5.9 after decorated alumina. This pH is suitable for decolorizing IC dye, which has a pH of solution equal to 5.3.

The triplet‐sensitized (by the solvent acetone) as well as the direct (λex=300–320 nm) photochemical decarboxylation of N‐phthaloylated γ‐aminobutyric acid (GABA) derivatives are versatile and high‐yielding routes to benzopyrrolizidines via intramolecular electron transfer initiated decarboxylation followed by radical coupling. The ß‐mono‐ and ß,ß'‐disubstituted N‐phthaloyl GABA derivatives 7 a–7 g, respectively, were applied as substrates. Decarboxylative photocyclization yielded hydroxy benzopyrrolizidines 8 a–8 g in high chemical yields and with moderate diastereoselectivities from the ß‐monosubstituted substrates. The analogous α‐substituted GABA derivatives 11 a–11 c were also applied as potential substrates for memory of chirality effects. The reaction quantum yields of the photodecarboxylation reactions for the parent GABA derivative 13 and for the new substrates 7 h and 11 a were determined by the quantum yield determination system (QYDS) and showed a remarkable concentration dependency indicating aggregation at higher substrate concentrations. Inhibition studies on the atherogenic human serine hydrolase cholesterol esterase showed derivatives 8 a and 8 d to exhibit a hyperbolic mode of inhibition with moderate IC50 values of about 60–80 μM. [ABSTRACT FROM AUTHOR]

The photosynthetic acclimation of boreal evergreen conifers is controlled by regulatory and photoprotective mechanisms that allow conifers to cope with extreme environmental changes. However, the underlying dynamics of photosystem II (PSII) and photosystem I (PSI) remain unresolved. Here, we investigated the dynamics of PSII and PSI during the spring recovery of photosynthesis in Pinus sylvestris and Picea abies using a combination of chlorophyll a fluorescence, P700 difference absorbance measurements, and quantification of key thylakoid protein abundances. In particular, we derived a new set of PSI quantum yield equations, correcting for the effects of PSI photoinhibition. Using the corrected equations, we found that the seasonal dynamics of PSII and PSI photochemical yields remained largely in balance, despite substantial seasonal changes in the stoichiometry of PSII and PSI core complexes driven by PSI photoinhibition. Similarly, the previously reported seasonal up-regulation of cyclic electron flow was no longer evident, after accounting for PSI photoinhibition. Overall, our results emphasize the importance of considering the dynamics of PSII and PSI to elucidate the seasonal acclimation of photosynthesis in overwintering evergreens. Beyond the scope of conifers, our corrected PSI quantum yields expand the toolkit for future studies aimed at elucidating the dynamic regulation of PSI. [ABSTRACT FROM AUTHOR]

Carbon nanodots (CDs) are a new type of carbon‐based fluorescent nanomaterials, but they are limited in many applications due to the inherent fluorescence weakening and quenching problems suffered in solid state. Herein, ZIF‐8, a class of metal–organic framework (MOF) is employed as a matrix to immobilize fluorescent CDs, resulting in the strong luminescence of CDs achieved in solid state. The as‐synthesized CDs@ZIF‐8 fluorescent powders possess blue, green, and red emissions with the main emission at ≈495, 528, and 600 nm, and the corresponding photoluminescence quantum yields (PLQYs) are as high as 25.89%, 52.24%, and 15.42%, respectively. It is found that the encapsulation of ZIF‐8 with CDs will increase the excitation dependence of the product fluorescence, which may be attributed to the carrier effect of ZIF‐8 as a carrier of CDs and some surface defects or surface functional groups change of the CDs introduced by ZIF‐8. In addition, the encapsulation of CDs with ZIF‐8 may result in the charge transfer. Importantly, the prepared CDs@ZIF‐8 phosphors present a promising application in the fabrication of monochromatic light‐emitting diodes (LEDs). The synthesis design is expected to provide technical support for future solid‐state fluorescent CDs preparation and applications. [ABSTRACT FROM AUTHOR]

The luminescent and photophysical properties of the etioporphyrin-I complex with indium(III) chloride, InCl-EtioP-I were experimentally studied at room and liquid nitrogen temperatures in pure and mixed toluene solutions. At 77 K, in a 1:2 mixture of toluene with diethyl ether, the quantum yield of phosphorescence reaches 10.2%, while the duration of phosphorescence is 17 ms. At these conditions, the ratio of phosphorescence-to-fluorescence integral intensities is equal to 26.1, which is the highest for complexes of this type. At 298 K, the quantum yield of the singlet oxygen generation is maximal in pure toluene (81%). Quantum-chemical calculations of absorption and fluorescence spectra at temperatures of 77 K and 298 K qualitatively coincide with the experimental data. The InCl-EtioP-I compound will further be used as a photoresponsive material in thin-film optoelectronic devices. [ABSTRACT FROM AUTHOR]

3‐Benzylidene‐indoline‐2‐ones play a prominent role in the pharmaceutical industry due to the diverse biomedical applications of oxindole heterocycles. Despite the extensive reports on their biological properties, these compounds have hardly been studied for their photochemical activity. Here, we present 3‐benzylidene‐indoline‐2‐ones as a promising class of photoswitches with high yields, robust photochemical switching with quantum yields reaching up to 50 % and potential for biological applications. [ABSTRACT FROM AUTHOR]

In this study, differently shaped silver nanoparticles used for the synthesis of gold nanoclusters with small capping ligands were demonstrated. Silver nanoparticles provide a reaction platform that plays dual roles in the formation of Au NCs. One is to reduce gold ions and the other is to attract capping ligands to the surface of nanoparticles. The binding of capping ligands to the AgNP surface creates a restricted space on the surface while gold ions are being reduced by the particles. Four different shapes of AgNPs were prepared and used to examine whether or not this approach is dependent on the morphology of AgNPs. Quasi-spherical AgNPs and silver nanoplates showed excellent results when they were used to synthesize Au NCs. Spherical AgNPs and triangular nanoplates exhibited limited synthesis of Au NCs. TEM images demonstrated that Au NCs were transiently assembled on the surface of silver nanoparticles in the method. The formation of Au NCs was observed on the whole surface of the QS-AgNPs if the synthesis of Au NCs was mediated by QS-AgNPs. In contrast, formation of Au NCs was only observed on the edges and corners of AgNPts if the synthesis of Au NCs was mediated by AgNPts. All of the synthesized Au NCs emitted bright red fluorescence under UV-box irradiation. The synthesized Au NCs displayed similar fluorescent properties, including quantum yields and excitation and emission wavelengths. [ABSTRACT FROM AUTHOR]

Studying the cis–trans isomerization process in crocin (CR), one of the few water-soluble carotenoids extracted from saffron, is important to better understand the physiological role of cis-carotenoids in vivo and their potential as antioxidants in therapeutic applications. For that, cis–trans isomerization of both methanol- and water-dissolved CR was induced by light or thermally generated singlet oxygen (1O2). The kinetics of molecular concentrations were monitored by both high-performance liquid chromatography (HPLC) and non-destructive spectrophotometric methods. These last made it possible to simultaneously follow the cis–trans isomerization, the possible bleaching of compounds and the amount of thermally generated 1O2. Our results were in accordance with a comprehensive model where the cis–trans isomerization occurs as relaxation from the triplet state of all-trans- or 13-cis-CR, whatever is the way to populate the CR triplet state, either by photon or 1O2 energy transfer. The process is much more (1.9 to 10-fold) efficient from cis to trans than vice versa. In H2O, a 1O2-induced bleaching effect on the starting CR was not negligible. However, the CR "flip-flop" isomerization reaction could still occur, suggesting that this process can represent an efficient mechanism for quenching of reactive oxygen species (ROS) in vivo, with a limited need of carotenoid regeneration. [ABSTRACT FROM AUTHOR]

The points of enzymatic activity, quantum yields, structure, functions of luminol chemiluminescence activated by physical activators natural dyes isoquinolysine coumarins C-334 and C-525 under the action of cytochrome c complex with cardiolipin in aqueous medium and in nonpolar environment were considered. It is shown: (1) the enzymatic activity points and quantum yields are significantly higher in the presence of the physical activator coumarin C-525 than in the case of its own unactivated luminescence or in the case of the physical activator C-334; (2) the enzymatic activity depends not only on the concentration of cytochrome c but also on the percentage ratio between the native form of cytochrome c with cardiolipin and the partially denatured one. [ABSTRACT FROM AUTHOR]

Neonicotinoid (NN) pesticides have widespread use, largely replacing other pesticides such as the carbamates. Hence, there is a need to understand their environmental fates at a molecular level in various media, especially water. We report here the studies of a nitroenamine NN, nitenpyram (NPM), in aqueous solution where the absorption cross sections in the actinic region above 290 nm are observed to dramatically decrease compared to those in nonaqueous solvents. Quantum chemical calculations show that addition of a proton to the tertiary amine nitrogen in NPM breaks the conjugation in the chromophore, shifting the absorption to shorter wavelengths, consistent with experiment. However, surprisingly, adding a proton to the secondary amine nitrogen leads to its immediate transfer to the NO2 group, preserving the conjugation. This explains why the UV absorption of ranitidine (RAN), which has a similar chromophore but only secondary amine nitrogens, does not show a similar large blue shift in water. Photolysis quantum yields in aqueous NPM solutions were measured to be φ = 0.18 ± 0.07 at 254 nm, (9.4 ± 1.6) × 10-2 with broadband radiation centered at 313 nm and (5.2 ± 1.1) × 10-2 for broadband radiation centered at 350 nm (errors are 2σ). The major products in aqueous solutions are an imine that was also formed in the photolysis of the solid and a carboxylic acid derivative that is unique to the photolysis in water. Combining the larger quantum yields in water with the reduced absorption cross sections results in a calculated lifetime of NPM of only 5 min at a solar zenith angle of 35°, typical of 40°N latitude on April 1. The products do not absorb in the actinic region and hence will be long-lived with respect to photolysis.

Ultra‐long room temperature phosphorescence (ULRTP) materials show valuable applications in encryption, biological imaging, and many other fields. Amazingly, the concomitant impurities from raw materials that are normally ignored contribute dramatically to the ULRTP. In this study, CzPMB [9‐(4‐bromo‐3‐methylphenyl)‐9H‐carbazole] with phosphorescent quantum efficiency of 64% is prepared from commercial carbazole, but the phosphorescent efficiency is drastically reduced to < 2% once trace impurity (5‐(4‐bromo‐3‐methylphenyl)‐5H‐benzo[b]carbazole) is separated. HPLC studies demonstrated the separated impurity is a byproduct derived from trace benzocarbazole in commercial carbazole. Subsequently, the ULRTP for the CzPMB synthesized from lab‐made carbazole is totally unobserved, strongly confirming the dramatic impact of impurity. A defect trapping mechanism in multicomponent system rather than heavy atom effect is proposed for highly efficient ULRTP after carefully analyzing the crystal packings and molecular energy levels. Inspired by this discovery, a series of effective ULRTP bi‐component systems with the highest phosphorescence efficiency of 64.1% are reproduced by directed host‐guest doping. This strategy paves a viable path for the design of organic materials with highly efficient ULRTP. [ABSTRACT FROM AUTHOR]

The previously not studied photochemical degradation of sulfamethoxazole (SMX) to the isomer of SMX (ISO) was measured via a polychromatic (Xe) and a monochromatic (Hg) light source and accompanied by quantum chemical DFT calculations. In addition to the p K a = 7.0 ± 0.1 of ISO, tautomer-dependent properties such as the K OW were measured and theoretically confirmed by DFT. The kinetics in solutions below and above the p K a = 5.6 of SMX were studied for the available and quantifiable products SMX, ISO, 3-amino-5-methylisoxazole (AMI), 2-amino-5-methyloxazole (AMO), and sulfanilic acid (SUA). The quantum yields of the neutral ( Φ N ) and anionic Φ A ) forms of SMX ( Φ A = 0.03 ± 0.001 , Φ N = 0.15 ± 0.01 ) and ISO ( Φ A = 0.05 ± 0.01 and Φ N = 0.06 ± 0.02 ) were found to be wavelength-independent. In a competitive reaction to the formation of ISO from SMX, the degradation product TP271 is formed. Various proposed structures for TP271 described in the literature have been studied quantum mechanically and can be excluded for thermodynamic reasons. In real samples in a northern German surface water in summer 2021 mean concentrations of SMX were found in the range of 120 ng/L. In agreement with the pH-dependent yields, concentrations of ISO were low in the range of 8 ng/L. [ABSTRACT FROM AUTHOR]

[Display omitted] • The Lewis base co-ligands enhance the efficiency of intramolecular energy transfer. • For Tb chelates, IET occurs mainly from S 1 state involving higher Tb excited levels. • IET in Eu3+ chelates is influenced via T 1 ligand state. • The exchange mechanism is the most effective interaction for Eu and Tb chelates. • The ability to accurately predict quantum yield has been demonstrated. Lanthanide chelates with dimethyl(phenylsulfonyl)amidophosphate (labeled as HSP) and Lewis base ligands (bpy = 2,2;-bipyridine and phen = 1,10-phenanthroline) of formula Na[Ln(SP) 4 ] (1Ln), [Ln(SP) 3 bpy] (2Ln); [Ln(SP) 3 phen] (3Ln) (Ln = Eu3+, Gd3+, Tb3+ and Lu3+) were obtained and characterized by the X-ray, photoluminescence spectroscopy at 293 and 77 K as well as by intrinsic (Q Ln Ln ) and overall (Q Ln L) luminescence quantum yields. These phosphors manifest a very strong emission after excitation in the UV range of the molecular singlet states (S 1) and two of them have very high Q Ln L values (Eu3+ and Tb3+ chelates of the type 2Ln and 3Ln). The dynamics of the excited states are discussed based on the intramolecular energy transfer theory, considering the dipole–dipole, the dipole-multipole and the exchange mechanisms. From the calculated energy transfer rates, a rate equation model was constructed and, thus, the theoretical Q Ln L can be obtained. A good correlation between the experimentally determined and theoretically calculated Q Ln L values was achieved, with the triplet state (T 1) playing a predominant role in the energy transfer process for Eu3+ compounds, while the sensitization for Tb3+ compounds is dominated by the energy transfer rates from the singlet state (S 1). [ABSTRACT FROM AUTHOR]

Ce-doped inorganic single crystals are currently used in scintillators in various instruments because of their outstanding luminescence properties. However, these crystals are expensive to manufacture and are inefficient in terms of their energy consumption. In this study, x CeF 3 -doped 40MgF 2 –20Al 2 O 3 –40B 2 O 3 glasses (x = 0−30 mol%) were prepared by a melt-quenching method in N 2 atmosphere, and their photoluminescence, scintillation, and dosimetry properties were investigated. The X-ray absorption fine edge spectroscopy of the Ce L 3 -edge indicated that the doped Ce exists in the form of Ce3+ ions, and that Ce4+ does not form because of the low basicity of the glass. The glasses underwent photoluminescence at 380 nm due to the 5d-4f transition of Ce3+, with a very high quantum yield of up to ∼100 % and low concentration quenching. The peak shape of the X-ray-induced luminescence was similar to that of the PL with a decay time of 110−70 ns. The light yields for gamma rays (137Cs source) were obtained from the pulse-height spectra, and the highest light yield among the present samples was 1071 photons/MeV with the energy resolution of 17 %. The thermoluminescence glow curves had peaks at 365 and 460 K and a good linear relationship existed in the range of 0.5–1000 mGy, with the dose response being comparable to that of a commercial dosimeter. The origin of the high quantum yield was probed by analyzing the glass structure using molecular dynamics simulation based on a graph neural network. A strong tendency to selectively bind cations and anion pairs was found: Mg preferably binds to F, B preferably binds to O, and Al binds to O and F, which can be explained by soft and hard acid and base theories. Because of this selectivity the glass forms fluoride- and oxide-rich domains, which seem to be responsible for the more effective dispersal of the luminescent center. The results of this study are expected to contribute to the development of glasses with enhanced photoluminescence and scintillation luminescence properties. • x CeF 3 -doped 40MgF 2 –20Al 2 O 3 –40B 2 O 3 glasses (x = 0−30 mol%) were prepared by a melt-quenching method in N 2 atmosphere. • The glasses underwent photoluminescence at 380 nm with a very high quantum yield of up to ∼100 % and low concentration quenching. • The origin of the high quantum yield was probed by analyzing the glass structure using molecular dynamics simulation based on a graph neural network. • Formation of fluoride- and oxide-rich domains is responsible for the excellent photoluminescence. [ABSTRACT FROM AUTHOR]

Correct photoluminescence quantum yield (PLQY) determination in the solid state is vital for numerous application fields, such as photovoltaics, solid lighting or the development of phosphors. In order to increase the limited number of suitable standards for such determinations, two new Ln3+‐based complexes with 4′‐phenyl‐2,2′ : 6′,2"‐terpyridine γ‐[Ln4(OAc)12(ptpy)2] (1‐Eu with europium and 1‐Tb with terbium) are presented. The corresponding complexes show solid‐state QYs of 58(4) % and 46(3) %, respectively, exhibiting broadband absorption in the UV range from 380–200 nm. As Ln3+ ions in general exhibit narrow f‐f transitions, spectral regions with a broadness of 20–35 nm can be checked. Both complexes have suitable thermal stability, up to 270 °C, and are stable with respect to air and humidity, for 1‐Eu up to 75 % and for 1‐Tb up to 53 % relative humidity. These complexes are altogether suitable as standards to increase the reliability of PLQY determination and proposed to be used for a relative PLQY determination in the solid state. [ABSTRACT FROM AUTHOR]

Absorption of ultraviolet (UV) radiation can trigger a variety of photophysical and photochemical reactions in nucleic acids. In the prebiotic era, on the surface of the early Earth, UV light could have played a major role in the selection of the building blocks of life via a balance between synthetic and destructive pathways. As nucleic acid monomers assembled into polymers, their survival and facility for non‐enzymatic replication hinged on their photostability and the ability for self‐repair of lesions, e. g. by UV‐induced charge transfer. Such photoprocesses are known to be sequence‐dependent and could have led to an additional prebiotic selection of the genetic sequence pools available to the earliest life forms. This review summarizes the photophysical processes in nucleic acids upon the absorption of a UV photon and their implications for chemical and genetic selection at the emergence of life and the origin of translation. [ABSTRACT FROM AUTHOR]

Fluorescence imaging is a noninvasive technique that affords real‐time fast feedback, high sensitivity, and harmless radiation and is thus effective in visualizing the anatomy and function of organs. Recently, second near‐infrared (NIR‐II, 1000–1700 nm) fluorescence imaging emerged as a popular imaging technique for both fundamental research and clinical practice, with strong potential for applications in the field of biomedicine. It affords a high signal‐to‐noise ratio and high spatial and temporal resolutions for the imaging of deep tissue owing to reduced scattering, minimal absorption, and negligible autofluorescence. Herein, the performance and advancement of fluorophores for NIR‐II fluorescence imaging are summarized. Further, the challenges to the NIR‐II fluorophores in terms of emission wavelengths, quantum yields, stability, targeting, and biocompatibility are discussed. Finally, perspective on the current development and the orientation for future studies on NIR‐II imaging, such as dual‐mode imaging, multiplexed imaging, surgical navigation, integrated diagnosis and treatment, and biosensing are discussed.

UV-C treatment is an effective method to inactivate microorganisms and therefore gets increasingly more attention in food industry, especially for liquid products. To test and monitor different UV-C reactor designs, a photochemical actinometer is required that gives reliable UV-C dose values and is non-toxic allowing frequent control of the production chain. Here, a variable concentrated aqueous uridine solution is tested as a photochemical actinometer. Uridine reacts at 262 nm by photohydration to a single photoproduct not absorbing any light. A concentration dependent quantum yield (Ф) was quantified in the range of 0.2–3.0 mM uridine. Results show that uridine is as accurate as the commonly accepted iodide/iodate actinometry, but not as precise. Especially at higher concentrations a higher number of measurements becomes necessary. Further, a temperature correction is presented for 10 °C > ϑ > 30 °C. Taking these results into account, uridine can certainly be considered as a non-toxic dosimeter for UV-C systems.

The development of pure red-emitting CsPbI 3 quantum dots (QDs) has been hindered by challenges including long-term instability, low yield and photoluminescence quantum yields (PLQYs), and self-absorption issues in solid-state applications. Herein, sodium citrate (SC) passivated CsPbI 3 QDs are prepared by using a simple post-treatment method, which is also applicable to other CsPbX 3 QDs. Due to the chelating coordination role of citrate, the PLQY of red SC-CsPbI 3 can reach 96 %. In addition to its passivating role, SC also acts as a matrix to increase inter-particle distances, reducing self-absorption and acquiring high PL intensity. Furthermore, SC treatment can also increase the yield of smaller QDs, which are typically challenging to isolate using conventional centrifugation methods. The passivation afforded by SC results in enhanced thermal and air stability in the samples. We utilized this narrow-band red phosphor to fabricate white light-emitting diodes (WLEDs) for lighting and display applications. Upon incorporating the red phosphor into the commercial WLED, there is a notable enhancement in the color rendering index (CRI), signifying its substantial impact on lighting WLED. For display application, the perovskite-based WLED achieves a color gamut coverage reaching up to 120 % of the National Television System Committee (NTSC) standard. This remarkable performance also underscores its significant potential for applications in display area. [Display omitted] • The presence of sodium citrate (SC) plays a crucial role in passivating quantum dot (QDs). • The SC-CsPbI 3 shows high photoluminescence quantum yield. • SC acts as a matrix to increase inter-particle distances, reducing self-absorption and acquiring high PL intensity. • The perovskite-based WLED reaches as high as 120% of NTSC standard. [ABSTRACT FROM AUTHOR]

Six different monoarylated N‐aryl‐1H‐imidazo[4,5‐f][1,10]phenanthroline (Rip) ligands and their corresponding ruthenium complexes [(tbbpy)2Ru(Rip)]2+ Ru(Rip) have been synthesized bearing different aryl substituents on the imidazole unit including electron donating and accepting groups. N,N'‐disubstitution on the imidazole unit yielded five new 1‐aryl‐3‐benzyl‐1H‐imidazo[4,5‐f][1,10]phenanthrolinium bromide (RR'ip)+ ligands and the corresponding ruthenium complexes [(tbbpy)2Ru(RR'ip)]3+ Ru(RR'ip). All complexes were characterized in terms of their structural, photophysical, photochemical and electrochemical properties. The photophysical data revealed a high luminescence quantum yield (21.6–22.8 %) for monoarylated Ru(Rip) complexes compared to [Ru(bpy)3]2+ (9.5 %) under inert conditions. Generating the imidazolium unit, yielding Ru(RR'ip)‐complexes lead to notable loss of quantum yields. Furthermore, we observed an enhanced photostability of Ru(RR'ip) complexes in the case of ortho substituted aryl groups. [ABSTRACT FROM AUTHOR]

Cold neutron has a strong ability to penetrate metal materials and identify light elements, making it an ideal nondestructive testing technique for detecting cracks, bubbles, or other defects in metals. However, the low imaging resolution and detection efficiency of scintillators limit the application of cold neutron technology in imaging. The particle size and luminescence properties of scintillator materials have an important influence on the spatial resolution and detection efficiency of cold neutron radiography. Here, we report a series of NaF-doped Gd2O2S:Tb3+ (NaF-d-GOS:Tb) scintillators with adjustable particle size, which were prepared through a two-step method of solution precipitation followed by solid-phase vulcanization calcination. It was found that the NaF-d-GOS:Tb scintillators showed the highest quantum yield, reaching up to 62.94%. They were applied to fabricating cold neutron ultrathin screens. The resolution can reach 12 μm in the cold neutron imaging system. These NaF-d-GOS:Tb scintillators with excellent fluorescence facilitate the development of nondestructive testing techniques based on cold neutron imaging. [ABSTRACT FROM AUTHOR]

Recently, lanthanide-based 0D metal halides have attracted considerable attention for their applications in X-ray imaging, light-emitting diodes (LEDs), sensors, and photodetectors. Herein, lead-free 0D gadolinium-alloyed cesium cerium chloride (Gd 3+ -alloyed Cs 3 CeCl 6 ) nanocrystals (NCs) are introduced as promising materials for optoelectronic application owing to their unique optical properties. The incorporation of Gd 3+ in Cs 3 CeCl 6 (CCC) NCs is proposed to increase the photoluminescence quantum yield (PLQY) from 57% to 96%, along with significantly enhanced phase and chemical stability. The structural analysis is performed by density functional theory (DFT) to confirm the effect of Gd 3+ in Cs 3 Ce 1- x Gd x Cl 6 (CCGC) alloy system. Moreover, the CCGC NCs are applied as the active layer in UVPDs with different Gd 3+ concentration. The excellent device performance is shown at 20% of Gd 3+ in CCGC NCs with high detectivity (7.938 × 10 11 Jones) and responsivity (0.195 A W -1 ) at -0.1 V at 310 nm. This study paves the way for the development of lanthanide-based metal halide NCs for next-generation UVPDs and other optoelectronic applications., (© 2024 The Author(s). Small published by Wiley‐VCH GmbH.)

The photosynthesis process is determined by the intensity level and spectral quality of the light; therefore, leaves need to adapt to a changing environment. The incident energy absorbed can exceed the sink capability of the photosystems, and, in this context, photoinhibition may occur in both photosystem II (PSII) and photosystem I (PSI). Quantum yield parameters analyses reveal how the energy is managed. These parameters are genotype-dependent, and this genotypic variability is a good opportunity to apply mapping association strategies to identify genomic regions associated with photosynthesis energy partitioning. An experimental and mathematical approach is proposed for the determination of an index which estimates the energy per photon flux for each spectral bandwidth (Δλ) of the light incident (QI index). Based on the QI, the spectral quality of the plant growth, environmental lighting, and the actinic light of PAM were quantitatively very similar which allowed an accurate phenotyping strategy of a rice population. A total of 143 genomic single regions associated with at least one trait of chlorophyll fluorescence were identified. Moreover, chromosome 5 gathers most of these regions indicating the importance of this chromosome in the genetic regulation of the photochemistry process. Through a GWAS strategy, 32 genes of rice genome associated with the main parameters of the photochemistry process of photosynthesis in rice were identified. Association between light-harvesting complexes and the potential quantum yield of PSII, as well as the relationship between coding regions for PSI-linked proteins in energy distribution during the photochemical process of photosynthesis is analyzed. [ABSTRACT FROM AUTHOR]

Dipyrrolydiketones BF2 complex was synthesized and characterized by NMR, HRMS, and single crystal diffraction. In non-polar environment, this BF2 containing dye emitted bright blue-green fluorescence. No significant spectra shift was observed both in absorption and emission spectra, which indicates the insensitivity of absorption/emission toward environment. The alkyl substituted pyrrole rings lead to its highly emission character in solid state by enhancing the distance between dye molecules. Absolute quantum yields were determined to be 0.51–0.78/0.36 in selected organic medium and solid state, respectively. The emission dynamics was investigated by fluorescence lifetime and both monoexponential and bi-exponential decay was observed. [ABSTRACT FROM AUTHOR]

Luminescent covalent organic frameworks (COFs) find promising applications in chemical sensing, photocatalysis, and optoelectronic devices, however, the majority of COFs are non or weakly emissive owing to the aggregation‐caused quenching (ACQ) or the molecular thermal motion‐based energy dissipation. Here, we report a previously unperceived approach to improve luminescence performance of COFs by introducing isotope effect, which is achieved through substitution of hydrogen from high‐frequency oscillators X‐H (X=O, N, C) by heavier isotope deuterium. Combining the "bottom‐up" and in situ deuteration methods generates the first deuterated COF, which exhibits an impressively 19‐fold enhancement in quantum yield over that of the non‐deuterated counterpart. These results are interpreted by theoretical calculations as the consequence of slower C/N‐D and OD⋅⋅⋅O vibrations that impede the nonradiative deactivation process. The proposed strategy is proved applicable to many other types of emissive COFs. [ABSTRACT FROM AUTHOR]

The α-methylated chalcone 3 with an electron-donor substituted A-aryl ring and an unsubstituted B-phenyl ring was synthesized by base-catalyzed aldehyde/acetophenone condensation. Compound 3 can be photo-switched from E→Z by irradiation with long-wavelength light λ > 350 nm, whereas irradiation with shorter wavelengths leads to photo-stationary states (PSS) with lower amounts of the Z-isomer. The limiting wavelength for fully equilibrated E⮀Z (PSS = 1) can be achieved around 240 nm. The stability of both E- and Z-isomers at the wavelength-dependent PSS under UV-irradiation between 250 and 350 nm is remarkably high as observed from UV and NMR spectroscopy. Compound 3 is fatigue resistant even after more than 10 days continuous irradiation and is also oxygenation-stable under singlet oxygen sensitization conditions. In remarkable contrast to many other α-methylated chalcones, no change in the E/Z-ratio was detected when PSS samples were treated with Broensted acids. The negative photochromic E→Z switch of 3 is accompanied by a conformational switch from the E-form in its preferred s-trans conformation to the Z-form in a distorted s-cis conformation (Es-c→Zs-t).

A number of synthetic methodologies and applications of carbon quantum dots (CQDs) have been reported since they were first discovered nearly two decades ago. Unlike metal‐based or semiconductor‐based (e. g. metal chalcogenides) quantum dots (MSQDs), CQDs have the unique feature of being prepared through a variety of synthetic protocols, which are typically understood from considerations of reaction models and photoluminescence mechanisms. Consequently, this brief review article describes quantum dots, in general, and CQDs, in particular, from various viewpoints: (i) their definition, (ii) their photophysical properties, and (iii) the superiority of CQDs over MSQDs. Where possible, comparisons are made between CQDs and MSQDs. First, however, the review begins with a general brief description of quantum dots (QDs) as nanomaterials (sizes≤10 nm), followed by a short description of MSQDs and CQDs. Described subsequently are the various top‐down and bottom‐up approaches to synthesize CQDs followed by their distinctive photophysical properties (emission spectra; quantum yields, Φs). [ABSTRACT FROM AUTHOR]

The naphthalenediimide (NDI) scaffold in contrast to its higher congeners possess low-fluorescence. In spite of elegant synthetic developments, a highly emissive NDI is quite rare to find, as well as, a green-light-emitting NDI is yet to be explored. Herein, we report a novel class of symmetric and asymmetric NH2-substituted core-NDIs (1-5) with tunable fluorescence in the visible region and extending to the NIR frontier. Importantly, the bis-NH2-substituted NDI 2 revealed quantum yield, Φ of ≈81 and ≈68% in toluene and DMSO, respectively, suggesting versatility of the fluorophore in a wide range of solvent polarity. The dye 1 is shown to be the first NDI-based green-light emitter. The donor piperidine group in 5 diminish the Φf by 40-fold providing a lever to modulate the excited-state intramolecular proton transfer (ESIPT) process. Our synthetic protocol applies a Pd catalyst and a benign hydride source simplifying the non-trivial -NH2 group integration at the NDI-core. TDDFT calculations predicted strong intramolecular hydrogen bonds in the excited state in the bulk nonpolar medium and responsiveness to solvent polarity. The maximization of the NDI emission outlined here would further boost the burgeoning repertoire of applications of the NDI scaffold. [ABSTRACT FROM AUTHOR]

Organic semiconductors with extended π-conjugate systems have been extensively investigated to be implemented and improve optoelectronic devices. It is well known that benzothiadiazole (BTD) derivatives have interesting semiconductor properties that make them suitable materials for optoelectronic applications. In this work, the photophysical properties of 4 BTD with triphenylmethyl and triphenylsilyl derivatives in solution exhibited larger Stokes shifts, which can be attributed to the length and conjugation of these molecules. On the other hand, the quantum yields observed for these systems were larger than 0.5. In addition, the formation of Langmuir monolayers at the air–water interface with isotherms showing high collapse pressures around 60 mN/m, and stable compression–decompression cycles (hysteresis) were obtained. Langmuir–Blodgett films onto glass substrates were formed with these compounds by using the Z-type deposit with transfer ratios close to 1. In addition, high-fluorescence emission responses were observed for the BTD derivatives that did not contain silicon in their structure. Also, using scanning electron and atomic force microscopies, regular surface morphologies were observed for the silicon-less compounds, but higher roughnesses and fiber-like structures for the other films. From these results, these BTD films can be potential candidates to be employed in photoelectronic applications. [ABSTRACT FROM AUTHOR]

Apart from numerous applications, for example in azo dye precursors, explosives, and industrial processes, the nitro group (−NO2) appears on countless molecules in photochemical research owing to its unique characteristics such as a strong electron‐withdrawing ability and facile conversion to the reduced substituent. Although it is well known as a fluorescence quencher, fluorescent chromophores that contain the nitro group have also emerged, with 3‐nitrophenothiazine being recently reported to have 100 % emission quantum yield in nonpolar solvents. The diverse characters of nitro‐containing chromophores motivated us to systematically review those chromophores with nitro substituents, their associated photophysical properties, and applications. In this Review, we succinctly elaborate the advance of the fluorescent nitro chromophores in fields of intramolecular charge transfer, fluorescent probes and nonlinear properties. Special attention is paid to the rationalization of the associated emission spectroscopy, so that the readers can gain insights into the structure‐photophysics relationship and hence gain insights for the strategic design of nitro chromophores. [ABSTRACT FROM AUTHOR]

Copyright of Journal of East China University of Science & Technology is the property of Journal of East China University of Science & Technology Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Photochromic systems have been used to achieve a number of engineering functions such as light energy conversion, molecular motors, pumps, actuators, and sensors. Key to practical applications is a high efficiency in the conversion of light to chemical energy, a rigid structure for the transmission of force to the environment, and directed motion during isomerization. We present a novel type of photochromic system (diindane diazocines) that converts visible light with an efficiency of 18 % to chemical energy. Quantum yields are exceptionally high with >70 % for the cis–trans isomerization and 90 % for the back‐reaction and thus higher than the biochemical system rhodopsin (64 %). Two diastereomers (meso and racemate) were obtained in only two steps in high yields. Both isomers are directional switches with high conversion rates (76–99 %). No fatigue was observed after several thousands of switching cycles in both systems. [ABSTRACT FROM AUTHOR]

The photocatalytic activity of indium(III) oxide in the oxidation of carbon monoxide upon absorption of light quanta from the region of indirect electronic transitions (quantum energies <2.9 eV) has been found. The quantum yields and spectral dependences of the quantum yields of photocatalytic oxidation of carbon monoxide and photoadsorption of oxygen have been determined. The adsorption, photoadsorption, and photocatalytic properties of indium oxide microparticles have been studied. [ABSTRACT FROM AUTHOR]

The weak fluorescence (quantum yield <1 % in cyclohexane) of phenothiazine (PTZ) impedes its further application. In addition, the nitro group (NO2) is a well‐known fluorescence quencher. Interestingly, we obtained a highly fluorescent chromophore by combining these two moieties, forming 3‐nitrophenothiazine (PTZ‐NO2). For comparison, a series of PTZ derivatives bearing electron‐withdrawing groups (EWGs; CN and CHO) or electron‐donating groups (EDGs; OMe) at the 3‐position have been designed and synthesized. The phenothiazines bearing EWGs exhibited enhanced emission compared with the parent PTZ or EDG derivatives. Computational approaches unveiled that for PTZ and PTZ‐OMe, the transitions are from HOMOs dominated by π orbitals to LUMOs of mixed sulfur nonbonding–π* orbitals, and hence are partially forbidden. In contrast, the EWGs lower the energy level of the lone‐pair electrons on the sulfur atom, thereby suppressing the mixing of the nonbonding orbital with the π* orbital in the LUMO, such that the allowed ππ* transition becomes dominant. This work thus demonstrates a judicious chemical design to fine‐tune the transition character in PTZ analogues, with PTZ‐NO2 attaining 100 % emission quantum yields in nonpolar solvent. [ABSTRACT FROM AUTHOR]

In this study, two new phthalocyanines (M = Zn and Co) were synthesized using the (E)-4-(4-(3-(4- (benzyloxy)phenyl)acryloyl)phenoxy)phthalonitrile (3) as ligand prepared from the chemical reaction of 4- nitrophthalonitrile with (E)-3-(4-(benzyloxy)phenyl)-1-(4-hydroxyphenyl)prop-2-en-1-one (2). All compounds were characterized using by 1H-NMR, 13C-NMR, UV-Vis, FT-IR, and MALDI-TOF mass spectra. Singlet oxygen quantum yields of the synthesized compounds, aggregates in different solutions, metal chelating and 2,2- Diphenyl-1-picrylhydrazyl (DPPH) radical scavenging properties were reported. [ABSTRACT FROM AUTHOR]

The study of a simple and facile microwave heating technique is introduced for the synthesis of nitrogen-doped carbon quantum dots (N-CQDs) with the most abundant and cheap chemicals- Citric acid (carbon source & precursor) and Urea (nitrogen source & reducing agent). TEM and DLS results indicated that such prepared N-CQDs have an average particle size of ∼0.8 nm and high Quantum Yields of ∼24.69%. UV-Vis and PL Spectroscopic results indicated that these N-CQDs have bright green color fluorescence under the excitation of 405 nm wavelength and are highly dispersible in water and provide a stable optically transparent yellowish solution in ambient light. FTIR results confirmed the Nitrogen Doping over these CQDs as it consists of N-H vibrational structural bonds. XRD results display a diffraction peak at 27°, which corresponds to the (002) plane of a graphitic structure revealing an amorphous carbon phase.TEM results also demonstrated that these materials have good spherical morphology. Their high fluorescence/ photoluminescence, small size, chemical stability, high quantum yields, broad excitation range, and porous nature make them better candidates in the field of optoelectronics such as Solar cells and Light emitting diodes (LEDs), biosensing/imaging, and energy storage such as Li-Ion Batteries and supercapacitors. [Display omitted] [ABSTRACT FROM AUTHOR]

A series of new benzoxazaborinines was prepared from the salicylaldehyde Schiff bases derived from amino acid esters by a simple complexation reaction between the Schiff bases and boron trifluoride with up to 85 % yield. Single crystal X-ray diffraction studies on 4b further threw light on the three-dimensional structure of the compound. The absorption and emission maxima for all the compounds were observed in the range of 330–353 nm and 435–517 nm, respectively. Compounds 4f and 4l with a tryptophan moiety displayed significantly higher Stokes shifts of 187 and 151 nm respectively, compared with the other derivatives which were in the range of 86–94 nm. Most of the compounds displayed significant quantum yields of up to 80.8 %. The band gaps of the compounds were also calculated by DFT calculations and were found to complement the same calculated by the UV–Vis spectra and were in the range of 2.46–3.93 eV. The tryptophan derivatives, 4f and 4l were found to possess the lowest band gap. [Display omitted] • 12 Novel benzoxazaborinines were prepared by a simple complexation reaction. • Three-dimensional structure of the compound 4b obtained by single crystal X-ray diffraction studies. • All compounds displayed Stokes shifts and significant quantum yields. • The band gap of the compounds was calculated by DFT calculations. [ABSTRACT FROM AUTHOR]

The [4+4] photocycloaddition of anthracene is one of most relevant photoreactions and is widely applied in materials science, as it allows to remote‐control soft matter material properties by irradiation. However, highly energetic UV irradiation is commonly applied, which limits its application. Herein, the wavelength dependence of the photodimerization of anthracene is assessed for the first time, revealing that the reaction is induced just as effectively with mild visible light (410 nm). To fully establish [4+4] cycloadditions within defined chemical environments, a conceptual framework for the solution kinetics of the photo‐dimerization up to long reaction times is established by developing a novel photoreaction rate law that is dependent on individual rate coefficients of the key reaction steps. These coefficients can be determined based on low conversion photochemical experiments. Both differential and integral quantum yields can subsequently be predicted that are strongly time‐dependent, highlighting the need for a detailed reaction pathway analysis. The presented approach simplifies a complex photochemical scenario, making the photochemical anthracene dimerization, or potentially any other photochemical dimerization, amenable to a time‐dependent understanding at the elementary reaction level. [ABSTRACT FROM AUTHOR]

Our knowledge of the effects of copper on microalgal physiology is largely based on studies conducted with high copper concentrations; much less is known when environmentally relevant copper levels come into question. Here, we evaluated the physiology of Chlorolobion braunii exposed to free copper ion concentrations between 5.7 × 10−9 and 5.0 × 10−6 mol · L−1, thus including environmentally relevant values. Population growth and maximum photosynthetic quantum yield of PSII were determined daily during the 96 h laboratory controlled experiment. Exponentially‐growing cells (48 h) were analyzed for effective quantum yield and rapid light curves (RLC), and total lipids, proteins, carbohydrates, chlorophyll a and carotenoids were determined. The results showed that growth rates and population density decreased gradually as copper increased in experiment, but the photosynthetic parameters (maximum and effective quantum yields) and photochemical quenching (qP) decreased only at the highest free copper concentration tested (5.0 × 10−6 mol · L−1); nonphotochemical quenching (NPQ) increased gradually with copper increase. The RLC parameters Ek and rETRmax were inversely proportional to copper concentration, while α and Im decreased only at 5.0 × 10−6 mol · L−1. The effects of copper in biomolecules yield (mg · L−1) varied depending on the biomolecule. Lipid yield increased at free copper concentration as low as 2.5 × 10−8 mol · L−1, but proteins and carbohydrates were constant throughout. [ABSTRACT FROM AUTHOR]

Platinum(II) complexes with an N‐heterocyclic carbene and a cyclometalating phenyl ligand (C^C*) are excellent candidates as efficient blue triplet emitters for OLED applications. The electronic and photophysical properties of these complexes can be fine‐tuned with the objective to increase the quantum yields and lower the phosphorescence decay times. We found that platinum complexes with an imidazopyrazine C^C* ligand and bulky acetylacetonates are sky‐blue triplet emitters, characterised by an almost unitary quantum yield and short phosphorescence decay times. [ABSTRACT FROM AUTHOR]

This Concept article highlights the development of a novel analytical tool, LED‐NMR (a combination of in situ light illumination using a light‐emitting diode and NMR spectroscopy) and its variant UVNMR (LED‐NMR coupled with UV/Vis absorption spectroscopy), as well as their applications in the mechanistic investigation of light‐induced transformations. The utility of these new tools has been demonstrated by providing rich kinetic and structural data of reaction species offering mechanistic insights into photochemical and photocatalytic reactions. Furthermore, NMR actinometry has been recently developed as a practical and simple method for quantum yield measurements. Quantum yield is an important parameter in photo‐induced processes, but is rarely measured in practice because of the barriers associated with traditional actinometry. These new tools and techniques streamline measurements of the quantum efficiency while affording informative mechanistic insights into photochemical reactions. We anticipate these techniques will enable chemists to further advance the rapidly emerging photochemistry field. [ABSTRACT FROM AUTHOR]