Turning on the Light

Ca5MgSi3O12:Eu2+, Dy3+ was synthesized by solid-state reaction. The luminescence center related to the oxygen vacancies existed in the host matrix. Comparing the fluorescence and phosphorescence properties of samples synthesized under different air condiction, we find that the oxygen vacancies played an important role in the fluorescence and phosphorescence properties. Oxygen vacancies can transfer its energy to the luminescence center. Thermoluminescence spectra were used to characterize the effect of oxygen vacancies on the phosphorescence properties. Ca5MgSi3O12:Eu2+,Dy3+ has a great potential to become a promising candidate to be used as long-lasting phosphors.

BaAl2O4:Eu2+, Dy3+ phosphors with a good long lasting property can be easily obtained via a solid state reaction assisted with Li2CO3. The influence of Li2CO3 quantity on the lattice structure of BaAl2O4:Eu2+, Dy3+ phosphors, their photoluminescence (PL) property, and decaying process was studied by XRD, PL, and afterglow decay measurement, respectively. The results show that incorporating Li2CO3 in preparing process would obviously affect their lattice structure, accompanied by the variation of their luminescent property. With the increase of Li2CO3, their fluorescence property would gradually increase, at [Formula: see text] ([Formula: see text] reach their maximum emission intensity, and then decrease; but their phosphorescence property would continue to strengthen whether in brightness and decaying time up to [Formula: see text], and then decrease.

Molecular structure, fluorescent properties and dynamics of excited state structural relaxation of the oxadiazolic ortho-analog of POPOP with the additional sterical hindrance

The effect of hydrogen bond strength on emission properties in 2-(2′-hydroxyphenyl)imidazo[1,2-a]pyridines

The synthesis of a [7]helicene bromide derivative with two fused 2,1,3‐thiadiazole heterocycles (TD[7]Br) and a comprehensive study of its photophysical and chiroptical characteristics are presented along with a comparison with 9‐bromo‐carbo[7]helicene ([7]Br) and 2,15‐dibromo‐carbo[6]helicene ([6]Br). The integration of a bromine heavy atom onto the helicene backbone facilitates efficient singlet‐to‐triplet conversion allowing to investigate the resulting fluorescence and phosphorescence properties. The steady‐state chiroptical features of the systems are demonstrated through electronic circular dichroism and circularly polarized luminescence. Interestingly, a fluorescence quantum yield of 14% is obtained, a 17‐fold increase compared to the corresponding bromo‐heptacarbohelicene, and phosphorescence dissymmetry factors reach ±1.2 × 10−2 at 580 nm at low temperature. Finally, the exploration of various excited states generated during the excitation process and their dynamics is delved into by employing nonpolarized transient absorption and emission spectroscopies, thus, highlighting the fruitful combination of heavy‐atom effect and charge transfer. The experimental results are understood through time‐dependent density functional theory computations.

Photochemical stability of biologically active compounds. III. Mefloquine as a photosensitizer

Deciphering the luminescence mechanism: Investigating ESIPT-attributed HPI2C molecule with coupled thermally activated delayed fluorescence and phosphorescence properties

Phosphorescent carbon nanodots (CNDs) have various attractive properties and potential applications, but it remains a formidable challenge to achieve large-scale phosphorescent CNDs limited by current methods. Herein, a large-scale synthesis method for phosphorescent CNDs has been demonstrated via precursors' self-exothermic reaction at room temperature. The as-prepared CNDs show fluorescence and phosphorescence property, which are comparable with that synthesized by solvothermal and microwave method. Experimental and computational studies indicate that exotic atom doped sp2 hybridized carbon core works as an emissive center, which facilities the intersystem crossing from singlet state to triplet state. The CNDs show phosphorescence with tunable lifetimes from 193 ms to 1.13 s at different temperatures. The demonstration of large-scale synthesis of phosphorescent CNDs at room temperature opens up a new window for room temperature fabrication phosphorescent CNDs.

This paper proposed a simple synthetic strategy towards a novel cationic europium luminescent copolymer, poly(METAC-co-NIPAm-co-Eu(AA)3Phen) (PMNEu), and investigation about their complexation ability with DNA. In this approach, first, Eu(AA)3Phen complex monomer containing Eu3+, acrylic acid (AA), and 1,10-phenanthroline (Phen) was synthesized, and subsequently, free radical copolymerization of Eu(AA)3Phen complex monomer with other two functional monomers, [2-(methacryloyloxy) ethyl] trimethylammonium chloride (METAC) and N-isopropylarylamide (NIPAm), was carried out in methanol using azodiisobutyronitrile (AIBN) as the initiator. 1HNMR, GPC, fluorescence spectroscopy, UV–vis spectroscopy, and TEM were used to investigate the chemical structures, molecular weight and molecular weight distribution, fluorescence properties, UV spectra, and morphologies of PMNEu copolymer, respectively. Furthermore, the interaction of PMNEu with DNA was also studied with fluorescence spectroscopy, UV–vis spectroscopy, and agarose gel electrophoresis. These results indicated that PMNEu could interact with DNA via an electrostatic bonding mode and the bonding constant was 2.2 × 105 L/mol. Additionally, TEM observation showed that pure PMNEu formed micelles in water solution, while the size-controllable aggregations of PMNEu with DNA were obtained when PMNEu was mixed with DNA at various concentration ratios. A good biocompability of PMNEu was demonstrated through in vitro cytotoxicity assays.

Morphological insights into uncompetitive fluorescence of coal-based carbon dots and strategies for improvement

Fluorescence microscopy has significantly advanced biological imaging at the nanoscale, particularly with the advent of super-resolution microscopy (SRM), which transcends the Abbe diffraction limit. Most cutting-edge SR methods require high-precision optical setups, which constrain the widespread adoption of SRM. Fluorescence fluctuation-based SRM (FF-SRM) can break the diffraction limit without complex optical components, making it particularly well-suited for biological imaging. However, conventional FF-SRM methods, such as super-resolution optical fluctuation imaging (SOFI), still require specific fluorescent molecular blinking properties. Instead of enhancing the intrinsic blinking characteristics by finding specific fluorescent markers, employing optical methods such as spatial light modulation to adjust the excitation light field allows for easier and more flexible matching of the on-time ratio with the analysis of temporal stochastic intensity fluctuations. Nevertheless, the specific parameters of the modulation patterns have not been thoroughly explored, despite their crucial influence on the reconstruction quality. Herein, we propose adaptive-modulated fast fluctuation super-resolution microscopy. Our method demonstrates theoretically and experimentally that restricting the size of modulation units in a certain range ensures better image quality with fewer artifacts and signal losses. We find it still significantly effective when applied to other FF-SRM. Overall, the further development of the adaptive modulation technique has made it more stable in behavior and maintained high-quality imaging, presenting broader prospects for super resolution imaging based on statistical analysis.

Fluorescence and phosphorescence properties of the low temperature forms of the MAl 2Si 2O 8:Eu 2+ ( M=Ca, Sr, Ba) compounds

An estimation of the atomic contribution to octanol-water partition coefficient and molar refractivity from fundamental atomic and structural properties: Its uses in computer aided drug design

The interaction of light with matter provides some of the most important tools for studying structure and dynamics on the microscopic scale. Atomic and molecular spectroscopy in the low pressure gas phase probes this interaction essentially on the single particle level and yields information about energy levels, state symmetries, and intramolecular potential surfaces. Understanding environmental effects in spectroscopy is important both as a fundamental problem in quantum statistical mechanics and as a prerequisite to the intelligent use of spectroscopic tools to probe and analyze molecular interactions and processes in condensed phases. Spectroscopic observables can be categorized in several ways. We can follow a temporal profile or a frequency resolved spectrum; we may distinguish between observables that reflect linear or nonlinear response to the probe beam; we can study different energy domains and different timescales and we can look at resonant and nonresonant response. This chapter discusses some concepts, issues, and methodologies that pertain to the effect of a condensed phase environment on these observables. For an in-depth look at these issues the reader may consult many texts that focus on particular spectroscopies. With focus on the optical response of molecular systems, effects of condensed phase environments can be broadly discussed within four categories: 1. Several important effects are equilibrium in nature, for example spectral shifts associated with solvent induced changes in solute energy levels are equilibrium properties of the solvent–solute system. Obviously, such observables may themselves be associated with dynamical phenomena, in the example of solvent shifts it is the dynamics of solvation that affects their dynamical evolution. Another class of equilibrium effects on radiation– matter interaction includes properties derived from symmetry rules. A solvent can affect a change in the equilibrium configuration of a chromophore solute and consequently the associated selection rules for a given optical transition. Some optical phenomena are sensitive to the symmetry of the environment, for example, surface versus bulk geometry. 2. The environment affects the properties of the radiation field; the simplest example is the appearance of the dielectric coefficient ε in the theory of radiation–matter interaction.

Tailoring the band-gap, optical and fluorescent properties of 3,5-diaminobenzoic acid via functionalization with chemical groups: A DFT study