Large Redshift Research Articles

1-Azaazulene: A Ligand Moiety for Boron Difluoride (BF2) Complexes To Achieve Long-Wavelength Absorption.

1-Azaazulene was adopted as a new ligand moiety for boron difluoride (BF2) complexes, resulting in large red shifts of the absorption bands up to 103 nm compared to their isomeric quinoline-based complexes. Such change was attributed to the nonalternant nature of 1-azaazulene, as the complexes maintained the intrinsic 10π-peripheral electronic structure. 1a exhibited the most red-shifted absorption among reported BF2 complexes containing a phenolic backbone, and the absorption edge of 1b reached the red region.

Size and chemistry of 1–2 layer graphene nanosheets at the transition into photoluminescence and assembly with large shifts from blue to red emission

Synthetic refinement of graphene photoluminescence remains challenging because underlying characteristics have not been well understood from polydisperse mixtures of different sizes and surface chemistries. Here, we isolate and characterise different populations of 1–2 layer graphene (1-2LG) each with narrow size range. Small 1-2LG nanosheets down to 25 nm size remained black and non-luminescent with N. and O. additions at their edges, whereas 15 nm nanosheets transitioned into photoluminescence, while retaining substantial sp2 carbon of graphene. Positively-charged amine modifications overcame the repulsion between nanosheets from the negative zeta potential of sp2 graphene faces in water and allowed assembly of similarly-sized nanosheets with large red shifts (>150 nm) taking blue emission into the red. However, more extensive edge modification into carboxyl groups and neutral amides built negative charge at the edges. Together with smaller nanosheet size and reduced sp2 carbon, red shifts were weakened by half in these isolates, which were most modified and more like graphene oxide and carbon quantum dots. N addition to form amines at nanosheet edges, while avoiding O atom addition and carboxyl groups, presents as a simple refinement for synthesis of self-assembling graphene quantum dots with multi-colour emission, which also retain sp2 carbon properties of graphene.

Synthesis, Characterization, and Optical Properties of Novel Heterocyclic Azo Dyes and Evaluation of Their Antioxidant Activity as an Active Sunscreen Agent

AbstractWe synthesized some novel isoxazole azo derivatives using conventional methods and studied their linear, non‐linear optical properties and antioxidant activity. UV‐Vis spectroscopy revealed absorption bands ranging from 310–470 nm for the obtained compounds. Compounds 3 c and 3 b, for example, showed a large redshift and solvatochromic behavior. NLO analysis results show that compounds exhibit a greater NLO response than the magnitude of urea done by the DFT method. The electrochemical properties of compounds are studied using cyclic voltammetry and results are used for calculation of HOMO and LUMO experimentally. The antioxidant activity of the synthesized azo dyes displayed that 3 c has excellent antioxidant activity with the highest percentage (71.54605 %) of radical inhibition as compared to reference standard Vit‐C. Molecular docking analysis shows that compounds have a strong binding affinity in the range of −7.0 to −4.6 kcal/mol compared to Vit‐C, which has a binding affinity of −3.6 kcal/mol. The sun protection factor performance was determined by UV‐Vis spectroscopy, and results show that compounds are most effective, exhibit a remarkable SPF value, and offer superior sun protection by absorbing UV rays.

Geometrical features, stability and electronic properties of (Cu3Sn)n clusters

Recently, significant advancements have been made in low-entropy Cu3Sn catalysts, showcasing their efficient catalytic CO oxidation capabilities. Hence, the atomic models of the Cu3Sn are worth established to further investigate their catalytic mechanisms. Here, the structural features and stability of (Cu3Sn)n clusters (n = 1–6) are investigated using the genetic algorithm combined with the density functional theory (DFT). The results reveal the structural evolution of these clusters from hollow cages to compact icosahedrons, where Cu atoms predominantly tend to grow together, while Sn atoms are dispersed at the edge positions. The Eb, Ef and Δ2E analyses show that the icosahedral (Cu3Sn)3 has a higher stability than that of its neighbors. The molecular dynamics simulations demonstrates its stability even at 1000 K. The molecular orbitals and density of states reveal that the (Cu3Sn)3 has an 1S21P61D102S21F1 superatomic electronic configuration. Electrostatic potential surfaces show that (Cu3Sn)n clusters have significant σ-hole regions at the Cu atomic sites, which can make the CO stretching frequency and bond length have a large red-shift. Moreover, the adsorption energy between the (Cu3Sn)3 and CO is the largest, reaching 1.17 eV. Our work provides inferences to the structural characteristics and adsorptions of the CuSn alloys at the atomic level.

Study on the effects caused by defect LaK in KH2PO4 crystal

Based on first-principles calculations, we have investigated the effects of different charged states of LaK on the defect formation energies (DFE), lattice distortions, electronic structures, and optical properties of paraelectric phase (PE-KDP) and ferroelectrical phase (FE-KDP) crystals. Our calculations indicate that LaK·· is readily formed in both crystal structures, and the degree of H–O bond distortion is more pronounced in PE-KDP. This could explain the formation of small growth mounds on the surface of La-doped crystals observed in the experiments, as well as the large decrease in the hardness of La-doped crystals. Furthermore, the band gap value of La-doped crystals is smaller than that of perfect crystals. This can be attributed to the fact that the 5d orbitals of La affect the 2p orbitals of O located in the conduction band minimum (CBM), resulting in a splitting of the energy levels and the formation of a defective energy level that enters the forbidden band. The optical spectra have been obtained considering the electron-phonon coupling. Large stokes redshift and nonradiative jump will lower the crystal laser damage threshold. The La-doped PE-KDP has an absorption band at 3.03 eV (409 nm) in good agreement with the experimentally observed absorption band at 390 nm.

Rational Design of Fluorophores Using MO Theory: Our Journey from BODIPYs to BOIMPYs

This short review demonstrates how MO-theoretical considerations can support the tailor-made design of new dye scaffolds, specifically the recently introduced BOIMPY class of fluorophores. Starting with historical and structural foundations, the influence of canonical streptocyanines on the electronic features of diarylmethenes and rhodamines is examined and the BODIPY scaffold is introduced as the primary structural inspiration for our work. The attachment of five-membered ring heterocycles at the meso position of the BODIPY core enables a relaxation into a co-planar and twofold chelating triarylmethene system. After introduction of two electron-withdrawing BF2 units, efficient rigidity is achieved since hindered rotation prevents non-radiative dissipation of energy via excited state relaxation. Hence, a lowered LUMO level allows the combination of a large red shift with high quantum efficiencies. The synthetic approach to BOIMPYs is straightforward and analogous to BODIPY syntheses starting from benzimidazole or tetrazole carbaldehydes. Cyclic voltammetric measurements prove that BOIMPYs are able to easily accept two electrons and might act as efficient photoredox catalysts.

Quasi-stars as a Means of Rapid Black Hole Growth in the Early Universe

JWST observations demonstrate that supermassive black holes (SMBHs) exist by redshifts z ≳ 10, providing further evidence for “direct collapse” black hole (BH) formation, whereby massive (∼103–5 M ⊙) SMBH seeds are generated within a few million years as a byproduct of the rapid inflow of gas into the centers of protogalaxies. Here we analyze the intermediate “quasi-star” phase that accompanies some direct-collapse models, during which a natal BH accretes mass from and energetically sustains (through accretion) an overlying gaseous envelope. We argue that previous estimates of the maximum BH mass that can be reached during this stage, ∼1% of the total quasi-star mass, are unphysical, and arise from underestimating the efficiency with which energy can be transported outward from regions close to the BH. We construct new quasi-star models that consist of an inner, “saturated convection” region (which conforms to a convection-dominated accretion flow near the BH) matched to an outer, adiabatic envelope. These solutions exist up to a BH mass of ∼60% of the total quasi-star mass, at which point the adiabatic envelope contains only 2% of the mass (with the remaining ∼38% in the saturated-convection region), and this upper limit is reached within a time of 20–40 Myr. We conclude that quasi-stars remain a viable route for producing SMBHs at large redshifts, which is consistent with recent JWST observations.

Coordination Synergistic-Induced J-Aggregation Enhanced Fluorescent Performance of HBT-Excimers and Imaging Applications.

Developing a novel strategy to improve the optical performances of fluorescent probes is a vital factor in elevating its practical application; viz., novel biocompatible fluorescent probes with excellent multifunctions exhibited unparalleled advantages in probing functions of intracellular molecules to elucidate intracellular events in living systems. Herein, we have successfully constructed a new strategy that aggregation and coordination synergistically induce (2-hydroxylphenyl-benzothiazole) HBT derivatives to form excimers with large red-shifted fluorescence and application for insight into stress-response zinc fluctuations in living systems. We have synthesized four HBT-based derivatives and deeply investigated the response mechanism by fluorescent spectral studies, demonstrating that probes 3 and 4 showcased large red shifts in emission wavelength due to J-aggregation. More interestingly, the fluorescence of probe 4 was significantly enhanced in the presence of a zinc ion, suggesting that zinc coordination synergistically induced J-aggregation. Probe 4 was successfully applied to image zinc fluctuations in different models of living systems, proving that this probe is a powerful tool to unveil the relationship between invasive stress and diseases by monitoring endogenous zinc fluctuations.

El Gordo needs El Anzuelo: Probing the structure of cluster members with multi-band extended arcs in JWST data

Gravitational lensing by galaxy clusters involves hundreds of galaxies over a large redshift range and increases the likelihood of rare phenomena (supernovae, microlensing, dark substructures, etc.). Characterizing the mass and light distributions of foreground and background objects often requires a combination of high-resolution data and advanced modeling techniques. We present the detailed analysis of a prominent quintuply imaged dusty star-forming galaxy ($ mainly lensed by three members of the massive galaxy cluster ACT-CL\,J0102$-$4915, also known as d =0.87$). We leverage JWST/NIRCam images, which contain lensing features that were unseen in previous HST images, using a Bayesian, multi-wavelength, differentiable and GPU-accelerated modeling framework that combines (lens modeling) and (field model and inference) software packages. For one of the deflectors, we complement lensing constraints with stellar kinematics measured from VLT/MUSE data. In our lens model, we explicitly include the mass distribution of the cluster, locally corrected by a constant shear field. We find that the two main deflectors (L1 and L2) have logarithmic mass density slopes steeper than isothermal, with $ L1 and $ L2 We argue that such steep density profiles can arise due to tidally truncated mass distributions, which we probe thanks to the cluster lensing boost and the strong asymmetry of the lensing configuration. Moreover, our three-dimensional source model captures most of the surface brightness of the lensed galaxy, revealing a clump with a maximum diameter of $400$ parsecs at the source redshift, visible at wavelengths $ rest mu m. Finally, we caution on using point-like features within extended arcs to constrain galaxy-scale lens models before securing them with extended arc modeling.

A Strained Donor‐Acceptor Carbon Nanohoop: Synthesis, Photophysical and Charge Transport Properties

AbstractHerein, we report the synthesis of a novel intramolecular donor‐acceptor (D−A) system ([12]CPP‐8TPAOMe) based on cycloparaphenylenes (CPPs) grafted with eight di(4‐methoxyphenyl)amino groups (TPAOMe) as donors. Compared to [12]CPP, D−A nanohoop exhibited significant changes in physical properties, including a large redshift (>78 nm) in the fluorescence spectrum and novel positive solvatofluorochromic properties with a maximum peak ranging from 484 nm to 546 nm. The potential applications of [12]CPP‐8TPAOMe in electron‐ and hole‐transport devices were further investigated, and its bipolar behavior as a charge transport active layer was clearly observed.

A Strained Donor-Acceptor Carbon Nanohoop: Synthesis, Photophysical and Charge Transport Properties.

Herein, we report the synthesis of a novel intramolecular donor-acceptor (D-A) system ([12]CPP-8TPAOMe) based on cycloparaphenylenes (CPPs) grafted with eight di(4-methoxyphenyl)amino groups (TPAOMe) as donors. Compared to [12]CPP, D-A nanohoop exhibited significant changes in physical properties, including a large redshift (>78 nm) in the fluorescence spectrum and novel positive solvatofluorochromic properties with a maximum peak ranging from 484 nm to 546 nm. The potential applications of [12]CPP-8TPAOMe in electron- and hole-transport devices were further investigated, and its bipolar behavior as a charge transport active layer was clearly observed.

Sulfato‐β‐cyclodextrin induced multivalent supramolecular directional aggregation of cyanovinylene derivatives for achieving reversible near‐infrared fluorescence

AbstractMolecular aggregation or supramolecular aggregation‐induced emission is one of the research hotspots in chemistry, biology, and materials. Herein, we report negatively charged sulfato‐β‐cyclodextrin (SCD) induced cyanovinylene derivatives (DPy‐6C) directional aggregation to form regular nanorods (DPy‐6C@SCD) through supramolecular multivalent interactions, not only achieves ultraviolet‐visible absorption redshifted from 453 to 521 nm but also displays near‐infrared (NIR) aggregation‐induced emission with a large spectral redshift of 135 nm. The DPy‐6C monomer presents random nanosheets with weak fluorescence but obtains regular aggregates after assembly with SCD through electrostatic interactions. In the presence of H+, the DPy‐6C@SCD can further aggregate into elliptical nanosheets without fluorescence changes due to the protonation of secondary amines. In contrast, the morphology of DPy‐6C@SCD becomes flexible and sticks together upon the addition of OH− with an emission blue shift of 72 nm and a 90‐fold intensity increase because of disrupting the stacking mode of aggregates, thereby achieving acid‐base regulated reversible fluorescence behaviors that cannot be realized by DPy‐6C monomer. The DPy‐6C@SCD can efficiently select the detection of volatile organic amines both in liquid and gas phases within 5 s at the nanomolar level. Taking advantage of RGB analysis and calculation formula application, the DPy‐6C@SCD has been successfully used to monitor various organic amines on a smartphone, accompanied by naked‐eye visible photoluminescence. Therefore, the present research provides an efficient directional aggregation method through supramolecular multivalent interactions, which not only realizes topological morphology transformation but also achieves reversible NIR luminescent molecular switch and high sensitivity organic amines fluorescent sensing devices.

Understanding the radio luminosity function of star-forming galaxies and its cosmological evolution

ABSTRACT We explore the redshift evolution of the radio luminosity function (RLF) of star-forming galaxies using galform, a semi-analytic model of galaxy formation and a dynamo model of the magnetic field evolving in a galaxy. Assuming energy equipartition between the magnetic field and cosmic rays, we derive the synchrotron luminosity of each sample galaxy. In a model where the turbulent speed is correlated with the star formation rate, the RLF is in fair agreement with observations in the redshift range 0 ≤ z ≤ 2. At larger redshifts, the structure of galaxies, their interstellar matter, and turbulence appear to be rather different from those at z ≲ 2, so that the turbulence and magnetic field models applicable at low redshifts become inadequate. The strong redshift evolution of the RLF at 0 ≤ z ≤ 2 can be attributed to an increased number, at high redshift, of galaxies with large disc volumes and strong magnetic fields. On the other hand, in models where the turbulent speed is a constant or an explicit function of z, the observed redshift evolution of the RLF is poorly captured. The evolution of the interstellar turbulence and outflow parameters appear to be major (but not the only) drivers of the RLF changes. We find that both the small- and large-scale magnetic fields contribute to the RLF but the small-scale field dominates at high redshifts. Polarization observations will therefore be important to distinguish these two components and understand better the evolution of galaxies and their non-thermal constituents.

Novel Iminocoumarin-substituted Tetraphenylethylene-based Near-infrared Fluorescent Probe for Ratiometric Detection of F- and H2S.

An iminocoumarin and tetraphenylethylene compound that exhibits aggregation-induced emission (AIE) and a significant Stokes shift (Δλ = 135nm) in THF was created via the Knoevenagel condensation method. TPICBT could also be used as a ratiometric near-infrared fluorescent probe for the naked color identification of F- and H2S. It showed a large red shift (˃ 90nm), good selectivity, and anti-interference. Test strip detection and cell imaging had both been accomplished using the probe. In addition, the probe could conveniently detect H2S produced during food spoilage without laboratory instruments.

Forecasting the BAO measurements of the CSST galaxy and AGN spectroscopic surveys

ABSTRACT The spectroscopic survey of the China’s Space Survey Telescope (CSST) is expected to obtain a huge number of slitless spectra, including more than one hundred million galaxy spectra and millions of active galactic nuclei (AGNs) spectra. By making use of these spectra, we can measure the Baryon Acoustic Oscillation (BAO) signals over large redshift ranges with excellent precisions. In this work, we predict the CSST measurements of the post-reconstruction galaxy power spectra at $0\lt z\lt 1.2$ and pre-reconstruction AGN power spectra at $0\lt z\lt 4$, and derive the BAO signals at different redshift bins by constraining the BAO scaling parameters using the Markov Chain Monte Carlo method. Our result shows that the CSST spectroscopic survey can provide accurate BAO measurements with precisions higher than 1 and 3 per cent for the galaxy and AGN surveys, respectively. By comparing with current measurements in the same range at low redshifts, this can improve the precisions by a factor of $2\sim 3$, and similar precisions can be obtained in the pessimistic case. We also investigate the constraints on the cosmological parameters using the measured BAO data by the CSST, and obtain stringent constraint results for the energy density of dark matter, Hubble constant, and equation of state of dark energy.

Synthesis of Styrylbenzazole Photoswitches and Evaluation of their Photochemical Properties.

Styrylbenzazoles form a promising yet under-represented class of photoswitches that can perform a light-driven E-Z isomerization of the central alkene double bond without undergoing irreversible photocyclization, typical of the parent stilbene. In this work, we report the synthesis and photochemical study of 23 styrylbenzazole photoswitches. Their thermal stabilities, quantum yields, maximum absorption wavelengths and photostationary state (PSS) distributions can be tuned by changing the benzazole heterocycle and the substitution pattern on the aryl ring. In particular, we found that push-pull systems show large redshifts of the maximum absorption wavelengths and the highest quantum yields, whereas ortho-substituted styrylbenzazole photoswitches exhibit the most favorable PSS ratios. Taking advantage of both design principles, we produced 2,6-dimethyl-4-(dimethylamino)-styrylbenzothiazole, a thermally stable and efficient P-type photoswitch which displays negative photochromism upon irradiation with visible light up to 470 nm to obtain a near-quantitative isomerization with a very high quantum yield of 59 %. Furthermore, 4-hydroxystyrylbenzoxazole was demonstrated to be a pH-sensitive switch which exhibits a 100 nm redshift upon deprotonation. Ortho-methylation of its benzothiazole analogue improved the obtained PSS ratio in its deprotonated state from E : Z=53 : 47 to E : Z=18 : 82. We anticipate that this relatively unexplored class of photoswitches will form a valuable expansion of the current family of photoswitches.

Chemo-photodynamic antitumour therapy based on Er-doped upconversion nanoparticles coated with hypocrellin B and MnO2

An antitumour chemo-photodynamic therapy nanoplatform was constructed based on phospholipid-coated NaYF4: Yb/Er upconversion nanoparticles (UCNPs). In this work, the amphiphilic block copolymer DSPE-PEG2000 was combined with the surface ligand oleic acid of the UCNPs through hydrophobic interaction to form liposomes with a dense hydrophobic layer in which the photosensitizer hypocrellin B (HB) was assembled. The coated HB formed J-aggregates, which caused a large redshift in the absorption spectrum and improved the quantum efficiency of energy transfer. Furthermore, MnO2 nanosheets grew in-situ on the liposomes through OMn coordination. Therefore, a multifunctional tumour microenvironment (TME)-responsive theranostic nanoplatform integrating photodynamic therapy (PDT) and chemodynamic therapy (CDT) was successfully developed. The results showed that this NIR-mediated chemo-photodynamic therapy nanoplatform was highly efficient for oncotherapy.

The Nonradiative Properties of Self‐Trapped Holes in Ultra‐Wide Bandgap Gallium Oxide Film

The photoluminescence (PL) of self‐trapped holes (STH) in ultra‐wide bandgap β‐Ga2O3 is commonly its most dominant light emission and is an inherent property. Thus, gaining knowledge of the crystal dynamics that impact the PL properties is vital to sensor and other technologies. The PL, Raman‐phonons, and their interactions are studied at an extreme temperature range of 77–622 K. The PL is studied up to the bandgap value of ≈5 eV. It is found that the high‐energy Raman modes provide a major route to the nonradiative process of the PL via STH–phonon interaction with an activation energy of 72 meV. This dynamic is modeled with the configurational coordinate scheme at the strong phonon coupling limit. The exceptionally broad Gaussian PL linewidth manifests this coupling. The weak temperature response of the PL energy peak position indicates that the STH has characteristics of a deep‐level defect. This contrasts with the large redshift of ≈220 meV of the optical gap of the film, ascertained from transmission. Unlike the temperature response of the high‐energy phonons, the behavior of the low‐energy phonons is found to follow the Bose–Einstein population increase, indicating no strong interaction with the STH.

High-Pressure Structural and Optical Studies of Pure Low-Dimensional Cesium Lead Chlorides CsPb2Cl5 and Cs4PbCl6.

We report high-pressure single-crystal X-ray diffraction, optical absorption, and photoluminescence investigations of all-inorganic perovskite-related materials CsPb2Cl5 and Cs4PbCl6. The crystal structure of CsPb2Cl5, composed of alternate layers of Cs+ cations and Pb-Cl frameworks, is stable under pressure up to at least 4.2 GPa. Because external stress is mainly absorbed by the Cs+ layers, the optical absorption edge of the crystal only slightly red-shifts with increasing pressure, which correlates well with a moderate shortening of the Pb-Cl bonds. A quite different response to pressure shows Cs4PbCl6, the crystal built of isolated PbCl64- octahedra and Cs+ cations. During the compression at around 3.4 GPa, the trigonal phase I, space group R3̅c, transforms to the orthorhombic phase II, space group Cmce, which at around 4 GPa transforms into phase III. On decompression, phase II is not restored, but phase III converts through a diffuse phase transition into another high-pressure phase IV, which is stable in a wide pressure range and transforms to the initial phase I only around atmospheric pressure. The red shift of the absorption edge and the profound modification of the absorption spectrum in phase II were ascribed to the deformation of the PbCl64- octahedra. The transition to phase III induces a blue shift of the absorption edge, while the transition to phase IV is associated with a large red shift. Photoluminescence was detected in phases I and II with the intensity quenched with increasing pressure.

Dithiocarbonate-Protected Au25 Nanorods of a Chiral D5 Configuration and NIR-II Phosphorescence.

Innovative surface-protecting ligands are in constant demand due to their crucial role in shaping the configuration, property, and application of gold nanoclusters. Here, the unprecedented O-ethyl dithiocarbonate (DTX)-stabilized atomically precise gold nanoclusters, [Au25(PPh3)10(DTX)5Cl2]2+ (Au25DTX-Cl) and [Au25(PPh3)10(DTX)5Br2]2+ (Au25DTX-Br), were synthesized and structurally characterized. The introduction of bidentate DTX ligands not only endowed the gold nanocluster with unique staggered Au25 nanorod configurations but also generated the symmetry breaking from the D5d geometry of the Au25 kernels to the chiral D5 configuration of the Au25 molecules. The chirality of Au25 nanorods was notably revealed through single-crystal X-ray diffraction, and chiral separation was induced by employing chiral DTX ligands. The staggered configurations of Au25 nanorods, as opposed to eclipsed ones, were responsible for the large red shift in the emission wavelengths, giving rise to a promising near-infrared II (NIR-II, >1000 nm) phosphorescence. Furthermore, their performances in photocatalytic sulfide oxidation and electrocatalytic hydrogen evolution reactions have been examined, and it has been demonstrated that the outstanding catalytic activity of gold nanoclusters is highly related to their stability.