UV Vis Absorption Spectra Research Articles

Old Acquaintances and Novel Complex Structures for the Ni(II) and Cu(II) Complexes of bis-Chelate Oxime-Amide Ligands.

In the process of systematically studying the methylhydroxyiminoethaneamide bis-chelate ligands with polymethylene spacers of different lengths, L1-L3, and their transition metal complexes, a number of new Ni(II) and Cu(II) species have been isolated, and their molecular and crystal structures were determined using single-crystal X-ray diffraction. In all of these compounds, the divalent metal is coordinated by the ligand donor atoms in a square-planar arrangement. In addition, a serendipitously discovered new type of neutral Ni(II) complex, where the propane spacer of ligand L2 underwent oxidation to the propene spacer, and one of the amide groups was oxidised to the ketoimine, is also reported. The resulting ligand L2' affords the formation of neutral planar Ni(II) complexes, which are assembled in the solid state on top of each other, and yield two polymorphic structures. In both structures, the resulting infinite, exclusively parallel metal ion columns in ligand insulation may serve as precursor materials for sub-nano-conducting connectors. Overall, this paper reports the synthesis and characterisation of seven new anionic, cationic, and neutral Ni(II) and Cu(II) complexes, their crystal structures, as well as experimental and computed UV-Vis absorption spectra for two structurally similar Ni(II) complexes, yellow and red.

Polymorphism and Red Photoluminescence Emission from 5s2 Electron Pairs of Sb(III) in a New One-Dimensional Organic-Inorganic Hybrid Based on Methylhydrazine: MHy2SbI5.

We explore the crystal structure and luminescent properties of a new 1D organic-inorganic hybrid, MHy2SbI5, based on methylhydrazine. The compound reveals the red photoluminescence (PL) originating from the 5s2 electron pairs of Sb(III) as well as complex structural behavior. MHy2SbI5 crystalizes in two polymorphic forms (I and II) with distinct thermal properties and structural characteristics. Polymorph I adopts the acentric P212121 chiral space group confirmed by SHG, and, despite a thermally activated disorder of MHy, does not show any phase transitions, while polymorph II undergoes reversible low-temperature phase transition and high-temperature reconstructive transformation to polymorph I. The crystal structures of both forms consist of 1D perovskite zig-zag chains of corner-sharing SbI6 octahedra. The intriguing phase transition behavior of II is associated with the unstable arrangement of the [SbI5]2-∞ chains in the structure. The energy band gap (Eg) values, estimated based on the UV-Vis absorption spectra, indicate that both polymorphs have band gaps, with Eg values of 2.01 eV for polymorph I and 2.12 eV for polymorph II.

Development of sustainable, eco-friendly antimicrobial finishing of cotton fabric using prodigiosin of Serratia marcescens SP1

Textile industries use synthetic colourants that often pollute soil, and water, which could be replaced with microbially derived pigment. The major aim of this study was to develop a textile fabric using microbially derived colourants that are eco-friendly in nature. A prodigiosin-producing bacterial strain was isolated and identified as Serratia marcescens SP1. The optimization of growth parameters revealed that yeast malt extract medium with pH of 7, temperature of 24 °C, and growth time of 3 days has maximum prodigiosin production. Further, the Rf value of 0.89 in TLC, UV visible absorption spectra of 534 nm, functional groups obtained in FTIR, a molecular weight of 322 D m/z in GC–MS, 81.13 % purity in HPLC, chemical shifts in NMR and an amorphous state in XRD confirmed the presence of prodigiosin pigment. It was found to have the highest antimicrobial activity against Staphylococcus aureus. Further, prodigiosin-imbibed fabrics possessed improved tensile strength, elongation, abrasion, crease recovery, stiffness, thickness, tearing strength, and bursting properties, confirming the stability and durability of the prodigiosin-coated fabric. The biodegradation ability of prodigiosin-coated fabric showed an increased degradation rate of 33.33 % compared to synthetic fabric. Overall, studies conferred the usage of prodigiosin to control infections on textile fabrics.

Interactions of CdSe Nanocrystals with Cationic Proteins Extracted from Moringa oleifera Seeds

Even with significant developments in nanoscience, relatively little is known about the interactions of nanocrystal semiconducting materials with bio-macromolecules. To investigate the interfacial phenomena of cadmium selenide quantum dot (CdSe QD) nanocrystals with proteins extracted from Moringa oleifera seeds, different concentrations of cadmium selenide quantum dots–Moringa oleifera seed protein (CdSe–MSP) complexes were prepared. Respective CdSe QDs with hexagonal phase and crystalline size in the range of 4–7 nm were synthesized and labelled with the purified mesoporous MSP having a surface area of 8.4 m2/g. The interaction mechanism between CdSe QDs and MSP was studied using UV–Vis absorption, fluorescence emission and Fourier Transform Infrared spectroscopies. The UV–Vis absorption spectra showed absorption bands of CdSe–MSP complexes at 546.5 nm. The fluorescence intensity of CdSe QDs was found to decrease with increasing concentration of MSP. The thermodynamic potentials ∆Hθ (−321.3 × 103 Jmol−1); ∆Sθ (156.0 JK−1mol−1) and ∆Gθ (−46.6 × 103 Jmol−1) were also calculated. The stability of the complex found is strongly influenced by electrostatics interaction and surface-bound complexation equilibrium attraction. This information can help to elucidate the surface characteristics of MSP and its potential interactions with other molecules or nanoparticles.

Nanohybrid of two-dimensional tellurium and metal sulfotelluride for solar-driven photocatalytic hydrogen production from seawater

The use of sunlight radiation to cause the dissociation of seawater has tremendous promise as a green method for hydrogen production. Herein, tellurides and sulfotellurides of cadmium and zinc and solid solutions like CdxZn(1−x)SyTe(1−y) were synthesized by a coprecipitation method at room temperature. The prepared materials were tested as photocatalysts to produce H2 from seawater using lactic acid as a sacrificial reagent assisted by a solar simulator. All photocatalysts were active for hydrogen production from seawater and artificial sunlight. The cadmium-free photocatalyst (ZnSTe) was the most active one with a hydrogen production rate of 378.85 µmol g−1 h−1, followed by CdZnSTe (374.7 µmol g−1 h−1). The low sulfur content profoundly changes the UV–vis absorption spectra of the sulfotellurides, improving photocatalytic activity. XPS and TEM analysis revealed that the ZnSTe is composed of elemental tellurium nanosheets decorated with nano amorphous ZnTe and cubic phase ZnO. Thus, the p-n heterojunction formation between the ZnTe and ZnO improves the separation and migration rates of photogenerated carrier pairs, improving the solar-driven H2 production. Furthermore, the presence of 2D Te nanosheets dispersed in ZnSTe may contribute as support for charge transfer, which is essential in increasing photocatalytic activity.

Effect of microstructure tuning by rapid heat cycle molding on the photodegradation behavior of isotactic polypropylene

AbstractRapid heat cycling molding (RHCM) is an injection molding technique that improves the product quality of isotactic polypropylene (iPP) by tuning the microstructure, but its effect on the photodegradation stability remains to be investigated. In this work, the effect of RHCM tuned microstructure on the photodegradation behavior of iPP was investigated and compared with conventional injection molding (CIM). Differential scanning calorimetry (DSC), x‐ray diffraction (XRD), Fourier transform infrared spectrometer (FTIR), atomic force microscopy (AFM), and shore durometer (D scale) were used to examine the photodegradation behavior of iPP samples. The results showed that RHCM increased the crystallinity, crystal size, and β‐crystal content of iPP samples. With the increase of photodegradation time, iPP samples injected with RHCM showed higher stability in terms of microstructure and surface quality. The relative changes in CI and Ra of RHCM90 were reduced by 48% and 40% after 800 h of UV irradiation, respectively. In addition, the combined results of dynamic mechanical analysis (DMA) and UV–visible absorption spectrum showed that RHCM promoted the development of crystalline structure and reduced the mobility of the surface chain segments as well as UV absorption coefficient. These combined effects contributed positively to its photodegradation stability.

Investigations on the optical, dielectric, electrical, and rheological properties of PEG200/ZnO semiconducting nanofluids for soft matter based technological innovations

Semiconducting nanofluids (SNFs) consisting of poly (ethylene glycol) (PEG200) as a green biocompatible base fluid with homogeneous dispersion of eco-friendly zinc oxide (ZnO) nanomaterial, concentrations ranging from 0.01 to 0.20 wt%, are prepared by state-of-the-art ultrasonic cavitation homogenized process. These PEG200/ZnO SNFs are characterized by employing an ultraviolet-visible (UV-Vis) spectrophotometer, precision inductance-capacitance-resistance (LCR) meter, and rotational viscometer. A detailed analysis of 200–800 nm range UV–Vis absorbance spectra of these SNFs revealed longer stability of suspended ZnO nanoparticles in PEG200 fluid, and their nanomaterial concentrations dependent absorbance and extinction coefficient with tunable dual energy band gaps ranging from 3 to 5 eV. Optical performance recognized the potential applications of these SNFs in the advances of soft matter based optoelectronic and photosensitive devices and also as an excellent UV radiation shielding material. The study of 20 Hz – 1 MHz range dielectric and electrical spectra explained that the ZnO concentrations have a significant impact on the electrical conductivity of these SNFs, while the dielectric permittivity and electrode polarization relaxation process are marginally altered. High static dielectric permittivity (∼ 22) and low electrical conductivity of about μS/cm order, at 303.15 K, evidence the suitability of these SNFs in advances of energy storage devices. The rheological behaviour of PEG200/ZnO materials is carried out at different temperatures ranging from 303.15 to 323.15 K, which illustrates the Newtonian characteristics of these nanofluids with moderate dynamic viscosity and activation energy, and therefore, they could be utilized as effective heat transfer materials in photovoltaic/thermal devices and systems.

Promising sensors for pharmaceutical pollutant adsorption using Clar’s goblet-based 2D membranes

This study focuses on the design of new 2D membranes from connected Clar’s Goblet as a potential sensor for pharmaceutical pollutants, specifically the painkiller drugs aspirin, paracetamol, ibuprofen, and diclofenac. The electronic, optical, and interaction properties are investigated using density functional theory calculations. The Clar’s Goblet membranes (CGMs) that were chosen are semiconductors with an energy gap of around 1.5 eV, according to energy gap calculations and density of states. Molecular electrostatic potential (ESP) analysis shows that CGMs have electrophilic and nucleophilic sites, suggesting their suitability for interacting with pharmaceutical pollutants. The adsorption energies confirm the chemical adsorption of pharmaceutical pollutants with diclofenac showing the strongest adsorption. The UV–Vis absorption spectra of CGMs-drug complexes are analyzed, revealing a redshift compared to the absorption spectrum of CGMs alone, confirming the adsorption of these drugs. Further analysis using hole/electron examinations indicates that the type of excitation is local excitation rather than charge transfer excitation. This study quantitatively characterized hole and electron distribution in excited states using various indices. The analysis revealed local excitation transitions and significant charge transfer between the CGMs molecule and pharmaceutical pollutants. Additionally, non-covalent interaction analysis indicates the presence of van der Waals interactions, highlighting the adsorption behavior of the drugs. These results demonstrate the potential of CGMs as a highly sensitive sensor for pharmaceutical pollutants.

Luminous and fluorescent cyanobiphenyls exhibiting super-cooled nematic phases

ABSTRACT A new series of liquid crystal dimers, 4-cyano-1,3-phenylene bis(4-((4’-cyano-[1,1’−biphenyl]-n-yl)oxy)alkanoate), has been synthesised and confirmed for their molecular structure using standard spectroscopic techniques. Thermal behaviour is assessed using optical polarising microscope (OPM), differential scanning calorimetry (DSC), and X-ray diffraction. Interestingly, all the dimers exhibit a super-cooled nematic phase without crystallisation during cooling cycles. These molecules self-assemble with head-on aggregation assessed by UV–Visible absorption spectra, and they also have a distinct fluorescence characteristic. A super-cooled nematogens self-assemble into head-on aggregation with a fluorescence property. Moreover, the materials were studied for their fluorescence properties and proved to be fluorescence active, making them excellent candidates to be used in designing photo-responsive optical sensor devices.

Investigating the binding of caffeic acid to human hemoglobin using multispectroscopic and molecular docking approaches

Caffeic acid (CA) is a hydroxycinnamic acid derivative that possess a wide variety of biological properties and is non-toxic to humans. The binding mechanism of CA with human hemoglobin (HHb) was studied for the first time using multispectroscopic and molecular docking methods. The UV–visible absorption spectra showed that CA interacts with HHb through the formation of ground state complex. The fluorescence studies revealed that CA quenches HHb fluorescence by the static mechanism and confirmed the presence of a single CA binding site on the HHb molecule. The negative values of thermodynamics parameters (ΔH,ΔSand ΔG) showed that the binding of CA to HHb is a spontaneous and exothermic process. Hydrogen bonds and van der Waal interactions are the major intermolecular forces that stabilize the HHb-CA complex. Synchronous fluorescence experiments showed that binding of CA altered the microenvironment around tryptophan residues of HHb. Fluorescence resonance energy transfer studies indicated a high propensity of energy transfer from tryptophan residues of HHb to CA. Circular dichroism spectra and catalytic esterase activity confirmed that only minor changes occur in the secondary structure of HHb in the presence of CA. Molecular docking study identified the HHb amino acid residues involved in binding to CA. Analysis of the binding mode of CA with HHb represents an important step in elucidating the molecular mechanism of the protection of HHb from oxidative damage. This will help in understanding the potential role of CA and related antioxidants as therapeutic agents in various blood-related diseases.

Influence of the content of stacked ZnO on the structural and optical properties of heterostructured ZnO/Ga2O3 films

The rising demand for heterojunction materials stimulated by the great achievements of modern nanotechnology has triggered enormous interests in the investigation of their materials properties. Heterostructured ZnO/Ga2O3 has been deployed for different device applications, but its several optical parameters have rarely been investigated. The present work attempts to investigate the influence of the thickness of stacked ZnO layer on the surface of Ga2O3 film. Optical parameters, such as absorption and extinction coefficient, Urbach energy, refractive index, dielectric constants, optical dispersion energy, single oscillator energy, static refractive index, oscillator strength, and oscillator wavelength of the ZnO/Ga2O3 films were studied. Morphological characterization showed microstructures of various shapes. Cross-section measurements showed that the thickness of the Ga2O3 layer remained approximately the same for all samples, while the thickness of the ZnO layer increased from 0 to 5.14 nm. Structural analysis revealed the coexistence of β-Ga2O3 and wurtzite ZnO crystal phases. UV–Vis absorption spectra demonstrated two distinct absorptions belonging to the β-Ga2O3 and ZnO. The bandgap of the composite ranged between 4.43 and 4.69 eV with an increase in the amount of ZnO at the surface. The absorption and extinction coefficient were in the order of 103 cm−1 and 10−5, respectively. The Urbach energy ranged between 0.688 and 1.125 eV. The refractive index was in the range 2.09–2.85, while the static refractive index ranged between 1.90 and 2.73. Also reported were other optical parameters, such as the real and imaginary dielectric constant, dispersive energy, single oscillator energy, oscillator strength, and oscillator wavelength.

Stabilization of myoglobin from different species (produced by cellular agriculture) using food-grade natural and synthetic antioxidants

Cellular agriculture products, like myoglobin, are increasingly used by the food industry to provide desirable sensory properties to plant-based meat substitutes. This study elucidated the physicochemical properties and redox stability of myoglobin from both natural (equine) and cellular agriculture (bovine, sperm whale, and leopard) sources. The electrical characteristics and water-solubility of the different myoglobin samples were measured from pH 2.5 to 8.5. The isoelectric point of the myoglobin samples depended on the species, being pH 5.5 for equine, pH 4.5 for leopard and bovine, and pH 6.5 for sperm whale. All myoglobin samples had a solubility greater than 80% across the entire pH range studied. All myoglobin solutions appeared red and had two peaks in their UV–visible absorbance spectra after one day, which is consistent with oxymyoglobin formation. Equine myoglobin at pH 8 was selected to study its redox and color stability over time, where the oxymyoglobin oxidative status closely paralleled with the redness of the solutions. The effects of antioxidants (ascorbic acid, caffeic acid, catechin, gallic acid, quercetin, taxifolin, Trolox, and 4-methylcatechol) on the redox and color stability (redness) of the equine myoglobin (pH 8.0) was also studied. Antioxidants with low reduction potential values (ascorbic acid and quercetin) were particularly effective at enhancing the color stability of oxymyoglobin. The computational modeling study showed that amino acids on the myoglobin interacted with antioxidants through hydrogen bonds. The insights obtained may have important implications for the use of cellular agriculture to produce myoglobin for food applications.

ZnS nanocrystallites as fluorescent probe for selective detection of bilirubin

Selective determination of bilirubin is much essential to identify neonatal hyperbilirubinemia. Herein, we present a simple and precise method for quantitative measuring of bilirubin levels using polyvinylpyrrolidone (PVP) capped ZnS nanocrystallites (ZSP). The crystalline structure and purity are studied from x-ray diffraction (XRD) patterns and the transmission electron microscope (TEM) images. The optical characteristics are analyzed using UV-visible absorption and photoluminescence spectra. For ZSP, the estimated value for the optical band gap is 4.06 eV, surpassing the band gap value of uncapped ZnS (3.89 eV). Upon 265 nm excitation, ZSP nanocrystallites exhibits blue emission peaked at 371 nm wavelength. The fluorescence intensity shows a consistent reduction as the bilirubin concentration rises from 3.0 μM to 80 μM. The spectral overlap between the emission spectrum of ZSP and the absorption spectrum of bilirubin, results in fluorescence attenuation due to the inner filter effect (IFE). The ZnS nanocrystallites exhibit remarkable fluorescence properties and demonstrate high sensitivity in detecting bilirubin, achieving a limit of detection (L.O.D) as low as 56 nM. The selectivity of bilirubin over certain co-existing biomolecules is also analyzed. The utility of the fluorescence probe for practical use is confirmed in spiked human serum and urine samples.

A highly active electrolyte for high-capacity iron‑chromium flow batteries

Iron‑chromium flow battery (ICFB) is the one of the most promising flow batteries due to its low cost. However, the serious capacity loss of ICFBs limit its further development. Herein, we analyze the capacity loss mechanism of ICFBs. The capacity loss is due to inactive Cr(H2O)63+ ions result in the mismatched content of active ions in catholyte and anolyte. Thus, a simple method is proposed to raise the content of active Cr3+ species (Cr(H2O)5Cl2+ and Cr(H2O)4Cl2+), achieving the match of Fe2+/Fe3+ and Cr3+/Cr2+ redox couples and reducing the capacity loss of ICFBs. Meanwhile, the increasing content of active Cr3+ ions was proved by the quantitative analysis of the UV–vis absorption spectra. As a result, the ICFB with the improved electrolyte of 1 M FeCl2 + 1.3 M CrCl3 + 3 M HCl (E-1.3Cr) exhibits an energy efficiency (EE) of 84.51%, which is much higher than the original one of 1 M FeCl2 + 1 M CrCl3 + 3 M HCl (E-1Cr) (82.32%) at a current density of 80 mA cm−2. Most importantly, the ICFB with E-1.3Cr (7.44 mAh/cycle) shows the much slower capacity decay rate than that with E-1Cr (9.16 mAh/cycle). This work provides an effective way to accelerate engineering applications of ICFBs.

Study of the Ternary Mixture of Methanol/Formamide/Acetonitrile via Solvatochromic Probes.

Following previous studies, the ternary mixture of methanol/formamide/acetonitrile (MeOH/Formamide/MeCN) was studied using the UV-Vis absorption spectra at 298.15 K with a set of five probes, 4-nitroaniline, 4-nitroanisole, 4-nitrophenol, N,N-dimethyl-4-nitroaniline and 2,6-diphenyl-4-(2,4,6-triphenyl-1-pyridinio)phenolate (Reichardt betaine dye), for a total of 22 mole ternary fractions. In addition, nine mole fractions of the underling binary mixtures, MeOH/Formamide and Formamide/MeCN were also tested. Spectroscopic results were used to model the preferential solvation order for each probe in the mixtures. The Kamlet-Taft solvatochromic solvent parameters, α, β, and π*, were also computed through the use of the solvatochromic shifts of the five probe indicators. Moreover, discrepancies in the spectroscopic behavior of 4-nitrophenol in formamide-rich mixtures were observed and analyzed.

Synthesis, optical and magnetic properties of Nd2O3/borate strontium fluoride glasses

The present work conducts the synthesis, thermal, optical, and magnetic characterization of (60-x)B2O3+20Li2O+20SrF2+ x Nd2O3 where x = 0, 0.5, 1, 1.5, 2 mol% glass samples. The samples were investigated via X-ray diffraction (XRD), Raman spectroscopy, differential scanning calorimetry (DSC), UV–Vis absorption spectroscopy, and vibrating sample magnetometry (VSM). XRD patterns for borate strontium fluoride glass samples doped with Nd2O3 showed broad humps around 30 and 43°, indicating their amorphous structure. Raman spectra of glass samples indicated that as Nd3+ ions were added to the host matrix, there was an increase in Raman intensity due to bond breakdown and the development of more non-bridging oxygen (NBO) species. The DSC data of the borate strontium fluoride glass samples doped with Nd2O3 demonstrated that the glass transition temperature (Tg) generally increased. UV–Vis absorption spectra showed transitions in Nd3+ ions doped borate glasses that are associated with the bands at different wavelengths, attributed to 4G5/2+2G7/2, 2H11/2, 4F9/2, 2H9/2 +4F5/2, and 4F3/2. The refractive index of borate strontium fluoride glass samples doped with Nd2O3 increased. The saturation magnetization values decreased from 0.9 to 0.29 upon increasing the Nd2O3 percentage (0–2 mol%). These low saturation magnetization glass samples can be used in spintronic devices to effectively reduce switching current density and lower the damping constant.

An improved prediction model for COD measurements using UV-Vis spectroscopy.

In the 21st century, although water quality has been improved in the last two decades, water pollution by organic contaminants has remained a non-negligible issue in China, so Chemical-Oxygen Demand (abbreviated as COD, unit: mg L-1) is often used as the main index to measure the degree of surface water pollution. UV-Vis spectroscopy, as a sensitive and rapid analytical technique, is a green detection technology suitable for automatic online COD detection equipment. However, due to the complex composition of surface water, the interference degree of the UV-Vis spectrum caused by turbidity is strongly correlated with the size, type and color of particulate matter in the solution, which results in noise sensitivity and poor generalization of the current detection model. Therefore, the main purpose of this research is to improve the traditional detection model performance by using deep learning and a spectrum preprocessing algorithm. Firstly, we used an improved noise filter based on discrete wavelet transforms to solve the noise sensitivity. Secondly, we proposed a novel COD detection network to address poor generalization. Thirdly, we collected a total of 2259 water samples' UV-Vis absorption spectra and corresponding COD as a dataset. Then, we pipelined the improved noise removal algorithm and proposed COD detection network, as a complete COD prediction model. Finally, the experiment on the dataset shows that the COD prediction model has a good performance in terms of both noise tolerance and accuracy.

Carbon pre-protected iron strategy to construct Fe, C-codoped g-C3N4 for effective photodegradation of organic pollutants via hole oxidation mechanism

Improving photocatalytic activity in graphitic carbon nitride (g-C3N4) by enhancing charge transfer and light absorption remains a challenge. Herein, iron-loaded carbon (FeC) was first prepared at low temperature, and then the Fe, C-codoped g-C3N4 (FeC–CN) was synthesized by high temperature thermal copolymerization of FeC with melamine. The carbon shell of FeC prevented the formation of iron oxide during high temperature thermal copolymerization, and Fe as electron channels existed in the interlayer, meanwhile, C atoms of FeC replaced part of the N atoms in the triazine ring. This designed structure facilitates in-plane and interlayer transfer of photogenerated carriers, as well as the separation of photogenerated carriers. Additionally, the UV–visible absorption spectra have demonstrated that the substitution of C atoms can greatly enhance visible light absorption. The catalyst exhibits significantly increased photocatalytic activity and excellent stability compared to g-C3N4. Interestingly, different from the reactive oxygen species-based g-C3N4 catalysis reaction, the degradation of organic pollutants was found to initiate from a hole-involved non-radical pathway. The increased electron transfer facilitates the reduction of O2 via a one-step two-electron pathway to generate hydrogen peroxide.

In situ sonochemical synthesis of flower-like N-graphyne/BiOCl0.5Br0.5 microspheres for efficient removal of levofloxacin.

In this work, N-graphyne is in situ coupled with BiOCl0.5Br0.5via a facile one-step sonochemical method. To our knowledge, both the synthesis strategy for BiOCl0.5Br0.5 and the N-graphyne/BiOCl0.5Br0.5 photocatalytic system are new developments. A collection of characterization methods is adopted to detect the morphologies, structures, and electronic and optical properties. The results demonstrate that wrinkle-like N-graphyne nanosheets successfully enwind around or on flower-like BiOCl0.5Br0.5 microspheres, which are regularly assembled by BiOCl0.5Br0.5 nanosheets. Compared with pristine BiOCl0.5Br0.5, N-graphyne/BiOCl0.5Br0.5 composites exhibit superior adsorption capacity and visible-light-driven photocatalytic degradation of levofloxacin. In particular, the optimal N-graphyne amount for ameliorating the photocatalytic performance of BiOCl0.5Br0.5 is ascertained. In addition, the good stable performance for photocatalysis is confirmed by four cycling experiments. The dominant active species is confirmed to be O2˙- during photodegradation. The improved photocatalytic activity is attributed to the enhanced visible light response and the accelerated transfer/separation of photogenerated carriers by N-graphyne, which are verified using UV-vis absorption spectra, photocurrents, photopotentials, Nyquist plots, and Mott-Schottky curves. This study develops a new perspective for the synthesis and modification of BiOX solid solution, which can be used as an efficient photocatalyst.

New pyrene and fluorene-based π-conjugated Schiff bases: Theoretical and experimental investigation of optical properties

The new Schiff bases with D-?-A system were synthesized by the reaction of polycyclic aldehydes and substituted benzothiazoles. The structures of the synthesized Schiff bases (7a and 9a) were determined by FT-IR, 1H- -NMR, 13C-NMR, ESI-Mass and elemental analyses. The optical properties of the new compounds were investigated and the optical band gaps (Eg) were calculated by the Tauc method using the UV?Vis absorption spectra. Density functional theory (DFT/B3LYP/6-31G(d,p)) calculations were conducted to get more insight on the structural and electronic properties of novel Schiff bases. The optimized molecular geometry, UV?Vis spectroscopic parameters and HOMO?LUMO energies were examined and the calculated results were compared with experimental data.