Maximum Absorption Wavelength Research Articles

UV-Vis Spectrophotometric Determination of Selected Heavy Metals (Pb, Cr, Cd and As) in Environmental, Water and Biological Samples with Synthesized Glutaraldehyde Phenyl Hydrazone as the Chromogenic Reagent

A simple, sensitive, selective, and non-extractive UV-Vis spectrophotometric method for the determination of cadmium, lead, chromium, and arsenic in biological, soil and water samples using synthesized and characterized phenyl hydrazone; glutaraldehydephenyl hydrazone (GPH) as the chromogenic reagent was developed. GPH was synthesized as new chromogenic analytical reagents for the direct UV-Vis spectrophotometric determination of the selected metals of interest in a slightly acidic pH of 6.5-7.5 and 20 % dimethylformamide (DMF) solution to give stable coloured metal-ligand complexes. The reactions were instantaneous; the wavelengths of maximum absorptions were followed spectrophotometrically and noted. The reagent GPH revealed a wavelength of maximum absorption between 360.0 (Cr) to 395.0 nm for (Pb and As) at a working pH of 6.5 to 7.5 room temperature (37 °C). The reagent GPH had a molar absorptivity (L mol-1 cm-1) ranging from 2.213×104 (Pb) to 2.460×104 (As), a mole ratio of metal to ligand of 2:1, the detection limit (µg/g) ranging from 0.3432 (As) to 0.5250 (Pb) and the metal-ligand complex was stable for 0-48 hours. The reagents had a Beer’s law validity range (mg L-1) of 0.001 to 100. The Sandell’s sensitivities (µg/cm2) ranged from 0000409 (As) to 0.00499 (Pb) for APDH and 0.00406 (As) to 0.00452 (Pb) respectively. Large excess of cations and anions as possible interferences up to 15 folds were studied and do not interfere with the determination of the selected metals of interest. The developed method is highly selective for Cd, Pb, and Cr and As and was successfully used for the determination for the said elements in soil, water, and biological samples. The results of the developed methods were comparable with AAS and were found to be in good agreement. The method had very high precision and very good accuracy.

DEVELOPMENT AND VALIDATION OF UV SPECTROSCOPIC METHOD OF PALIPERIDONE PALMITATE IN BULK AND ITS APPLICATION FOR DRUG LOADING AND ENTRAPMENT EFFICIENCY ANALYSIS OF LONG-ACTING INJECTABLE MICROSPHERES

Objective: The objective of the current study was to develop simple, precise and cost-effective ultraviolet (UV) spectroscopic method for estimation of paliperidone palmitate (PP) as a bulk and in the polymeric depot dosage form.
 Methods: UV spectrophotometer with quartz sample cells and spectral manager software was used for analysis samples. 20 % Methanol in Mili-Q-Water was used as a solvent for the sample and standard preparations. Method validation was carried out as per ICH Q2 (R1) guidelines. Stress degradation studies were carried out to check the stability-indicating performance of the developed method. The validated method was applied for the estimation of the PP content of long-acting injectable microspheres of PP.
 Results: The wavelength of maximum absorption was found to be 283 nm. The proposed method was validated in the range of 5-30 µg/ml of PP. The mean recovery for 80%, 100% and 120% standard solution was found to be 99.03%, 99.21% and 99.35% respectively with less than 2% relative standard deviation (RSD). Intra-day and inter-day method precision ranged from 0.54 to 1.62% and 0.67 and 1.24% respectively. Limit of detection (LOD) and limit of quantitation (LOQ) were estimated to be 0.03 and 0.10 µg/ml respectively. The developed method was found to be robust and rugged. Stress degradation studies were carried out under acidic, alkaline, hydrolytic and oxidative and photo stress. The proposed method was capable to detect changes in assay due to stress conditions.
 Conclusion: The developed method was successfully employed for routine analysis of drug loading in long-acting injectable microspheres of PP.

METHOD DEVELOPMENT AND VALIDATION OF THE CHROMATOGRAPHIC ANALYSIS OF FLUTICASONE PROPIONATE AND SALMETEROL XINAFOATE COMBINATION IN SOLUTIONS AND HUMAN PLASMA USING HPLC WITH UV DETECTION

Objective: A simple, Rapid, and sensitive HPLC method utilizing UV detection was developed and validated for the simultaneous estimation of Fluticasone propionate (FP) and Salmeterol xinafoate (SX) in solutions and in vitro human plasma.
 Methods: Chromatographic analysis was done on SUPELCO® RP-C18 column (150 x 4.6 mm, 5 μm particle size) with an isocratic mobile phase composed of methanol, acetonitrile, and water (50:20:30, v/v) mixture while flow rate was set to 1 ml/min. Detection with UV at maximum absorbance wavelength (ʎmax) values of 236 and 252 for FP and SX, respectively. Spiked plasma samples were liquid-liquid extracted by diethyl ether and reconstituted using methanol.
 Results: Method was accurate and precise over a linear (R2>0.995) range of (0.067-100 µg/ml) and (0.0333-50 µg/ml) for FP and SX, respectively. LOD/lOQ values were 0.13/0.6 and 0.06/0.3 µg/ml for FP and SX, respectively.
 The developed method was successfully applied for the analysis of FP and SX in spiked human plasma samples. The method is considered to be accurate and precise over a linear (R2>0.9969) range of (6.67-66.67 µg/ml) and (3.33-33.3 µg/ml) for FP and SX, respectively. Extraction efficiency was approved by recovery values of (94.98–102.46 %) and (96.54–102.62 %) for FP and SX, respectively.
 Conclusion: This validated method revealed simple and cheap extraction procedures and detectors, non-buffered mobile phase, and short retention times with excellent resolution.

Spectroscopic Analysis of Apoferritin Associates with the Water-Soluble Porphyrins.

The association behavior of apoferritin species with the anionic porphyrins, 5,10,15,20-tetrakis(4-sulfonatophenyl)porphyrin (H2 TPPS4- ) and its zinc(II) complex (ZnTPPS4- ), which are water-soluble even in acidic solutions, was investigated for the first time through UV-Vis absorption and fluorescence spectroscopy in order to evaluate a potential ability of apoferritin as a stimuli-responsive molecular capsule. The absorption maximum wavelengths of both porphyrins were redshifted and the fluorescence intensity decreased, indicating the effective association between apoferritin species and the porphyrins, although it depended on the pH adjustment procedure. At pH 2, the ZnTPPS4- associated with apoferritin subunits without demetallating and protonating, while the free base porphyrin formed the J-aggregate of the diprotonated species (H4 TPPS2- )n , with extremely low fluorescence. As the concentration of apoferritin subunits increased, the H2 TPPS4- -subunits associates were formed accompanied by recovering the fluorescence. The association stoichiometries of 1 or 2 subunits/porphyrin obtained under neutral and acidic conditions. The significantly large association constant of ZnTPPS4- as compared with that of H2 TPPS4- indicated that the coordination to the zinc(II) center strongly contributes to the association in addition to the electrostatic interaction between apoferritin subunits and the porphyrin under acidic conditions.

Effect of solid-state fermentation by three different Bacillus species on composition and protein structure of soybean meal.

Fermentation efficiency of thermophiles of Bacillus licheniformis YYC4 and Geobacillus stearothermophilus A75, and mesophilic Bacillus subtilis 10 160 on soybean meal (SBM), was evaluated by examining the nutritional and protein structural changes. SBM fermentation by B. licheniformis YYC4, B. subtilis 10 160 and G. stearothemophilus A75 increased significantly the crude and soluble protein from 442.4 to 524.8, 516.1 and 499.9g kg-1 , and from 53.9 to 203.3, 291.3 and 74.6g kg-1 , and decreased trypsin inhibitor from 8.19 to 3.19, 2.14 and 5.10mg g-1 , respectively. Bacillus licheniformis YYC4 and B. subtilis 10 160 significantly increased phenol and pyrazine content. Furthermore, B. licheniformis YYC4 fermentation could produce abundant alcohols, ketones, esters and acids. Surface hydrophobicity, sulfhydryl groups and disulfide bond contents of SBM protein were increased significantly from 98.27 to 166.13, 173.27 and 150.71, from 3.26 to 4.88, 5.03 and 4.21 μmol g-1 , and from 20.77 to 27.95, 29.53 and 25.5μmol g-1 after their fermentation. Fermentation induced red shifts of the maximum absorption wavelength (λmax ) of fluorescence spectra from 353 to 362, 376 and 361 nm, while significantly reducing the fluorescence intensity of protein, especially when B. subtilis 10 160 was used. Moreover, fermentation markedly changed the secondary structure composition of SBM protein. Analyses by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and atomic force microscopy showed that macromolecule protein was degraded into small-sized protein or peptide during fermentation of SBM. Bacillus licheniformis YYC4 fermentation (without sterilization) improved nutrition and protein structure of SBM as B. subtilis 10 160, suggesting its potential application in the SBM fermentation industry. © 2021 Society of Chemical Industry.

Remarkable Size Effect on Photophysical and Nonlinear Optical Properties of All-Carboatomic Rings, Cyclo[18]carbon and Its Analogues.

Inspired by recent experimental observation of molecular morphology and theoretical predictions of multiple properties of cyclo[18]carbon, we systematically studied the photophysical and nonlinear optical properties of cyclo[2N]carbons (N=3-15) allotropes through density functional theory. This work unveils the unusual optical properties of the sp-hybridized carbon rings with different sizes. The remarkable size dependence of the optical properties of these systems and their underlying nature are profoundly explored, and the relevance between aromaticity and optical properties are highlighted. The extrapolation curves fitted for energy level of frontier molecular orbitals, maximum absorption wavelength, and (hyper)polarizability of considered carbon rings are presented, which can be used to reliably predict corresponding properties for arbitrarily large carbon rings. The findings in this study will facilitate the exploration of potential application of cyclocarbons in the field of optical materials.

Time dependent synthesis of gold nanoparticles using chitosan as reducing agent: A spectroscopic approach

The present study attempted synthesis of gold nanoparticle using chitosan from shrimp waste and evaluated the kinetics of gold nanoparticle (AuNPs) formation. Two different forms of chitosan (high molecular weight and medium molecular weight forms) were used for the preparation of AuNPs. The formation of nanoparticles was studied using UV-VIS spectra obtained at different time intervals during synthesis. The typical UV-VIS spectrum of non-aggregated spherical AuNPs at 520 nm was obtained for both chitosan forms and the maximum absorbance was higher for the sample prepared with medium molecular weight chitosan. The results clearly indicated that the characteristic surface plasmonic resonance (SPR) peak became recognisable at 5 min of heating for the sample with high molecular weight chitosan and 3 min of heating for medium molecular weight chitosan. This indicated that, the lower the molecular weight, the faster the formation of nanoparticles. The wavelength (λ) of absorption maxima was selected and normalised with respect to the absorption maxima at 15 min. The sigmoidal shape of kinetic curve implied the autocatalytic character of AuNP formation. The data from the samples were fitted with two step Finke-Watzky kinetics model and the kinetics constants were derived. The rate constant of the nucleation reaction was found higher for the medium molecular weight chitosan. Keywords: AuNPs, Chitosan, Gold nanoparticles, Molecular weight, Rate constant

건조 쪽을 이용한 모발 천연염색의 표면 염색성 및 염착량

The purpose of this study is to determine the degree of hair dyeing according to the presence or absence of mordant use and the dyeing time using the dry indigo, the bleached hair sample was pre-mordded in alum (reagent, 5%, owh, on the weight of hair) solution for 10 minutes and then When dyeing at ℃ for 10 minutes, 20 minutes, 30 minutes, and 40 minutes, the maximum absorption wavelength of dyeing on the dry side was 420 nm. The result is as follows. First, when a mordant (Al) was used, the overall color was dyed green, and the L* value was the highest when staining for 10 minutes, followed by 20 minutes and 30 minutes. Also, both a* and b* values were found to be high in the order of 10 minutes, 20 minutes, and 30 minutes. In the case of 40-minute staining, it was the lowest. Second, when no mordant was used, all were dyed in blue green, and the L* values were high for a* and b* values in the order of 10 minutes, 20 minutes, and 30 minutes. In the case of 40-minute staining, it was the lowest. Third, in the case of K/S of the amount of dyeing, the K/S value was higher when alum mordant was not applied, and the K/S value was lower when alum mordant was applied. In both mordant and non-mordant staining, the amount of dyeing increased as the time increased for 10, 20, and 30 minutes of staining, but after 30 minutes, the dyeing was no longer combined and the dye was no longer darkly dyed. It was found that the amount of dyeing and saturation decreased as the time increased.

Moringa oleifera ROOT-MEDIATED SYNTHESIS OF NANO SILVER PARTICLES AND THE ANTIBACTERIAL APPLICATIONS

In this work, Moringa oleifera root extract was used as the reducing agent in the reaction with AgNO3 leading to the formation of Ag NPs. The formation of the silver nanoparticles was indicated by a visual color changed. The synthesized nanoparticles were characterized using UV-Visible Spectrophotometer, Fourier Transformation Infrared (FT-IR), Scanning Electron Microscope (SEM), X-ray Diffractometer (XRD) and Energy-Dispersive X-ray (EDX) Spectroscopic Techniques. Agar Well method was used in the antibacterial bioassay against two gram positive and two-gram negative bacteria. Optical measurements using UV-Visible Spectrophotometer reveal the maximum absorption wavelength at 400 nm. The Fourier Transform Infrared Spectrophotometer confirmed the stabilization and capping process by the appearance of some peaks formally absent in the root extract spectra. EDX confirmed the presence of elemental silver. Investigations using SEM and XRD revealed that the NPs have crystalline shapes. The antibacterial bioassay showed significant inhibition values with better activity against gram negative bacteria compared to gram positive bacteria. The activity of the Ag NPs against these targeted organisms especially Salmonella typhi suggests that the research if further studied can be a basis for developing powerful antibacterial agents.

Original boron cluster covalent with poly-zwitterionic BODIPYs for boron neutron capture therapy agent

Currently, boron neutron capture therapy（BNCT） is the most innovative and promising highly selective targeted radiotherapy for cancer. Therefore, this paper designed and synthesized two kinds of boron-polymers, wrapped in the same fluorophore -BODIPYs, as fluorescent targeting markers for rapid, accurate, real-time, and inexpensive detection of boron-containing drugs. The spherical polymer o-carborane (PBC) in different polar solvents, the ultraviolet maximum absorption wavelength is in the range of 530–545 nm. The maximum ultraviolet absorption wavelength of PBD is in the range of 440–520 nm. The fluorescence spectra of the two boron-polymer are very similar, and the maximum emission wavelength is concentrated in the range of 550–560 nm. In terms of cytotoxicity and in vitro cell imaging, the in vitro biological toxicity evaluation of the two boron-polymer reached the expected high level, especially the cytotoxic concentration of PBD reached 1.347 ± 0.033 μM, which was higher than the 2.829 ± 0.351 μM of PBC. By transmission electron microscopy, it was found that the two terminal zwitterions of BODIPY polymer tightly wrapped boron clusters to form small particle nanoclusters. The imaging of the two boron-polymers was tested in the Hera cell lines of low, medium, and high densities. The in vitro study results revealed high levels of accumulation in HeLa cells with higher cytotoxicity and boron uptake compared to L-boron-phenylalanine (BPA). In vivo imaging, large number of borane polymers were observed to accumulate in the subcutaneous tumor sites of mice over time, indicating that it has high selectivity and high aggregation.

Benzylidene ketones as visible light radical photoinitiator: The effects of electron-donating group and co-initiator

Benzylidene ketones (BK) are promising visible photoinitiator due to their facile synthesis and photochemical hydrogen atom transfer (HAT) reaction between tertiary amines. However, the effect of electron donating (ED) groups on their photophysical, electrochemical properties, and initiation efficiency were not fully disclosed. Moreover, it is not clear which co-initiator is suitable for BK. In this work, four benzylidene ketones bearing hydrogen (C3PH), methoxy (C3PO), methylthio (C3PS), and dimethylamine (C3PN) substitution were synthesized and characterized. BK’s maximum light absorption wavelengths increase following the order of C3PH < C3PO < C3PS < C3PN. Photopolymerization and steady state photolysis show that only C3PO and C3PS display higher HAT efficiency than C3PH, which is highly relating to the free energy change calculations results. Overall, C3PO is the most efficient one because good polymerization rate and final monomer conversion can be achieved. Triethanolamine is the best co-initiator because of its low oxidation potential and the lowest energy barrier to form a complex with C3PO.

Synthesis of benzothiazole-azo disperse dyes for high resistance to alkaline treatments and peroxide bleaching

PurposeThis paper aims to synthesize benzothiazole-azo disperse dyes which can be applied not only for dyeing and alkaline reduction of polyester fabric in one bath, but also for dyeing and peroxide bleaching of cotton/polyester blend fabric in one bath.Design/methodology/approachThe synthesized benzothiazole-azo disperse dyes were confirmed by proton nuclear magnetic resonance (1H-NMR) spectroscopy, mass spectroscopy (MS) and UV–visible spectrophotometry. The performance on resistance to alkaline treatment and peroxide bleaching was tested by measuring the color strength of polyester fabric dyed with the synthesized benzothiazole-azo disperse dyes under high-temperature and high-pressure conditions.FindingsIncreasing the electron-withdrawing ability of the substituents in the diazo component and the electron-donating ability of the substituents in the coupling component resulted in a significant bathochromic shift of the maximum absorption wavelength. Except that the disperse dyes synthesized from the coupling components containing the hydroxyethyl group were unstable in alkaline solution, all others exhibited high resistance to alkaline treatment and peroxide bleaching.Practical implicationsThe synthesized benzothiazole-azo disperse dyes provide the opportunities to combine dyeing and alkaline reduction of polyester fabric into one bath, and combine dyeing and peroxide bleaching of cotton/polyester blend fabric into one bath.Originality/valueThe synthesized benzothiazole-azo disperse dyes help to establish short processes of polyester and polyester/cotton blend fabrics so as to reduce energy consumption and raise production efficiency.

A Portable Fluorometer with Multiple Excitation LEDs

Fluorescent probes are widely used in biological research due to their sensitivity, selectivity, and versatility [1, 2]. Many fluorescence probes, such as fluorophores, typically have a variety of absorption and emission peaks ranging from UV to near-infrared. Therefore, a wide range of excitation wavelengths is required to simultaneously detect multiple fluorescent target analytes. Here, we propose a portable fluorometer with 13 different excitation LEDs (280 – 730 nm) that can be a viable option for simultaneously detecting multiple fluorophores. For fluorescence detection, a monochromator module was implemented to separates the color components of fluorescent emission and sequentially scan a range of wavelength (400 nm – 780 nm) with 1 nm resolution. For demonstration, fluorescein was selected as target analyte for this study. Fluorescein is an organic compound dye that is commonly used in many bioscience applications.For the excitation light source, different LEDs were used to offer a broad range of excitation wavelengths, ranging from 280 nm to 725 nm. Each LED was coupled with a color filter and a collimator lens to carry out a narrow excitation spectrum. LEDs were controlled by an LED driver IC and a microcontroller to provide a linear output current in the range of 0 to 300 mA. A multiplexer IC was implemented to sequentially turn on and off each excitation LED. The maximum absorbance and emission wavelength of fluorescein were 485 nm and 514 nm, respectively. For excitation, 434 nm LED was chosen instead of 470 nm to minimize spectral overlap between the excitation and emission spectra. The fluorescein was dissolved in methanol at a concentration of 220 mg/ml at room temperature (25 ºC). The figure shows the spectra of the excitation LED and fluorescein fluorescence measured with a developed portable fluorometer. The spectral profile of the excitation LED and the peak fluorescence of fluorescein was well-matched with previously measured value from the laboratory-based benchtop fluorometer (Fluorolog 3 FL3-22, Horiba, Japan).In summary, we have developed a portable fluorometer multiple LEDs covering a broad range of excitation wavelengths to simultaneously detect multiple fluorescent targets. Our compact fluorometer provides a viable option for multi-analyte detection in a variety of remote sensing applications such as point-of-care or environmental monitoring. Figure 1

Simultaneous Determination of Five Coumarins in Peucedanum Decursivum Radix by UPLC

To establish an ultra-high performance liquid chromatography (UPLC) method for simultaneous determination of umbelliferonel, nodakenin, psoralen, xanthotoxin and bergapten contents in Peucedanum decursivum Radix. The analysis was achieved on a Symmetry®C18 column (4.6mm×250mm, 5μm), with acetonitrile and water as the mobile phase in gradient elution mode. The column temperature was maintained at 30°C, with flow rate 1.0mL·min-1. The injection volume of sample was 10μL. The ultraviolet detection wavelength was set at the maximum absorption wavelength 325nm for umbelliferonel and nodakenin, 259nm for psoralen, xanthotoxin and bergapten, respectively. The five kinds of coumarins in Peucedanum decursivum Radix were separated well and the linear relation was obtained (R2≥0.9998). The average recoveries were 101.31, 105.27, 90.85, 106.42 and 90.19%, respectively, with Relative standard deviation (RSD) 3.07, 3.17, 1.62, 2.53 and 4.54%, respectively. The established method was accurate and feasible, which could be used as the basis of quality control of Peucedanum decursivum Radix.

Population assessment of common storage pests in deiri date palm cultivar using spectrophotometric method

Opportune and accurate identification of Date pests during storage, is prerequisite for reducing pest damages and having a good export. The present study aimed to define a new sampling method for three main storage pests Oryzaephilus surinamensis (Linnaeus), Ephestia kuehniella (Zeller) and Plodia interpunctella (Hübner) in date Deiri Cultivar, by Spectrophotometer. The experiments were conducted in a completely randomized design with factorial arrangement in two levels. The first factor consisted of 4 levels including different stages in pests life cycle and the second factor had 10 levels including different densities of each development stage of insect species. First, the curve of changes in absorbance level in each life cycle stage was plotted against the wavelength changes and again it was repeated for each species. This curve enabled us to determine the absorption range of the device in different wavelengths. Our results showed that the maximum absorption wavelength for egg, larva, pupa and adult of O. surinamensis, in Deiri Cultivar was 1210, 1230, 1250, 1270 nm, respectively. These values were 1320, 1340, 1380, 1390 nm for E. kuehniella and 1350, 1400, 1410, 1480 nm for P. interpunctella, respectively. The lowest sample size (each sample consisted of 110 g of date fruits) for an accurate estimation of theegg, larva, pupa and adult of O. surinamensis were 1, 2, 2, 2, respectively. These values were 1, 1, 3, 3 samples for E. kuehniella and 1, 2, 2, 2 samples for P. interpunctella, respectively. The Relative Variation values for the four development stages of O. surinamensis were 1.39, 2.41, 2.91 and 3.12, respectively. These values were 1.59, 1.63, 4.62 and 4.34 for E. kuehniella and 1.78. 3.24, 2.62 and 2.24 for P. interpunctella, respectively. The accuracy level of samplings was lower than 10 in all the cases. The Relative net precision values for three studied pests in all life cycle stages were 35.95, 20.73, 17.19, 16.06 for O. surinamensis; 31.32, 30.69, 10.82, 11.53 for E. kuehniella and 28.15, 15.42, 19.05, 22.27 for P. interpunctella, respectively. Therefore, we can conclude that the spectrophotometer can detect the hidden life cycle stages of studied pests in Deiri cultivar during storage and reduce the cost of sampling.

Adsorption and absorption behavior of cationic porphyrin on titania and clay nanosheets

In this study, the adsorption and absorption behavior of porphyrin derivatives on inorganic nanosheets were investigated. The relationship between the adsorption orientation angle (θad) and the maximum absorption wavelength (λmax) of tetra (N-methyl-4-pyridinium)-porphyrin (p-TMPyP4+) derivatives adsorbed on clay nanosheet (Sumecton SA (SSA)) and titania nanosheet (TNS, Ti0.89□0.11O2−0.11) monolayer film prepared by the Langmuir-Blodgett method was examined by dichroic waveguide spectroscopy. The λmax of each TMPyP4+ was red-shifted by an adsorption on the nanosheets. For example, the λmax of p-TMPyP4+ in water was 422 nm, while that was shifted to 450 and 459 nm upon an adsorption on SSA and TNS, respectively. According to dichroic measurements, the θad of p-TMPyP4+ was estimated to be 13 and 3 degrees on SSA and TNS, respectively. Judging from the results for all porphyrin, a strong correlation between the λmax shift upon an adsorption and the θad on nanosheets was found out. In addition, it was turned out that the θad depends on the electrostatic interactions between porphyrin and anionic nanosheets. Thus, the λmax shift upon an adsorption can be controlled by the combination of porphyrin and nanosheet.

Theoretical prediction on photoelectric and supramolecular properties of benzoquinone-tetrathiafulvalene macrocyclic molecules.

Benzoquinone has the ability to serve as an electron acceptor, and tetrathiafulvalene has the ability to serve as an electron donor. Based on the facts above, this work creatively cycles the benzoquinone unit and the tetrathiafulvalene unit alternately into macrocyclic molecules, the cyclopolymers of benzoquinone-tetrafluorene (C[n]QTTF, n = 3~6). To explore their structure and properties, the M06-2X functional of density functional theory (DFT) with 6-311g(d) basis set was used to optimize the ground-state structures of C[n]QTTF. Based on the stable configurations of the ground states, the electronic structure property is analyzed systematically. The results show that these macrocyclic molecules have excellent electron transport capability and electrochemical activity. Then, the electron absorption spectra of each system are carried out by using time-dependent density functional theory (TD-DFT) at the M062X/6-311+G(d) level. It turns out that their maximum absorption wavelengths are all in the visible range. Further calculation suggests that C[n]QTTF can also be characterized with one-dimensional self-assembly, double-walled assembly, and the host-guest inclusion performance, based on which it gains a variety of supramolecular structures. In summary, the benzoquinone-tetrafluorofurene macrocyclic molecules predicted by DFT calculations may be of assistance to the potential applications in organic electronics and supramolecular chemistry.

A strong acid-resistant flavanthrone with excellent photophysical properties

Based on a vat dye of anthraquinone type, simple modification of the structure of flavanthrone (Benzo[h]Benz[5,6]Acridino[2,1,9,8-Klmna]Acridine-8,16-Dione). By introducing the electrochemically inert group 1-bromo-3,5-di-tert-butylbenzene after the reduction of the carbonyl group, increasing the probability of fluorescence transition. And discussed the new simple compound that under different strongly acidic conditions, the optical properties are obviously distinction. Sulfuric acid, methanesulfonic acid and hydrochloric acid were added, the maximum ultraviolet absorption wavelength of the original product is redshifted from 510 nm to about 590 nm, and the fluorescence emission wavelength is around 523 nm to 526 nm and the fluorescence intensity decreased significantly. Especially, the addition of trifluoromethanesulfonic acid, the maximum ultraviolet absorption wavelength is redshifted to 602 nm, and the fluorescence quenching. Nevertheless, the addition of nitric acid, hydrofluoric acid and phosphoric acid had no obvious effect on the optical properties of the flavanthrone compound. Also, even in different strong acid conditions the flavanthrone compound has excellent fluorescence stability and high fluorescence quantum yield of about 50%. To better comprehend the electronic properties, the values of the energy levels of the highest occupied molecular orbitals (HOMOs, EHOMO = -5.2937 eV) and the lowest unoccupied molecular orbitals (LUMOs, ELUMO = −2.7021 eV) of the flavanthrone as well as energy band gaps determined electrochemically (△E = 2.5916 eV) were carried out at the B3LYP/6-311G** level of the density functional theory (DFT) calculations.

Charge Transport and Optical Absorption Properties of Dibenzocoronene Tetracarboxdiimide Based Liquid Crystalline Molecules: A Theoretical Study.

Structure, optical absorption, and charge transport properties of dibenzocoronene tetracarboxdiimide (DCDI) based molecules were studied using electronic structure calculations. Based on the optimized neutral, cationic, and anionic geometries the ionized state properties, such as ionization potential, electron affinity, hole extraction potential, electron extraction potentials, and reorganization energy, were calculated. On the basis of the ground state geometry of the studied molecules, the absorption spectra were calculated using the time-dependent density functional theory (TDDFT) method at the PBE0/def-TZVP level of theory. It has been observed that the substitution of different functional groups significantly alters the absorption spectra of DCDI. The methoxy- (OCH3-) substituted DCDI molecule has a maximum absorption wavelength of 529 nm. The charge transport parameters, such as the charge transfer integral, spatial overlap integral, and the site energy, are calculated directly from the Kohn-Sham matrix elements. The reorganization energy for the presence of excess positive and negative charges and the charge transfer rate calculated from Marcus' theory were used to find the mobility of charge carriers. The computed results show that the mobility of charge carriers is strongly influenced by the functional groups present on the DCDI molecule. The effect of intermolecular structural fluctuations on charge transport properties was studied through molecular dynamics and Monte Carlo simulations based on the polaron hopping mechanism. The calculated charge carrier mobility shows that the cyano- (CN-) substituted DCDI molecules are having n-type semiconducting property while, methoxy- (OCH3-) and thiol- (SH-) substituted DCDI molecules exhibit ambipolar semiconducting properties.

Development of a high‐throughput method for examining bacterial supernatant pH using ratiometric UV‐VIS spectrophotometry

Background Bacterial supernatant pH measurements are highly relevant to downstream applications, such as organoid or cell line treatment, mass spectrometry, and metabolic analysis. Although high-throughput systems have been implemented for examining bacterial growth, high-throughput systems for measuring bacterial supernatant pH are lacking. The traditional method for measuring the solution pH of bacterial supernatants uses pH meters and electrodes. However, this method is not compatible with high throughput approaches which employ microplate readers. While fluorescent dyes can be used to measure solution pH, bacterial media is highly auto-fluorescent, making this system incompatible for microbial analysis. To overcome these limitations, we have developed a simple, high-throughput assay to measure bacterial supernatant pH using ratiometric UV-VIS spectrophotometry and phenol red, the pH indicator dye contained in the medium DMEM. Phenol red exhibits a gradual transition from yellow to fuchsia from acid to basic solution pH, respectively. The aim of this study was to develop a high-throughput and accessible method to monitor pH changes in multiple samples using a standard microplate reader. Methods & Results As a proof of concept, we prepared a series of solutions with pHs that ranged from 3 to 10 in DMEM and DMEM containing a fully defined bacterial media, termed ZMBI, at a ratio 3:1. UV-VIS spectral analysis of phenol red from 350-750 nm confirmed the reported wavelengths for the isosbestic point - a specific wavelength at which the total absorbance of an indicator dye remains consistent – and the wavelength of maximum absorption (λmax) to be 470 and 560 nm, respectively. Calibration curves generated by the ratio of these two wavelengths (560 nm/470 nm) revealed a sigmodal curve, which could be fit by a four-parameter logistics curve. To test the ability of this system to correctly calculate pH, commensal gut microbes Lactobacillus reuteri and Escherichia coli were grownin ZMBI overnight anaerobically and aerobically, respectively. A comparison between standard pH electrode analysis and our newly developed wavelength analysis revealed similar calculated pHs. To generate a high-throughput system, L. reuteri and E. coli were grown in 1 mL of ZMBI in DeepWell microplates overnight. To examine bacterial growth, 100 µL of culture was transferred to flat bottomed 96-well microplates and optical density was measured at OD600nm. For pH analysis, a 200-µL volume of culture was transferred to round bottomed 96-well plates, centrifuged and cell-free supernatant was blended with ZMBI at a 3:1 ratio. Back calculated solution pH values using the sigmodal calibration curve yielded similar results to the pH electrode values. Conclusions We have successfully employed DMEM's phenol-red dye, which is well suited for a colorimetric assay, to study bacterial supernatant pH. This method allows for rapid and accurate pH measurement which can be easily be applied to multiple organisms and adapted to several downstream applications.