scholarly journals Effect of Structure of Monocyclic Aromatic Solvents on the Packing Density of Fullerene Solvation Shell

2012 ◽  
Vol 2012 ◽  
pp. 1-5
Author(s):  
E. V. Chubarova ◽  
E. Yu. Melenevskaya
Keyword(s):  
Packing Density ◽  
Uv Spectroscopy ◽  
Solvation Shell ◽  
Uv Spectra ◽  
Solvent Structure ◽  
Aromatic Solvents ◽  
The Difference ◽  
Effect Of Structure

Fullerene C60 solutions in various monocyclic aromatic solvents (AS) diluted by tetrahydrofurane (THF) were studied using UV spectroscopy. An algorithm was proposed which made it possible to obtain the data from the UV spectra of (C60+AS) solutions in THF which pointed to the difference between the packing density of AS molecules in solvation shell of C60 and that in the pure AS solvent. The presence of asymmetrical substituents in the AS molecule has been shown to result in loosening of solvent structure in the solvation shell, while the absence of the substituents or presence of symmetrical substituents leads to compacting of solvent structure.

scholarly journals Ultraviolet Spectroscopy Used to Fingerprint Five Wild-Grown Edible Mushrooms (Boletaceae) Collected from Yunnan, China

2016 ◽  
Vol 2016 ◽  
pp. 1-8 ◽  
Author(s):  
Yan Li ◽  
Ji Zhang ◽  
Tao Li ◽  
Tianwei Yang ◽  
Yuanzhong Wang ◽  
...  
Keyword(s):  
Cluster Analysis ◽  
Discriminant Analysis ◽  
Hierarchical Cluster Analysis ◽  
Visual Discrimination ◽  
Uv Spectroscopy ◽  
Hierarchical Cluster ◽  
Uv Spectra ◽  
Edible Mushrooms ◽  
Ultraviolet Spectroscopy

Nowadays, wild-grown edible mushrooms which are natural, nutritious, and healthy get more and more popular by large consumers. In this paper, UV spectra of different Boletaceae mushrooms with the aid of partial least squares discriminant analysis (PLS-DA) and hierarchical cluster analysis (HCA) were shown to be a practical and rapid method for discrimination purpose. The specimens of Boletus edulis, Boletus ferrugineus, Boletus tomentipes, Leccinum rugosiceps, and Xerocomus sp. were described based on the UV spectra. From the results, all the specimens were characterized by strong absorption at the wavelengths of 274 and 284 nm and showed the shoulder at 296 nm. However, changes could be seen in the peak heights at the same wavelength for different samples. After analyzing by chemometrics, visual discrimination among samples was presented and the relationships among them were also obtained. This study showed that UV spectroscopy combined with chemometrics methods could be used successfully as a simple and effective approach for characterization of these five wild-grown edible mushrooms at species and genus levels. Meanwhile, this rapid and simple methodology could also provide reference for the discrimination of edible mushrooms.

scholarly journals UPLC-Q-TOF/MS Coupled with Multivariate Statistical Analysis as a Powerful Technique for Rapidly Exploring Potential Chemical Markers to Differentiate between Radix Paeoniae Alba and Radix Paeoniae Rubra

2013 ◽  
Vol 8 (4) ◽  
pp. 1934578X1300800 ◽  
Author(s):  
Nian-cui Luo ◽  
Wen Ding ◽  
Jing Wu ◽  
Da-wei Qian ◽  
Zhen-hao Li ◽  
...  
Keyword(s):  
Statistical Analysis ◽  
Multivariate Statistical Analysis ◽  
Ultra Performance Liquid Chromatography ◽  
Uv Spectra ◽  
Chemical Markers ◽  
Multivariate Statistical ◽  
Flight Mass Spectrometry ◽  
The Difference ◽  
Radix Paeoniae Alba ◽  
Tof Ms

To explore rapidly the potential chemical markers for differentiating Radix Paeoniae Alba and Radix Paeoniae Rubra, a method is proposed based on ultra-performance liquid chromatography-quadrupole time-of-flight mass spectrometry (UPLC-Q-TOF/MS) coupled with multivariate statistical analysis. Batches of commercial samples were analyzed by UPLC-Q-TOF/MS. The datasets of tR-m/z pair, ion intensities and sample codes were further processed with orthogonal partial least squared discriminant analysis (OPLS-DA) to compare holistically the difference between these two kinds of samples. Then statistics were used to generate an S-plot, in which the variables (tR-m/z pair) contributing most to the difference were clearly depicted as points at the two ends of “S”, and the components correlated to these ions should be regarded as the chemical markers. The identities of the most changed markers can be identified by comparing the mass/UV spectra and retention times with those of reference compounds and/or tentatively assigned by matching empirical molecular formulae with those of known compounds published in the literature. Using this proposed approach, albflorin, paeoniflorin, oxypaeoniflorin, benzoylpaeoniflorin, galloylalbiflorin and paeoniflorigenone were found to be the differentiating components for discrimination of Radix Paeoniae Alba and Radix Paeoniae Rubra. Moreover, paeoniflorin sulfonate and its isomer, isomaltopaeoniflorin sulfonate, were found to be the characteristic markers for all Radix Paeoniae Alba samples that were processed by sulfurdioxide gas fumigation. The results suggested that this newly established approach could be used to explore rapidly the potential chemical markers for herbs with similar chemical characteristics.

scholarly journals Exploring Abundance and Isotope Anomalies in CP Stars with the HST/GHRS: High Resolution UV Spectroscopy of χ Lupi

1993 ◽  
Vol 138 ◽  
pp. 42-59 ◽  
Author(s):  
David S. Leckrone ◽  
Glenn M. Wahlgren ◽  
Sveneric G. Johansson ◽  
Saul J. Adelman
Keyword(s):  
High Resolution ◽  
Uv Spectroscopy ◽  
Uv Spectra ◽  
Heavy Elements

AbstractWe are using the HST/GHRS in a long-term program to obtain UV spectra of unprecedented resolution and precision for bright, ultra-sharp-lined Bp (HgMn) stars and comparable normal stars. To date we have doubled the number of heavy elements for which abundances may be estimated in χ Lupi, and have obtained the first observations of Hg III lines with which to test diffusion scenarios for its extreme Hg isotope anomaly.

scholarly journals Exploring the Photodynamic Properties of Two Antiproliferative Benzodiazopyrrole Derivatives

2020 ◽  
Vol 21 (4) ◽  
pp. 1246 ◽  
Author(s):  
Concetta Imperatore ◽  
Mohammadhassan Valadan ◽  
Luciana Tartaglione ◽  
Marco Persico ◽  
Anna Ramunno ◽  
...  
Keyword(s):  
High Resolution Mass Spectrometry ◽  
Light Emitting Diode ◽  
Uv Spectroscopy ◽  
Ionic Species ◽  
Uv Spectra ◽  
Solution Ph ◽  
Null Cell ◽  
Degree Of Ionization ◽  
Promising Therapeutic Approach ◽  
Led Irradiation

The identification of molecules whose biological activity can be properly modulated by light is a promising therapeutic approach aimed to improve drug selectivity and efficacy on the molecular target and to limit the side effects compared to traditional drugs. Recently, two photo-switchable diastereomeric benzodiazopyrrole derivatives 1RR and 1RS have been reported as microtubules targeting agents (MTAs) on human colorectal carcinoma p53 null cell line (HCT 116 p53-/-). Their IC50 was enhanced upon Light Emitting Diode (LED) irradiation at 435 nm and was related to their cis form. Here we have investigated the photo-responsive behavior of the acid derivatives of 1RR and 1RS, namely, d1RR and d1RS, in phosphate buffer solutions at different pH. The comparison of the UV spectra, acquired before and after LED irradiation, indicated that the trans→cis conversion of d1RR and d1RS is affected by the degree of ionization. The apparent rate constants were calculated from the kinetic data by means of fast UV spectroscopy and the conformers of the putative ionic species present in solution (pH range: 5.7–8.0) were modelled. Taken together, our experimental and theoretical results suggest that the photo-conversions of trans d1RR/d1RS into the corresponding cis forms and the thermal decay of cis d1RR/d1RS are dependent on the presence of diazonium form of d1RR/d1RS. Finally, a photo-reaction was detected only for d1RR after prolonged LED irradiation in acidic medium, and the resulting product was characterized by means of Liquid Chromatography coupled to High resolution Mass Spectrometry (LC-HRMS) and Nuclear Magnetic Resonance (NMR) spectroscopy.

Determination of Seawater Salinity by Ultraviolet Spectroscopic Measurements

1997 ◽  
Vol 51 (9) ◽  
pp. 1294-1302 ◽  
Author(s):  
Vito Di Noto ◽  
Mauro Mecozzi
Keyword(s):  
Organic Matter ◽  
Uv Spectroscopy ◽  
Sample Pretreatment ◽  
Uv Spectra ◽  
Linear Calibration ◽  
Synthetic Seawater ◽  
Seawater Salinity ◽  
Seawater Samples ◽  
Nitrate Species

A method for the determination of seawater salinity by ultraviolet (UV) spectroscopy is proposed. The effects of single salt concentrations and of salinity on UV absorption in the 190–250-nm range were investigated. These studies revealed that the absorption spectrum of a solution with a given salinity is due mainly, in order, to KBr >MgCl 2>NaCl. The influence of the temperature and salt concentration on UV spectra was studied by using synthetic seawater samples with the salinities ranging from 1 to 50 parts per thousand (%). Results showed that, in the absence of interferences, the most sensitive and reliable conditions for measuring the salinity are at 212 nm and at temperatures in the range of 25–30 °C. Under these conditions this method shows quite linear calibration curves and allows us to perform salinity determinations in seawater solutions at concentrations as low as 4%. Moreover, it requires no sample pretreatment and offers a precision of 0.20%. The proposed method is very simple and rapid for laboratory and on-board analysis. Finally, the interference of organic matter, nitrite, and nitrate species with the salinity determinations was investigated. These studies show that organic matter does not interfere at concentrations of carbon lower than 1 mg/L and at 210 nm. Interferences due to NO− x species can be ignored if these species are dissolved in solution at concentrations lower than ≈0.2 mg/L and the analyses are carried out at wavelengths lower than 212 nm.

uv Spectra of Mercuric Halides in Aromatic Solvents

1971 ◽  
Vol 55 (5) ◽  
pp. 2300-2307 ◽  
Author(s):  
I. Eliezer ◽  
P. Avinur
Keyword(s):  
Uv Spectra ◽  
Aromatic Solvents ◽  
Mercuric Halides

Studies on the synthesis and properties of bischelating dioxotetraamine macrocycle, its metal complexes and thermodynamic stability in aqueous solution

2001 ◽  
Vol 79 (2) ◽  
pp. 221-225
Author(s):  
Xun-Cheng Su ◽  
Zhi-Fen Zhou ◽  
Hua-Kuan Lin ◽  
Shou-Rong Zhu ◽  
Hong-Wei Sun ◽  
...  
Keyword(s):  
Aqueous Solution ◽  
Metal Complexes ◽  
Copper Ions ◽  
Copper Ion ◽  
Uv Spectra ◽  
Titration Method ◽  
Potentiometric Titration Method ◽  
Ion Stability ◽  
The Difference ◽  
Chelating Groups

A new route to obtain C-functionalized dioxotetraamine, in which two independent chelating groups 8-quinolinol and dioxotetraamine are included, is described. In addition, two trinuclear metal complexes are synthesized and fully characterized. The thermodynamic properties of the ligand and its respective metal complex were investigated by a potentiometric titration method. Coupled with UV spectra, the difference in affinities for copper ion between dioxotetraamine and 8-quinolinol in the new ligand are investigated and the results show that 8-quinolinol is a stronger donor group than the dioxotetraamine macrocycle in an aqueous solution. Over pH 3~11, 8-quinolinol interacts 100% with the copper ions while dioxotetraamine is only partially coordinated.Key words: macrocycle, dioxotetraamine, 8-quinolinol, copper ion, stability constants.

scholarly journals UV Spectrophotometric Determination of Thermodynamic Dissociation Constants of Some Aromatic Hydrazones in Acid Media

2019 ◽  
Vol 63 (4) ◽  
Author(s):  
Mirjana Jankulovska ◽  
Ilinka Spirevska ◽  
Vesna Dimova ◽  
Milena Jankulovska
Keyword(s):  
Proton Affinity ◽  
Dissociation Constants ◽  
Uv Spectroscopy ◽  
Sodium Perchlorate ◽  
Atomic Charge ◽  
Protonated Form ◽  
Uv Spectra ◽  
Semiempirical Methods ◽  
Acid Media ◽  
Protonation Site

The spectral behavior of some p-nitro-p-substituted benzoylhydrazones in the perchloric acid media was followed, applying the UV spectroscopy. The position of the absorption maximum in the spectra was defined in acidic media and the electronic transitions were discussed, as well (7<pH<1). The equilibrium between neutral and protonated form was investigated in the ethanol-water (V/V, 1:1) solutions. The observed changes in the UV spectra suggested that protonation process took place in one step. The pH region of protonation ranges between 1.4 and 2.9. Using the changes in the UV spectra which appear as a result of the protonation reaction the stoichiometric dissociation constants were determined numerically (pKBH+ = n·pH + logI) and graphically (intercept of the dependence of logI on pH). Thermodynamic dissociation constants were estimated as an intercept of dependence of pKBH+ on square root of the ionic strength. In order to achieve that, measurements were performed at different ionic strengths: 0.1, 0.25 and 0.5 mol/dm3, adjusted with sodium perchlorate. The obtained thermodynamic pKBH+ values ranged between 2.07 and 2.58. In order to predict proton transfer at a given pH, semiempirical methods AM1 and PM3 were applied. The influence of the substituents present in the p-position of the benzene ring on pKBH+ values of investigated hydrazones was discussed, too. Total energy, binding energy, enthalpy of formation, Gibbs energies of formation, atomic charge and proton affinity values were used to predict protonation site in hydrazone molecule. Furthermore, the stability and the proton affinity of the isomers (E and Z) in which hydrazones exist and their protonated forms were defined.

Photoisomerization of azobenzene-substituted alkanethiolates on Au(111) substrates in the context of work function variation: the effect of structure and packing density

2019 ◽  
Vol 21 (18) ◽  
pp. 9098-9105 ◽  
Author(s):  
Swen Schuster ◽  
Matthias Füser ◽  
Andika Asyuda ◽  
Piotr Cyganik ◽  
Andreas Terfort ◽  
...  
Keyword(s):  
Work Function ◽  
Packing Density ◽  
Self Assembled Monolayers ◽  
Stimuli Responsive ◽  
Molecular Dipole ◽  
Assembled Monolayers ◽  
Self Assembled ◽  
Effect Of Structure

Novel azobenzene-substituted self-assembled monolayers were used for stimuli-responsive work function variation, with control of the molecular dipole and sterical constraints.

Synthesis and Characterization of Graphene Sheets from Graphite through Electrochemical Exfoliation and Microwave Reduction

2021 ◽  
Vol 875 ◽  
pp. 127-137
Author(s):  
Arshad Hussain Wazir ◽  
Imran Waseem Kundi ◽  
Wahib Noor Khan ◽  
Abdul Manan ◽  
Imdadullah Querashi ◽  
...  
Keyword(s):  
Graphene Oxide ◽  
Microwave Irradiation ◽  
Uv Spectra ◽  
High Yield ◽  
Graphene Sheets ◽  
X Ray ◽  
Force Microscopy ◽  
Exfoliated Graphene ◽  
The Difference ◽  
Few Layer Graphene

Graphene as a wonder material has received great attention and importance due to its fascinating properties. Here in this study, we also demonstrate a simple two step process to prepare graphene sheets (GSs) from the electrochemical exfoliated graphene oxide (EE-GO) followed by microwave irradiation reduction. The properties and structure of the resulted product samples were studied by Ultraviolet spectroscopy (UV), Fourier-transform infrared spectroscopy (FTIR), Thermogravimetric analysis (TGA), X-ray diffraction (XRD), Scanning electron microscopy (SEM), Energy-dispersive X-ray (EDX or EDS), Raman spectroscopy and Atomic force microscopy (AFM) for validation of their distinguishing characteristics. UV spectra of microwave irradiation reduced graphene oxide (MI-RGO) and EE-GO exhibited an intense and sharp absorption peak concentrated at wavelengths of 236 and 266nm, respectively. The elimination of oxygen functionalities present in the EE-GO plane was illustrated by FTIR as a result of microwave irradiation treatment. The relative layer structures of MI-RGO and EE-GO were confirmed by XRD. Similarly, the Raman spectra revealed the difference in between the EE-GO and MI-RGO characteristic reflection bands. The thin, crumpled and curved type morphology of the obtained graphene sheets (GSs) was also displayed by SEM while the composition of a few layer graphene sheets with atomic mass percents of carbon (75%) and oxygen (25%) was established by EDX. The Synthesis procedure is simple, rapid and eco-friendly with high yield.

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