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Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy

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https://www.readbyqxmd.com/read/29783148/comparative-study-of-six-sequential-spectrophotometric-methods-for-quantification-and-separation-of-ribavirin-sofosbuvir-and-daclatasvir-an-application-on-laboratory-prepared-mixture-pharmaceutical-preparations-spiked-human-urine-spiked-human-plasma-and-dissolution
#1
Wafaa S Hassan, Manal S Elmasry, Heba M Elsayed, Dalia W Zidan
In accordance with International Conference on Harmonisation of Technical Requirements for Registration of Pharmaceuticals for Human Use (ICH) guidelines, six novel, simple and precise sequential spectrophotometric methods were developed and validated for the simultaneous analysis of Ribavirin (RIB), Sofosbuvir (SOF), and Daclatasvir (DAC) in their mixture without prior separation steps. These drugs are described as co-administered for treatment of Hepatitis C virus (HCV). HCV is the cause of hepatitis C and some cancers such as liver cancer (hepatocellular carcinoma) and lymphomas in humans...
May 18, 2018: Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
https://www.readbyqxmd.com/read/29778710/some-structural-aspects-of-ammeline-keto-preference-and-dimerization
#2
Masashi Hatanaka
Subtle tautomerism in ammeline is clarified by means of IR- and UV-spectroscopic measurements and DFT calculations. While the enol form is narrowly preferred as an isolated molecule, dimerization of the keto form is plausible in solid phase due to double hydrogen bonds. In aqueous solutions, the keto form is proved to be more stable than the enol form due to the large electric dipole moment of the peptide group. The keto preference is also consistent with the acidity and basicity of the related heterocycles...
May 17, 2018: Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
https://www.readbyqxmd.com/read/29778702/theoretical-studies-on-electroluminescent-mechanism-of-a-series-of-thermally-activated-delayed-fluorescence-emitters-possessing-asymmetric-triazine-cored-triads
#3
Jinglai Zhang, Huijuan Yuan, Songyan Feng, Keke Wen, Xugeng Guo
A series of thermally activated delayed fluorescence (TADF) emitters using asymmetric-triazine-cored triad as the electron-accepting unit have been investigated theoretically. Based on two experimentally reported TADF molecules (TPXZ-as-TAZ and oDPXZ-as-TAZ), two new molecules (mDPXZ-as-TAZ and pDPXZ-as-TAZ) have been designed to explore the isomeric effect on their TADF properties. The present results reveal that the absorption and emission spectra calculated by the time-dependent density functional theory (TD-DFT) method at the M06-2X level are match well the available experimental findings, and mDPXZ-as-TAZ and pDPXZ-as-TAZ are found to exhibit the same yellow emission as their analogue oDPXZ-as-TAZ...
May 17, 2018: Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
https://www.readbyqxmd.com/read/29778707/synthesis-spectroscopic-single-crystal-diffraction-and-potential-nonlinear-optical-properties-of-novel-pyrazoline-derivatives-interplay-of-experimental-and-computational-analyses
#4
Muhammad Nadeem Arshad, Abdulhadi Salih Birinji, Muhammad Khalid, Abdullah M Asiri, Khalid A Al-Amry, Faisal M S Aqlan, Ataualpa A C Braga
Pyrazoline are widely being studied due to their potential applications in chemical field. Herein, five pyrazolines compounds were synthesized and characterized spectroscopically using nuclear magnetic resonance techniques (1 H NMR &13 C NMR) to determine the structures of molecules along-with UV-Visible and infrared (FT-IR) studies for additional spectroscopic support in characterization of entitle synthesized molecules. Unit cells, specific space groups, bond lengths, bond angles and hydrogen bonding interactions were determined by the x-ray diffraction studies...
May 16, 2018: Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
https://www.readbyqxmd.com/read/29777935/effect-of-different-alkyl-groups-on-excited-state-tautomerization-of-7ai-azaindole-h-2-o-a-theoretical-study
#5
Jiacheng Yi, Hua Fang
The effect of substituted alkyl groups at different substituted position on the first excited-state proton transfer of nR7AI-H2 O (n = 2-6; R = CH3 , C2 H5 , CF3 ) complexes were theoretically investigated at the TD-M06-2X/6-31 + G(d, p) level. Here n value denoted the substituted position Cn of R group. The replacement of alkyl R group had no effect on the features of HOMO and LUMO, but influenced the S0  → S1 adiabatic transition energies of the nR7AI-H2 O complex. Through computation, we found that the double proton transfer took place in a concerted but asynchronous protolysis pattern regardless of substituted group R and substituted position in the nR7AI-H2 O complex...
May 16, 2018: Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
https://www.readbyqxmd.com/read/29777934/specific-stability-indicating-spectrofluorimetric-method-for-determination-of-ledipasvir-in-the-presence-of-its-confirmed-degradation-products-application-in-human-plasma
#6
Ramadan Ali, Adel A Marzouk, Reda A Abdelhameid, Mahmoud A Omar
A rapid and specific spectrofluorimetric method with higher sensitivity was developed for determination of ledipasvir (LDS) in tablets and human plasma. The proposed method relies on hydrogen bonding formations between the hydroxyl groups of polyoxyethylene 50 stearate and LDS, causing significant enhancement of its native fluorescence. The fluorescence intensity was measured at 430 nm after excitation at 340 nm. The fluorescence-concentration plot was rectilinear over the range 1-400 ng mL-1 with detection and quantification limits of 0...
May 16, 2018: Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
https://www.readbyqxmd.com/read/29777929/substituent-effect-on-the-acid-induced-isomerization-of-spiropyran-compounds
#7
Lixia Cui, Honghong Zhang, Guomei Zhang, Ying Zhou, Li Fan, Lihong Shi, Caihong Zhang, Shaomin Shuang, Chuan Dong
Spiropyran compounds are well known as an isomeric system, the closed spiropyran (SP) could be converted into the open merocyanine (MC) via acid-induced because stable protonated merocyanine (MCH) were formed by combination of MC and H+ . In order to understand how the substituent affect the isomerization of spiropyran. A series of the chromene 7-subsituted spiropyran compounds were designed and synthesized. The photophysical properties of them were studied comparatively by UV-absorption and fluorescence spectra in different pH...
May 16, 2018: Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
https://www.readbyqxmd.com/read/29778711/atr-ir-study-of-skin-components-lipids-proteins-and-water-part-ii-near-infrared-radiation-effect
#8
S Olsztyńska-Janus, Z Kiełbowicz, M A Czarnecki
Near infrared (NIR) radiation has been widely used in medicine and biomedical engineering. In spite of numerous studies the molecular mechanism of NIR radiation on biological systems has not been established as yet. The objective of this work was examination of the effect of NIR irradiation on the skin components. Modifications of lipid organization after NIR exposure vs. temperature (from 20 to 90 °C) have been investigated using Attenuated Total Reflectance Infrared (ATR-IR) spectroscopy. This work is a continuation of our previous studies on the temperature effect on skin components [1]...
May 11, 2018: Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
https://www.readbyqxmd.com/read/29778704/spectrophotometric-resolution-of-the-severely-overlapped-spectra-of-clotrimazole-with-dexamethasone-in-cream-dosage-form-by-mathematical-manipulation-steps
#9
Hayam Mahmoud Lotfy, Yasmin Mohammed Fayez, Shereen Mostafa Tawakkol, Nesma Mahmoud Fahmy, Mostafa Abd El-Atty Shehata
Several spectrophotometric techniques were recently conducted for the determination of binary mixtures of clotrimazole (CLT) and dexamethasone acetate (DA) without any separation procedure. The methods were based on generation of ratio spectra of mixture then applying simple mathematic manipulation. The zero order absorption spectra of both drugs could be obtained by the constant center (CC) method. The concentration of both CLT and DA could be obtained by constant value via amplitude difference (CV-AD) method depending on ratio spectra, Ratio difference (RD) method where the difference between the amplitudes at two wavelengths (ΔP) on the ratio spectra could eliminate the contribution of the interfering substance and bring the concentration of the other, and the derivative ratio (DD1 ) method where the derivative of the ratio spectra was able to determine the drug of interest without any interference of the other one...
May 10, 2018: Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
https://www.readbyqxmd.com/read/29777930/experimental-and-theoretical-study-of-fingerprint-spectra-of-2-4-fluorophenyl-benzimidazole-and-2-4-chlorophenyl-benzimidazole-in-terahertz-range
#10
Maojiang Song, Fei Yang, Liping Liu, Li Shen, Pengfei Hu, Caixia Su
Due to wide variety of biological and pharmacological activities of benzimidazole derivatives, the terahertz fingerprint spectra of 2-(4-fluorophenyl)benzimidazole and 2-(4-chlorophenyl)benzimidazole are researched by employing terahertz time-domain spectroscopy and density functional theory systematically. Although the substituent at the para position on the benzene moiety are the same family elements (F, Cl) in the periodic table, both experimental and theoretical results show that there are substantial differences in their fingerprint spectra in the range of 0...
May 10, 2018: Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
https://www.readbyqxmd.com/read/29775931/a-nanocomposite-optosensor-containing-carboxylic-functionalized-multiwall-carbon-nanotubes-and-quantum-dots-incorporated-into-a-molecularly-imprinted-polymer-for-highly-selective-and-sensitive-detection-of-ciprofloxacin
#11
Naphat Yuphintharakun, Piyaluk Nurerk, Kochaporn Chullasat, Proespichaya Kanatharana, Frank Davis, Dhassida Sooksawat, Opas Bunkoed
A nanocomposite optosensor consisting of carboxylic acid functionalized multiwall carbon nanotubes and CdTe quantum dots embedded inside a molecularly imprinted polymer (COOH@MWCNT-MIP-QDs) was developed for trace ciprofloxacin detection. The COOH@MWCNT-MIP-QDs were synthesized through a facile sol-gel process using ciprofloxacin as a template molecule, 3-aminopropylethoxysilane as a functional monomer and tetraethoxysilane as a cross-linker at a molar ratio of 1:8:20. The synthesized nanocomposite optosensor had high sensitivity, excellent specificity and high binding affinity to ciprofloxacin...
May 10, 2018: Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
https://www.readbyqxmd.com/read/29775930/synthesis-photophysical-and-electrochemical-properties-of-a-blue-emitter-with-binaphthalene-and-carbazole-units
#12
Lixia Guo, Xiaoju Wang, Liheng Feng
A blue emitter, 3,3'-(2,2'-dimethoxy-[1,1'-binaphthalene]-6,6'-diyl)bis(9-benzyl-9H-carbazole), was synthesized by Suzuki coupling reaction. The photophysical properties of the emitter in solution were firstly investigated by UV-Vis absorption and fluorescence emission techniques. The results indicate that the emitter has excellent optical and electron transfer properties. The maximum absorption and emission peaks of the emitter are 302 nm and 406 nm with 67.4% fluorescence quantum yield in chloroform, respectively...
May 10, 2018: Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
https://www.readbyqxmd.com/read/29783149/potential-of-near-infrared-spectroscopy-for-quality-evaluation-of-cattle-leather
#13
Carlos Eduardo M Braz, Manuel Antonio C Jacinto, Edenir R Pereira-Filho, Gilberto B Souza, Ana Rita A Nogueira
Models using near-infrared spectroscopy (NIRS) were constructed based on physical-mechanical tests to determine the quality of cattle leather. The following official parameters were used, considering the industry requirements: tensile strength (TS), percentage elongation (%E), tear strength (TT), and double hole tear strength (DHS). Classification models were constructed with the use of k-nearest neighbor (kNN), soft independent modeling of class analogy (SIMCA), and partial least squares-discriminant analysis (PLS-DA)...
May 9, 2018: Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
https://www.readbyqxmd.com/read/29778709/a-novel-and-simple-deep-eutectic-solvent-based-liquid-phase-microextraction-method-for-rhodamine-b-in-cosmetic-products-and-water-samples-prior-to-its-spectrophotometric-determination
#14
Erkan Yilmaz, Mustafa Soylak
A novel and green deep eutectic solvent based liquid phase microextraction (DES-LPME) methodology has been proposed for the assessment of rhodamine B from cosmetic products and water samples. A deep eutectic solvent (DES) consist of tetrabutyl ammonium chloride-decanoic acid (1:2) as extraction solvent and tetrahydrofuran as emulsification agent were used for the microextraction of rhodamine B. The quantitative recoveries were achieved at pH 3 by using 0.3 mL of DES and 0.3 mL of THF. The rhodamine B concentration in last volume was analyzed by mirco-cuvette UV-VIS spectrophotometer at 550 nm...
May 9, 2018: Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
https://www.readbyqxmd.com/read/29778705/investigating-the-coumarin-capability-in-chalcogenide-20ti-2-se-80pr-2-se-3-system-based-photovoltaics
#15
M Soylu, A Dere, C Ahmedova, G Barim, Abdullah G Al-Sehemi, Ahmed A Al-Ghamdi, W A Farooq, F Yakuphanoglu
Chalcogenide films containing various contents of coumarin (CO) are deposited on the p-type Si substrates. Al/coumarin doped chalcogenide films/p-Si contact exhibits a rectifying behavior. The electrical and photoresponse properties of the prepared diodes are characterized by current and capacitance measurements under various illumination intensities. The addition of coumarin to TI2 Se-Pr2 Se3 significantly affects the characteristic parameters of diodes. Kohlrausch function is used as an appropriate way to obtain the photo charge density (ρph ) and the relaxation time constant from the photocurrent/capacitance transients...
May 9, 2018: Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
https://www.readbyqxmd.com/read/29778703/sequential-injection-analysis-for-the-determination-of-fluoroquinolone-antibacterial-drug-residues-by-using-eosin-y-as-complexing-agent
#16
Kanokwan Chaiyasing, Boonsom Liawruangrath, Surapol Natakankitkul, Sakchai Satienperakul, Narabhats Rannurags, Poachanee Norfun, Saisunee Liawruangrath
A sequential injection analysis (SIA) method was developed for the rapid and sensitive determination of fluoroquinolone residues, including norfloxacin, ciprofloxacin and enrofloxacin, in fish samples. The method is based on the reaction between fluoroquinolone drug and eosin Y in Britton-Robinson buffer (pH 2.0), forming pink colored complexs with maximum absorptions at 522, 525 and 527 nm for norfloxacin, ciprofloxacin and enrofloxacin, respectively. Linearity ranges were found to be 0.05-10.0 mg L-1 (r2  = 0...
May 9, 2018: Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
https://www.readbyqxmd.com/read/29777936/fast-synthesis-of-porous-copper-nanoclusters-for-fluorescence-detection-of-iron-ions-in-water-samples
#17
Yihong Huang, Hanqiang Zhang, Xiaofen Xu, Jiangcong Zhou, Fenfen Lu, Zhusen Zhang, Zhibiao Hu, Jiangshui Luo
Copper nanoclusters (Cu NCs) have attracted great research interest in recent years owing to its unique physical, electrical and optical properties. Macromolecules have been widely used as templates to synthesize fluorescent Cu NCs. In this study, a simple method for synthesis of albumin chicken egg capped porous copper nanoclusters (p-Cu NCs) was developed for the first time. The obtained p-Cu NCs exhibited intense emission and excitation peaks at 280 nm and 340 nm, respectively. Besides, the p-Cu NCs fluorescence probe could be quenched by Fe3+ ions in aqueous solutions...
May 9, 2018: Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
https://www.readbyqxmd.com/read/29777933/novel-amidine-derivatives-of-benzanthrone-effect-of-bromine-atom-on-the-spectral-parameters
#18
E M Kirilova, A I Puckins, E Romanovska, M Fleisher, S V Belyakov
Several new substituted amidine derivatives of benzanthrone were synthesized by condensation reaction from 2-bromo-3-aminobenzo[de]anthracen-7-one and appropriate aromatic or aliphatic amides. The novel benzanthrone derivatives were characterized by TLC analysis, NMR, IR, MS, UV/Vis, and fluorescence spectroscopy. The obtained derivatives have yellow or orange fluorescence in organic solvents. The solvent effect on photophysical behaviors of these dyes was investigated, and the results showed that the introduction of a bromine atom causes a blue-shift of the absorption and emission bands and decrease in the fluorescent quantum yield in comparison with unbromated analogues...
May 9, 2018: Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
https://www.readbyqxmd.com/read/29777932/application-of-a-surfactant-assisted-dispersive-liquid-liquid-microextraction-method-along-with-central-composite-design-for-micro-volume-based-spectrophotometric-determination-of-low-level-of-cr-vi-ions-in-aquatic-samples
#19
Hamid Reza Sobhi, Efat Azadikhah, Mohammad Behbahani, Ali Esrafili, Mahnaz Ghambarian
A fast, simple, low cost surfactant-assisted dispersive liquid-liquid microextraction method along with central composite design for the determination of low level of Cr(VI) ions in several aquatic samples has been developed. Initially, Cr(VI) ions present in the aqueous sample were readily reacted with 1,5‑diphenylcarbazide (DPC) in acidic medium through complexation. Sodium dodecyl sulfate (SDS), as an anionic surfactant, was then employed as an ion-pair agent to convert the cationic complex into the neutral one...
May 9, 2018: Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
https://www.readbyqxmd.com/read/29777931/the-order-of-multiple-excited-state-proton-transfer-in-ternary-complex-of-norharmane-and-acetic-acids
#20
Yan-Zhen Ma, Yun-Fan Yang, Wei Shi, Yu-Zhi Song, Yong-Qing Li
Dolores Reyman et al. found the norharmane (9H-pyrido [3,4-b] indole) (NHM) and two acetic acid molecules can form the ternary complex (NHM-2A) in component solvent of dichloromethane and acetic acid via the hydrogen bond chain (J. Lumin. 2014, 148, 64). But the specific reaction details during this process were rarely reported. In this study, we will give an insight into the reasons which promote the occurrence of this reaction as well as its reaction order. The hydrogen bond enhancing behavior in first excited state (S1 ) is verified through the analysis of geometric configurations, infrared spectra, frontier molecular orbitals and potential energy curves...
May 9, 2018: Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
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