Addition Of HCl Solution Research Articles

Preconcentration of liposoluble constituents in Salvia Miltiorrhiza using acid-assisted liquid phase microextraction based on a switchable deep eutectic solvent

A switchable deep eutectic solvent-based liquid-phase microextraction was proposed and applied to the preconcentration and determination of liposoluble quality-markers of diterpenoid quinones (dihydrotanshinone I, cryptotanshinone, tanshinone I, and tanshinone IIA) in traditional Chinese medicine coupled with high performance liquid chromatography-ultraviolet detection. In the procedure, the hydrophilic deep eutectic solvent of diethanolamine-hexanoic acid (molar ratio 1:1) was prepared and added into the sample phase as an extractant, and a homogeneous solution was formed under slight vortex stirring. After the addition of HCl solution, the deep eutectic solvent miscible with the sample phase was converted to hydrophobic form, and a cloudy solution was generated. Then, the upper hydrophobic layer enriching the target analytes was collected through centrifugation for high performance liquid chromatography analysis. Several critical parameters affecting the extraction performance including the composition and consumption of switchable deep eutectic solvent, the type and amount of acid, salt amount and extraction time were investigated and optimized. Moreover, the structures of the deep eutectic solvent and the recovered hydrophobic layer were both characterized using Fourier transform infrared spectroscopy, further demonstrating the switching mechanism of the extractant during the extraction process. Under the optimal conditions, enrichment factors of diterpenoid quinones ranged from 59 to 274. Good linearities (r≥0.9963), low detection limits (0.5–0.7 ng/mL), satisfactory precisions (relative standard deviations 0.5%-8.6%) and accuracies (recoveries 94.6%-104.6%) were also obtained. Comparing the proposed switchable deep eutectic solvent-based liquid-phase microextraction with other published methods, the characteristics of the procedure were summarized. The developed method was successfully applied for the preconcentration of four liposoluble diterpenoid quinones from a traditional Chinese herbal medicine of Salvia Miltiorrhiza.

A New Saddle-Shaped Aza Analog of Tetraphenylene: Atroposelective Synthesis and Application as a Chiral Acylating Reagent

A New Saddle-Shaped Aza Analog of Tetraphenylene: Atroposelective Synthesis and Application as a Chiral Acylating Reagent

Multicolor and photothermal dual-mode assay of alkaline phosphatase based on the UV light-assisted etching of gold nanorods

A multicolor and photothermal dual-mode assay for sensitive alkaline phosphatase (ALP) determination was realized based on the 3,3′,5,5′-tetramethylbenzidine (TMB)-induced etching of gold nanorods (AuNRs). TMB was oxidized under ultraviolet light irradiation to form TMB+. In the presence of ALP, ascorbic acid phosphate (AAP) is converted to ascorbic acid, which can then reduce the levels of TMB+, resulting in lower concentrations of TMB+. The remaining TMB+ was transformed into TMB2+ after the addition of HCl solution. AuNRs were etched by TMB2+ to produce a multicolor and photothermal change. Based on the degree of AuNRs etching, this highly sensitive dual-mode assay provided a linear range of 1.0–8.0 mU/mL, with detection limits of 0.34 mU/mL for the multicolor assay and 0.11 mU/mL for the photothermal assay. This method was successfully applied to the determination of ALP in serum samples.

Chemical exfoliation and microwave absorption of reduced graphene oxide synthesized from old coconut shells

In this study, chemical exfoliation with the addition of hydrochloric acid (HCl) solution of old coconut shell reduced graphene oxide (rGO) was carried out. The purpose of this study was to confirm the formation of the rGO phase and to investigate the effect of heating temperature variations and chemical exfoliation processes with the addition of HCl solution on the reflection loss value of old coconut shell rGO. The heating temperature variation is at 400°C and 700°C. Three variations of 1: 1, 1: 5, and 1:10 mole ratios are used in the mixing process of HCl with rGO. Based on the results of XRD testing, the old coconut shell charcoal has formed an rGO phase. Furthermore, VNA testing shows that the biggest reflection loss value is -8.42 dB at a frequency of 10.52 GHz achieved by the sample with the lowest electrical conductivity.

PH-Control of Oxidative Degradation of Methylene Blue Over Octahedral Molecular Sieve Cryptomelane-Type Manganese Oxide (OMS-2) and Fe-OMS-2

The octahedral molecular sieve cryptomelane-type manganese oxide (OMS-2) and Fe-doped OMS-2 (1%, 5%, 10%) were successfully synthesized by the redox reaction between KMnO4 and citric acid using the sol-gel method. The sol products were heated at 120°C and followed by calcination at 600°C. The as-synthesized pristine manganese oxide and Fe-OMS-2 were then characterized by XRD to determine their crystallinity and phase structure. The XRD results indicated that both the pristine and Fe-doped manganese oxides produced tunnel cryptomelane-type manganese oxides. No other peaks due to other phases are detected, indicating that Fe ions are well distributed in the framework of cryptomelane. The oxidative activities, either the pristine and Fe-OMS-2, were evaluated for degradation of methylene blue (MB) at pH ranges 2-6 by the addition of HCl solution. The oxidative tests showed that the oxidative degradation of methylene blue greatly increase with a decrease in solution pH and decrease with an increase in concentration Fe species in Fe-OMS-2 compared to pristine cryptomelane.

SYNTHESIS, SPECTRAL AND QUANTUM CHEMICAL RESEARCHES OF (Z)-10-(2-(4-AMINO-5-THIOXO-4,5-DIHYDRO-1H-1,2,4-TRIAZOLE-3-IL)HYDRAZONO)-9-PHENANTHRONE

(Z)-10-(2-(4-amino-5-thioxo-4,5-dihydro-1H-1,2,4-triazole-3-il)hydrazono)-9-phenanthrone (I) was obtained by a condensation of 4-amino-5-hydrazino-4H-1,2,4-triazole-3-thiol with 9,10-phenanthrenequinone. The compound I was characterized by IR, UV-VIS, 1Н, 13С NMR and chromatography-mass spectrometry. The electronic absorption spectra of I in aproton solvents (DMF, DMSO) are characterized by the existence of an intensive long-wave band in the range of 468 - 485 nm. The absorption maximum of a freshly prepared solution of I (485 nm) after 48 h gradually undergoes hypsochromic shift to 474 nm, and after 72 h it shifts to 468 nm. In the UV-VIS spectrum of I, at addition of NaOH the batochromic shift of a long wave band to 511 nm with a significant increase in intensity is observed. The presence of one isobestic point in the spectrum indicates the formation of a mono-anion. In the UV-VIS spectrum of I at addition of HCl solution, the long wave absorption band undergoes hypsochromic shift to 376 nm with a small decrease in intensity. In the 1Н NMR spectrum of I, in the range of 15.08 ppm a singlet signal of a proton of a hydrazo-group is observed. In the 13С NMR spectrum of I, in the range of 180.80 ppm a signal which corresponds to carbonyl C-atom is observed. Quantum chemical modeling of the electronic structure of I as well as its ionic forms was performed in the frames of the density functional theory approach (DFT) using of a hybride tri-parametric exchange Becke functional with a correlational Lee-Yang-Parr functional (B3LYP) and basis sets def2-SV(P), def2-TZV(P). According to the spectral and quantum chemical studies, in the crystalline state and saturated solution the compound I exists in the form of the thione quinone hydrazone tautomer stabilized by intramolecular hydrogen bonds. The thione tautomer is 44 kJ/mol more stable than a thiol tautomer, the transition barrier is 135 kJ/mol. However, it is not possible to exclude possibility of transition of the thione form into the thiol one in the diluted solutions. Forcitation:Polyanskaya N.A., Ryabov M.A., Strashnov P.V., Linko R.V., Davydov V.V., Kobrakov K.I., Karavaeva E.B. synthesis, spectralandquantumchemicalresearchesof (Z)-10-(2-(4-amino-5-thioxo-4,5-dihydro-1H-1,2,4-triazole-3-il)hydrazono)-9-phenanthrone. Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol. 2018. V. 61. N 1. P. 55-65

Phase and morphology changes induced by acid treatment following alkaline reaction of mesoporous anatase: Effect of anions

Acid treatment, with aqueous solutions of HCl, HNO3, H2SO4, HNO3 + NaCl and H2SO4 + NaCl, for the amorphous reaction paste resulted from mesoporous anatase particles dispersed in KOH solution at 90 °C has been performed. The alkaline reaction paste transforms into hexatitanate after addition of HCl solution (0.1 M) to a pH value from 6.0 to 12.0, but into TiO2-B at pH 1.2. Different phase changes are observed when a HNO3 or H2SO4 solution is used. Anatase starts to appear at pH 9.0 for HNO3 and at 12.0 for H2SO4 and persists down to pH 1.2. Besides, in the pH range studied, no other crystal phase is detected. The particle morphology of the TiO2-B and anatase produced at pH 1.2, using HCl, HNO3 or H2SO4 solution, is nanowire, with a width of ∼10 nm. Although NO3− or SO42− alone in the pH 1.2 solution favors anatase phase, co-existence Cl− leads to TiO2-B formation. Cl− plays a role dominating the formation of hexatitanate, which is then transformed into TiO2-B. However the particle morphology is affected due to the adsorption of NO3− and SO42−. The mechanism for the process from hexatitanate to TiO2-B, not relating to the anion nature, and the anion effect based on the binding manner and strength of the anions to titanium ions are discussed.

PtII Complexes with 6‐(5‐Trifluoromethyl‐Pyrazol‐3‐yl)‐2,2′‐Bipyridine Terdentate Chelating Ligands: Synthesis, Characterization, and Luminescent Properties

A series of Pt(II) complexes Pt(fpbpy)Cl (1), Pt(fpbpy)(OAc) (2), Pt(fpbpy)(NHCOMe) (3), Pt(fpbpy)(NHCOEt) (4), and [Pt(fpbpy)(NCMe)](BF(4)) (5) with deprotonated 6-(5-trifluoromethyl-pyrazol-3-yl)-2,2'-bipyridine terdentate ligand are prepared, among which 1 is converted to complexes 2-5 by a simple ligand substitution. Alternatively, acetamide complex 3 is prepared by hydrolysis of acetonitrile complex 5, while the back conversion from 3 to 1 is regulated by the addition of HCl solution, showing the reaction sequence 1-->5-->3-->1. Multilayer OLED devices are successfully fabricated by using triphenyl-(4-(9-phenyl-9H-fluoren-9-yl)phenyl) silane (TPSi-F) as host material and with doping concentrations of 1 varying from 7 to 100 %. The electroluminescence showed a substantial red-shifting versus the normal photoluminescence detected in solution. Moreover, at a doping concentration of 28 %, the device showed a saturated red luminescence with a maximum external quantum yield of 8.5 % at 20 mA cm(-2) and a peak luminescence of 47,543 cd m(-2) at 18.5 V.

Gastroesophageal Reflux Disease–Associated Esophagitis Induces Endogenous Cytokine Production Leading to Motor Abnormalities

Gastroesophageal reflux disease is a condition frequently associated with esophagitis and motor abnormalities. Recent evidence suggests that proinflammatory cytokines, such as interleukin (IL)-1beta and IL-6, may be implicated because they reduce esophageal muscle contractility, but these results derive from in vitro or animal models of esophagitis. This study used human esophageal cells and tissues to identify the cellular source of cytokines in human esophagitis investigate whether cytokines can be induced by gastric refluxate, and examine whether esophageal tissue- or cell-derived mediators affect muscle contractility. Endoscopic mucosal biopsy specimens were obtained from patients with and without esophagitis, organ-cultured, and undernatants were assessed for cytokine content. The cytokine profile of esophageal epithelial, fibroblast, and muscle cells was analyzed, and esophageal mucosa and cell products were tested in an esophageal circular muscle contraction assay. The mucosa of esophagitis patients produced significantly greater amounts of IL-1beta and IL-6 compared with those of control patients. Cultured esophageal epithelial cells produced IL-6, as did fibroblasts and muscle cells. Epithelial cells exposed to buffered, but not denatured, gastric juice produced IL-6. Undernatants of mucosal biopsy cultures from esophagitis patients reduced esophageal muscle contraction, as did supernatants from esophageal epithelial cell cultures. The human esophagus produces cytokines capable of reducing contractility of esophageal muscle cells. Exposure to gastric juice is sufficient to stimulate esophageal epithelial cells to produce IL-6, a cytokine able to alter esophageal contractility. These results indicate that classic cytokines are important mediators of the motor disturbances associated with human esophageal inflammation.

Biodegradable cationic PEG–PEI–PBLG hyperbranched block copolymer: synthesis and micelle characterization

A novel amphiphilic biodegradable cationic hyperbranched poly(ethylene glycol)–polyethylenimine–poly( γ-benzyl l-glutamate) (PEG–PEI–PBLG) block copolymer was successfully synthesized by ring-opening polymerization (ROP) of N-carboxyanhydride of γ-benzyl- l-glutamate (BLG–NCA) with PEG–PEI as a macroinitiator. PEG–PEI was firstly prepared by coupling of PEG and PEI using hexamethylene diisocyanate (HMDI). The structural properties of PEG–PEI–PBLG copolymers were confirmed by 1H NMR and GPC. The copolymers were found to be self-assembled in water with critical micelle concentration (CMC) in the range of 0.00368–0.0125 g/l and high hydrophobic micelle core. The micelle size and CMC obviously depended on the hydrophobic block content in the copolymer and the ionic state of the PEI block. The CMC decreased with the increase in the PBLG block content. The decrease of micelle size and the increase of CMC simultaneously occurred with the protonated degree of PEI block by addition of HCl solution. ESEM and Gel retardation assay showed that the cationic micelles had ability to encapsulate plasmid DNA. The copolymer has potential medical applications in drug and gene delivery.

Synthesis of tungsten trioxide hydrates and their structural properties

Tungsten trioxide hydrates were synthesized by (a) cation exchange reaction from sodium tungstate solution and (b) precipitation from sodium tungstate solution by the addition of HCl solution. The samples were analyzed by XRD, DTA/TGA, Raman and FT-IR spectroscopy. XRD showed formation of WO 3·H 2O by cation exchange reaction, whereas WO 3·0.33H 2O was identified by XRD as a product of the acidification of sodium tungstate solution with HCl solution. After heating at 320°C, WO 3·H 2O transformed into WO 3, whereas the WO 3·0.33H 2O crystal structure remained and these results were in agreement with DTA/TGA measurements. The WO 3·H 2O sample synthesized by cation exchange reaction showed a weight loss corresponding to one molecule of water in the crystal structure. However, samples WO 3·0.33H 2O showed a much greater weight loss upon heating than could be expected on the basis of the WO 3 0.33H 2O formula. The phase transition WO 3·H 2O→WO 3 was also monitored by Raman and FT-IR spectroscopy. In the case of WO 3·0.33H 2O samples, the basic features of Raman and FT-IR spectra did not change on heating to 320°C, thus indicating that the heating of WO 3·0.33H 2O up to this temperature did not destroy the original crystal structure. Contrary to this, after heating the WO 3·H 2O sample to 320°C, the Raman and FT-IR spectra showed a series of new bands caused by the phase transition WO 3·H 2O→WO 3.