Radiation damage produced in powder of α-(methylamino)isobutyric acid, α -aminoisobutyric acid methyl ester hydrochloride and diethylmalonic acid

The electron paramagnetic resonance spectra of γ-irradiated powders of α-(methylamino)isobutyric acid – CH₃NHC(CH₃)₂COOH, α -aminoisobutyric acid methyl ester hydrochloride – NH₂(CH₃)₂CCOOCH₃ HCl, and diethylmalonic acid – (CH₃CH₂)₂C(COOH)₂ have been investigated at room temperature. It has been found that γ -irradiation produces the (CH₃)₂C˙COOH radical in the first, the (CH₃)₂C˙COOCH₃ radical in the second and the (CH₃CH₂)₂C˙COOH radical in the third compound. The spectra were computer-simulated. The g values and the hyperfine coupling constants of the unpaired electron with the environmental methyl, methylene protons and OH proton were determined. The results were found to be in good agreement with the existing literature data and theoretical predictions.     

From designer Lewis acid to designer Brønsted acid towards more reactive and selective acid catalysis

This review focuses on the development of acid catalysis for selective organic transformations conducted in our laboratories for the past 30 years. Several important concepts in designing of catalysts are described with some examples. Further, recent developments in super Brønsted acid and their applications in a one-pot procedure to construct complex molecules with high diastereoselectivities are described.     

A simultaneous analysis of ν5, ν6, and the ground state of hydrazoic acid

The pure rotational spectrum in the vibrational ground state [J. Bendtsen and F. M. Nicolaisen, J. Mol. Spectrosc. 119, 456–466 (1986)] and the infrared spectrum of the fundamental bands ν₅ and ν₆ [J. Bendtsen, F. Hegelund, and F. M. Nicolaisen, J. Mol. Spectrosc. 118, 121–131 (1986)] of HN₃ have been simultaneously analyzed using a three-level model taking into account resonance between the ground state and ν₅ due to centrifugal distortion [K. Yamada, J. Mol. Spectrosc. 81, 139–151 (1980)] and a- and b-Coriolis interactions between ν₅ and ν₆. A set of ground- and upper-state constants have been obtained and values for the centrifugal distortion parameter C₅^ab and the Coriolis coupling constant ζ_5,6^b are derived. A complete set of ground-state energies for J ≦ 50 and K_a ≦ 10 is tabulated.     

Ultrasonic study of nitric acid

I.IntroductionBymeansofu1trasonicwavesthedynamicspecificpropertiesofmolecu1esinmediacouldbeapprehended.Fromthe195ostol96osacousticiansstudiedmo1ecu1aracousticandthermodynamicspecificpropertiesof1iquidsandmixtureswithgreate.th.siasm['-'],andkeptonbringto1ighttheirreportsofrc1evantstudiesinthe1astten-oddyearsl'-'l.overrecentyearstheauthorhasbeenengagedinthemeasurementandstudyofsoundve-locityofsevera1chemica1so1utionsinassociationwithu1trasonicmeasurementstudyofthecon-centrationofsolutionsproduce…     

Sonochemical effects on fabrication,characterization and antioxidant activities of β-lactoglobulin-chlorogenic acid conjugates

The β-lactoglobulin-chlorogenic acid (LG-CA) conjugate was explored to be formed through ultrasonication, redox-pair method and their combination, the ultrasonication used a probe ultrasonic machine with a 6 mm probe at 270 W, and the frequency was 20–25 kHz. The formation of the conjugate was confirmed by SDS-PAGE with a larger molecular weight. Besides, Fourier infrared spectroscopy (FTIR) and Circular dichroism (CD) indicated changes in the secondary structure of the LG-CA conjugate. The α-helix and β-sheet contents of LG decreased and the unordered content increased significantly after the formation of covalent complexes. In addition, both the ultrasonic treatment and its combination with redox-pair method could significantly improve the antioxidant properties of LG. The former increased to 23.16 μmol Trolox/g sample, the latter 82–106 μmol Trolox/g sample. Therefore, ultrasonication could be used both individually and in combination with the redox-pair method to produce LG-CA conjugates with stronger antioxidant activities.     

Crystal growth,spectral, thermal and optical properties of an organic single crystal – Dye doped hippuric acid

A new organic dye doped hippuric acid (DHA) single crystals have been grown from aqueous solution of acetone by doping with rhodamine using slow evaporation technique. Rhodamine is a dye, an organic molecule well-studied in laser physics and nonlinear optics for its fluorescent properties. Dyeing of crystals is a practice that was developed particularly for quantum optical applications because of the very significant increase in surface area achieved in growing crystals. In the present work, The DHA single crystals were successfully grown by the slow evaporation method. Good quality single crystals were harvested after 5 days. The grown crystal was characterized by various techniques namely Single crystal X-ray diffraction, FT-IR, UV–vis, NLO and thermal analysis. The FT-IR analysis confirms the presence of various functional groups available in DHA. The optical transmission study and Kurtz and Perry SHG measurement shows the suitability of doped crystals for NLO applications.     

Synthesis, structural and conductivity characterization of alginic acid–Fe3O4 nanocomposite

Alginic acid–Fe₃O₄ nanocomposite is synthesized by the precipitation of Fe₃O₄ in the presence of alginic acid (AA). Structural, surface, morphological, thermal and electrical transport properties of the nanocomposite were performed by XRD, FT-IR, TEM-SEM, TGA and conductivity measurements respectively. FT-IR analysis revealed that Fe₃O₄ NPs are strongly capped with AA and TGA analysis showed that nanocomposite have 80% of Fe₃O₄ content. TEM analysis of Fe₃O₄ NPs show an average particle size of 9.5 nm, and upon nanocomposite formation with AA these particles are observed to form aggregates of ~150 nm. The frequency-dependency of the AC conductivity show electrode polarization effect. Analysis of electrical modulus and dielectric permittivity functions suggest that ionic and polymer segmental motions are strongly coupled. DC electrical conductivity is strongly temperature dependent, and is classified into three regions over a limited temperature range of up to 100 °C.     

Novel metal complexes containing 6-methylpyridine-2-carboxylic acid as potent α-glucosidase inhibitor: synthesis,crystal structures,DFT calculations,and molecular docking

Molecular Diversity - The World Health Organization (WHO) report shows that diabetes mellitus (DM) will be one of the ten deadly diseases in the near future. The best way to prevent DM is to...     

EPR study of γ-irradiated three-furancarboxylic acid

The electron paramagnetic resonance of γ-irradiated single crystals of three-furancarboxylic acid has been studied for different orientations of the crystals in a magnetic field. The radicals produced by γ-irradiation have been investigated between 123 and 350 K. The spectra were found to be temperature dependent, and radiation damage centers were attributed to the radical. The principal values of the g-tensor were determined. The results were found to be in good agreement with the existing literature data and theoretical predictions.     

Research of ultrasonic hydrochloric acid concentration meter

I.InstrumentUltrasonichydroch1oricacidconcentrationmeter(Fig.l)measureson-linetheconccntra-honofhydroch1oricacidsolutioninwhichtheultrasonicve1ocitychangeswiththevariationoftheconcentrationandtemperatureoftheso1ution[1].Theconcentrationofhydrochloricacidso1utiotiwithdifferentconcentrationcanbegiven[']asD=ffc,T,P)(l)wherecistheu1trasonicvc1ocityinhydroch1oricacidsolution,Tisthctemperatilreofhydrochloricacidso1utionandPisthepressureofhydroch1oricacidsolution.Whenthcprcs-surePisaconstanLtheco…     

Application of MCR: Facile one-pot diastereoselective syntheses of novel chiral α,α'-iminodiacetic acid analogues

Several pairs of enantiomeric alpha,alpha'-iminodiacetic acid analogues (2 and 4) were prepared separately by highly diastereoselective 3CR, which involves a reaction of an isocyanide, an aldehyde, and an enantiomerically pure amino acid in methanol. Synthesis of each of the enantiomers was controlled by the configuration of the amino acid; L-amino acid produces one enantiomer and D-amino acid generates the other. The diastereoselectivity of the 3CR is very sensitive to the substituent size of both aldehyde and enantiomerically pure amino acid.     

Young’s modulus and fracture during Knoop indentation of potassium, rubidium, cesium, and ammonium acid phthalate single crystals on the (010) plane

The correlation of the anisotropy of the Young??s modulus of organic single crystals of potassium, rubidium, cesium, and ammonium acid phthalates with strain and fracture patterns during Knoop indentation on the (010) cleavage plane in the [001] and [100] directions has been studied. The data on the maximum anisotropy of the strain and fracture patterns of the ammonium acid phthalate single crystal have been discussed in view of the published data on the structure, mechanical, elastic, and X-ray spectral properties of these crystals.     

Silica–zirconium phosphate–phosphoric acid composites: preparation,proton conductivity and use in gas sensors

Mesoporous composites made of silica and α-zirconium phosphate (SiO₂·xZrP) were synthesized starting from mixtures of delaminated ZrP dispersions and tetrapropylammonium oligosilicate solutions. The surface area of the composites reaches a maximum of 700 m²/g for x≈0.02, while the average pore diameter is about 40 Å for x in the range 0.05–0.35. In order to increase proton conductivity at low relative humidity (r.h.), SiO₂·xZrP·yH₃PO₄ composites were prepared and characterised by ²⁹Si and ³¹P MAS NMR and conductivity measurements. At 100 °C and 6% r.h., the conductivity of the composites, with H₃PO₄ loadings of 80% of the pore volume, rises from 5×10⁻⁴ to 2×10⁻² S/cm for x decreasing between 0.35 and 0.05, as a consequence of the concomitant increase of pore volume. For the composite with x=0.18, the dependence of conductivity on H₃PO₄ loading was also investigated at different temperatures and r.h. values. The combined increase of humidity, temperature and H₃PO₄ loading results in an increase of conductivity from 1×10⁻⁷ S/cm (y=0.09, T=25 °C, 0% r.h.) to 4×10⁻² S/cm (y=0.61, T=100 °C, 30% r.h.). SiO₂·0.18ZrP·0.61H₃PO₄ was also tested as a proton electrolyte in an oxygen sensor consisting of a disk of the composite sandwiched between a platinum sensing electrode and a reference electrode based on Ni_1−xO. The sensor is able to detect O₂ at room temperature in a dry environment with a response time of 20–30 s.     

Modelling electron-induced processes in “condensed” formic acid

Quantum calculations and experiments with molecular beams have been carried out for the Formic Acid dimeric structures colliding with a beam of slow (<20 ev) electrons.=" the=" corresponding=" computed=" s-matrix=" poles,=" seen=" as=" signatures=" for=" the=" formation=" of=" transient=" negative=" ions,=" allow=" us=" to=" assign=" the=" resonances=" to=" specific=" doorway=" states=" which=" are=" suggested=" to=" be=" responsible=" for=" the=" fragmentation=" patterns=" observed=" in=" the=" present=" experiments=" and=" in=" earlier=" measurements=" carried=" out=" both=" in=" molecular=" beams=" and=" with=" films=" of=" formic=" acid.=" we=" further=" show=" the=" computed=" behaviour=" of=" partial=" cross-sections=" and=" partial=" eigenphase=" sums=" for=" the=" dominant=" symmetry=" components.=">     

Ultrasound-assisted assembly of β-lactoglobulin and chlorogenic acid for non covalent nanocomplex: fabrication,characterization and potential biological function

It is essential to understand the ultrasound-induced changes in assembly of proteins and polyphenols into non covalent nanocomplex. β-Lactoglobulin (LG) and chlorogenic acid (CA) with various biological activities can be combined to form food-grade nanocomplexes. This study systematically explored the role of high-intensity ultrasound pretreatment on the binding mechanisms of LG and CA, and the potential biological function for embedding curcumin (Cur). The scanning electron microscopy (SEM) revealed that ultrasound treatment could destroy the structure of LG, and the particle size of the protein was reduced to<50 nm. The change in secondary structure of the protein by ultrasound treatment could be revealed by the fourier transform infrared (FTIR) and fluorescence spectra. Besides, it was found that LG and CA were combined to form a complex under the hydrophobic interaction, and CA was bound in the internal cavity of LG with a relatively extended conformation. The result demonstrated that the ratio of Cur embedded in the ultrasonic sample could be effectively increased by 7% − 10%, the particle size in the emulsion was smaller, and the dispersion was more stable. This work contributes to the development of protein–polyphenol functional emulsion systems with the ability to deliver Cur.     

Synthesis,optical, thermal and second harmonic generation studies of pure,urea and thiourea doped organic l-tartaric acid–nicotinamide (LTN) crystals

Nonlinear optical pure, urea and thiourea doped LTN crystals have been successfully grown from aqueous solution using slow evaporation technique. XRD analysis has been carried out to determine the lattice parameters of the pure and doped LTN crystals. The grown crystals were characterized by thermogravimetric analysis (TGA), differential thermal analysis (DTA), energy dispersive x-ray analysis (EDX) analysis and UV–vis–NIR spectroscopy. The fundamental modes of pure and doped crystals have been qualitatively assigned by FTIR analysis. The hardness of the grown crystals has been assessed and the results show the minor variation in the hardness value for the pure and doped LTN samples. Furthermore, second harmonic generation (SHG) measurements conducted indicate that the efficiency of thiourea doped LTN is 4.2 times greater than that of the KDP crystals and is suitable for frequency conversion applications.     

Synthesis of zincosilicate mordenite using citric acid as complexing agent

The zincosilicate analog of zeolite mordenite was hydrothermally synthesized in the presence of citric acid and characterized with several spectroscopic techniques.The zeolite thus prepared had a higher crystallinity and Zn concentration in the framework compared with the one obtained in the absence of citric acid.XRD and FTIR provided evidence for the incorporation of Zn in the framework.Results of XAFS indicated a tetrahedral structure of Zn in the lattice framework with a Zn-O distancd of 0.1938nm.It is speculated that the citric acid might decrease the concentration of Zn^2 in the synthesis mixture,there by preventing the unfavorable-formation of oxide or hydroxide species.2001 Elsevier Science B.V.All rights reserved.     

Correction to: Novel metal complexes containing 6‑methylpyridine‑2‑carboxylic acid as potent α‑glucosidase inhibitor: synthesis,crystal structures,DFT calculations,and molecular docking

Molecular Diversity -     

NMR spin–spin coupling constants in microhydrated ortho-aminobenzoic acid

The influence of the hydrogen-bond formation on the NMR spin–spin coupling constants, including the Fermi contact, the diamagnetic spin–orbit, the paramagnetic spin–orbit and the spin dipole term, has been investigated for the ortho-aminobenzoic acid microhydrated with up to three water molecules. The one-bond and two-bond spin–spin coupling constants for several intra-molecular and across-the-hydrogen-bond atomic pairs are calculated employing high-level density functional theory in combination with the B3LYP functional with two different types of extended basis sets for each level of microhydration. The spin–spin coupling constants, in general, vary inversely with the hydrogen bond length. The Fermi contact term is found to be the dominant contributor to the total value of spin–spin coupling constant followed by the paramagnetic spin–orbit term. The variations of Fermi contact term and atomic charge distribution with size of microhydration follow quite similar trend. The effect of explicit solvation provided by microhydration has also been compared briefly with that of bulk implicit solvation obtained through polarised continuum model and mixed microhydration/continuum approach.