Nuclear Magnetic Resonance Spectral Analysis Research Articles

Structure and Crystallization of Alkaline-Earth Aluminosilicate Glasses: Prevention of the Alumina-Avoidance Principle.

Aluminosilicate glasses are considered to follow the Al-avoidance principle, which states that Al-O-Al linkages are energetically less favorable, such that, if there is a possibility for Si-O-Al linkages to occur in a glass composition, Al-O-Al linkages are not formed. The current paper shows that breaching of the Al-avoidance principle is essential for understanding the distribution of network-forming AlO4 and SiO4 structural units in alkaline-earth aluminosilicate glasses. The present study proposes a new modified random network (NMRN) model, which accepts Al-O-Al linkages for aluminosilicate glasses. The NMRN model consists of two regions, a network structure region (NS-Region) composed of well-separated homonuclear and heteronuclear framework species and a channel region (C-Region) of nonbridging oxygens (NBOs) and nonframework cations. The NMRN model accounts for the structural changes and devitrification behavior of aluminosilicate glasses. A parent Ca- and Al-rich melilite-based CaO-MgO-Al2O3-SiO2 (CMAS) glass composition was modified by substituting MgO for CaO and SiO2 for Al2O3 to understand variations in the distribution of network-forming structural units in the NS-region and devitrification behavior upon heat treating. The structural features of the glass and glass-ceramics (GCs) were meticulously assessed by advanced characterization techniques including neutron diffraction (ND), powder X-ray diffraction (XRD), 29Si and 27Al magic angle spinning (MAS)-nuclear magnetic resonance (NMR), and in situ Raman spectroscopy. ND revealed the formation of SiO4 and AlO4 tetrahedral units in all the glass compositions. Simulations of chemical glass compositions based on deconvolution of 29Si MAS NMR spectral analysis indicate the preferred formation of Si-O-Al over Si-O-Si and Al-O-Al linkages and the presence of a high concentration of nonbridging oxygens leading to the formation of a separate NS-region containing both SiO4 and AlO4 tetrahedra (Si/Al) (heteronuclear) in addition to the presence of Al[4]-O-Al[4] bonds; this region coexists with a predominantly SiO4-containing (homonuclear) NS-region. In GCs, obtained after heat treatment at 850 °C for 250 h, the formation of crystalline phases, as revealed from Rietveld refinement of XRD data, may be understood on the basis of the distribution of SiO4 and AlO4 structural units in the NS-region. The in situ Raman spectra of the GCs confirmed the formation of a Si/Al structural region, as well as indicating interaction between the Al/Si region and SiO4-rich region at higher temperatures, leading to the formation of additional crystalline phases.

DESIGN, SYNTHESIS OF BIOLOGICALLY ACTIVE HETEROCYCLES CONTAINING INDOL- THIAZOLYL- THIAZOLIDINONE DERIVATIVES

Objective: The present study envisage a novel series of thiazole, indole and thiazolidine derivatives, namely, N-((5-Substituted-2-phenyl-1 H-indol-3-yl)methylene)-4,5,6,7-tetrahydro-5,7,-dimethylbenzo [d]thiazole-2-amine (4a-c), 2-(5-substituted-2-phenyl-1H-indol-3-yl)-3-(4,5,6,7- trimethylbenzo[d]thiazol-2-yl)-thiazolidin-4-one (5a-c) and 5-benzylidine-2-(5-substituted-2phenyl-1H-indol-3yl)-3-(4,5,6,7-tetrahydro-5,5,7- trimethylbenzo[d]thiazol-2-yl) thiazolidin-4-one (6a-c).Methods: All the newly synthesized compounds were characterized by infrared, 1H, 13C nuclear magnetic resonance and mass spectral data and elemental analysis and evaluated for in vitro antimicrobial activity.Results: Novel compounds N-((5-Substituted-2-phenyl-1H-indol-3-yl)methylene)-4,5,6,7-tetrahydro-5,7,-dimethylbenzo [d]thiazole-2-amine (4a-c), 2-(5-substituted-2-phenyl-1H-indol-3-yl)-3-(4,5,6,7-trimethylbenzo[d]thiazol-2-yl)-thiazolidin-4-one (5a-c) and 5-benzylidine-2-(5-substituted- 2phenyl-1H-indol-3yl)-3-(4,5,6,7-tetrahydro-5,5,7-trimethyl benzo[d]thiazol-2-yl)thiazolidin-4-one (6a-c) have been made and characterized using spectral and analytical data. The results of antibacterial and antifungal activities showed that some of the synthesized compounds exhibited promising activities.Conclusion: All the newly synthesized compounds were carried out by the broth microdilution method (NCCLS. 2002) in a DMF concentration of 500, 250, 125, and 62.5 μg/ml. Gentamycin and fluconazole are used as reference standards for antibacterial and antifungal activity, respectively. The final results revealed that compounds 4b, 5b, and 6b exhibited potent antimicrobial activity when compared to the standard drugs.

Study of the effect of Sodium dodecyl sulphate (SDS) on isolation of Curcumin from oleoresin of Turmeric (Curcuma longa)

This study was undertaken for extraction and isolation of Curcumin from Curcuma longa rhizomes. In the present study effect of sodium dodecyl sulphate on the isolation of Curcumin was carried out and it was found that it helps in the isolation of Curcumin from the oleoresin of Curcuma longa. The structure of the compound was elucidated and confirmed by thin layer chromatography, infrared spectroscopy, mass spectrometry and nuclear magnetic resonance spectral analysis. HPLC method was used for the identification and quantification of Curcumin by comparing with a standard.

Nematotoxic coumarins from Angelica pubescens Maxim. f. biserrata Shan et Yuan roots and their physiological effects on Bursaphelenchus xylophilus.

Abstract The ethanol extracts from the roots of Angelica pubescens Maxim. f. biserrata Shan et Yuan was toxic against the pine wood nematode Bursaphelenchus xylophilus. The ethyl acetate-soluble fraction derived from this extract increased its potency with a mortality of 95.25% in 72 hr at 1.0 mg/mL. Four nematotoxic coumarins were obtained from the ethyl acetate extract by bioassay-guided isolation. These were identified as osthole 1 , columbianadin 2 , bergapten 3 and xanthotoxin 4 by mass and nuclear magnetic resonance spectral data analysis. The LC50 values against B. xylophilus in 72 hr were 489.17, 406.74, 430.08, and 435.66 μM, respectively. These compounds also altered the smooth morphology of the B. xylophilus exoskeleton to a rough and pitted appearance as visualized by electron microscopy. The coumarins 1-4 possessed significant acetylcholinesterase inhibitory activities but had negligible effects on amylase and cellulase. This research provides additional clues to the nematotoxic mechanism of coumarins against the pine wood nematode B. xylophilus. This work will assist in the development of coumarin nematicides with enhanced activity using molecular modifications of the core coumarin structure.

Optical, mechanical and thermal behaviors of Nitrilotriacetic acid single crystal

An organic nonlinear single crystal of Nitrilotriacetic acid (NTAA) was grown for the first time by employing a simple slow evaporation technique. Single crystal X-ray diffraction (XRD) analysis reveals that the grown crystal belongs to the monoclinic system with noncentrosymmetric space group [Formula: see text]. Fourier transform infrared (FTIR) spectral study ascertains the presence of functional groups in NTAA. The molecular structure of the grown crystal was confirmed by Nuclear Magnetic Resonance (NMR) spectral analysis. The optical parameters such as transmittance, absorption coefficient and band gap were calculated from UV–Visible and fluorescence studies. Dielectric measurements were carried out for different frequency and temperature. The mechanical strength of the grown crystal was measured using Vickers microhardness test. The high thermal stability and the melting point of the grown crystal were also estimated using thermogravimetric (TGA) and differential thermal analyses (DTA). The confirmation of the grown crystals belonging to nonlinear optical crystals was performed by Kurtz–Perry technique and found as suitable candidate for optoelectronics applications.

Synthesis, crystal structure and growth of a new inorganic- organic hybrid compound for nonlinear optical applications: Aquadiiodo (3-aminopropanoic acid) cadmium (II)

The new inorganic-organic hybrid material aquadiiodo (3-aminopropanoic acid) cadmium (II) [ADI (3-AP) Cd] has been successfully synthesized and good quality crystals have been grown by slow evaporation solution technique. The structure was determined by single crystal X-ray diffraction at room temperature. The compound crystallizes in monoclinic crystal system with centro symmetric space group P21/c and four molecules in the unit cell. The structure of the title compound was further confirmed by 1H and 13C nuclear magnetic resonance spectral analysis. FT-IR spectroscopy was used to confirm the presence of various functional groups in the compound. The transmittance and optical parameters of the crystal were studied by UV- Visible-NIR spectroscopy. The thermal stability of the grown crystal was evaluated using thermogravimetric and differential thermal analyses. Mechanical hardness has been identified by Vickers micro hardness study and work hardening coefficient was calculated. Dielectric measurement was carried out as a function of frequency and results are discussed. The growth mechanism of the crystal was assessed by chemical etching studies. The third-order nonlinear optical susceptibility of [ADI (3-AP) Cd] was derived using the Z-scan technique, and it was 3.24955 × 10−8 esu. The positive nonlinear refractive index 2.48505 × 10−11 m2/W, is an indication of self-defocusing optical nonlinearity of the sample. It is believed that the [ADI (3-AP) Cd] is a promising new candidate for developing efficient nonlinear optical and optical power limiting devices.

Effect of molecular weight on crystallization and rheological properties of poly(3,3-bis(azidomethyl)oxetane)

Various molecular weight of poly(3,3-bis(azidomethyl)oxetane) were prepared from 3,3-bis(chloromethyl) oxetane. The structure of those were confirmed by Fourier transform infrared, proton nuclear magnetic resonance spectral analysis and gel permeation chromatograph, meanwhile the properties were also compared by X-ray diffraction, differential scanning calorimetry and rheological analysis. The results indicated that increasing molecular weight weakened the crystallization ability of PBAMO and increased the glass transition temperature. Furthermore, the viscosity, shear stress, G′ and G″ of PBAMO increased gradually with increasing of the molecular weight.

Selection, Characterization and Application of Artificial DNA Aptamer Containing Appended Bases with Sub-nanomolar Affinity for a Salivary Biomarker

We have attained a chemically modified DNA aptamer against salivary α-amylase (sAA), which attracts researchers’ attention as a useful biomarker for assessing human psychobiological and social behavioural processes, although high affinity aptamers have not been isolated from a random natural DNA library to date. For the selection, we used the base-appended base (BAB) modification, that is, a modified-base DNA library containing (E)-5-(2-(N-(2-(N6-adeninyl)ethyl))carbamylvinyl)-uracil in place of thymine. After eight rounds of selection, a 75 mer aptamer, AMYm1, which binds to sAA with extremely high affinity (Kd < 1 nM), was isolated. Furthermore, we have successfully determined the 36-mer minimum fragment, AMYm1-3, which retains target binding activity comparable to the full-length AMYm1, by surface plasmon resonance assays. Nuclear magnetic resonance spectral analysis indicated that the minimum fragment forms a specific stable conformation, whereas the predicted secondary structures were suggested to be disordered forms. Thus, DNA libraries with BAB-modifications can achieve more diverse conformations for fitness to various targets compared with natural DNA libraries, which is an important advantage for aptamer development. Furthermore, using AMYm1, a capillary gel electrophoresis assay and lateral flow assay with human saliva were conducted, and its feasibility was demonstrated.

Synthesis of allitol from D-psicose using ribitol dehydrogenase and formate dehydrogenase

Purpose: To synthesize allitol from D-psicose by a combination of novel ribitol dehydrogenase (RDH) and formate dehydrogenase (FDH) under optimised production conditions. Methods: RDH and FDH genes were cloned and introduced into pET-22b(+) vectors for expression in Escherichia coli to produce the corresponding enzymes. The effects of temperature, pH, shaking velocity (75, 100, 125, and 150 rpm), and shaking type (horizontal and vortex) were optimised to maximise the production yield of allitol. The final product was purified and subjected to nuclear magnetic resonance (NMR) spectroscopy, infrared (IR) spectrometry, and liquid chromatography-mass spectrometry (LC-MS) to confirm its structure. Results: The optimal pH and temperature for the reaction were 7.5 and 40 °C, respectively. The results revealed that allitol yield significantly increased with increase in reaction shaking velocity and reached a maximum yield of 95.60 ± 0.54 % at 150 rpm shaking velocity after 6 h of reaction. When the reaction was run under horizontal shaking, allitol yield increased from 100.00 ± 6.05 (without shaking) to 124.20 ± 9.70 %. Twenty milligrams of D-psicose were successfully reduced to allitol under optimum conditions with a high production yield of 16.7 ± 0.62 mg after 6 h. No by-products were formed during or after the reaction. The produced allitol had a purity of 95 %, and its structure was confirmed by HPLC, IR, LCMS, and NMR spectral analyses. Conclusion: Using D-psicose as a substrate, allitol with 95 % purity was successfully produced by the combination of novel RDH and FDH. Keywords: Allitol, Ribitol dehydrogenase, Formate dehydrogenase, D-Psicose, Providencia alcalifaciens

Study on growth, spectral, optical and thermal characterization of an NLO crystal: 6-Methyl nicotinic acid (6MNA)

6-methyl-nictinic acid (6MNA), organic non linear optical (NLO) single crystals were grown by slow evaporation solution technique. The cell parameters of 6MNA were confirmed from single crystal X-ray diffraction analysis. The Fourier transforms infrared and proton Nuclear magnetic resonance spectral analysis confirm the presence of various functional groups and the placement of protons respectively in 6MNA compound. UV–vis–NIR spectral studies revealed that the grown 6MNA has good optical transmission in the range of entire visible region. The thermal properties of crystals were evaluated from thermogravimetric (TG) and differential thermal analysis (DTA). It has shown that the grown crystals were stable up to 213°C. The second harmonic generation (SHG) measurements indicated that the efficiency of 6MNA is two times greater than that of the KDP crystals and is suitable for frequency conversion applications.

Studies on the growth and characterization of organic crystal l-Arginine glutarate by liquid diffusion technique

An organic single crystal of l-Arginine glutarate (LAG) was successfully grown by liquid diffusion technique at room temperature. From X-ray diffraction study it was determined that the crystal crystallized in the monoclinic system with centrosymmetric space group. The optical absorption spectrum of l-Arginine glutarate has been recorded. The structure of grown crystal was established using Nuclear magnetic resonance spectral analysis. The presence of functional group was identified by FTIR and FT Raman spectral studies. Thermal property of l-Arginine glutarate crystal have been reported. SHG test was carried out to reconfirm the centrosymmetric nature of the grown crystal.

Design and UV-curable behaviour of boron based reactive diluent for epoxy acrylate oligomer used for flame retardant wood coating

Difunctional boron-containing reactive flame retardant for UV-curable epoxy acrylate oligomer was synthesized from phenyl boronic acid and glycidyl methacrylate. The synthesized reactive diluent was utilized to formulate ultraviolet (UV)-curable wood coatings. The weight fractions of reactive diluent in coatings formulation was varied from 5 to 25 wt % with constant photoinitiator concentration. The molecular structure of reactive flame retardant was confirmed by Fourier-transform infrared, Nuclear magnetic resonance (NMR) and 11B NMR spectral analysis. Further, the efficacy of flame retardant behaviour of coatings was evaluated using limiting oxygen index and UL-94 vertical burning test. Thermal stability of cured coatings films were estimated from thermogravimetric and differential scanning calorimetry analysis. The effects of varying concentration of reactive diluent on the viscosity of coatings formulation along with optical, mechanical and chemical resistance properties of coatings were also evaluated. The coatings gel content, water absorption behaviour, contact angle analysis and stain resistance were also studied.

Isolation and purification of plant secondary metabolites using column-chromatographic technique

&lt;p&gt;Chromatographic techniques have significant role in natural products chemistry as well as contribute dramatically in the discovery of novel and innovative compounds of pharmaceutical and biomedical importance. This study focused on step-by-step visual demonstration of fractionation and isolation of biologically active plant secondary metabolites using column-chromatographic techniques. Isolation of bioactive compounds using column-chromatographic involves: a) Preparation of sample; b) Packing of column; c) Pouring of sample into the column; d) Elution of fractions; and e) Analysis of each fractions using thin layer chromatography. However, depending on nature of research, compounds can be further purified using high performance liquid chromatography (HPLC), and nuclear magnetic resonance (NMR) spectral analyses.&lt;/p&gt;&lt;p&gt;&lt;strong&gt;Video Clips&lt;/strong&gt;&lt;/p&gt;&lt;p&gt;&lt;a href="https://www.youtube.com/v/pr8mrBoI8xA"&gt;Part 1:&lt;/a&gt; 3 min 45 sec&lt;/p&gt;&lt;p&gt;&lt;a href="https://www.youtube.com/v/rYrfClKn-og"&gt;Part 2:&lt;/a&gt; 6 min 21 sec&lt;/p&gt;&lt;p&gt;&lt;a href="https://www.youtube.com/v/kffHXxuPwbo"&gt;Part 3&lt;/a&gt;: 4 min 45 sec&lt;/p&gt;

Microbial transformation of hederagenin by Cunninghamella echinulate, Mucor subtilissimus, and Pseudomonas oleovorans

The pentacyclic triterpenoid hederagenin (1) was subjected to biotransformation by Cunninghamella echinulate CGMCC 3.2000, Mucor subtilissimus CGMCC 3.2454 and Pseudomonas oleovorans CGMCC 1.1641. Three metabolites were obtained. On the basis of nuclear magnetic resonance and high-resolution mass spectral analyses, their structures were characterized as 3β, 23-dihydroxyolean-12-en-28-oic acid 28-O-β-D-glucopyranosyl ester (2), 3β, 15α, 23-trihydroxyolean-12-en-28-oic acid (3), 1β, 3β, 23-trihydroxyolean-12-en-28-oic acid (4), and metabolite (3) was a new compound. This was the first report on the biotransformation of hederagenin.

Novel Polycarbonates via Phosgenation of Unsaturated Diols

A new interesting class of linear unsaturated polycarbonates based on methyl- cyclohexanone and 4-tert. butyl- cyclohexanone moieties has been synthesized. An interfacial phosgenation technique carried out at ambient temperature was used for the synthesis of these polycarbonates. The resulting polycarbonates were characterized by elemental analyses, infrared spectroscopy, 1H nuclear magnetic resonance spectral analyses, viscometry, differential scanning calorimetry and thermogravimetric analysis measurements. All the polycarbonates were soluble in polar solvents like dimethylsulphoxide and sulphuric acid. The crystallinity of some selected polycarbonates was examined by X-ray analysis. In addition, the morphology of selected examples of the polycarbonates was examined by scanning electron microscopy.

2H nuclear magnetic resonance study of deuterated water dynamics in perfluorosulfonic acid ionomer Nafion

We have employed deuteron nuclear magnetic resonance (NMR) spectroscopy in order to study the dynamics of the deuterated water (D2O) molecules introduced into a perfluorosulfonic acid ionomer Nafion (NR-211) film. According to the 2H NMR spectral analysis, the deuterated water molecules at low temperatures occupied either relatively rigid or mobile sites up to the temperature TM=240K where all the deuterated water molecules became mobile. The temperature-dependent NMR linewidths sensitively reflected the motional narrowing of the rigid and mobile sites, and the NMR chemical shift reflected significant changes in the hydrogen bonds of the deuterated water. While a slow- to fast-limit motional transition was manifested at TM in the laboratory-frame NMR spin–lattice relaxation, the rotating-frame spin–lattice relaxation indicated no bulk liquid water state down to 200K.

A nematicidal tannin from Punica granatum L. rind and its physiological effect on pine wood nematode (Bursaphelenchus xylophilus)

The ethanol extract of Punica granatum L. rind was tested to show significant nematicidal activity against pine wood nematode. Three nematicidal compounds were obtained from the ethanol extract by bioassay-guided fractionation and identified as punicalagin 1, punicalin 2, and corilagin 3 by mass and nuclear magnetic resonance spectral data analysis. Punicalagin 1 was most active against PWN among the purified compounds with the LC50 value of 307.08μM in 72h. According to the enzyme assays in vitro, punicalagin 1 could inhibit the activity of acetylcholinesterase, amylase and cellulase from PWN with IC50 value of 0.60mM, 0.96mM and 1.24mM, respectively. The morphological structures of PWNs treated by punicalagin 1 were greatly changed. These physiological effects of punicalagin 1 on PWN may helpful to elucidate its nematicidal mechanism.

Extraction, isolation and purification of exopolysaccharide from lactic acid bacteria using ethanol precipitation method

&lt;p&gt;Lactic acid bacteria are classified ‘Generally Recognized As Safe’ (GRAS) with most effective potential to divert significant amount of fermentable sugars towards the biosynthesis of functional exopolysaccharide. Exopolysaccharides from lactic acid bacteria are receiving a renewed interest due to the claims of human health benefits, such as modulation of immune response system and more importantly in food and pharma industries as a texturizer, viscosifer, emulsifier and syneresis-lowering agent. Its purification methodology involves: a) Extraction of cell-free supernatant from lactic acid bacteria; b) Denature of protein using trichloroacetic acid; c) Ethanol precipitation; d) Dialysis; and e) Freeze drying. However, depending on nature of research, compounds can be further purified using scanning electron microscopy (SEM), infrared spectrum (IR); and nuclear magnetic resonance (NMR) spectral analyses.&lt;/p&gt;&lt;p&gt;&lt;strong&gt;Video Clips&lt;/strong&gt;&lt;/p&gt;&lt;p&gt;&lt;a href="https://www.youtube.com/v/PGDyHPEk5jY"&gt;Part 1&lt;/a&gt;: 7 min 42 sec&lt;/p&gt;&lt;p&gt;&lt;a href="https://youtube.com/v/G8ZMZ4z1DMs"&gt;Part 2&lt;/a&gt;: 3 min 36 sec&lt;/p&gt;

UV-curable behavior of phosphorus- and nitrogen-based reactive diluent for epoxy acrylate oligomer used for flame-retardant wood coating

Multifunctional phosphorus and nitrogen containing tris-diethanolamine spirocyclic pentaerythritol bisphosphorate reactive diluent (TDSPBRD) for epoxy acrylate oligomer was synthesized from spirocyclic pentaerythritol bisphosphorate diphosphoryl chloride, diethanolamine, and allyl chloroformate. The synthesized reactive diluent was utilized to formulate ultraviolet (UV)-curable wood coating. The weight fraction of reactive diluent in the coating formulation was varied from 5 to 25 wt% with constant photoinitiator concentration. The molecular structure of the reactive flame retardant was confirmed by Fourier transform infrared (FTIR), 1H nuclear magnetic resonance (NMR) and 31P NMR spectral analysis and energy dispersive spectroscopy (EDAX). Further, the effectiveness of the flame retardant behavior of the coatings was evaluated using the limiting oxygen index and UL-94 vertical burning test. Thermal stability was estimated from thermogravimetric analysis and differential scanning calorimetry. The effects of varying the concentration of TDSPBRD on the viscosity of the coating formulation along with the optical, mechanical and chemical resistance properties of the coatings were evaluated. The coatings gel content, water absorption behavior, and stain resistance were also studied.

Production and optimization of curdlan produced by Pseudomonas sp. QL212

Curdlan is a polysaccharide that consists of β-1,3-linked glucose residues. A polysaccharide-producing bacterium isolated from soil samples was identified as Pseudomonas sp. QL212. The polysaccharide was purified to homogeneity via sequential ethanol precipitation, deproteinization, CM ion-exchange, and gel chromatography sequentially. Analysis of the purified polysaccharide revealed that it consisted of many glucosyl residues, and its molecular weight was only 6.18×105Da. This low molecular weight endowed it with excellent solubility. Infrared and nuclear magnetic resonance spectral analysis confirmed that the polysaccharide was curdlan. Single-factor and Response surface methodology experiments were used to optimize the culture medium and conditions. The optimal culture conditions consisted of seed culture age of 12h, and an incubation temperature of 30°C, with 10% inoculum and a total fluid volume of 75mL in a 250-mL Erlenmeyer flask. The maximum curdlan yield of about 5.92gL−1 was achieved with an optimal medium consisting of 30.11gL−1 of sucrose, 5.94gL−1 of yeast extract, and an initial pH of 8.03. To our best knowledge, this is the highest reported yield of curdlan produced by Pseudomonas sp., and the curdlan production medium components were much simpler than those in previous reports.