Carbon-13 Nuclear Magnetic Resonance Spectroscopy Research Articles

Design, Synthesis and Bio-Evaluation of Novel Chalcones Bridged with 1,3,4-Oxadiazole Linkers: ADMET and Docking Analysis.

In this article, we prepared a novel series of 1,3,4-oxadiazoles containing chalcone analogs via replacement of phthalazine which had increased antibacterial activity and the final compounds were confirmed by proton, carbon nuclear magnetic resonance spectroscopy, infrared and mass spectral analysis. Two sets of 1,3,4-oxadiazoles like 2-methyl-5-substitutedbenzylthio-1,3,4-oxadiazolyl-4-methylphthalazine-2-ones (3a-f), (E)-substituted phenyl acryloylphenyl-4-methyl-1-oxophthalazine-1,3,4-oxadiazolylthioacetamides (5a-f) were designed, synthesized and evaluated for their in vitro antibacterial potency against different Gram-(+ve), Gram-(-ve) microorganisms and fungal strains. The synthesized 4-methyl-2-{[5-({[2-(trifluoromethyl)phenyl]methyl}sulfanyl)-1,3,4-oxadiazol-2-yl]methyl}phthalazin-1(2H)-one (3c), 4-methyl-2-[(5-{[(4-nitrophenyl)methyl]sulfanyl}-1,3,4-oxadiazol-2-yl)methyl]phthalazin-1(2H)-one (3d), N-(4-{(2E)-3-[2-(dimethylamino)phenyl]prop-2-enoyl}phenyl)-2-({5-[(4-methyl-1-oxophthalazin-2(1H)-yl)methyl]-1,3,4-oxadiazol-2-yl}sulfanyl)acetamide (5d), and N-{4-[(2E)-3-(3-hydroxy-4-methoxyphenyl)prop-2-enoyl]phenyl}-2-({5-[(4-methyl-1-oxophthalazin-2(1H)-yl)methyl]-1,3,4-oxadiazol-2-yl}sulfanyl)acetamide (5e) displayed improved activity with MICs 1.41, 0.87, 2.16, 0.89 μg/mL as compared to the standard drugs rifamycin, ciprofloxacin, fluconazole (MIC=1.52, 1.94, 3.02 μg/mL). The prepared compounds were also analyzed with better target binding towards bacterial bioavailability, 5e exhibited highest bonds with amino acids ArgA45 , LysA20 , LysA17 , ArgA171 , AspA49 , IleA14 , HisA18 and having docking energy -8.68 Kcal/mol and dissociation constant 432.48 nM, respectively. These compounds were further evaluated for their ADMET and physicochemical properties by using SwissADME.

Development of polymeric electrolytes for fuel cells: Synthesis and characterization of new sulfonated polystyrene-co-acrylonitrile-co-butyl acrylate terpolymers

To improve the physical and chemical properties of styrene-derived polymers, new polystyrene-co-acrylonitrile-co-butyl acrylate terpolymers were synthesized and subsequently sulfonated. Six terpolymer compositions were prepared under mass radical polymerization conditions and further sulfonated to promote proton conductivity. The terpolymers were characterized by Fourier Transformed Infrared Spectroscopy (FTIR), proton and carbon nuclear magnetic resonance spectroscopy (1H NMR and 13C NMR), Gel Permeation Chromatography (GPC), Thermomechanical Analysis (TMA), Thermogravimetric Analysis (TGA), Differential Scanning Calorimetry (DSC) and Electrochemical Impedance Spectroscopy (EIS). All synthesized terpolymers have molecular weights over 160,000 g/mol and solubility on several organic solvents. Terpolymers also showed high thermal stability by TGA and comonomers reduced Tg transitions and complex moduli along BuA content; the complex moduli clearly increased with ACN content. Intermediate aliquots taken during the sulfonation reaction were characterized indicate that incorporation of the sulfonic group decreases the thermal stability from over 350 °C in terpolymers down to 150 °C after sulfonation. The degree of sulfonation analyzed by TGA ranged between 11.2 and 15.9% leading to a proton conductivity interval from 2.9 to 4.0 mS/cm. The results suggest a lateral crosslinking reaction through sulfone groups. The proton ion conductivity values obtained are similar to those of commercially available membranes described in the literature.

Extraction, Separation and Purification of Bioactive Anticancer Components from Peganum harmala against Six Cancer Cell Lines Using Spectroscopic Techniques

Conventional cancer treatments normally involve chemotherapy or a combination of radio- and chemotherapy. However, the adverse effects of synthetic medicines encouraged the exploration of novel therapeutic medications of a bio-friendly nature. In an effort to explore anticancer compounds from natural resources, crude extract of Peganum harmala (seeds) was fractionated on the basis of polarity, and the fractions were further tested for anticancer activity. Brine shrimp lethality assays and potato disc antitumor assays were used to test each fraction for cytotoxic and antitumor potential. The ethyl acetate fraction was found to be most potent, with LC50 and IC50 values of 34.25 µg/mL and 38.58 µg/mL, respectively. Further activity-guided fractionation led to the isolation of the bioactive compound PH-HM-10 which was identified and characterized by Mass Spectroscopy (MS), Infrared Spectroscopy (IR), Proton Nuclear Magnetic Resonance Spectroscopy (1HNMR), Carbon Nuclear Magnetic Resonance Spectroscopy (13CNMR) and Heteronuclear Single Quantum Correlation (HSQC). Anticancer aspects in the isolated compound were determined against six human cancer cell lines with a maximum anticancer effect (IC50 = 36.99 µg/mL) against the tested human myeloid leukemia (HL-60) cell line, followed by the human lung adenocarcinoma epithelial cell line (A549) and the breast cancer cell line (MCF-7) with an IC50 of 63.5 µg/mL and 85.9 µg/mL, respectively). The findings of the current study suggest that the isolated compound (Pegaharmine E) is significantly active against the tested cancer cell lines and can be further investigated to develop future novel anticancer chemotherapeutic agents.

CHARACTERIZATION STUDIES ON A TETRAHYDROCURCUMIN-ZINC COMPLEX

Objective: Preparation and characterization studies on tetrahydrocurcumin complexed with zinc, with particular reference to the location of zinc in the complex. Methods: Structural characteristics of tetrahydrocurcumin and its complex with zinc were compared using elemental analysis, mass spectrometry (MS), proton, and carbon-13 nuclear magnetic resonance spectroscopy (NMR), ultraviolet-visible (UV) absorption spectroscopy, and Fourier transform infrared (FTIR) spectroscopy. Results: MS data indicates a Zn molecule holds two THCur components together. NMR data provide evidence that the zinc ion is associated with the 1,3-diketone part of the linker region of the associated THCur. FTIR data is consistent with zinc interaction with the enol tautomer of the 1,3-diketone at the center of the linker region of THCur. UV data indicate that a zinc-dependent shift in absorbance maximum is consistent with changes in the structure of THCur resulting from complexation with zinc. Together, this data indicates the complexation of zinc with tetrahydrocurcumin is consistent with zinc linking two molecules of tetrahydrocurcumin together by binding to the enol forms of the 1,3-diketone moieties located in the linker regions between the aromatic rings. Conclusion: The spectral properties of the tetrahydrocurcumin-zinc complex are consistent with a structure in which zinc is encased in two tetrahydrocurcumin moieties. Additional studies are needed to determine if this structure results in altered bioavailability, antioxidant activity and other properties important for pharmaceutical development.

Relationship between aromatic hydrogen and aromatic carbon in straight run and converted oils

In the conversion of high boiling oil fractions, it is difficult to track compositional changes that affect the chemical nature of species. For reaction engineering, monitoring changes related to hydrogen transfer reactions and formation of aromatic species as thermal conversion progresses to coking is useful. Proton and carbon-13 nuclear magnetic resonance (1H and 13C NMR) spectrometry can measure the aromatic hydrogen and aromatic carbon content in oils of diverse origin and distillation range. 13C NMR analyses are more time consuming than 1H NMR analyses. The ability to calculate the aromatic carbon content of oils directly from measured aromatic hydrogen content is alluring and is reportedly feasible (Cookson, et al. Fuel 1986; 65:1247–1253). In this work previously reported 1H and 13C NMR data for different petroleum and coal derived oils were collated and supplemented with experimental measurements that included narrow cuts of straight run and refined oils, as well as bitumen-derived mixtures that were thermally converted at different levels of severity. It was found that aromatic carbon content, CAr, was only broadly related to aromatic hydrogen content, HAr. A wide range of values for CAr was possible for a specific value of HAr. The medium atmospheric equivalent boiling point temperature, T50, was a poor descriptor for indicating a directional change in the relationship between CAr and HAr, both for wide and narrow boiling range distillation fractions. An increase in heterocyclic aromatic content caused a decrease in the (H/C)Ar ratio, since heteroatoms in aromatics are mainly found in ring-edge and not in ring-junction positions. When the changes in HAr and CAr of different bitumen-derived materials with respect to thermal conversion severity were evaluated, it was found that changes in HAr and CAr were not in a fixed relation to each other.

Synthesis and properties of PAM/PLA composite degradable particle temporary plugging agent

AbstractUsing acrylamide (AM) and polylactic acid (PLA) as raw materials, polyacrylamide (PAM)/PLA composite temporary plugging agent TZDJ (TZDJ is a synthetic self‐degrading stopper) was synthesized by inverse suspension polymerization. The chemical structure, chemical composition, microscopic morphology, and thermal stability of TZDJ were characterized by Fourier infrared spectral analysis (FT‐IR), carbon nuclear magnetic resonance spectroscopy (13C NMR), scanning electron microscope (SEM), and thermogravimetric analysis (TGA). The degradation and plugging properties of TZDJ were studied by laboratory experiments, and the self‐degradation mechanism of TZDJ was proposed. The results show that TZDJ has good temperature and salt resistance, and it is completely degraded by hydrolysis at 180°C for 120 h. The fracture core displacement experiment shows that TZDJ has good plugging and core permeability recovery performance, and its temporary plugging rate and core permeability recovery rate are all above 90%. The FT‐IR and SEM analysis showed that the degradation process of TZDJ was divided into three stages: degradation of shell PAM, core PLA, and degradation product small molecules.

Antagonistic activity of synbiotics: Response surface modeling of various factors

Synbiotic compositions have a great potential for curing microbial intestinal infections. Novel targeted synbiotics are a promising field of the modern functional food industry. The present research assessed the effect of various fructan fractions, initial probiotic counts, and test strains on the antagonistic properties of synbiotics.
 The research involved powdered roots of Arctium lappa L. and strains of Bifidobacterium bifidum, Bacillus cereus, and Salmonella enterica. The experiment was based on the central composite rotatable design. A water extract of A. lappa roots was purified and concentrated. Fructan fractions were precipitated at various concentrations of ethanol, dried, and sub jected to carbon-13 nuclear magnetic resonance (13C-NMR) spectrometry. The bifidobacteria and the test strains were co-cultivated in the same medium that contained one of the fractions. Co-cultivation lasted during 10 h under the same conditions. The acid concentrations were determined by high-performance liquid chromatography to define the synbiotic factor.
 The obtained fructans were closer to commercial oligofructose in terms of the number and location of NMR peaks. However, they were between oligofructose and inulin in terms of signal intensity. The response surface analysis for bacilli showed that the minimal synbiotic factor value corresponded to the initial probiotic count of 7.69 log(CFU/mL) and the fructan fraction precipitated by 20% ethanol. The metabolites produced by the bacilli also affected their growth. The synbiotic factor response surface for the experiments with Salmonella transformed from parabolic to saddle shape as the initial test strain count increased. The minimal synbiotic factor value corresponded to the lowest precipitant concentration and the highest probiotic count. 
 The research established a quantitative relationship between the fractional composition of fructans and the antagonistic activity of the synbiotic composition with bifidobacteria. It also revealed how the ratio of probiotic and pathogen counts affects the antagonism. The proposed approach can be extrapolated on other prebiotics and microbial strains in vivo.

Comparative study on sensing and optical properties of carbazole linked novel zinc(II) and cobalt (II) phthalocyanines

In the current work, symmetrically carbazole linked Zn(II) and Co(II) phthalocyanines (Pcs) have been succesfully synthesized and characterized through Fouirer Transform Infrared (FT-IR), Ultraviolet–visible (UV–vis) spectroscopies, Matrix-assisted laser desorption - ionisation-time of flight mass spectrometry (MALDI-TOF MS) along with proton and carbon Nuclear Magnetic Resonance (1H and 13C- NMR) spectroscopies. The electrochemical performance of the targeted metallo- phthalocyanines was demonstrated with cyclic voltammetry (CV), and square wavevoltammetry (SWV). The final phthalocyanines were used as hybrid materials for the preparation of the modified glassy carbon electrode (GCE). The hybrid materials were then deposited on GCE via an electropolymerization or electrodeposition method. The surface morphologies of the hybrid electrodes were investigated using scanning electron microscope/energy dispersive X-ray spectroscopy (SEM/EDX). IR, UV–vis and Raman spectroscopies were carried out to evaluate the surface of the hybrid electrodes. The N-ethylcarbazole moiety and redox active Zn(II), Co(II) metal centers were employed in order to improve the sensing performance of targeted compounds. Furthermore, hybrid material-graphene modified GCEs have been designed to compare and rise the analytical activity. The sensing properties of the designed electrodes was investigated to detect electrochemically active biomolecules namely, dopamine (DA), ascorbic acid (AA), and uric acid (UA) in both phosphate buffered saline (PBS) and tap water sample. The Grp/ Ply(Car-CoPc)/GCE electrode was only detected DA with a limit of detection (LOD) of 16 nM. On the other hand, LOD values of Grp(Car-CoPc)/GCE were determined by voltammetric analyses as 3.38 μM and 0.62 μM for AA and UA, respectively. Sensing performances of the designed electrodes were eximined for the concurrently determination of DA and UA using differential pulse voltammetry (DPV) method.

Green synthesis, crystal structure, and antifungal activities of (E)-4-arylidene-5-oxotetrahydrofuran.

A series of γ-lactone derivatives (E)-4-arylidene-5-oxotetrahydrofuran derivatives were synthesized via a tandem Passerini 3CC/SN cyclization microwave-assisted one-pot method efficiently starting from Baylis Hillman acids, aryl glyoxals and isocyanides, and using ionic liquid as reaction medium. The products were characterized by hydrogen nuclear magnetic resonance spectroscopy (1H-NMR), carbon nuclear magnetic resonance spectroscopy (13C-NMR). Single crystal X-ray analysis of the compound RPDFB clearly confirmed its assigned chemical structures. Meanwhile, the effects of four compounds (RPDFB, RPDFC, RPDFI, RPDFJ) on the growth inhibition activity of Gibberella zeae were detected, and found that the compound RPDFB has significant growth inhibition activity to Gibberella zeae.

Visible Light Mediated Heck Coupling of Inactivated Aryl Fluoride/Chloride Over a Sulfonic Acid Functionalized, Melamine‐based Metal‐free Porphyrin Photocatalyst

AbstractWe report the synthesis of a new, sulfonic acid functionalized, melamine‐based metal‐free porphyrin photocatalyst (MBMFPc) for the C−C coupling of the most unreactive aryl halides with alkenes under visible light irradiation. The ionic liquid‐based photocatalyst was characterized using various analytical techniques Proton Nuclear Magnetic Resonance (1HNMR) Spectroscopy, Carbon Nuclear Magnetic Resonance (13CNMR) Spectroscopy, Fourier Transformed Infrared Spectroscopy (FT‐IR), Energy‐dispersive X‐ray Spectroscopy (EDAX), Scanning Electron Microscope (SEM), Brunauer‐Emmett‐Teller (B.E.T) and Ultraviolet‐Visible Spectroscopy (UV‐Vis). The MBMFPc photocatalyst with noticeable Hammett acidity (0.56) and optimal bandgap of 1.44 eV was found to as an effective catalyst in the Mizoroki‐Heck coupling of inactivated aryl fluoride/chloride using 5 W LED in a homemade photoreactor under ambient conditions. The protocol comprising metal‐free green photocatalyst tolerated a variety of aliphatic/aromatic alkenes bearing different substituents afforded good to excellent yields. The role of photogenerated excitons was confirmed by scavenger studies with K2S2O8 and EDTA. The leaching test, stability, and reusability of MBMFPc photocatalyst evidenced as a perfect heterogeneous photocatalyst and afford appreciable yield (80 %) after 5 cycles. A plausible mechanism for photocatalytic C−C coupling has been proposed and described. A metal‐free acid‐functionalized ionic liquid‐based MBMFPc photocatalyst with appreciable TON (4,51,948) and TOF (22,597 h−1) could gain significant attraction as a green catalyst in the pharmaceutical industries for the synthesis of intermediates by C−C coupling using commercial aryl chlorides.

Pharmacological evaluation of newly synthesized organotin IV complex for antiulcer potential

The present study aims to investigate the newly synthesized organotin (IV) complex (2E, 2′E) dibutylstannanediyl bis (4-(4-nitrophenyl) amino)-4-oxobut-2-enoate (DTN) for its anti-ulcer potential. Characterization performed by carbon nuclear magnetic resonance spectroscopy proved that all values are in the expected ranges of the new compound. Gastroprotective activity of DTN was evaluated through in-silico, anti-H. pylori, in-vitro, in-vivo, and ex-vivo proteomic analysis. In-silico analysis shows that DTN possess stable binding with protein targets involved in gastric ulcer pathophysiology. DTN exhibited an inhibitory effect against 2,2-diphenyl-1-picrylhydrazyl, H. pylori and hydrogen potassium ATPase (H+/K+-ATPase). The antiulcer activity was performed using an ethanol-induced gastric ulcer model in rats. Anti-oxidant profile of DTN showed a significant increase in glutathione-S-transferase, glutathione and catalase levels whereas lipid peroxidation levels were reduced. Histopathological findings confirmed that DTN protected the gastric mucosa of rats. Inflammatory markers tumor necrosis factor-alpha, nuclear factor kappa B, cyclooxygenase-2, interleukin 6 and interleukin-1β were reduced and prostaglandin-E2 restored expression of these cytokines in DTN pretreated animals when analyzed by using immunohistochemistry, enzyme-linked immunosorbent assay and western blot techniques. In real-time polymerase chain reaction technique, the expression of H+/K+-ATPase was downregulated in DTN pretreated group. DTN did not cause any mortality up to 400 mg/Kg. This study indicates that the newly synthesized compound DTN, possess stable binding against selected targets. DTN exhibits a gastro-protective effect, mediated via anti-H. pylori, H+/K+-ATPase inhibition, anti-oxidant and anti-inflammatory pathways, exploring its therapeutic potential in gastric ulcer management.

Utility of Chemical Upcycling in Transforming Postconsumer PET to PBT-Based Thermoplastic Copolyesters Containing a Renewable Fatty-Acid-Derived Soft Block.

Thermoplastic copolyesters (TPCs) are important structural components in countless high performance applications that require excellent thermal stability and outstanding mechanical integrity. Segmented multiblock architectures are often employed for the most demanding applications, in which semicrystalline segments of poly(butylene terephthalate) (PBT) are combined with various low T g soft blocks. These segmented copolymers are nearly always synthesized from pristine feedstocks that are derived from fossil-fuel sources. In this work, we show a straightforward, one-pot synthetic approach to prepare TPCs starting from high-molar mass poly(ethylene terephthalate) recyclate (rPET) combined with a hydrophobic fatty acid dimer diol flexible segment. Transesterification is exploited to create a multiblock architecture. The high molar mass and segment distribution are elucidated by detailed size-exclusion chromatography and proton and carbon nuclear magnetic resonance spectroscopy. It is also shown that rPET can be chemically converted to PBT through a molecular exchange, in which the ethylene glycol is substituted by introducing 1,4-butane diol. A series of copolymers with various compositions was prepared with either PET or PBT segments and the final thermal properties and mechanical performance is compared between the two different constructs. Ultimately, PBT-based TPCs crystallize faster and exhibit a higher modulus over the range of explored compositions, making them ideal for applications that require injection molding. This represents an ideal, sustainable approach to making conventional TPCs, utilizing recyclate and biobased components to produce high performance polymer constructs via an easily accessible upcycling route.

New Metal Complexes Derived from Heterocyclic Schiff-base Ligand; Preparation, Structural Investigation and Biological Activity

The formation of a Schiff-base with N2O2 donor atoms derived from the hydrazine segment and its metal complexes are reported. The Schiff-base ligand; N’-((1R,2S,4R,5S,Z)-2,4-diphenyl-3-azabicyclo[3.3.1]nonan-9-ylidene)furan-2-carbohydrazide (HL) was prepared from the reaction of furan-2-carbohydrazide with (1R, 2R, 4R, 5S)-2,4-diphenyl-3-azabicyclo[3.3.1]nonan-9-one (M1) in ethanol medium. The reaction of the title ligand with selected metal ions Cr(III), Mn(II), Ni(II), Cu(II), Zn(II) and Cd(II) gave complexes with the general formula [M(L)Cl2], (where: M = Cr(III), Mn(II), Ni(II), Cu(II), Zn(II) and Cd(II)). Spectroscopic analyses Fourier transform infrared (FT-IR), Nuclear Magnetic Resonance (NMR) Carbon-13 nuclear magnetic resonance (1H- and 13C-NMR), mass and electronic spectroscopy and atomic absorption) along with elemental microanalysis (C.H.N), chloride percentage, conductivity measurements, magnetic moments and melting point were used to establish the identity of ligand and complexes. The biological activity of the synthesized compounds towards bacterial strains (G+ and G-) was investigated.

Star-type melamine based conjugated carboxy functionalized porphyrin trimer for DSSCs: An efficient approach to clean, aggregation free and true energy generation

A novel, π-conjugated melamine-based trimeric porphyrin dye with serving nine carboxylate linker groups has been prepared to use as a panchromatic dye for application in dye-sensitized solar cells (DSSCs). The star-shaped trimer was characterized by using Proton Nuclear Magnetic Resonance (NMR) Spectroscopy, Carbon Nuclear Magnetic Resonance Spectroscopy (CMR), Fourier Transformed Infrared Spectroscopy (FT-IR), UV-VIS Absorption Spectroscopy, Thermo-gravimetric analysis (TGA), Cyclic Voltammetry (CV) and Electrochemical Impedance Studies (EIS). CV studies revealed frontiers energy levels at −5.654 (HOMO) and −3.879 eV (LUMO) versus vacuum. The optical band gap evolved via absorption spectra measurements was found to be 1.49 eV. A planar perfect conjugation among three porphyrins sets up multiple push-pull communication and lowers the bandgap, while nine carboxylate linkers cover-up TiO2 surface effectively leading to better electronic dynamics. The DSSC set up using iodide-based redox couples forms a simple, stable, additive-free, truly energy generating device with 7.1% conversion efficiency, the highest among trimeric porphyrin category.

Synthesis of (6-Methoxy-2,5-dinitro-quinoline-4-yl)-(5-vinyl-1-aza-bicyclo[2.2.2]oct-2-yl)-methanol) and In Vitro Assay Against Plasmodium falciparum 3D7

Quinine, a naturally happening alkaloid initially utilized for the treatment of muscle cramps, is currently most usually utilized to treat malaria. Symptoms of poisonous quinine, called Cinchonism, include wooziness, tinnitus (ringing in the ears), blurred vision, nausea, vomiting, serious adverse reaction to excessive quinine use, vision impairment and deafness. This research aimed to obtain more polar quinine derivatives using reactions with sulfuric acid and nitric acid to reduce toxicity. The reactions were performed analogously to the procedures reported in the literature. The characterization of reaction products utilizing proton (1H) and carbon-13 (13C) nuclear magnetic resonance (NMR) spectroscopy showed that the reaction using reagents led to nitration of the quinoline ring with the yields of 7.09 %. The IC50 value of >10.000 μg/mL was obtained from the antimalarial test against Plasmodium falciparum 3D7. The IC50 values proved that the synthesis products (6-Methoxy-2,5-dinitro-quinoline-4-yl)-(5- vinyl-1-aza-bicyclo[2.2.2]oct-2-yl)-methanol) was not potential for malaria treatment.

Mechanistic Study of Controlled Zinc Electrodeposition Behaviors Facilitated by Nanoscale Electrolyte Additives at the Electrode Interface.

Nanoparticle organic hybrid materials (NOHMs) are liquid-like materials composed of an inorganic core to which a polymeric canopy is ionically tethered. NOHMs have unique properties including negligible vapor pressure, high oxidative thermal stability, and the ability to bind to reactive species of interest due to the tunability of their polymeric canopy. This makes them promising multifunctional materials for a wide range of energy and environmental technologies, including electrolyte additives for electrochemical energy storage (e.g., flow batteries) and the electrochemical conversion of CO2 to chemicals and fuels. Due to their unique transport behaviors in fluid systems, an understanding of the near-electrode surface behavior of NOHMs in electrolyte solutions and their effect on electrochemical reactions is still lacking. In this work, the complexation of zinc (Zn) by NOHMs with an ionically tethered polyetheramine canopy (HPE) (NOHM-I-HPE) was studied using attenuated total reflectance Fourier transform infrared and Carbon-13 nuclear magnetic resonance spectroscopy. Additionally, various electrochemical techniques were employed to discern the role of NOHM-I-HPE during zinc electrodeposition, and the results were compared to those of the electrochemical system containing untethered HPE polymers. Our findings confirmed that NOHM-I-HPE and HPE reversibly complex zinc in the aqueous electrolyte. NOHM-I-HPE and HPE were found to block some of the electrode active sites, reducing the overall current density during electrodeposition, while facilitating the formation of smooth zinc deposits, as revealed by surface imaging and diffraction techniques. Observed variations in the current density responses and the degree of passivation created by the NOHM-I-HPE and HPE adsorbed on the electrode surface revealed that their different packing behaviors at the electrode-electrolyte interface influence the zinc deposition mechanism. The presence of the nanoparticle and ordering offered by the NOHMs as well as the structured conformation of the polymeric canopy allowed the formation of void spaces and free volumes for enhanced transport behaviors. These findings provided insights into how structured electrolyte additives such as NOHMs can allow for advancements in electrolyte design for controlled deposition of metal species from energy-dense electrolytes or for other electrochemical reactions.

Quantitative chemical profiling of cellulose acetate excipient via 13C NMR spectroscopy in controlled release formulations

Cellulose acetate (CA) is the main component of controlled-release (CR) coating of formulations such as osmotic-controlled release oral delivery system (OROS) and CR microspheres. Despite multiple applications, there are limited or no reports dealing with the characterization and quantification of CA in the formulated systems. Thus, the present investigation deals with the development of the Quantitative Carbon-13 Nuclear Magnetic Resonance (q13CNMR) spectroscopy method for the determination of CA amount in the CR microsphere formulations. The developed q13CNMR method was also verified using control CA samples from marketed OROS formulation. Thereafter, the concentration of CA in the microspheres was calculated. Furthermore, the impact of different concentrations of CA on the critical quality attributes such as the drug release profile from the formulation was investigated. The study demonstrated the CA coating levels to be inversely proportional to the extent and rate of release of API. The developed q13CNMR method was found to be accurate and precise and can be explored further to investigate the effect of different stability conditions on the degree of polymerization and degradation of CA resulting in altered quality of pharmaceutical products.

Application of butane-1,4-diyl bis(2-mercaptoacetate) as dithiol prepolymer for preparation of polythiourethane and clay-based nanocomposites

In this work, we have synthesized butane-1,4-diyl bis(2-mercaptoacetate) (BBMA) as dithiol compound via esterification of 1,4-butanediol and thioglycolic acid. Fourier-transform infrared (FT-IR) and proton and carbon nuclear magnetic resonance (1H NMR and 13C NMR) spectroscopies were used to prove the success of the synthesis process. BBMA as a prepolymer has been reacted with 4,4'-diphenylmethane diisocyanate (MDI) to prepare neat poly(thiourethane) (PTU). Moreover, Cloisite 30B (1–5 wt.%) has been used to prepare clay/poly(thiourethane) nanocomposites. Finally, the effect of Cloisite 30B content on structural, thermophysical, and thermal properties of nanocomposites has been investigated. Results showed that PTU0 as a neat polythiourethane had an amorphous structure with good thermal stability whereas its glass transition temperature was < 0°C. The incorporation of Cloisite 30B into PTU resulted in a significant improvement of thermal stability, whereas it elevated crystallinity and thermophysical properties up to 2 wt.%.

Construction of Pingdingshan coal molecular model based on FT-IR and 13C-NMR

To construct a molecular model of coal and study the adsorption characteristics from the perspective of microscopic molecules, the microstructure of coal samples from Pingdingshan mining area in China was studied by means of Fourier transform infrared spectroscopy (FT-IR) and carbon-13 nuclear magnetic resonance spectroscopy (13C-NMR). The coal mainly possesses an aromatic molecular structure with fa (aromaticity), faH and XBP (the ratio of aromatic bridge carbon to surrounding carbon) being 0.86, 0.29 and 0.54, respectively. According to the results, the aromatic structure, with a high degree of condensation, is mainly dominated by pyrene and chrysene, while the aliphatic structure is mainly composed of methyl and methylene whose ratio is about 0.52. Furthermore, it contains a small amount of oxygen-containing functional groups such as carbonyl group, phenolic hydroxyl group and ether bond. In light of the above-mentioned molecular structure characteristics, the periodic structure model of Pingdingshan coal with the molecular formula C108H71O4N was constructed based on molecular mechanics and molecular dynamics by using the Materials Studio software. The model has a density of 1.3 g/cm3, a porosity of 4.1% and a specific surface area of 614.5 m2/g, faithfully reflecting the structural information of coal sample. Moreover, methane isothermal adsorption curves were simulated by the model at the temperatures of 318, 333 and 348 K. The experimentally measured and simulated isothermal methane adsorption curves both exhibit an error of smaller than 5% under high pressure. The results verify rationality and accuracy of the model structure. The study provides a model basis for further research on coal on the microscopic level.

Synthesis and Antibacterial Properties of Oligomeric Dehydrogenation Polymer from Lignin Precursors.

The lignin precursors of coniferin and syringin were synthesised, and guaiacyl-type and guaiacyl-syringyl-type oligomeric lignin dehydrogenation polymers (DHP and DHP-GS) were prepared with the bulk method. The carbon-13 nuclear magnetic resonance spectroscopy showed that both DHP-G and DHP-GS contained β-O-4, β-5, β-β, β-1, and 5-5 substructures. Extraction with petroleum ether, ether, ethanol, and acetone resulted in four fractions for each of DHP-G (C11–C14) and DHP-GS (C21–C24). The antibacterial experiments showed that the fractions with lower molecular weight had relatively strong antibacterial activity. The ether-soluble fractions (C12 of DHP-G and C22 of DHP-GS) had strong antibacterial activities against E. coli and S. aureus. The C12 and C22 fractions were further separated by preparative chromatography, and 10 bioactive compounds (G1–G5 and GS1–GS5) were obtained. The overall antibacterial activities of these 10 compounds was stronger against E. coli than S. aureus. Compounds G1, G2, G3, and GS1, which had the most significant antibacterial activities, contained β-5 substructures. Of these, G1 had the best antibacterial activity. Its inhibition zone diameter was 19.81 ± 0.82 mm, and the minimum inhibition concentration was 56.3 ± 6.20 μg/mL. Atmospheric pressure chemical ionisation mass spectrometry (APCI-MS) showed that the antibacterial activity of G1 was attributable to a phenylcoumarin dimer, while the introduction of syringyl units reduced antibacterial activity.