Carbon 13C NMR Research Articles

Isolation of Novel 6-methylideneoxecane-3,4,5,7,8,9-hexol from the Leaves of Rauwolfia vomitoria, Apocynaceae

Rauwolfia vomitoria (Wennberg) belongs to the family Apocynaceae, the dried leaves were extracted successively using n-hexane, dichloromethane, and 70% methanol, concentrated in vacuo. Extracts were subjected to antibacterial assay and the butanol fraction was subjected to chromatographic purification to obtain NBF12 which was subjected to spectral analysis. The antibacterial of n-Hexane, dichloromethane, and 70% methanol extracts was inactive against the screened organisms assessed (Staphylococcus aureus, Bacillus subtilis, Escherichia coli, Pseudomonas aeruginosa). NBF12 is yellowish crystals (10.5 mg), Rf (0.69), UV, max Abs (248) The carbon 13C-NMR spectrum displayed ten carbon atoms; one methylene, two methylene oxide carbon, 6-carbinolic carbon (Sp3) and a quaternary carbon (SP2). The spectrum showed a tertiary carbon at δ131.09 ppm, due to C-6 and at δ 114.74 ppm due to exocyclic methylidene carbon (Sp2) (C=CH2) linked to the C-6position. Based on the spectral data NBF12 is 6-methylideneoxecane-3,4,5,7,8,9-hexol with a molecular formula C10H18O7, molecular weight 250 g/mol.

Synthesis, Characterisation, in vitro antibacterial and in silico docking studies of Schiff bases of p-nitro benzaldehyde

Schiff base ligands have more pharamaceutical applications and are widely used in pharmaceutical industries. Herein, two kinds of Schiff base ligands were synthesized using p-nitrobenzaldehyde with (L1) 1H-1,2,4-triazol-3-amine and (L2) 1,4 phenylene diamine backbone. Synthesised ligands were characterized utilizing ultraviolet visible spectroscopy, Fourier Transform Infra-red Spectroscopy, Carbon 13C NMR and Proton 1H. Then in vitro antimicrobial activity, PASS analysis, Drug likeness and in silico docking studies of synthesized ligands (L1 and L2) were carried out. With the help of PASS and bioactive score results, docking studies were done using two different proteins (PDB ID:6D9T and PDB ID:6HZQ) by Auto dock 4.2.6 program. BNBBDA has good affinity with target protein S. aureus (PDB ID:6D9T) and PNBTAA has with protein E.coli (PDB ID:6HZQ). The findings demonstrated that the compounds are the ideal candidates for the subsequent steps of drug discovery.

Synthesis, crystal structure, Hirshfeld surface, nonlinear optical properties and computational studies of (E)-4-bromo-N'-(3,4-dimethoxybenzylidene)benzohydrazide single crystal for nonlinear optical applications

(E)-4-bromo-N'-(3,4-dimethoxybenzylidene)benzohydrazide (DMBH) single crystals were synthesized by Schiff base method. The crystal structure of DMBH single crystal was determined using single crystal X-ray diffraction technique. The proton 1H and carbon 13C NMR spectral analysis were studied to identify the molecular structure of the crystal. From UV–Vis spectral analysis the maximum absorption for the DMBH molecule was observed around 338 nm and it reveals the presence of π-π* transition. The different functional group properties were studied via Fourier transform infrared (FTIR) analysis. Density functional theory (DFT) method was used to investigate the HOMO and LUMO energies and their energies were interrelated with the UV spectral analysis. Inter and intra molecular interactions with the assistance of colour coding were discussed using Hirshfeld surface analysis. The intramolecular stabilization by donor-acceptor interactions was investigated with the aid of natural bond orbital (NBO) analysis. In addition, the reactivity of the title compound was calculated by molecular electrostatic potential (MEP) analysis. For DMBH crystal, the first order hyperpolarizability value β0 = 5.0786 × 10−30 esu was obtained and is around 14 times greater than that of urea (0.3728 × 10−30 esu). The third order nonlinear optical (NLO) properties were studied through Z-scan method.

Phytochemical Investigation of New Algerian Lichen Species: Physcia Mediterranea Nimis.

The present study provides new data concerning the chemical characterisation of Physcia mediterranea Nimis, a rare Mediterranean species belonging to the family Physciaceae. The phytochemical screening was carried out using GC-MS, HPLC-ESI-MS-MS, and NMR techniques. Hot extraction of n-hexane was carried out, followed by separation of the part insoluble in methanol: wax (WA-hex), from the part soluble in methanol (ME-hex). GC-MS analysis of the ME-hex part revealed the presence of methylbenzoic acids such as sparassol and atraric acid and a diterpene with a kaurene skeleton which has never been detected before in lichen species. Out of all the compounds identified by HPLC-ESI-MS-MS, sixteen compounds are common between WA-hex and ME-hex. Most are aliphatic fatty acids, phenolic compounds and depsides. The wax part is characterised by the presence of atranorin, a depside of high biological value. Proton 1H and carbon 13C NMR have confirmed its identification. Atranol, chloroatranol (depsides compound), Ffukinanolide (sesquiterpene lactones), leprolomin (diphenyl ether), muronic acid (triterpenes), and ursolic acid (triterpenes) have also been identified in ME-hex. The results suggested that Physcia mediterranea Nimis is a valuable source of bioactive compounds that could be useful for several applications as functional foods, cosmetics, and pharmaceuticals.

Electronic investigation and spectroscopic analysis using DFT with the long-range dispersion correction on the six lowest conformers of 2.2.3-trimethyl pentane.

The conformational stability and internal rotation barriers, HOMO-LUMO gap and related properties, molecular static polarizability and hyperpolarizability parameters, and the NBO delocalization energies associated with the internal charge transfer (ICT) of 2.2.3-trimethylpentane in the ground state were carried out taking into account the long range dispersion correction through CAM-B3LYP and WB97XD levels at aug-cc-pvtz basis set. The six lowest conformations were differentiated by a deep and multiple spectroscopic investigation. The ultraviolet-visible (UV-Vis) absorption bands are assigned using molecular orbital data obtained by TD-WB97XD/aug-cc-pvtz calculations, and carbon 13C NMR signal peaks have been assigned using GIAO-WB97XD/aug-cc-pvtz method. In addition, the normal mode calculations of the most and less stable conformers using a scaled force field in terms of non-redundant local symmetry coordinates have been confronted to the experimental vibrational spectra temperature dependency.

Synthesis, characterization, anticancer activity, and molecular docking of some new sugar hydrazone and arylidene derivatives

New sugar hydrazone moieties, their oxadiazoline derivatives, and arylidene analogues were prepared and chemically elucidated using spectroscopic analysis, such as nuclear magnetic resonance, for hydrogen 1HNMR, carbon 13CNMR, elemental analysis, and Infrared (IR). The prepared compounds were purified and tested against breast cancer cells (MCF-7). Compounds 4c, 4d, 6b, and 6d exhibited moderate to very high anti-breast cancer activity, with a percentage of inhibition of 96.19%, 93.08%, 74.33%, and 86.05% respectively; the reference 5-fluorouracil had an inhibitory percentage of 96.02%.

A combined experimental and DFT computations study of novel (E)-3-(benzofuran-2-yl)-2-(thiophen-2-yl)acrylonitrile(TACNBNF): Insight into the synthesis, single crystal XRD, NMR, vibrational spectral analysis, in vitro antioxidant and in silico molecular docking investigation with human peroxiredoxin 5 protein

Abstract The synthesized (E)-3-(benzofuran-2-yl)-2-(thiophen-2-yl)acrylonitrile (TACNBNF) crystal compound was characterized using FT-IR, 1H and 13C NMR analyses, ESI-mass and photoluminescence studies. Single crystal X-ray diffraction investigations reveal that the molecule is associated with the C (7)–H (7) … S (1) donor-acceptor hydrogen bond interaction. The bond angle at C7 gives a strong indication that H7⋯S1 contact is repulsive. However, the C5–C7–C8 bond angle = 128.8 (2) °, is distorted due to strain induced by double bond linkage at C5=C7. The computational work such as optimized geometry by Density functional theory (DFT), FT-IR, Molecular electrostatic potential (MEP), Frontier Molecular orbitals (FMOs), Mulliken’s population analysis, Nonlinear optical effects (NLO), and Natural bond orbitals (NBO) were analyzed with the aid of Gaussian 03 program using basic set B3LYP/6–311++G (d,p). The proton 1H and carbon 13C NMR chemical shifts of molecules were simulated by the gauge-independent atomic orbital (GIAO) manner and also compared with experimental 1H and 13C NMR results. The in vitro antioxidant study was carried out in DPPH assay ascorbic acid, a standard drug. The in silico molecular docking, ADMET and toxicity studies were performed by Discovery Studio 4.0.

Ab initio study on the six lowest energy conformers of iso-octane: conformational stability, barriers to internal rotation, natural bond orbital and first-order hyperpolarizability analyses, UV and NMR predictions, spectral temperature sensitivity, and scaled vibrational assignment

In this paper, we present the quantum electronic study of iso-octane, based on MP2 and B3LYP methods using the 6-311++G(d,p) basis set. In addition to conformational stability and internal rotation barriers studies, the delocalization energies associated with the internal charge transfer (ICT) within each of the six lowest energy conformers were evaluated using NBO analysis. With the aim to differentiate even more between these conformers, the energy gap between HOMO and LUMO orbitals, chemical softness, and first-order hyperpolarizability (nonlinear optics property) were evaluated. Similarly, their spectral behavior was investigated at different levels; the ultraviolet (UV) absorption bands were assigned using molecular orbitals data obtained by TD-B3LYP calculations with 6-311++G(d,p) basis set, while carbon 13C NMR and proton 1H signal peaks were assigned using the GIAO-B3LYP/6-311++G(d,p) method. In addition, the normal mode calculations of the most and least stable conformers using a scaled force field in terms of nonredundant local symmetry coordinates were carried out to approach the vibrational spectra temperature dependency.

Pyrrole polymerization on polyimide surfaces creates conductive nano-domains

Oxidative polymerization of pyrrole on the surface of polyimide (PI) films was demonstrated to generate uniform, adherent coatings consisting of polypyrrole (PPy) electro-active nano-domains. This polymerization was carried out in aqueous methanol solution with FeCl3 as oxidant/dopant. Model kinetic reactions carried out by hydrogen Nuclear Magnetic Resonance (1H NMR) spectroscopy using ammonium persulfate (APS) as oxidant found evidence for an increase in the polymerization rate of pyrrole in the presence of a molar excess of PI. Attempts to identify changes to the PI chemical structure during pyrrole polymerization were investigated by high-resolution carbon 13C NMR spectroscopy and Infrared Attenuated Total Reflection (IR-ATR) spectroscopy. No differences were observed in concentrated D2SO4 solutions by NMR. However, IR-ATR noted a shift to lower wavenumbers of the PI carbonyl band and a higher wavenumber shift of the aromatic ether band. The morphology of PPy-coated PI films was analyzed by atomic force microscopy (AFM). The average size of PPy nanospheres was in the range of 20 nm with narrow distribution and was found to increase with reaction time.

The alternating of substituent effect on the 13C NMR shifts of all bridge carbons in cinnamyl aniline derivatives

Bridge carbon 13C NMR shifts of a wide set of substituted cinnamyl anilines p-XC6H4CHCHCHNC6H4Y-p (XNO2, Cl, H, Me, MeO, or NMe2; YNO2, CN, CO2Et, Cl, F, H, Me, MeO or NMe2) had been used as a probe to study the change of substituent effect in the conjugated system. The goal of this work was to study the difference among the substituent effect on SCS of all bridge carbons, and find the alternating of substituent effect in this model compounds. In this study, it was found that the change of the inductive effect and the conjugative effect on different bridge carbons is related to the bond number (m) from the substituent to the corresponding carbon, and the adjusted parameters σF(rel)∗ and σR(ver)∗ can be suitable to scale the difference of the inductive effect and the conjugative effect on bridge carbons. Moreover, because of the difference of substituent effect on bridge carbons, the substituent cross-interaction item Δσ2Δσ2=σF(rel)∗(X)+σR(ver)∗(X)-σF(rel)∗(Y)-σR(ver)∗(Y)2 was not suitable simply to scale the interaction between substituents X and Y for all bridge carbons, so the Δσ2 was recommended to be divided into two parts: ΔσF(rel)2ΔσF(rel)2=σF(rel)∗(X)-σF(rel)∗(Y)2 and ΔσR(ver)2ΔσR(ver)2=σR(ver)∗(X)-σR(ver)∗(Y)2. With σF(rel)∗, σR(ver)∗, ΔσF(rel)2, ΔσR(ver)2, and δC,parent, the obtained correlation equation can be used to correlate with the 159 sorts of SCS of the different bridge carbon in cinnamyl aniline derivatives. The correlation coefficient is 0.9993, and the standard deviation is only 0.53ppm. The multi-parameter correlation equation can be recommended to predict well the corresponding bridge carbons SCS of disubstituted cinnamyl anilines.

Effect of ortho substituents on carbonyl carbon 13C NMR chemical shifts in substituted phenyl benzoates

Abstract13C NMR spectra of 37 ortho‐, meta‐, and para‐substituted phenyl benzoates, containing substituents in benzoyl and phenyl moiety, 4 ortho‐substituted methyl and 5 ethyl benzoates as well as 9 R‐substituted alkyl benzoates have been recorded. The influence of the ortho substituents on the carbonyl carbon 13C NMR chemical shift, δCO, was found to be described by a linear multiple regression equation containing the inductive, σI, resonance, σ°R, and steric, E, or υ substituent constants. For all the ortho‐substituted esters containing substituents in the acyl part as well as the phenyl part, the substituent‐induced reverse inductive effect (ρI < 0), the normal resonance effect (ρR > 0), and the negative steric effect (δortho < 0) with the E were observed. In the case of ortho substituents in the phenyl part, the resonance effect was negligible. Due to inductive effect, the ortho electron‐withdrawing substituents showed an upfield shift or shielding of the carbonyl carbon, while the electron‐donating substituents had an opposite effect. Because of the sterical consequences, ortho substituents revealed a deshielding effect on the 13C NMR chemical shift of the carbonyl carbon. For all the meta‐ and para‐substituted esters, the reverse substituent‐induced inductive and resonance effects (ρI < 0, ρR < 0) were found to be significant. In alkyl benzoates, the alkyl substituents showed the reverse inductive and steric effects. The log k values for the alkaline hydrolysis in water, aqueous 0.5 M Bu4NBr and 2.25 M Bu4NBr, and the IR frequencies, νCO, for the ortho‐, meta‐, and para‐substituted phenyl benzoates and alkyl benzoates were correlated nicely with the corresponding 13C NMR substituent chemical shifts, ΔδCO. Copyright © 2009 John Wiley & Sons, Ltd.

Nuclear magnetic resonance (NMR) and quantitative structure–activity relationship (QSAR) studies on the transacylation reactivity of model 1β-O-acyl glucuronides. II: QSAR modelling of the reaction using both computational and experimental NMR parameters

1. In a previously reported study, a number of 4-substituted benzoic acid acyl glucuronides were synthesized and their degradation rates determined using nuclear magnetic resonance (NMR) spectroscopy. It was shown that this reaction was strongly influenced by the nature of the substituent at the 4-position of the benzoyl moiety.2. The overall degradation reaction rates for this series of compounds have been modelled successfully using Hammett substituent constants, computational chemistry-derived partial atomic charges and the experimentally determined carbonyl carbon 13C-NMR chemical shifts of the benzoic acids and their ethyl and glucuronide esters.3. The primary contribution to reactivity is the scale of the electron-donating or -withdrawing effect of the substituent; however, additional contributions such as steric parameters must also be considered when modelling reactions outside a single chemical series.4. The derived property–reactivity relationships should find utility in medicinal chemistry efforts for optimizing chemical series in pharmaceutical discovery programmes.

Investigations into the structure and composition of β-cyclodextrin/poly(acrylic acid) microspheres

Microspheres composed of the hydrophilic polymer poly(acrylic acid) (PAA), with and without β-cyclodextrin (β-CD), were prepared by a water-in-oil (w/o) solvent evaporation technique. Microspheres were characterised for particle size, β-CD and residual oil content. The type of matrix formed during microsphere synthesis was investigated by solid state carbon 13C NMR, in vitro release of β-CD and swelling measurements. A high encapsulation efficiency of the β-CD was observed (>90%). The in vitro release of β-CD in water over 24 h was initially rapid (≈70% in 3 h) with no further loss thereafter, suggesting potential covalent binding of the residual β-CD. NMR indicated that in the presence of β-CD, two concomitant chemical processes occur during microsphere synthesis: (i) esterification of the hydroxyl group(s) of the β-CD with the carboxylic acid groups of the PAA; and (ii) the formation of intra-/inter-polymer acid anhydrides.

Correlation analysis of carbonyl carbon 13C NMR chemical shifts, IR absorption frequencies and rate coefficients of nucleophilic acyl substitutions. A novel explanation for the substituent dependence of reactivity

Rate coefficients of nucleophilic acyl substitutions, carboxylate carbon 13C NMR chemical shift values and ν(CO) frequencies of several series of aryl and acyl substituted aryl acetates or alkyl benzoates have been investigated. An increasing electron-withdrawal by the acyl or aryl substituents results in higher reaction rates, upfield 13C NMR chemical shifts and higher frequencies of the CO stretching. Good correlations are observed for the log kversus δC(CO) plots. The increase of the reaction rate with increased electron density at the CO carbon (as proved by 13C NMR shifts) contradicts the previous concept of increased electrophilicity of the carbonyl carbon by electron-withdrawing substituents. The rate increase is now attributed to the decrease of the ester ground state resonance stabilization caused by electron-withdrawing substituents. The use of log kversus δC(CO) correlations is presented as a practical method to evaluate rate coefficients especially for compounds for which Hammett type correlations cannot be used.

Synthesis and acidity constants of 13CO 2H-labelled dicarboxylic acids. pK as from 13C-NMR

Simple dicarboxylic acids: adipic ( 1), succinic ( 2) and malonic ( 3); more complex linear tetrapyrroles with two propionic acid groups: mesobiliverdin-XIIIα ( 4) and mesobilirubin-XIIIα ( 5), and a rubin analog with a gem-dimethyl at C 10 ( 6) were prepared with 99% 13C-enrichment in their CO 2H groups. Their pK a values were determined from titration curves in water and in H 2O-(CD 3) 2SO solutions: plots of carboxyl carbon 13C-NMR chemical shifts with varying pH. Titration curves of diacids 1–3 with known pK a's in H 2O served as calibration standards for determination of pK as of tetrapyrrole diacids 4–6: pK a1 = 3.9, pK a2 = 5.3 for 4; pK a1 = 4.2, pK a2 = 4.9 for 5, and pK a1 = 4.7, pK a2 = 5.7 for 6 in H 2O.

Eight years experience of the Ortho Gyne ‘T’ IUCD in general practice

International Journal of Clinical PracticeVolume 42, Issue 11 p. 453-455 Clinical Study Eight years experience of the Ortho Gyne ‘T’ IUCD in general practice T H Baker MRCP, Corresponding Author T H Baker MRCP General Practitioner n/a@dne.dne Congleton, CheshireAddress correspondence to Dr T H Baker, 19 Beechwood Drive, Eaton, Congleton, Cheshire, CW12 2NQSearch for more papers by this author T H Baker MRCP, Corresponding Author T H Baker MRCP General Practitioner n/a@dne.dne Congleton, CheshireAddress correspondence to Dr T H Baker, 19 Beechwood Drive, Eaton, Congleton, Cheshire, CW12 2NQSearch for more papers by this author First published: 01 November 1988 https://doi.org/10.1111/j.1742-1241.1988.tb08626.xRead the full textAboutRelatedInformationPDFPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessClose modalShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL No abstract is available for this article. Volume42, Issue11November 1988Pages 453-455 RelatedInformation RecommendedGyne development in the Argentine ant Iridomyrmex humilis: role of overwintering and queen controlEDWARD L. VARGO, LUC PASSERA, Physiological Entomology17O NMR studies of ortho-substituent effects in substituted phenyl tosylatesVilve Nummert, Vahur Mäemets, Mare Piirsalu, Ilmar A. Koppel, Magnetic Resonance in ChemistryIntranidal mating, gyne polymorphism, polygyny, and supercoloniality as factors for sympatric and parapatric speciation in antsBERNHARD SEIFERT, Ecological EntomologySteric effects on mesomerism: I. General considerations on the deacylation of aromatic acylaminocompounds with a nitro group in the ortho‐ or para‐positionB. M. Wepster, P. E. Verkade, Recueil des Travaux Chimiques des Pays-BasEffect of ortho substituents on carbonyl carbon 13C NMR chemical shifts in substituted phenyl benzoatesVilve Nummert, Mare Piirsalu, Vahur Mäemets, Signe Vahur, Ilmar A. Koppel, Journal of Physical Organic Chemistry

Synthesis of [guanidino-13C]creatine and measurement of the creatine phosphokinase reaction in vitro by 13C NMR spectroscopy.

[guanidino-13C]Creatine has been synthesized by reaction involving synthesis of [13C]cyanamide followed by its condensation with sarcosine. The creatine guanidino carbon 13C NMR frequency shifts upon the formation of phosphocreatine by 0.83 ppm with a splitting (2JCP = 3.3 Hz) due to two-bond phosphorus-carbon coupling. The high 13C enrichment (99%) at the guanidino carbon of creatine gave rise to an adequate signal-to-noise ratio for both creatine and phosphocreatine so that a study of the time course of the creatine phosphokinase reaction could be performed and provided the means for a determination of the Km (15.5 mM) of the reaction.

Organocobalt cluster complexes : XIX. Nonacarbonyltricobaltcarbon-substituted carbonium ions. Further 13C NMR data and discussion

By using either neat samples or very concentrated solutions in CDCl 3, the apical cluster carbon 13C NMR resonances in some neutral RCCo 3 (CO) 9 complexes have been observed in the region δ (C) 255–310 ppm. Apical cluster carbon atom resonances occur in the 13C spectra of concentrated sulfuric acid solutions of [(OC) 9 Co 3 CCRR′] + cations in the region δ (C) 255–286 ppm. Further discussion of the structure and bonding in these charged species is given.