COSY Techniques Research Articles

Synthesis, characterization, spectroscopic properties, theoretical calculation, and antimicrobial activity of new aryldisulfonamides

New aryldisulfonamides were synthesized and characterized by FTIR, 1H NMR, 13C NMR, HETCOR, COSY, LC-MS and elemental analysis techniques. The compounds gave intense emissions, where λ max = 405, 379 and 402 nm, upon irradiation by Ultra-Violet light. The photoluminescence quantum yields and long excited-state lifetimes of the compounds were calculated and were found to have photoluminescence quantum yields 39 ± 1.8%, 45 ± 2.2% and 34 ± 1.4% and long excited-state lifetimes of 3.65 ± 0.16, 4.17 ± 0.20 and 3.15 ± 0.12 ns, respectively. The photoluminescence intensities and quantum yields of compounds varied with the position of substituent on the ring and the chain length between aromatic rings. These novel compounds may be of interest as organic emitting materials for electroluminescent devices. The visible absorption maxima were calculated using time-depended density-functional theory (TD-DFT) and Zerner’s intermediate neglect of differential overlap/spectroscopic (ZINDO/S) method in the gas phase. Further, the compounds were evaluated for in vitro antimicrobial activity against various microorganisms by microdilution and disk diffusion methods.

Intramolecular charge-transfer interactions in a julolidine–Bodipy molecular assembly as revealed via 13C NMR chemical shifts

13C NMR spectra were recorded in a series of six deuterated solvents of disparate polarity for three difluoroborondipyrromethene (Bodipy) derivatives bearing an aryl group at the meso position; these aryl residues were julolidine ( JULBD), 4-nitrobenzene ( NITBD) and phenylene ( PHBD). Complete 13C chemical shift assignments were made for all three compounds using a combination of COSY, HMBC and HMQC NMR spectroscopic techniques. The extreme assembly, JULBD, displays pronounced charge-transfer character in polar solvents owing to effective electron donation from the nitrogen atom of the julolidine unit to the electron-affinic Bodipy residue. The 13C chemical shift differences (Δ δ) between the meso and N-α dipyrrin carbon atoms recorded for JULBD exhibit a linear correlation with certain solvent polarity functions, including Reichardt’s E T N parameter and Catalán’s solvent dipolarity/polarizability (SPP) function. Similar correlations are not found for NITBD, where the charge-transfer vector lies in the opposite direction and the computed dipole moment is close to zero. Quantum chemical calculations performed on JULBD, PHBD and four other Bodipy derivatives at the DFT (B3LYP/6-311++G ∗∗) level afforded the Mulliken charges resident on the dipyrrin carbon centers. A reasonable correlation is found between these calculated Mulliken charges and the corresponding 13C chemical shifts for the various Bodipy derivatives.

Synthesis and Characterization of New Schiff Base Metal Complexes and Their Use as Catalysts for Olefin Cyclopropanation

New transition metal complexes of CoII, CuII, NiII, and FeIII of the ligands 2N,2-bis((7- hydroxy-5-methoxy-2-methyl-4-oxo-4H-chromen-6-yl)methylene)hydrazinecarbo-thioamide H3L1 and (E)-2-((7-hydroxy-5-methoxy-2-methyl-4-oxo-4H-chromen-6-yl)methylene)-N- phenylhydrazinecarbothioamide H2L2 have been prepared and characterized. Mass spectra and NMR assignments for the ligands, using COSY, NOESY homonuclear, and HMQC and HMBC heteronuclear correlation techniques were carried out. Electronic and magnetic moments of the complexes indicate that the geometries of the metal centers are either distorted square pyramidal or octahedral. The structures are consistent with the IR and UV-VIS, as well as conductivity and magnetic moments measurements. Cyclopropanation reactions of unactivated olefins by ethyldiazoacetate (EDA) in the presence of H3L1Cu2.Cl4.H2O as catalyst proceed with excellent turn over numbers (TON: up to 12556). Supplemental materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the Related Elements to view the free supplemental file.

Transformation of substituted 5-amino-1,3-oxazole-4-carbonitriles into new 3,4,5-triaminopyrazole derivatives

Reactions of accessible 5-alkylamino- and 5-arylamino-1,3-oxazole-4-carbonitriles with hydrazine hydrate on heating involved a complex transformation sequence resulting in the formation of 3,4,5-triaminopyrazole derivatives. The structure of the products was confirmed by their cyclocondensation with acetylacetone, leading to 2-alkyl(aryl)amino-3-acylamino-5,7-dimethylpyrazolo[1,5-a]pyrimidines which were identified by NMR spectroscopy using COSY, NOESY, HMQC, and HMBC techniques.

Excellent Ag+ selective receptors: Syntheses and complexation properties of novel biscalix[4]arene with benzalazine groups

By reacting mono-substituted or 1,3-bi-substituted [2-(p-formylphenyloxy)ethyloxy]-p-tert-butylcalix[4]arene (3 or 4) with hydrazine hydrate in ‘1+2’ or ‘2+2’ condensation mode, novel benzalazine-bridging biscalix[4]arenes 5 and 7 were conveniently obtained in the yields of 76 and 81%, respectively. Condensation of compound 4 and salicylide hydrazone gave a novel calix[4]arene benzalazine derivative 6 in the yield of 85%. The structures and conformations of all new compounds were characterised by elemental analyses, ESI-MS, 1H NMR and 1H–1H COSY techniques. Biscalix[4]arene 7 adopts a symmetrical cone conformation with tube cavity. The liquid–liquid extraction experiment showed that all new hosts possessed excellent complexation abilities towards soft metal cations. Compound 7 exhibited high complexation selectivity towards Ag+. The Ag+/Na+ and Ag+/Hg2+ extraction percentages of host 7 were as high as 73.1 and 54.9, respectively. The UV–vis spectra complexation experiments revealed that the complexation constant of receptor 7 with Ag+ was 1.9 × 105 M− 1 and the 1:1 stoichiometry of receptor 7–Ag+ complex was formed. The 1H NMR spectra complexation experiments suggested that Ag+ was bound in a cavity composed of two benzalazine groups on bridging chains.

Phosphorus−Nitrogen Compounds. 18. Syntheses, Stereogenic Properties, Structural and Electrochemical Investigations, Biological Activities, and DNA Interactions of New Spirocyclic Mono- and Bisferrocenylphosphazene Derivatives

The reactions of hexachlorocyclotriphosphazatriene, N(3)P(3)Cl(6), with mono- (1 and 2) and bisferrocenyldiamines (3-5), FcCH(2)NH(CH(2))(n)NHR(1) (R(1) = H or FcCH(2)-), produce mono- (6 and 7) and spirocyclic bisferrocenylphosphazenes (8-10). The fully substituted phosphazenes (11-15 and 18-21) are obtained from the reactions of corresponding partly substituted phosphazenes (6-10) with excess pyrrolidine and NH(2)(CH(2))(3)ONa, respectively. The reactions of 6 with 1-aza-12-crown-4 afford geminal (16) and tris (17) crown ether-substituted phosphazenes. The structural investigations of the compounds have been verified by elemental analyses, mass spectrometry, Fourier transform IR, (1)H, (13)C, and (31)P NMR, and DEPT, COSY, HETCOR, and HMBC techniques. The crystal structures of 7, 10, 11, and 15 have been determined by X-ray crystallography. In 16 and 17, there are one and two stereogenic P atoms, respectively, and they are expected to be in enantiomeric mixtures. The structures of 18-21 look similar to a propeller. In 20 and 21, there are two stereogenic P atoms, and they exist as cis (meso; 20a and 21a) and trans (racemic; 20b and 21b) geometric isomers, according to the chiral solvating agent (S)-(+)-2,2,2-trifluoro-1-(9'-anthryl)ethanol experiments. Moreover, the compounds 18 and 19 have three stereogenic P atoms, and they exist as enantiomeric mixtures. Cyclic voltammetric investigations of compounds 6-21a reveal that ferrocene redox centers undergo oxidation concurrently at the same potential with basically reversible peaks, and these compounds appear to be quite robust electrochemically. The compounds 11-15 have been screened for antibacterial activity against gram positive and gram negative bacteria and for antifungal activity against yeast strains.The compounds 11, 12, 14, and 15 are evaluated for antituberculosis activity against reference strain Mycobacterium tuberculosis H37Rv (ATCC 27294). Interactions between compounds 11-15 and pBR322 plasmid DNA are studied by agarose gel electrophoresis. These compounds induce conformational changes in the DNA helix.

Reaction of N-(2,3-epoxypropyl)arenesulfonamides with (bicyclo[2.2.1]hept-5-en-endo-2-yl)methanamine

Reactions of bicyclo[2.2.1]hept-5-en-endo-2-ylmethanamine with N-(2,3-epoxypropyl)arenesulfonamides gave amino alcohols having a norbornene fragment and sulfonamide group. The major products were formed via opening of the oxirane ring according to the Krasuskii rule. The product structure was determined by 1H and 13C NMR spectroscopy using DEPT and two-dimensional COSY, NOESY, HMQC, and HMBC techniques.

The microwave-assisted synthesis and structural characterization of novel, dithia-bridged polymeric phthalocyanines containing a substituted thiophenylamine Schiff base

Novel polymeric metal-free and metallo(Cu(II), Co(II), Ni(II), Zn(II) and Pb(II))–phthalocyanine complexes were synthesized using microwave irradiation and the products were purified by several (crystallization and preparative thin layer) techniques. The newly prepared compounds were characterized by a combination of elemental analyses, IR, 1H/ 13C NMR, 1H– 1H COSY, MS and UV–Vis spectroscopy. In order to better understand the spectroscopy data (especially for 1H/ 13C NMR and 1H– 1H COSY techniques), computational calculations were used for characterization at DFT/6-31G(d) level. The electronic spectra exhibited an intense π → π* transition with characteristic Q and B bands of the phthalocyanine core.

Investigation of the correlations between 19F and 1H NMR signals for various mono‐ and di‐substituted octafluoro[2.2]paracyclophanes

A selection of mono- and pseudo ortho di-substituted octafluoro[2.2]paracyclophane derivatives were analyzed using (19)F-(1)H HOESY, (1)H COSY and (19)F COSY techniques. This resulted in the unambiguous assignment of the (19)F and (1)H NMR resonances, and also revealed interesting solvent effects and noteworthy coupling patterns for various J(HH), J(HF), and J(FF) interactions, including observable through bond (7)J(FF) and (8)J(FF) couplings. For the four mono-substituted derivatives, the assignments were achieved through the combination of (19)F-(1)H HOESY, (1)H COSY and (19)F COSY techniques. The C(2) symmetry of the six pseudo ortho di-substituted derivatives that were examined produced simplified spectra, and careful inspection of the characteristic (1)H coupling patterns led to the assignment of (1)H signals. Therefore only (19)F-(1)H HOESY experiments were required to complete the assignments for those molecules. Refinements and alternative strategies for previous protocols are presented for the molecules that were less responsive to nuclear Overhauser effect (nOe) experiments.

Synthesis and cations complexation of dumbbell shaped biscalix[4]-1,3-aza-crown with rigid thiourea-bridge

By reacting calix[4]-1,3-aza-crown 2 with 1,4-phenyl diisothiocyanate in “1 + 2” condensation mode, the novel dumbbell shaped biscalix[4]-1,3-aza-crown 3 with rigid thiourea-bridge was conveniently prepared in yield of 85%. Its structure and conformation were characterized by elemental analyses, ESI-MS, 1H NMR and 1H–1H COSY techniques. The complexation properties of compound 3 were investigated by liquid–liquid extraction experiments and 1H NMR titration experiments. The results showed that compound 3 has excellent complexation abilities for soft cations and outstanding extraction selectivity for Ag+. The Ag+/Na+ and Ag+/Hg2+ extraction percentage of host 7 were as high as 43.2 and 16.9, respectively. 1H NMR titration experiments revealed the 1:2 stoichiometry of receptor 3-Ag+ complex was formed.

New Labdane Diterpenes fromLeonurus cardiaca

Leonurus cardiaca L. has been used in oriental medicine against several types of disorders. The ethanolic extract of leaves of Leonurus cardiaca yielded three new labdane-type diterpenes: 15- O-ethylleopersin C (1), 15- O-methylleopersin C (2), and 15- EPI- O-methylleopersin C (3). Their structures were determined using 1 D and 2 D NMR including 1H-1H COSY, HMQC, HMBC, and ROESY spectroscopic techniques. Compounds (1 - 3) were evaluated for in vitro antiplasmodial activity (D6 and W2 clones) and cytotoxicity (Vero cells).

Dynamic NMR study and theoretical calculations on the conformational exchange of valsartan and related compounds

Valsartan (1), an antihypertensive drug of the sartan family, and three related compounds, 3-methyl-2-((2'-(1-methyl-1H-tetrazol-5-yl)biphenyl-4-ylmethyl) pentanoylamino)butyric acid (2), 3-isopropyl-6-propyl-4-(2'-(1H-tetrazol-5-yl)biphenyl-4-ylmethyl) morpholine-2,5-dione (3), and 3-isopropyl-6-propyl-4-(4'-(1H-tetrazol-5-yl)biphenyl4-ylmethyl) morpholine-2,5-dione (4), were studied by nuclear magnetic resonance (NMR) spectroscopy. Assignment of (1)H and (13)C NMR resonances for the compounds were completed using COSY, HSQC and HMBC techniques. It was found that each of the compounds 1, 2, and 4 had two sets of (1)H and (13)C resonances, suggesting the presence of two conformers in solution. Based on NOESY experiments at different temperatures, thermodynamic parameters of the conformational exchange process were deduced for these compounds. The exchange barrier was found to be 17.9 +/- 0.7, 18.5 +/- 0.8, and 17.7 +/- 0.6 kcal mol(-1) with the corresponding free energy difference (DeltaG) of 0.32 +/- 0.04, 0.23 +/- 0.01, and 0.13 +/- 0.04 kcal mol(-1) for 1, 2, and 4, respectively, at 298 K. Two conformations of valsartan were elucidated by NMR spectroscopy and quantum chemistry calculation. The results showed that two conformers of valsartan interchange via rotation about the C(O)--N bond.

Isolation and structure elucidation of photodegradation products of fexofenadine

The photostability of the antihistamine fexofenadine hydrochloride is described. The stress studies revealed the photostability of the drug as the most adverse stability factor. The main photodegradation products were isolated and its structures were elucidated by 1H, 13C, COSY, HSQC, HMBC NMR and mass spectrometry techniques. The drug was exposed to UVC light at 254 nm in methanolic solutions and the degradation was followed by HPLC and TLC. The photostability of fexofenadine tablets was studied and the same degradation products were observed. The two photodegradation products isolated were characterized as the isopropyl derivative, obtained by decarboxilation of fexofenadine, and a benzophenone compound, which was obtained by rearrangement of aromatic rings and oxidation reactions. The results show the importance of appropriate light protection during the drug development process, storage and handling.

Detection of cerebral metabolites by single‐voxel‐based PRESS and COSY techniques at 3T

To compare point-resolved spectroscopy (PRESS) and localized two-dimensional (2D) correlated spectroscopy (L-COSY) in the detection of cerebral metabolites in humans on a clinical scanner at 3T and to estimate their respective inter- and intrasubject variances. Measurements were made on nine healthy subjects to assess intersubject variance, and daily on a single subject over a period of seven days to assess intrasubject variance. All L-COSY measurements were performed with a voxel size of 27 mL (3 x 3 x 3 cm(3)) and a measurement time of approximately 34 minutes in the occipitoparietal lobe of the brain. Relative metabolite concentrations were estimated with respect to N-methyl creatine. While the sensitivity of PRESS is twice that of L-COSY, the greater spectral resolution offered by L-COSY resulted in greater consistency in estimates of the concentrations of several cerebral metabolites, as indicated by a superior intraclass correlation and a significantly lower standard deviation (SD) in a matched pair intrasubject analysis. Our pilot results demonstrate that L-COSY is an effective approach for resolving cerebral metabolites, and demonstrates a lower coefficient of variance (CV) than the conventional 1D localized spectroscopic approach using LC Model for quantification.

Shikonin pigments from hairy root culture of Lithospermum canescens

Pigments of shikonin type, beyond cosmetic applications, show inflammatory, antibacterial, antifungal, immunosti- mulating and anticancer activities [1]. Lithospermum canescens (Michx.) Lehm. (Boraginaceae) is a common plant in northern America also known as Indian paint. Recently, the natural roots of L. canescens have been found to contain the red pigments acetylshikonin, isobutyl shikonin as well as isovalerylshikonin and α-methyl butyrylshikonin [2]. In the pesent study, hairy root cultures of L. canescens were established using three strains of Agrobacterium rhizogenes: ATCC 15834, LBA 9402 and NCIB 8196. In the n-hexane extract of the hairy root culture of L. canescens [3]) the presence of acetylshikonin (ACS), isobutylshikonin (IBS) and β-hydroxyva- lerylshikonin (HO-IVS) has been confirmed so far, by means of 1H-NMR, 13C-NMR and COSY techniques. Antioxidative, antimicrobial and cytotoxic activities assays are under research

Resorcinarenes are hexameric capsules in solution

The host-guest complexes of resorcin[4]arenes with small molecules in organic solutions are examined using modern NMR spectroscopic methods. The complexation of glutaric acid and beta-methyl d-glucopyranoside in chloroform were investigated through 2D COSY, 2D NOESY, 1D NOE, and diffusion-ordered NMR spectroscopy (DOSY) techniques. These methods indicate that the complex is a self-assembled capsule composed of six resorcinarenes that surround six guest molecules of glutaric acid or three molecules of beta-methyl d-glucopyranoside inside. The multiplicity of guest proton signals shows that the capsule provides an asymmetric magnetic environment that persists on the (1)H NMR time scale. The encapsulation of these guests and common solvents suggests that the phenomenon of reversible encapsulation in chemistry may be a century old.

The Reaction of Amino‐Imidazoles, ‐Pyrazoles and ‐Triazoles with α,β‐Unsaturated Nitriles.

AbstractFor Abstract see ChemInform Abstract in Full Text.

New sesquiterpene lactones from water extract of the root of Lindera strychnifolia with cytotoxicity against the human small cell lung cancer cell, SBC-3

In the present study, new sesquiterpene lactones ( 1 ) and ( 2 ) were isolated from the EtOAc soluble fraction of the water extract of Linderae Radix through bioassay-guided fractionation and isolation methods. The structure of these compounds was elucidated by spectroscopic analysis of their 2D NMR spectra, including COSY, HMBC, and HMQC techniques. Two isolates showed significant cytotoxicity against the human small cell lung cancer cell SBC-3, and lesser cytotoxicity against mouse fibroblast cell 3T3-L1.

Eremophilane esters of Robinsonecio gerberifolius and their rearranged products. Study of the coupling constants 2JH, H, 3JH, H and 4JH, H

In the course of the basic hydrolysis of four eremophilane esters isolated from Robinsonecio gerberifolius, some rearrangements, eliminations, and additions occurred. Five compounds were obtained, three of them not previously described. Additionally, a new sesquiterpene was produced by autooxidation of compound 1. The (1)H and (13)C NMR spectra of these compounds were completely assigned by utilization of HMQC, HMBC, COSY, DEPT, and NOESY techniques. The long-range coupling constants of the peroxide 10 are reported, and all its coupling constants (2)J(H, H), (3)J(H, H), and (4)J(H, H) are calculated at the B3LYP/6-31G(d,p) level of theory. Their magnitude is explained in terms of electronic delocalization and the additivity of stereoelectronic effects.

The reaction of amino-imidazoles, -pyrazoles and -triazoles with α,β-unsaturated nitriles

The reactions of α,β-unsaturated nitriles (1, 9, 12) as bielectrophiles with aminoazoles (2, 4, 6) as binu-cleophiles were investigated. Acrylonitrile (1) reacts almost exclusively in a chemoselective Michael-type addition yielding the substituted azoles 3, 5 and 7, respectively. Cinnamonitriles 9a,b behave in a similar way, but the free CN group adds a second molecule 4 yielding 10a,b and its cyclocondensation product 11a,b as minor component. The attempted formation of azolopyrimidines is best achieved by the reaction of the benzylidenemalononitriles 12a - f with 2 or 4. The process is chemo- and regioselective. The structure determinations were based on NMR measurements including DEFT, COSY, ROESY, HMQC and HMBC techniques and correct earlier suggestions.