摘要:

The 200 MHz1H NMR spectra of citiolone,1, have been studied in CDC13solution at ambient temperatures with the achiral lanthanide shift reagent (LSR) tris (6, 6, 7, 7, 8, 8, 8-heptafluoro-2, 2-dimethyl-3, 5-octanedionato) europium (III), Eu (FOD)3,2, for spectral simplification, and with the chiral LSR, tris [3-heptafluoropropylhydroxymethylene)-(+)-camphorato] europium (III), Eu (HFC)3,3. With3, substantial enantiomeric shift differences were obtained for the H-3, NH and CH3CO resonances, with the H-3 signals essentially baseline resolved and free from overlaps with [3]/[1] molar ratios ca. 0.8–1.0. For the acetyl signal, valley heights as low as 4–5% were achieved between the signals of the antipodes when [3]/[1] ratios ca. 0.7–0.8 were used. These conditions should permit direct determinations of enantiomeric excess of1.

ISSN:0038-7010    

DOI:10.1080/00387019708006670

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

4-Aminophenyl ammonium dithiocabamate can easily be chemisorbed on chemically deposited silver film and HNO3etching silver to form monolayer molecular films. The adsorption state was characterized by Foruier transform surface-enhanced Raman scattering spectroscopy (FT-SERS). The results indicated that the adsorbed molecules stand on the surface in tilting conformation.

ISSN:0038-7010    

DOI:10.1080/00387019708006671

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

New series of uranyl complexes derived from 7-formyl-8-hydroxy quinoline with hydrazine hydrate (HL1), methyl hydrazine (HL2), 1,2-diaminoethane (HL3), 1,2-diaminobenzene (HL4) and 2-aminopyridine (HL5) have been prepared and characterized by elemental analyses, (1H NMR and13C NMR, electronic and vibrational spectra) and different physical techniques. The magnetic and spectral data suggest a distorted octahedral structure for all complexes. The labile EtOH molecule in compounds (5), (7) and (9) is equatorially bonded to the uranium ion and its hydrogen is bonded to the axial oxygen of the uranyl moiety. The ligands contain intramolecular hydrogen bonds. The FU-O(mydn/Ao) and the bond length RU-O(Ao) of the bond were calculated from the IR data. In the present work it has been proposed a novel relationship between symmetric “V1” and asymmetric “v3” O-U-O frequencies independent on the masses of oxygen (Mo) and uranium (Mu) atoms.

ISSN:0038-7010    

DOI:10.1080/00387019708006672

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

Via CNDO-SCF calculations, the charge densities, ionization potentials, electron affinities and dipole moments were calculated for trinitrobenzene, TNB, trinitrotoluene, TNT, and picric acid using the closed shell system eigenvectors. Also, the electronic energies, total energies and binding energies of ground state of these compounds have been calculated.

ISSN:0038-7010    

DOI:10.1080/00387019708006673

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

The structure of Dynamical (time dependent) Optogalvanic Signal (DOGS) is due to the transient processes which transform the absorbed photon into light induced conductivity: light induced population and its relaxation, change of the effective ionization potential, light and electron induced ionization. Thus DOGS is also of diagnostic importance for an OG detector.

ISSN:0038-7010    

DOI:10.1080/00387019708006674

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

Infrared spectra of M(1,6-diaminohexane)Ni(CN)4˙ C6H6(M-Co, Ni or Cd) are reported. The spectral data suggest that the compounds are similar in structure to Cd(1,6-diaminohexane)Ni(CN)4˙m-Toluidine and have Hofmann-diam-type structure.

ISSN:0038-7010    

DOI:10.1080/00387019708006675

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

Two dimensional inverse detected heteronuclear correlation experiments HMQC and HMBC and the homonuclear correlation experiment COSY were performed on the natural alkaloid, codeine enabling complete assignments of the1H and13C spectra. The assignments presented follow directly from observed internuclear interactions without the need for arguments based on relative chemical shifts and relaxation rates.

ISSN:0038-7010    

DOI:10.1080/00387019708006676

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

Resonance Raman and electronic spectra of the μ-tris(bipyrazine)ruthenium(II)-hexaquis{ruthenium(II)EDTA} supramolecular complex are reported in this paper. Excitation in the 457–676 nm range leads to the selective enhancement of the Ru-bipyrazine vibrational peaks according to distinct patterns, supporting the assignment of the absorption bands at 670 and 490 nm as charge-transfer (MLCT) transitions from the [RuIIEDTA] dπorbitals to the π1* and π2* LUMO levels of the bipyrazine ligand. A vibronic coupling mechanism involving the two excited states is suggested for the excitation at 490 nm. The occurrence of MLCT transitions in the [Ru(bpz)3]2+central unity, around 440 nm, is supported by the Raman and fluorescence excitation profiles.

ISSN:0038-7010    

DOI:10.1080/00387019708006677

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

The1H NMR spectra of the title benzodiazepines derivatives is highly congested because all the protons are in aromatic enviroment so many proton signals remain overlap even 300 MHz or higher fields. With this in mind, the assignment of the1H and13C spectra of these compounds obtained using COSY, NOESY, HMQC and HMBC experiments is reported.

ISSN:0038-7010    

DOI:10.1080/00387019708006678

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

The IR spectra of the crystalline complexes of 4-nitroaniline with crown ethers were studied, viz., 18-crown-6, benzo-18-crown-6, dibenzo-18-crown-6, dicyclohexano-18-crown-6 and dibenzo-24-crown-8. The hydrogen bonding interaction was found to be predominant in these complexes. The strongest among them was the one formed with the most flexible crown ether dicyclohexano-18-crown-6, in which both the N-H bonds of 4-nitroaniline were shown to be equivalently hydrogen bonded to the crown ether oxygens. The shift of the NO2absorption bands indicated that the resonance form (−C2N-C6H4=N+H2) is favored upon complexation with the larger ring size dibenzo-24-crown-8, while for the other complexes, the resonance form (C2N-C6H4-NH2) is favored; a fact which was attributed to geometrical factors.

ISSN:0038-7010    

DOI:10.1080/00387019708006679

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor