摘要:

A theoretical investigation of SBH and a bicomplex ion, [(Fe III (SBH)2)]+is used as a basis to control and clarify previous vibrational assignments for complexes formed between iron and ligands related to SBH. Main conclusions are the following:1.Complexation shifts the vC=0 vibration by about 100 cm−1towards low wavenumbers.2.vC=N and δHC=N modes are enhanced by complexation.3.In the complex, the enhanced vC=N mode hides the amide II vibration.4.The v-O-stretching mode is expected to be near 1400 cm−1in the complex.5.Point 1 provides a criterion for carbonyl involvement in complexation. Points 2 and 4 are possible probes for hydrazide nitrogen and phenate involvement.6.Despiteab initiocalculations, the vibration at 1360 cm−1is, as previously, assigned to the amide III mode.

ISSN:0038-7010    

DOI:10.1080/00387019909350002

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

The effects of pyridine derivatives and some other nitrogenous ligands(including 2-methyl-pyridine, 3-methyl-pyridine, 4-methyl-pyridine. 2,6-dimethyl-pyridine, imidazole and azide) on the alkaline isomerization of ferric cytochrome c were studied by1H-NMR. Bulky ligands like pyridine and its derivatives can facilitate the formation of alkaline form of cytochrome c and selectively stabilize one conformer of alkaline cytochrome c at enough concentration of such ligands. However, in the case of small ligands such as cyanide and azide, no such phenomena was observed. Being a ligand of medium size, imidazole has quite weak effect on alkaline isomerization of cytochrome c. It is interesting that 2-methyl-pyridine and 2,6-dimethyl-pyridine also have such effects on the alkaline isomerization of cytochrome c although they can not bind to the heme iron of cytochrome c due to the severe steric interactions between their methyl groups and the heme plane. This finding provides new evidence for the suggestion that the effects of pyridine and its derivatives on the alkaline isomerization of cytochrome c may not involve the binding of these exogenous ligands to the heme iron. The effect of 3-methyl-pyridine on the alkaline isomerization of cytochrome c was further quantitatively investigated by 2D-EXSY.

ISSN:0038-7010    

DOI:10.1080/00387019909350003

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

We presented the time-resolved thermal lens spectra of C60-benzene system under nitrogen-saturated condition. The theoretical explanation for C60thermal lens spectra was indicated and in agreement with the experimental data. The theoretical model for C60thermal lens spectra and the lifetime of triplet C60(τT=10.2μs) were also given.

ISSN:0038-7010    

DOI:10.1080/00387019909350004

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

Photoacoustic (PA) spectra of powdered neodymium oxide: Nd2O3(A type), neodymium hydrated chloride: NdCl3-6H2O and neodymium fluoride: NdF3are reported. PA band shifts as compared to their positions in aqueous Nd(III) ion have been used to calculate the nephelauxetic parameters of their compounds. The variation of these parameters and correlation with the nature of metal-ligand bonding have been discussed. A novel method is introduced to determine relative values of Judd-Ofelt parameters and oscillator strengths of powdered samples using PA spectroscopy. It is found that a linear correlation exists between relative values of τ2and relative oscillator strengths of hypersensitive transitions of the title compounds. It can be hoped that the new method of PA technique may serve for the Judd-Ofelt quantitative analysis of powdered rare earth compounds.

ISSN:0038-7010    

DOI:10.1080/00387019909350005

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

Experimental and theoretical evaluations have proven that very low fluorescence quantum yields of azlactones in solution are not caused by an efficient inter system crossing from S1*(ππ) to T*(nπ) states, but rather from solvation and steric effects, that result in non-planarity of the molecular system. High fluorescence quantum yields in the solid state are attributed to the planarity of the azlactone molecule upon packing into the crystal lattice. Supporting evidence was found upon observation of the excited state proton transfer (ESIPT) bands of fluorescence emissions ofo-hydroxyarylidene derivatives. The photoinstability of azlactones in liquid states are attributed to photochemical E-Z isomerization and cleavage of the hetero ring α to the carbonyl group.

ISSN:0038-7010    

DOI:10.1080/00387019909350006

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

The EPR spectra of Cu2+in Sodium hydrogen oxalate monohydrate, NaHC2O4.H2O(SHOMH hereafter) single crystal was studied at room temperature. The angular variation of EPR spectra showed that the Cu2+ion in SHOMH single crystal substitutes with Na+monovalent cation together with a monovalent vacancy to compensate oxygen in the crystal. Since the crystal symmetry is triclinic, only one site is observed in the EPR spectra in three perpendicular axis. The spin Hamiltonian parameters were obtained, and the ground state wave function of Cu2+ion in the lattice was constructed.

ISSN:0038-7010    

DOI:10.1080/00387019909350007

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

A novel family of chelating bis-bidentate azodye compounds1with Cu(II), Co(II), Ni(II), Fe(II), Hg(II), Pd(II), UO2(II), Fe(III), Cr(III), La(III), Ru(III) and Zr(IV) has been prepared and characterized on the basis of analytical, magnetic,1H and13C NMR, EPR and electronic spectral studies. Tentative structures for the polymeric complexes are proposed. The important IR bands and the main1H and13C signals are assigned and discussed relative to the molecular structure. Various EPR parameters for Cμ(II), have been calculated. The ligand acts as a dibasic bis-bidentate chelating agent coordinating through CO, N=N, COOH and OH groups by replacement of a proton from the two latter groups. Considerable interest has also been focused on the synthesis of the azo compound and its polymeric metal complex due to its wide potential applications. The thermal decomposition behavior of the complexes is also discussed.

ISSN:0038-7010    

DOI:10.1080/00387019909350008

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

Electron impact mass spectra of some substituted 10,11-dihydro-5H-dibenzo[a,d]cyclohepten-5-one and 9,10-dihydro-4H-benzo[4,5] cyclohepta[1,2-b] thiophene-4-one have been recorded and the identity of various ions in the mass spectra established. Substituted dibenzosuberones (2-6) exhibit one main fragmentation route, which include the elimination of the tropolone molecule from the dibenzosuberone fragment cation. Their monothiophene analogues(7-11) exhibit characteristic CO elimination from the molecular ion and formation of corresponding naphtho[1,2-b]thiophene radical cation which after elimination of CS or HCS from the thiophene nuclei give rise to the benzotrophyne radical cation.

ISSN:0038-7010    

DOI:10.1080/00387019909350009

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

The simultaneous determination of cadmium and lead in cigarette smoke was achieved using a unique impaction-graphite furnace atomic absorption spectrometry system (I-GFAAS), and in inert cigarette parts (whole, tobacco, filter, and paper) using conventional graphite furnace atomic absorption spectrometry (GFAAS) following digestion using a previously established microwave digestion method. Results showed that in both the whole cigarette and the smoke there was about a factor of two in lead compared to cadmium concentrations, typically 17.56 compared to 31.94 mg/g for whole cigarette and 13.41 to 25.72 ng/m3for cigarette smoke.

ISSN:0038-7010    

DOI:10.1080/00387019909350010

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

Differential cross sections for coherent scattering of 59.5 keV gamma rays at 115° were measured for 12 elements in atomic range 26≤7≤82. Experimental results were compared with theoretical values.

ISSN:0038-7010    

DOI:10.1080/00387019909350011

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor