摘要:

In continuation of our work on the measurement of binding constants of organic substrates with Europium shift reagents, we have studied the steric effects of one or more alkyl groups on the binding of a series of eleven amines (anilines, pyridines and piperidines). Both steric and inductive parameters have proved to be important in determining binding constants for carbinols1, aromatic aldehydes and ketones2,3and esters3,4. The balance of these parameters is discussed for the amines and the results for the three anilines compared with figures derived by Infrared spectroscopy in an earlier study.

ISSN:0038-7010    

DOI:10.1080/00387018008064046

出版商:Taylor & Francis Group    

年代:1980

数据来源: Taylor

摘要:

Recent publications in this series have described the binding constants (K) of the lanthanide shift reagent Eu(thd)3with aldehydes and ketones1,2esters2,3and amines4. In this paper we measure the introduction (or enhancement) of binding properties associated with the changes sulphide to sulphoxide (SO), phosphite to phosphate (PO) and amine to N-oxide (NO) and relate these to hard and soft properties of organic bases.

ISSN:0038-7010    

DOI:10.1080/00387018008064047

出版商:Taylor & Francis Group    

年代:1980

数据来源: Taylor

摘要:

Paper 16 in this series1, 2, 3was concerned with the equilibrium binding constants (K) of the shift reagent Europium tris (2, 2, 6, 6-tetramethylheptane-3, 5-dionate), Eu(thd)3, with primary, secondary and tertiary amines. One nitrogen heterocycle, pyridine, and two of its derivatives (see Table) were included. In the present paper we describe the binding constants for a further 9 nitrogen containing heterocycles and relate these to basicity and steric effects.

ISSN:0038-7010    

DOI:10.1080/00387018008064048

出版商:Taylor & Francis Group    

年代:1980

数据来源: Taylor

摘要:

X-ray emission spectroscopy has become an increasingly more useful tool to probe the nature of the electronic structure of ionic substances. Recently, Mazalov et al.(1)have reported on the effect of cations on the X-ray emission spectra of complex anions. There have also been reports(2, 3)on the reciprocal effect, viz, of anions on the spectra of cations. Both of these effects seem to reflect the nature of the “ionic bond.”

ISSN:0038-7010    

DOI:10.1080/00387018008064049

出版商:Taylor & Francis Group    

年代:1980

数据来源: Taylor

摘要:

An approximate force field for the in-plane and out-of-plane vibrations of aromatic molecules is applied to benzene and naphthalene. Refined force fields for the same molecules were produced to make them consistent with experimental frequencies. Calculated mean amplitudes of vibration and perpendicular amplitude correction coefficients are discussed. The latter quantities are given here for the first time.

ISSN:0038-7010    

DOI:10.1080/00387018008064050

出版商:Taylor & Francis Group    

年代:1980

数据来源: Taylor

摘要:

The application of fluorescence correlation spectroscopy to the measurement of diffusion coefficients of atoms is proposed. After a theoretical analysis of the problem the experimental viability of this technique is studied in the particular case of Tl. Finally applications to other experiments such as ground state level-crossing are proposed.

ISSN:0038-7010    

DOI:10.1080/00387018008064051

出版商:Taylor & Francis Group    

年代:1980

数据来源: Taylor

摘要:

UV absorption and MCD data of a complete series of netropsin-like oligopeptides containing between one and five N-methyl-pyrrole residues are reported. The presence of three MCD bands in the region between 220 and 350 nm can be related to the resonance of the peptide groups with the methylpyrrole systems of the oligopeptides. The longest wavelength absorption bands of all netropsin-like compounds investigated are ascribed to two electronic transitions of the resonance methypyrrole-carboxamide units. - Complex formation with DNA affects these MCD bands and hence modifies the transitions. This is explained by hypercon-jugation in the chromophoric system as a result of specific hydrogen bonding of peptide groups with dA·dT pairs of double stranded DNA.

ISSN:0038-7010    

DOI:10.1080/00387018008064052

出版商:Taylor & Francis Group    

年代:1980

数据来源: Taylor

摘要:

The mechanisms of mass spectral break down of unsubstituted malonate and succinate esters have been more completely defined by this study of unsymmetrical diesters. Rate determining rearrangement prior to extrusion of CO in daughter ions of succinate esters was verified by observation of broad metastable peaks. A Hammett plot correlation was interpreted as resulting from a greater degree of charge localization on the ester moiety in the decreasing order of -CO2(i-Pr)≥-CO2(n-Pr)≥-CO2Et≥-CO2CH3.

ISSN:0038-7010    

DOI:10.1080/00387018008064053

出版商:Taylor & Francis Group    

年代:1980

数据来源: Taylor

摘要:

The comparison of infra red spectra of different kinds of silicas of high specific surface area allowed to draw conclusions about the structure regularity, which appeared to be different for the various kinds of amorphous silicas, such as fine and large pore silica gels, beer stabilizers and white rubber fillers1/. In comparison with the silica gels the fillers of Arsil, Ultrasil and Aerosil type show a more crystallinic nature, which goes together with increased pore volumes and decreased bulk densities. Such feature of the infra red spectrum as the lack of the 960 om−1hydroxyl band was found to be characteristic for Aerosil and enables to distinguish this kind of material from silicic acids precipitated in solution.

ISSN:0038-7010    

DOI:10.1080/00387018008064054

出版商:Taylor & Francis Group    

年代:1980

数据来源: Taylor

摘要:

13C-NMR studies of certain 2-acyl-1, 3-indandiones indicate that the preferred tautomeric form is the enol structure and not the triketo structure. The13C-NMR spectral assignment of 2-propionyl and 2-benzoyl-1, 3-indandiones are discussed.

ISSN:0038-7010    

DOI:10.1080/00387018008064055

出版商:Taylor & Francis Group    

年代:1980

数据来源: Taylor