摘要:

1H and13C NMR, as well as UV and IR, spectra of a new class of bipyridinium salts made by double quaternization oftrans−1, 2-bis(4-pyridyl) ethene unit with n-alkyl salts are reported. The effect of quaternization on the1and13C NMR spectra of the salts is discussed.

ISSN:0038-7010    

DOI:10.1080/00387019008054460

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

Various photophysical parameters of three substituted 7-diethylamino benzimidazo quinolines (I, II, and III) have been evaluated in three solvents: DMSO, DMF and chloroform. Based on these parameters, the probability of lasing action by the dyes is predicted and is confirmed from the preliminary laser investigations. Dye I (-CN Substitution in 3-position) and Dye III, which has an extended conjugated system in 3-position, have been found to be potential laser dyes, while Dye II (-CHO substitution in 3-position) is not.

ISSN:0038-7010    

DOI:10.1080/00387019008054461

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

The compounds of beryllium - Be(IO3)2.4H2O, its deuterated analogue and Be(IO3)2were studied by IR-spectroscopy over the range of 200 to 4000 cm−1.

ISSN:0038-7010    

DOI:10.1080/00387019008054462

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

The heterogeneous isotopic exchange reaction of precipitated barium oxalate in barium chloride solution has been studied using Ba-133 as tracer. The effect of barium chloride concentration on the rate of isotopic exchange reaction has been studied. It was found that the rate was controlled by surface mass reaction and particle diffusion process in the solid particle. The result also indicate that the effect of recrystallization can be neglected.

ISSN:0038-7010    

DOI:10.1080/00387019008054463

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

Variable temperature water T1relaxation times have been measured on some normal and neoplastic human lung tissues. The corresponding activation energies have been derived and a short discussion of the experimental results is given.

ISSN:0038-7010    

DOI:10.1080/00387019008054464

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

The first study on the mass spectroscopy of various bis(amidinohydrazones) is reported. The compounds studied included the investigational antileukemic drugs methylglyoxal bis(amidino-hydrazone) [‘methylglyoxal bis(guanylhydrazone)’, MGBG] and glyoxal bis(amidinohydrazone), as well as seven mono- and dialkylglyoxal analogs thereof. The results indicate that the free bases of these high-melting compounds are volatilized well enough to allow a facile detection of the molecular ions and to make mass spectroscopy of the underivatized compounds a suitable method for the verification of the identity of the substances. This result is of importance considering the development of novel analogs and derivatives. A compilation of electron-impact mass spectra is reported and possible fragmentation routes are outlined. The fragmentation of the various congeners appears to occur essentially similarly, the main paths involving breakage of the carbon-carbon single bond in the glyoxal moiety or breakage of either one of the nitrogen-nitrogen single bonds.

ISSN:0038-7010    

DOI:10.1080/00387019008054465

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

The first 2D-NMR study on bis(amidinohydrazones) [‘(guanylhydrazones)’] is reported. Heteronuclear shift correlation (HETCOR) experiments were performed on the enzyme inhibitors methylpropylglyoxal bis(amidinohydrazone) (MPGBG) and butylmethylglyoxal bis(amidinohydrazone) (BMGBG). The results obtained made possible the unambiguous assignment of the previously unassigned resonances of the side-chain carbon atoms of MPGBG. The results indicate that the chemical shifts of the protons of the propyl side chain of MPGBG are positively correlated to the13C chemical shifts of the corresponding carbon atoms. The chemical shifts of the carbon atoms of the propyl side chain decrease as a function of the position of the atom in the side chain, the terminal methyl group having the lowest shift value. These results are in full agreement with previous results on the analogous compound dipropylglyoxal bis(amidinohydra- zone), whose side-chain carbon resonances were assigned using totally different techniques. In the case of BMGBG, however, HETCOR contour plots clearly indicate that there is no correlation between the chemical shifts of the protons of the butyl side chain and the 13C chemical shifts of the corresponding carbons. Because the 200 MHz proton spectrum of BMGBG is not fist-order, only the 1 3 resonance∼ of the methyl substituent and the resonances of carbons 1 and 4 (but not those of carbons 2 and 3) of the butyl side chain could be assigned on the basis of the HETCOR study. Yet, the results gave a rough estimate of the previously unknown chemical shifts of the protons bound to butyl carbon atoms 2 and 3.

ISSN:0038-7010    

DOI:10.1080/00387019008054466

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

The emission band spectrum of gallium monobromide has been excited in a dc hollow cathode discharge. bands of the3Π0,1−X1Σ+system, lying in the range from 340 to 370 nm have been recorded at high resolution and measured. The previous vibrational analysis has been revised and corrected. New vibrational assignment has been proposed and improved vibrational constants of the upper and lower electronic states have been determined.

ISSN:0038-7010    

DOI:10.1080/00387019008054467

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

A simple rapid and accurate UV-spectroscopic method have been developed for determination of tetramethrin in presence of piperonyl butoxide, which are present in LicidR, a newly introduced pharmaceutical drug in Egypt used as antilice, and antiscopis. The method is applicable in the concentration range of 1–12 μg.ml−1and 1–50 μg.ml−1for tetramethrin and piperonylbutoxide respectively. Average recoveries for tetramethrin and piperonyl butoxide in LicidRspray and LicidRlotion are 98.14 ± 0.3 – 103.88 ± 1.88 (Tetra), 103.78 ± 1.23 (piperonyl) and 100.62 ± 0.89 – 100.94 ± 1.10 (Tetra), 102.38 ± 1.02 (piperonyl) for the spray and lotion, respectively.

ISSN:0038-7010    

DOI:10.1080/00387019008054468

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

The behaviour of electron energy function distribution in hollow cathode discharge at resonant light irradiation is analyzed. The function is calculated for energies near and higher than the energy excitation ε1of the hellium metastable levels. It turns out that the electron energy function distribution is essentially influenced in the vicinity of point ε1.

ISSN:0038-7010    

DOI:10.1080/00387019008054469

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor