摘要:

The reduction of RE3+to RE2+(RE=EU, Sm and Tm) in SrB6O10prepared in air by high-temperature solid state reaction was observed. The luminescent properties of Eu2+and Tm2+show f-d transition and Sm2+shows f-f transition at room temperature. Three crystallographic sites for Sm2+in matrix are available. Vibronic transition of5D0-7F0of Sm2+was studied. The coupled phonon energy about 108 cm−1, was determined from the vibronic transition. Due to the thermal population from5D0level,5D1-7Fj(J=0, 1, 2) transitions of Sm2+were observed at room temperature. A charge compensation mechanism is proposed as a possible explanation.

ISSN:0038-7010    

DOI:10.1080/00387019909350036

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

A simple and sensitive spectrophotometric method is developed for the assay of some antihistamines. The method is based on the interaction of these basic compounds with picrolonic acid in chloroform to give a yellow color exhibiting maximum absorption at 359 nm.

ISSN:0038-7010    

DOI:10.1080/00387019909350037

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

The interaction of Ru(phen)2(dppx)2+(phen=1.10-phenanthroline, dppx=7,8-dimethyl dipyrido[3,2-a:2′,3′-c]phenazine) and the calf thymus DNA were studied with fluorescence and ultraviolet visible absorption spectroscopy. Fe(CN)64and NaCl can not quench the fluorescence of Ru(phen)2(dppx)2+-DNA. which indicate that Ru(phen)2(dppx)2+intercalate into the double helix of DNA. The ultraviolet visible absorption spectrum of Ru(phen)2(dppx)2+calf thymus DNA, and the results of their interaction reveal that Ru(phen)2(dppx)2+intercalate into the double helix of DNA via the ligand dppx.

ISSN:0038-7010    

DOI:10.1080/00387019909350038

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

Equilibrium dialysis and NMR spin-lattice relaxation time (T1) studies of the interaction of the trypanocidal drug 3-nitrobenzaldehyde guanyl hydrazone (3NBGH) with bovine serum albumin (BSA) were used to show that this interaction is weak and nonspecific, making 3NBGH a potential agent for the prophylaxis ofTrypanosoma cruziinfected blood.

ISSN:0038-7010    

DOI:10.1080/00387019909350039

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

The infrared and Raman spectra of a platinum complex of the antiinflammatory drug piroxicam (Pir) and dimethylsulfoxide (DMSO) of composition [PtCl2Pir(DMSO)] were recorded and briefly discussed on the basis of its structural characteristics. The metal-to-ligand vibrations are analyzed in detail.

ISSN:0038-7010    

DOI:10.1080/00387019909350040

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

A novel pentanuclear iron(II)-polyimine complex containing four pentacyanoferrate(II) groups attached to peripheral pyridine residues has been synthesized, exhibiting a characteristic iron-to-pyridine charge-transfer band at 395 nm, in addition to the iron-to-polyimine charge-transfer bands at 490 and 600 nm. The corresponding Mössbauer spectrum has been deconvoluted in terms of two symmetric doublets of 4:1 relative intensities, respectively, at IS = 0.345 and 0.021 mm/s and QS = 0.841 and 0.845 mm/s, associated with the pentacyanoferrate(II) and the iron(II)-polyimine centers. The peripheral groups can be reversibly oxidized at 0.38 V, in aqueous solution, leading to the decay of the 395 nm band. This process is not accessible in the corresponding Prussian-blue film; instead, the electrochromic behavior observed in this case reflects the changes in the intervalence-transfer band at 750 nm, accompanying the electrochemical process at 0.4 V associated with the FeIII/IIredox couple in the matrix.

ISSN:0038-7010    

DOI:10.1080/00387019909350041

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

A multi-linear-regression analysis using the Kamlet-Abboud-Taft (KAT) solvatochromic parameters in order to elucidate and quantify the solvent effects on the17O chemical shifts of (E)-1,1,1-trichloro-4-methoxy-3-penten-2-one (1) and (E)-1,1,1-trichloro-4-methoxy-3-methyl-3-buten-2-one (2) are reported. The chemical shifts of carbonyl group of the two molecules show similar dependencies (in ppm) on the solvent polarity-polarizability (-17*, -15*) and the solvent hydrogen-bond-donor (HBD) acidities (-7α, -6α). The influence of the solvent hydrogen-bond-acceptor (HBA) basicities is significant for compound 1 (3β) and small for compound 2 (0.7β).

ISSN:0038-7010    

DOI:10.1080/00387019909350042

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

The transient spectra of aqueous CCl4solution by laser flash photolysis (LFP) was studied in this paper. The transient absorption band (λmax<300nm) of aqueous CCl4solution bubbled with N2was attributed to the trichloromethyl radical (CCl3·) with a 2nd-order decayed reaction rate of 3.80 × 108mol−1·L·s−1. The transient absorption band (λmax320nm) of the same solution bubbled with O2was attributed to the peroxytrichloromethyl radical (CCl3O2·) with a 1st-order decay reaction rate of 1.9 × 104s−1. The transient absorption band around 330 nm of aqueous CCl4solution always exists insolutions bubbled with either N2or O2and was attributed to the solvated chlorine atom (Cl). COCl2as a photolysis product of aqueous CCl4solution, in the presence of O2, was observed directly in the transient absorption spectra. The results indicate that CCl4can be degraded by the photooxidation process.

ISSN:0038-7010    

DOI:10.1080/00387019909350043

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

The reaction of a cellulosic material (Whatman no. 42 filter paper) with two silanes was studied by Diffuse Reflectance Ultraviolet-Visible Spectroscopy and Diffuse Reflectance Fourier Transform Infrared Spectroscopy. The silanes were 3-aminopropyltriethoxysilane (APS) and methyltrimethoxysilane (MS), a silane with a non-reactive organofunctional group. The use of organic peroxides was required in order to achieve an efficient cellulose modification with the silanes. The Diffuse Reflectance UV-VIS Spectroscopy can provide valuable information about the mechanism of the reactions between silanes and cellulose. The reaction between APS and cellulose involves not only the silanol groups of the silane, but also the amino groups. The spectra of APS-trealed celluloses show an absorption band at 325 nm. This band was assigned to imines produced in the reaction of the amino groups of APS with the cellulose. This absorption band increased when APS-treated cellulose was cured at 120°C. The amino groups attached to the cellulose dissappeared in this process

ISSN:0038-7010    

DOI:10.1080/00387019909350044

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

In addition to the plant sterols β-sitosterol and daucosterol, a new bisabolane-typed sesquiterpene glycoside and three bioactive compounds (artemetin, geniposide and 6β-hydroxygeniposide) were characterized from the whole plant ofBiebersteinia heterostemonendemic to the Tibetan area. The structure determination of the novel glycoside and identification of the known phytochemicals were accomplished by a combination of modern spectroscopic methods. Tests of all isolates for the antimicrobial activity indicated that the new sesquiterpene glycoside exhibited pronounced antibacterial activities againstBacillus subtilis, Staphylococcus aureusandPseudomonas sp.with MICs at 50, 50 and 70 μg/ml, respectively.

ISSN:0038-7010    

DOI:10.1080/00387019909350045

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor