摘要:

Quenching of Fluorescence and Excimer Formation of Sodiumpyren‐3‐sulfonate in Aqueous Solutions of Polydimethyldiallylammonium ChlorideThe fluorescence spectra and lifetimes of sodium‐pyren‐3‐sulfonate have been measured in the presence of polydimethyldiallylammonium chloride. It is shown, that the excimer formation by static self‐quenching of fluorescence of the pyren‐3‐sulfonate is based on the cooperative effect of the macroion. The association constants of interaction between the aromatic compound and the polycation are determined. Presence of diazoniumcations leads to quenching of fluorescence of pyren‐3‐sulfonate in both the polyelectrolyte and aqueous phases. The quenching cons

ISSN:0021-8383    

DOI:10.1002/prac.19873290112

出版商:WILEY‐VCH Verlag GmbH    

年代:1987

数据来源: WILEY

摘要:

Quenching of Fluorescence of Aromatic Compounds by Diazonium Cations in Aqueous Solutions of PolyelectrolytesThe absorption and fluorescence spectra, and lifetimes of sodiumpyrene‐3‐sulfonate, N‐phenylacridone and acridizinium perchlorate have been measured in the absence and in the presence of sodiumpolyvinylsulfate. A study is made of the quenching by diazonium ions of the fluorescence of the aromatic compounds. The results of Stern‐Volmer plots are discussed by a micro‐heterogeneous model and compared with results in homogeneous solutions. It is suggested that contributions of quencher and aromatic compound in both polyelectrolyte and aqueous phases are

ISSN:0021-8383    

DOI:10.1002/prac.19873290113

出版商:WILEY‐VCH Verlag GmbH    

年代:1987

数据来源: WILEY

摘要:

Quinoxalines. XXIV. Synthesis of 4‐Substituted 1,2,3‐Triazolo [1, 5‐a] quinoxalines3‐Substituted quinoxaline‐2‐carbaldehydes1react with tosylhydrazide to give 3‐substituted quinoxaline‐2‐carbaldehyde tosylhydrazones2. The treatment of2with a boiling solution of sodium methoxide or ethoxide – the so called Bamford‐Stevens reaction – leads to 4‐substituted 1,2,3‐triazolo[1,5‐a]quinoxalines4in high yields. Some of these compounds were als

ISSN:0021-8383    

DOI:10.1002/prac.19873290114

出版商:WILEY‐VCH Verlag GmbH    

年代:1987

数据来源: WILEY

摘要:

1H‐N.M.R. Investigation of Pyrido [1.2‐a]1.3.5‐triazines: Through Bond and Through Space Effects of Ringintegrated Carbonyl, Thiocarbonyl, and Iminocarbonyl GroupsFrom the1H‐n.m.r. spectra of pyrido[1.2‐a]1.3.5‐triazines1a–ithe characteristic data δ(H6), δ(H8), and J(H6, H7) are submitted. The ring‐integrated carbonyl groups in the position 2 (CX) show a deshielding electronic through bond effect on the protons H6and H8in the order of CNPh

ISSN:0021-8383    

DOI:10.1002/prac.19873290115

出版商:WILEY‐VCH Verlag GmbH    

年代:1987

数据来源: WILEY

摘要:

β‐Fur‐2‐yl‐α‐halogenacrylonitriles. VII. Reactions of β‐(5‐Bromo‐fur‐2‐yl)‐α‐bromoacrylonitriles with Mercaptans, Thiourea and Thiourea Derivativesβ‐(5‐Bromo‐fur‐2‐yl)‐α‐bromoacrylonitrile1reacts with ethylmercaptan to yield β‐(5‐bromo‐fur‐2‐yl) β‐ethylthioacrylonitrile3. With thiourea β,β′‐thio‐bis[β‐(5‐bromo‐fur‐2‐yl)]‐acrylonitrile2is formed. The pyrimidines4and5have been prepared by the reaction of1with s‐methylthiourea and 2‐aminothiazole, respectively. The structure of the new compounds wer

ISSN:0021-8383    

DOI:10.1002/prac.19873290116

出版商:WILEY‐VCH Verlag GmbH    

年代:1987

数据来源: WILEY

摘要:

Absorption Behaviour of Pyrazoline‐5‐one Azomethine Dyes – Quantumchemical Description of the Influence of SubstituentsThe VIS absorption of the pyrazoline‐5‐one azomethine dyes1a–his measured in dependence of the substituents of the amino group.HMO calculations confirm that the „x‐ and y‐bands”︁ have a strong charge transfer character. The absorptions in the visible region correspond to a transition from the HOMO mainly localized at the amino‐substituted phenyl to the complex acceptor 4‐imino‐pyrazoline‐5‐one (“x‐band”) or to the pyrazoline‐5‐one fragment (“y‐band”). The calculated transition energies correlate with the valuesνmaxof the x‐band (r = 0.993). There is also a linear correlation between the square of the LCAO‐MO coefficient

ISSN:0021-8383    

DOI:10.1002/prac.19873290117

出版商:WILEY‐VCH Verlag GmbH    

年代:1987

数据来源: WILEY

ISSN:0021-8383    

DOI:10.1002/prac.19873290118

出版商:WILEY‐VCH Verlag GmbH    

年代:1987

数据来源: WILEY

ISSN:0021-8383    

DOI:10.1002/prac.19873290119

出版商:WILEY‐VCH Verlag GmbH    

年代:1987

数据来源: WILEY

ISSN:0021-8383    

DOI:10.1002/prac.19873290120

出版商:WILEY‐VCH Verlag GmbH    

年代:1987

数据来源: WILEY

ISSN:0021-8383    

DOI:10.1002/prac.19873290121

出版商:WILEY‐VCH Verlag GmbH    

年代:1987

数据来源: WILEY