UV-Vis-spektroskopische Eigenschaften 3,5-disubstituierter 1,3,4-Oxadiazolin-2-imine. II. Fluoreszenzeigenschaften und Dipolmomente von Grund- und Anregungszustand

✍ Scribed by Dr. Jürgen Bendig; Prof. Dr. Dieter Kreysig; Dr. Erika Sauer; Doz. Dr. Manfred Just

• Publisher: John Wiley and Sons
• Year: 1981
• Tongue: English
• Weight: 562 KB
• Volume: 323
• Category: Article
• ISSN: 1615-4150
• DOI: 10.1002/prac.19813230403

✦ Synopsis

The U.V.‐vis‐spectroscopic Properties of 3,5‐disubstituted 1,3,4‐Oxadiazoline‐2‐imines. II. Fluorescence Properties and Dipol Moments of the Ground and the Excited State

With increasing polarity of the solvent the fluorescence maxima of 3,5‐disubstituted 1,3,4‐oxadiazoline‐2‐imines are shifted to longer wavelengths. In alcohol, Stokes shifts are in the range of 8 · 10^5^ m^−1^. The dipol moments of the molecules in the excited state (determined in terms of the Onsager theory) are different from those of the ground state. The differences are competible with the push‐pull effect of the substituents and its influence on the polarity of the oxadiazoline‐imine system. The kinetic parameters of the fluorescence (quantum yields, rate constants, decay times) correlate with Hammett's substituent constants. Iod‐ and nitroaryl substituted compounds as well as some of the o‐substituted phenyl derivatives show specific deactivation processes like predissociation and others.