UV-Vis-spektroskopische Eigenschaften 3,5-disubstituierter 1,3,4-Oxadiazolin-2-imine. I. Einfluß der Substituenten und des Lösungsmittels auf die Absorption

✍ 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: 415 KB
• Volume: 323
• Category: Article
• ISSN: 1615-4150
• DOI: 10.1002/prac.19813230402

✦ Synopsis

The U.V.‐vis‐spectroscopic Properties of 3,5‐disubstituted 1,3,4‐Oxadiazoline‐2‐imines. I. The Influence of the Substituents and the Solvent on the Absorption

The u.v.‐vis data of 38 derivatives of 3,5‐disubstituted 1,3,4‐oxadiazoline‐2‐imines, measured in 12 different solvents, are discussed. The long wave absorption bands have charge‐transfer character, the observed solvatochromic shifts correlate with the solvent parameter E~T~. The assumed intramolecular charge‐transfer upon excitation is polarized in the direction R^1^N^3^C^5^R^2^. Derivatives which are donor‐substituted in the 3‐position of the oxadiazolinimine cycle (R^1^) and acceptor‐substituted in the 5‐position (R^2^) show a typical push‐pull effect. In this case bathochromic and hyperchromic effects on the long‐wave absorption bands result. On the other hand, R^1^ is a donor and R^2^ is an acceptor substituent the excitation energy is increasing.