Substituent-dependence of photophysical properties of trans-2-styrylpyridazin-3(2H)-ones

• Published in: Journal of heterocyclic chemistry 2009-07, Vol.46 (4), p.691-701
• Main Authors: Kim, Bo Ram, Cho, Su-Dong, Lee, Hyung-Geun, Yim, Heung-Seop, Kim, Min-Jung, Hwang, Jaeyoung, Park, Song-Eun, Kim, Jeum-Jong, Jung, Kwang-Ju, Yoon, Yong-Jin
• Format: Article
• Language: English
• ISSN: 0022-152X; 1943-5193
• DOI: 10.1002/jhet.137

The photophysical behavior of trans‐2‐styrylpyridazin‐3(2H)‐ones 3 strongly depend on the number and the position of substituents in the phenyl ring in THF, methylene chloride, acetonitrile and methanol. The absorption spectra of 3 containing the electron‐donating substituents at the para‐position show the red‐shift, whereas the spectra of 3 containing the electron‐withdrawing substituents show the blue‐shift. For the trans‐2‐(p‐substituted‐styryl)pyridazin‐3(2H)‐ones 3b, 3c, 3d, 3e, 3f, 3g, 3h and 3k, 3l, 3m, 3n, 3o, the magnitude of the solvatochromic shifts and the shape of the fluorescence spectra depend on the number and/or the position of substituents in benzene ring. The emission maximum of trans‐2‐styrylpyridazin‐3(2H)‐ones involving the electron‐donating group is larger than one of trans‐2‐styrylpyridazin‐3(2H)‐ones involving the electron‐withdrawing group in the phenyl ring. The magnitude of the emission maximum is roughly parallel to the relative electron‐withdrawing ability of the substituents of the phenyl ring. J. Heterocyclic Chem., (2009).