Spiropyran-azobenzene-DBU system as solvent indicator was written by Xu, Zhiping;Li, Shen;Shen, Yujun;Chen, Meijun;Shao, Xusheng. And the article was included in Tetrahedron Letters in 2018.Formula: C12H15N This article mentions the following:
A dyad bearing azobenzene and spiropyran units was synthesized and its applications in indicating the polarity and protic or aprotic properties of a solvent were explored. The spiropyran-azobenzene derivative (SPAB) can be induced to different forms in different miscellaneous solvents accompanied with different color changes and spectral characteristics at the presence of organic base DBU. In a nonpolar or low-polar solvent, SPAB exists in thermostable spiropyran form with yellow color output. While in an aprotic polar solvent, the spiropyran part isomerized to merocyanine form giving a blue color. When SPAB is subjected to a protic solvent, the alkylation reaction occurs at the oxygen generating the alkylated-SPAB with red color. This solvent-dependent property can be used for discriminating solvent type. In the experiment, the researchers used many compounds, for example, 1,3,3-Trimethyl-2-methyleneindoline (cas: 118-12-7Formula: C12H15N).
1,3,3-Trimethyl-2-methyleneindoline (cas: 118-12-7) belongs to indole derivatives. Indole exists overwhelmingly in the 1H-indole form as do other simple indoles. Moreover, it is known that it controls biofilm formation. However, the role of indole in the cell has not been fully elucidated.Formula: C12H15N
Referemce:
Indole alkaloid derivatives as building blocks of natural products from聽Bacillus thuringiensis聽and聽Bacillus velezensis聽and their antibacterial and antifungal activity study,
Preparation of Indole Containing Building Blocks for the Regiospecific Construction of Indole Appended Pyrazoles and Pyrroles