Chiroptical Properties and the Racemization of Pyrene and Tetrathiafulvalene-Substituted Allene: Substitution and Solvent Effects on Racemization in Tetrathiafulvalenylallene

Molecules

Masashi Hasegawa¹  Seiya Iwata²  Yasuto Sone²  Junta Endo²  Hideyo Matsuzawa² 

[1]id="af1-molecules-19-02829">Department of Chemistry, School of Science, Kitasato University, Sagamihara, Kanagawa 252-0373, Jap

关键词: axis chirality;    allene;    tetrathiafulvalene;    electronic circular dichroism;    racemization;   

DOI  :  10.3390/molecules19032829

来源: mdpi

【 摘 要 】

Dissymmetric 1,3-diphenylallene derivative 3 connected with 4,5-bis(methyl-thio)tetrathiafulvalenyl and 1-pyrenyl substituents was prepared and characterized. The molecular structure was determined by X-ray crystallographic analysis. Optical resolution was accomplished using a recycling chiral HPLC, and its chiroptical properties were examined with optical rotation and electronic circular dichroism (ECD) spectra. The title compound underwent photoracemization under daylight. This behavior was investigated in various solvents and compared with that of 1,3-bis(tetrathiafulvalenyl)allene (bis-TTF-allene) derivative 2. The first-order rate plot of the intensity of the ECD spectra at a given time interval gave the rate of racemization. Mild racemization was observed in polar solvents, whereas a relatively fast rate was obtained in less polar solvents. In addition, the TTF groups of the allene also accelerate the racemization rate. These results suggest that the racemization mechanism occurs via a non-polar diradical structure.

【 授权许可】

CC BY   
© 2014 by the authors; licensee MDPI, Basel, Switzerland.