Abstract
Many interests of organic chemists concerning with structual chemistry have concerned to the properties of pi-electron aggregated compounds for example biphenyl and p-terphenyl constructed with multi benzene rings. In particular, p-terphenyl was noted in the viewpoint of structural and photochemical properties. Now, we wish to report the synthesis and characterization of p-terphenyl having alkylthio groups on the benzene ring of p-terphenyl. First, 4,4"-dimercapto-p-terphenyl was synthesized from p-terphenyl by chlorosulfonation followed by reduction with lithium aluminium hydride. Similarly, 3,3",4,4"-tetramercapto-p-terphenyl was obtained from 4,4-di(N,N-diethyl)sulfonamide-p-terphenyl by lithiation, thiation with elemental sulfur and followed by reduction with lithium aluminium hydride. The tetramercapto-p-terphenyl was converted to the corresponding tetramethylthio-p-terphenyl by alkylation with methyl iodide. At the same time, bis-(p-terphenyl) disufide was also obtained. The UV absorption and emission of the thiol derivatives of p-terphenyl obtained were measured to show a interesting photochemical properties. Thus, the thiol derivatives of p-terphenyl showed a red-shift of its absorption and emission, compared to p-terphenyl. In contrast, bis-(p-terphenyl) disulfide showed substantial red-shift of its emission, compared to thiol derivative of p-terphenyl. The red-shift may be attributed excimeric emission arising from interaction between two p-terphenyl.
