Coumarin-embedded [5]helicene derivatives: synthesis, X-ray analysis and photoconducting properties.

Two novel coumarin-embedded π-extended [5]helicene derivatives (3a and 6a) have been strategically synthesized and characterized, and the structure of 3a was determined via single crystal X-ray analysis. Both of them exhibit green fluorescence in dichloromethane. In addition, molecule 3a can aggregate to form a large quantity of nanowires through the re-precipitation method. More importantly, the photoelectric conversion properties of 3a nanowire-C 60 based films are much better than those of the thin film of bulk 3a-C 60 , indicating that the ordered nanostructures are a crucial factor for enhancing device performance.