Tunable thiopyrylium end group for all optical switching applications

All-optical switching (AOS) requires materials with strong third order optical nonlinearities. There is a great interest in using Cyanine-like molecules, which should posse very large magnitude of third order optical nonlinearities, in AOS applications. The aim of our research is to control aggregation and improving process ability of cyanine-like molecules by post-end-group modification in order to reach large magnitude of third order optical nonlinearities for a given length of conjugated chain and minimize potential optical loss. The first target end-group that we worked on was thiopyrylium, which has been proved to be an excellent end-group. In this work, a newly developed versatile synthetic route has been developed so that a wide variety of thiopyrylium end-groups can be made efficiently.  The newly synthetic route is shortened to three steps in high yield, and will be used to control the overall shape of the cyanine to promote favorable molecular J-type aggregation.