Dendrimeric Oligo(phenylenevinylene)-Extended Dithieno[3,2-b:2′3′-d]phospholes-Synthesis, Self-Organization, and Optical Properties

To establish this system as a fluorescent core in pi-conjugated dendrimers, a series of oligo(phenylenevinylene) (OPV)-extended dithieno[3,2-b:2',3'-d]phospholes has been prepared by means of a Wittig-Horner protocol with a dithienophosphole dialdehyde and appropriately functionalized phosphonates. The "zero-generation" model compounds have provided the general accessibility of OPV-functionalized dithienophospholes, and show varying emission colors covering the optical spectrum from green to red. Expansion of the synthetic strategy towards the corresponding first-generation dendrimers has provided materials that show intriguing self-organization features in case of the phenyl-terminated dendrimer, forming large one-dimensional microfibres, as well as desirable energy-transfer processes from the dendrons to the dithienophoshole core resulting in an enhanced emission intensity for the latter. The present study has revealed that the terminal end-groups of the OPV branches have significant impact on optical features of the OPV dendrimers as a whole.