Platinum-Centered Oligoynes Capped by Boron Difluoride Formazanate Dyes and Their Thin-Film Properties

Since the Nobel prize winning discovery that polyacetylene could act as a semiconductor, there has been tremendous efforts dedicated to understanding and harnessing the unusual properties of π-conjugated polymers. Much of this research has focused on the preparation of oligoynes and polyynes with well-defined numbers of repeating alkyne units as models for carbyne. These studies are usually hampered by a structure-property relationship where the stability of the resulting materials decrease with the incorporation of additional alkyne units. Here, we describe a series of oligoynes, with up to 12 alkyne units, where electron-rich [Pt(PBu₃)₂]²⁺ units are incorporated at the center of the oligoyne backbones which are capped by electron-poor BF₂ formazanate dyes. These compounds exhibit excellent stability and solubility, panchromatic absorption, and redox activity characteristic of their structural components. These traits facilitated thin-film studies of extended oligoyne materials, where it is shown that incorporating [Pt(PBu₃)₂]²⁺ units leads to smoother films, decreased conductivity on the microscale, and increased conductivity on the nanoscale when compared to metal-free analogs. Remarkably, our oligoynes have superior conductivity compared to the ubiquitous poly(3-hexylthiophene) semiconductor.