Blending the Optical and Redox Properties of Oligoynes and Boron Difluoride Formazanates

Oligoynes and polyynes are 1D chains of conjugated sp-hybridized carbon atoms consisting of alternating single and triple bonds. Their stability rapidly decreases with increasing chain length beyond only a few repeating units. Design strategies, such as the use of bulky end-capping groups, allow for their characterization and isolation while not contributing significantly to their physical properties. In this study, we incorporate redox-active BF2 formazanate dyes (BF2) as end-caps to prepare symmetric (BF2-[C equivalent to C](n)-BF2) and asymmetric (BF2-[C equivalent to C](n)-Si(iPr)(3)) families of oligoynes containing up to 10 alkyne units. In doing so, we introduce stable oligoynes that possess a blend of optical and redox properties that cannot be achieved by either oligoynes or BF2 formazanates individually (e.g., panchromatic absorption, multiple and tunable reversible redox waves). This approach is transferable to other functional end-caps to facilitate the preparation of pi-conjugated materials with utility in the organic electronics arena.