An Iterative Divergent Approach to Conjugated Starburst Borane Dendrimers.

Rauch, Florian; Endres, Peter; Friedrich, Alexandra; Sieh, Daniel; Hähnel, Martin; Krummenacher, Ivo; Braunschweig, Holger; Finze, Maik; Ji, Lei; Marder, Todd B.

Using a new divergent approach, conjugated triarylborane dendrimers were synthesized up to the 2nd generation. The synthetic strategy consists of three steps: 1) functionalization, via iridium catalyzed C−H borylation; 2) activation, via fluorination of the generated boronate ester with K[HF2] or [N(nBu4)][HF2]; and 3) expansion, via reaction of the trifluoroborate salts with aryl Grignard reagents. The concept was also shown to be viable for a convergent approach. All but one of the conjugated borane dendrimers exhibit multiple, distinct and reversible reduction potentials, making them potentially interesting materials for applications in molecular accumulators. Based on their photophysical properties, the 1st generation dendrimers exhibit good conjugation over the whole system. However, the conjugation does not increase further upon expansion to the 2nd generation, but the molar extinction coefficients increase linearly with the number of triarylborane subunits, suggesting a potential application as photonic antennas.

DENDRIMERS; BORANES; GRIGNARD reagents; BORONIC esters; REDUCTION potential; PALLADIUM; LINOLEIC acid; CLASS B metals

Chemistry - A European Journal, 2020, Vol 26, Issue 57, p12951

0947-6539

Academic Journal

10.1002/chem.202001985