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We developed two synthetic strategies towards triptycene-derived bulky boranes, boronates, and boron ate-complexes. Starting from borylated or brominated anthracenes and using a Br/Li exchange and [4+2] cycloaddition reaction with in-situ generated benzyne, we produced a series of triptycene boronates and borates with various boron substituents in positions 1 and 9, such as BPin, Bneo, BF3K and B(Mes)2. Single-crystal X-ray diffraction analysis and UV-Vis/photoluminescence measurements provided quantitative information on the effect of the triptycene scaffold on the photophysical and electronic properties of the obtained compounds.

A highly bent triarylborane, 9-boratriptycene, was generated in solution by selective protodeboronation of the corresponding tetra-aryl boron ate complex with the strong Brønsted acid HNTf2. The iptycene core confers enhanced Lewis acidity to 9-boratriptycene, making it unique in terms of structure and reactivity. We studied the stereoelectronic properties of 9-boratriptycene by quantifying its association with small N- and O-centered Lewis bases, as well as with sterically hindered phosphines. The resultant Lewis adducts exhibited unique structural, spectroscopic, and photophysical properties. Beyond the high pyramidalization of the 9-boratriptycene scaffold and its low reorganization energy upon Lewis base coordination, quantum chemical calculations revealed that the absence of π donation from the triptycene aryl rings to the boron vacant pz orbital is one of the main reasons for its high Lewis acidity.