Pnictogen-Bonding Catalysis Compared with Ion Transport in Lipid Bilayer Membranes: Entering the Goldilocks Inverted Region

Antimony-centered pnictogen bonds at the stibine level have provided access to good catalysis in solution and outstanding ion transport and catalysis in lipid bilayer membranes. Strengthened pnictogen bonds on the stiborane level have increased catalytic activity in solution to an extent attractive for use in practice. Thus, the debate was whether or not transport and catalysis in lipid bilayer membranes would equally increase from σ-acidic stibines to σ-acidic stiboranes. The response, we report, is no. Experimental support for this conclusion covers a new set of σ-acidic catecholatostiborane catalysts with bioinspired catecholates, supramolecular structural X-ray and computational data, transfer hydrogenation catalysis in water, micelles and membranes, and, of course, ion transport across lipid bilayers. Decreasing ion transport with increasing ion binding defined the inverted region in the Goldilocks principle. Our results placed σ-acidic stibines with weaker pnictogen bonds in the well-explored Goldilocks normal region. σ-acidic stiboranes, however, with their strong pnictogen bonds, provided unprecedented access to the Goldilocks inverted region and emerged as unique tools to generalize the Goldilocks principle from transport to catalysis and from membranes to micelles. The reported methods and results should be of general interest in the design and rationalization of supramolecular function in biphasic systems (Figure presented.).