Selective scission of pyridine-boronium complexes: mechanical generation of Brønsted bases and polymerizationcatalystsElectronic supplementary information (ESI) available: Additional synthetic and characterization details. See DOI: 10.1039/c0jm03619f

• Main Authors: Wiggins, Kelly M, Hudnall, Todd W, Tennyson, Andrew G, Bielawski, Christopher W
• Format: Article
• Language: English
• ISSN: 0959-9428; 1364-5501
• DOI: 10.1039/c0jm03619f

Coupling two pyridine-capped poly(methyl acrylate) (PMA) chains of varying molecular weights to bis(pentafluorophenyl)boron chloride afforded the first examples of boronium-based polymers. Ultrasonication of CH 3 CN solutions of these polymers with number average molecular weights ( M n ) > 40 kDa induced selective scission of a boron-pyridine bond, affording a two-fold reduction in M n . The liberated pyridine was used to effect a colorimetric change, via a stoichiometric Brønsted acid-base reaction with an indicator, and to catalyze the polymerization of α-trifluoromethyl-2,2,2-trifluoroethyl acrylate. No reduction in M n , colorimetric response, or polymerization activity were observed ( i ) in the absence of sonication, ( ii ) for polymers with M n < 40 kDa, ( iii ) for a high molecular weight PMA ( M n = 110 kDa) containing a terminal boronium species, or ( iv ) when the boron-pyridine adduct was not covalently linked to a PMA chain. Collectively, these results support the notion that the aforementioned scission processes were induced by an applied mechanical force. Mechanical force was used to selectively cleave novel boronium-based polymers and liberate catalytically active, Brønsted bases.