Tunable Pnictogen Bonding at the Service of Hydroxide Transport across Phospholipid Bilayers
Brendan L. Murphy, François P. Gabbaı̈
Abstract
High Resolution Image Download MS PowerPoint Slide Our growing interest in the design of pnictogen-based strategies for anion transport has prompted an investigation into the properties of three simple triarylcatecholatostiboranes ( 1 – 3 ) of the general formula ( o -C 6 Cl 4 O 2 )SbAr 3 with Ar = Ph ( 1 ), o -tolyl ( 2 ), and o -xylyl ( 3 ) for the complexation and transport of hydroxide across phospholipid bilayers. A modified hydroxypyrene-1,3,6-trisulfonic acid (HPTS) assay carried out in artificial liposomes shows that 1 and 2 are potent hydroxide transporters while 3 is inactive. These results indicate that the steric hindrance imposed by the three o -xylyl groups prevents access by the hydroxide anion to the antimony center. Supporting this interpretation, 1 and 2 quickly react with TBAOH·30 H 2 O ([TBA] + = [ n Bu 4 N] + ) to form the corresponding hydroxoantimonate salts [ n Bu 4 N][ 1 -OH] and [ n Bu 4 N][ 2 -OH], whereas 3 resists hydroxide coordination and remains unperturbed. Moreover, the hydroxide transport activities of 1 and 2 are correlated to the +V oxidation state of the antimony atom as the parent trivalent stibines show no hydroxide transport activity.