pK(a) values and geometries of secondary and tertiary amines complexed to boronic acids - Implications for sensor design

[GRAPHICS] The pK(a) values and the geometries of secondary and tertiary amines adjace nt to boronic acids were determined using potentiometric and B-11 NMR titra tions, The studies showed that the secondary ammonium ion has a pK(a) simil ar to that of the tertiary ammonium species, which leads to the formation o f tetrahedral boron centers at pH values above approximately 5.5. Therefore , secondary amines as well as tertiary amines, when placed proximal to boro n centers, can be used to create tetrahedral boronic acids at neutral pH fo r diol complexation.