Ryuhei Nishiyabu, Shiori Teraoka, Yusuke Matsushima
Mar 1, 2012
Citations
0
Influential Citations
26
Citations
Journal
ChemPlusChem
Abstract
Pyridine-assisted sequential boronate esterification of benzene-1,4-diboronic acid and 1,2,4,5-tetrahydroxybenzene has induced hierarchical molecular self-assembly, and in turn producing well-defined submicrospheres. Spectroscopic analyses such as FE-SEM, TEM, DLS, NMR, XRD, and IR absorption spectroscopy indicates that the particles are composed of lamellar structures of sp2-hybridized trigonal planar poly(dioxaborole). The spontaneous self-organization is ascribable to reactive layer-by-layer assembly through sequential boronate esterification of the diboronic acid and the tetrahydroxybenzene whereby initially formed oligo(dioxaborole) may provide a platform for further reactions, thus resulting in the production of submicrospheres. It is interesting to note that the dynamic covalent functionality as a result of the dioxaborole linkage induced a stimuli-responsive change in morphology by not only a pH switch but also the exchange reaction with pentaerythritol. Further, a selective saccharide-induced change in the submicrosphere morphology was observed through a simple exchange reaction of dynamic covalent boronate esters with saccharides in THF; the selective change in morphology is visually detected through the color change in the solution. These findings can provide a useful insight into the design of stimuli-responsive hierarchical architectures based on boron-containing dynamic covalent bond.