Boron nitride nanotubes and their functionalization via quinuclidine-3-thiol with gold nanoparticles for the development and enhancement of the HPLC performance of HPLC monolithic columns.

In this paper, a new and effective method was described for attaching gold nanoparticles (Au-NPs) on to the surface of thiol-terminated Boron Nitride Nanotubes (BNNT) functionalized with quinuclidine-3-thiol, acting as a bridging agent. The quinuclidine-3-thiol was first grafted onto the surface of the BNNTs via strong interactions between the electron pair from the nitrogen atom of the quinuclidine structure and the electronic gap from the boron atom of the BNNT. The bare surface of Au-NPs facilitates to attach on the thiol group of the thiol-terminated BNNTs. These two nanomaterials (pristine BNNTs and Au-BNNTs) were then incorporated into a monolithic polymer. The obtained monolithic BNNT and AuBNNT stationary phases were very useful columns for the HPLC isocratic mode separation of a series of benzene and naphtalene derivatives. The retention on these two stationary phases was due to the different intermolecular interactions including the dispersion interaction (area of the delocalized π bond), the dipole-dipole interactions, and the electrostatic repulsion. The presence of Au-NPs on the BNNT surface improved significantly the retention and column efficiency for compounds with thiol groups in their structure. As well, it was shown that both retention and column efficiency linearly increased with the nanotube (NT) amount in the polymerization mixture. This manuscript thus established for the first time the fact that BNNT was a very useful nanomaterial for the development of novel HPLC stationary phases and increased the performance of classical equivalent C18 monolithic columns.