Covalent Immobilization Using Perfluorophenylazides (PFPAs)

When the PFPA-functionalized surface is irradiated (1) or heated, (2) singlet perfluorophenylnitrenes are generated and subsequently undergo C-H, N-H insertion and C=C addition reactions with neighboring molecules. The functional group, R, serves as the anchoring point to the substrate, whereas the azido groups form covalent bonds to the neighboring molecules upon UV activation. The functionalized PFPA therefore acts as a coupling agent attaching molecules to the substrate surface. (3) This approach offers several unique features in comparison to other surface immobilization methods, which include versatility, (4) defect tolerance, (5) and addressability. (6,7)

a)

b)

a) Photochemistry of PFPAs, a simplified schematic, b) covalent immobilization on silicon oxide surface using PFPA-silane.

Patterned polypropylene thin films (left), (4) polymer thin film-based micro/nanowell arrays (middle), (6) and covalently immobilized polystyrene molecule (right). (7)

 

References:
1. Bartlett, M. A.; Yan, M., Fabrication of polymer thin films and arrays with spatial and topographical controls. Adv. Mater. 2001, 13, 1449-1451.
2. Yan, M.; Ren, J., Covalent immobilization of ultrathin polymer films by thermal activation of perfluorophenyl azide. Chem. Mater. 2004, 16, 1627-1632.
3. Yan, M., Photoactive reagents for the covalent immobilization of polymer thin films. Polym. News 2002, 27, 6-12.
4. Yan, M.; Ren, J., Covalent immobilization of polypropylene thin films. J. Mater. Chem. 2005, 15, 523-527.
5. Liu, L.; Engelhard Mark, H.; Yan, M., Surface and interface control on photochemically initiated immobilization. J Am Chem Soc 2006, 128, 14067-72.
6. Yan, M.; Bartlett, M. A., Micro/nanowell arrays fabricated from covalently immobilized polymer thin films on a flat substrate. Nano Lett. 2002, 2, 275-278.
7. Liu, L.; Yan, M., A general approach to the covalent immobilization of single polymers. Angew Chem Int Ed Engl 2006, 45, 6207-10.