The synthesis of a phosphonic-acid-functionalized porphyrin is presented and a procedure for the reproducible assembly of the porphyrins into thin films on glass or conductive glass surfaces is described. The assembly scheme, which utilizes established zirconium phosphonate (ZrP) chemistry, yields highly oriented films (normal to the surface) of well-defined thicknesses. In the lateral direction (plane parallel to the surface) the porphyrins interact by edge-on-edge contact and are characterized by significant porosity. Electrochemical redox-probe experiments indicate the existence of openings or pores of several angstroms in width in both monolayer and multilayer ZrP porphyrin films. Micropatterned versions of the films, capable of diffracting visible light, have also been prepared and have been used for the direct evaluation of film thicknesses via atomic force microscopy.
Bibliographical noteFunding Information:
We thank Jose Lozano at the Center for Materials Chemistry, Department of Chemistry and Biochemistry, University of Texas at Austin for XPS measurements. We thank the US Dept. of Energy (Grant No. DE-FG02-01ER15244) and the Camille and Henry Dreyfus Postdoctoral Program in Environmental Chemistry (fellowship for RWG) for financial support.
- Diffraction gratings
- Thin films
- Zirconium phosphonates