Formation of Extended Covalently Bonded Ni Porphyrin Networks on the Au(111) Surface

Abstract

The growth and ordering of {5,10,15,20-tetrakis(4-bromophenyl)porphyrinato}nickel(II) (NiTBrPP) molecules on the Au(111) surface have been investigated using scanning tunneling microscopy, x-ray absorption, core-level photoemission and microbeam low-energy electron diffraction. When deposited onto the substrate at room temperature the NiTBrPP forms a well-ordered close-packed molecular layer in which the molecules have a flat orientation with the porphyrin macrocycle plane Published as: Krasnikov, S. A.; Doyle, C. M.; Sergeeva, N. N.; Preobrajenski, A. B.; Vinogradov, N. A.; Sergeeva, Y. N.; Zakharov, A. A.; Senge, M. O.; Cafolla, A. A. (2011): Formation of Extended Covalently Bonded Ni Porphyrin Networks on the Au(111) Surface. Nano Research 4, 376?384. 2 lying parallel to the substrate. Annealing of the NiTBrPP layer on the Au(111) surface at 525 K leads to dissociation of bromine from the porphyrin followed by the formation of covalent bonds between the phenyl substituents of the porphyrin. This results in the formation of large covalently bonded porphyrin networks, which are stable up to 800 K and can be recovered after exposure to ambient conditions. By controlling the experimental conditions a robust, extended porphyrin network can be prepared on the Au(111) surface that has many potential applications including protective coatings, sensing or as a host structure for molecules and clusters.