Direct Synthesis of a Metalloporphyrin Complex on a Surface

Abstract

We demonstrate that well-defined monolayers of a metal complex on a surface can be prepared by direct vapor deposition of the metal atoms on monolayers of the ligand. In particular, ordered monolayers of adsorbed tetraphenylporphyrin (2H-TPP) on a silver surface were exposed to cobalt vapors, resulting in the complexation of the metal by the porphyrin. The formation of the metal complexes was monitored by means of X-ray photoelectron spectroscopy (XPS), which reveals that this metalation reaction leads to a chemical equivalence of all four nitrogen atoms. The described in situ metalation provides a convenient way to produce adsorbed monolayers of more reactive (e.g., air- or solvent-sensitive) or thermally unstable metalloporphyrins that are difficult to evaporate or even to obtain as pure compounds at room temperature.

Deprotection, Tethering, and Activation of a One-Legged Metalloporphyrin on a Chemically Active Metal Surface: NEXAFS, Synchrotron XPS, and STM Study of [SAc]P−Mn(III)Cl on Ag(100)

“…This is important because it confirms that no de-metallation occurred upon adsorption or heating: the free base porphyrin would exhibit two distinct N 1s signals corresponding to pyrrolic and iminic species. 22,23 The N 1s binding energies of these species are 400 eV and ~ 397 eV respectively so that they would have been readily resolved in our experiment. The weak Cl 2p emission and the undetectability of Mn 2p emission are consistent with the low number density of Cl and Mn atoms on the surface at saturation coverage, even though both were studied at the optimum photon energies that 6 maximized the respective photoionozation cross sections: Cl 2p = 3 Mb at 251 eV, Mn 2p = 1 Mb at 720 eV.…”

Self-Organized Monolayer ofmeso-Tetradodecylporphyrin Coordinated to Au(111)

“…The position of the third peak with an intermediate binding energy at 399.3 eV corresponds to the energy of nitrogen atoms in metalated TPPs. 12,25,27 Because the formation of gold metalated porphyrins was ruled out by the observation that the Au(111) reconstruction is not lifted under the monolayer, we suggest that this peak corresponds to the photoemission of lone pairs of iminic nitrogens coordinated onto Au(111). The fact that not all iminic lone pairs are coordinated onto Au(111) could be due either to the presence of a residual partial bilayer, or more probably to a slow exchange phenomenon occurring at room temperature.…”

Studying the dynamic behaviour of porphyrins as prototype functional molecules by scanning tunnelling microscopy close to room temperature

“…4,32,35,36,56,58,[72][73][74][75][76][77][78][79][80][81][82][83][84][85] It is nowadays well established that metalloporphyrins can be synthesised readily on a metal surface by the reaction of a corresponding free base porphyrin with an ''available'' metal atom. The respective metal atom can be provided on the surface by pre-or postdeposition, or originate from the surface itself.…”

“…Depending on the metal, this in situ metalation can proceed already at room temperature or after moderate annealing. 72,73,83 It was studied in detail for 2HTPP with Co, 4 …”