Cairo University

MTPR Journal

 

METALLOPORPHYRINS: STRUCTURE, BONDING and SELF-ASSEMBLING

2016-12-17
A.M.Ionov, S.I.Bozhko, V.S.Bozhko, R.N.Mozhchil
Institute of Solid State Physics, Chernogolovka, Russia
Vol./Issue: 16 , id: 178

Organic molecular films of porphyrins have attracted attention over the past years in view of potential applications as the templates for nanomaterials synthesis, nanoelectronic devices and for biology and medicine. For understanding and tailoring their properties the knowledge of electronic structure and bonding in porphyrins is required. The goal of these studies was to investigate the surface topography and the electronic structure of a valence band(VB) and core levels of tetraaril-porphyrins, RE(Yb, Er,) metals and Pt-group compounds (Pt-TPP(n-COOH3)4;etc). The electronic structure of VB, C1s, O1s, N1s, metal core levels and the topography of porphyrins were studied by PES and AFM. The HRPES studies were performed at the RGBL BESSY II using photon energies 120-600 eV. All elements of the compounds were found in XPS spectra. In TPP spectra two peaks of N1s at 399.8 and 397.8 eV (BE range) were assigned to sp3 and sp2 nitrogen, respectively. In metalloporphyrins the charge distribution is more uniform for N1s spectra of metalloporphyrins. Different peaks in spectra were related to the unequivalent C atoms in the molecules (aromatic and C-N-C groups). The valence band is formed by the states corresponding to π (2- 12 eV BE) and σ-states (8-16 eV) of macrocycles. AFM studies of thin films structure show that the structure of solid-phase films is determined by their chemical nature, supramolecular structure and interaction with substrates. These films self-assemble in the air under ambient conditions into partially ordered large rod-shaped and flat supramolecular nanostructures on flat substrates, with an average size in nanoscale, where the molecules are approximately parallel and cofacial to one another. The results of PES and AFM studies of topography and self-assembling processes in thin films of porphyrins are presented and discussed.

Acknowledgement This work was supported by Russian Academy of Sciences and the bilateral program “Russian-German Laboratory at BESSY”.