Platinum complex/Zn-porphyrin macrosystem assemblies: Electronic structureand conformational investigation by x-ray photoelectron spectroscopy

In this study we used x-ray photoelectron spectroscopy (XPS) to characteriz e newly synthesized platinum/zinc-porphyrin assemblies. Our investigation p rovides information both on the electronic structure and on the composition and conformation of the linked systems. In particular, the N is and Pt 4f( 7/2,5/2) spectra reveal the presence of a charge transfer interaction betwe en the two subunits in which the charge flows from the Zn-porphyrin towards the platinum unit. Analysis of the: Cl 2p(3/2) core level electrons has le d to a greater understanding of the conformational structure of these syste ms, verifying the occurrence of cis-trans isomerization from the pristine p latinum complex to the linked assemblies, or the persistence of the conform ation of the precursor platinum complex. We used XPS quantitative evaluatio n of the atomic ratios to estimate the subunit ratio between the Zn-porphyr inato and the Pt complex and also identified a platinum linked tetramer. Th e XPS results are consistent with nuclear magnetic resonance, infrared and matrix assisted laser desorption ionization spectroscopy. (C) 1999 American Vacuum Society. [S0734-2101(99)04103-2].