Macromolecular arrays containing Zn-diethynylporphyrin coordinated to platinum tethers were studied using near-edge X-ray absorption fine structure (NEXAFS) spectroscopy at the N K-edge. Porphin (Pf), 2,8,12,18-tetraethyl-5,15-diethynyl-3,7,13,17-tetramethylporphyrin (PfNH) and 2,8,12,18-tetraethyl-5,15-diethynyl-3,7,13,17-tetramethylporphyrinatozinc(II) (Zn-Pf2), have been taken as experimental models. The resonances assignment is supported by static-exchange (STEX) calculations for the porphin (Pf) and Zn-porphin (Zn-Pf1) molecules. By calculation, four pi* resonances occur for porphin (Pf) and two for Zn-Pf1. Experimentally we detect four resonances for porphin and PfNH, and two for the Zn-complexed ones. They can be assigned to core excitations to a couple of energy split pi* orbitals for each not equivalent N atom. Our calculations justify the observed low pi* intensity as due to an extended delocalization of the pi* orbitals. The NEXAFS investigations on platinum complex/Zn-porphyrinato assembled macrosystems (i.e. Pt-ZnPf1, Pt-ZnPf2 and Pt-ZnPf3) show the influence of the Pt tethers bound to the porphyrin through the ethynyl moiety on the electronic structure of the tetrapyrrolic cycle. (C) 2003 Elsevier B.V. All rights reserved.
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|Titolo:||Electronic structure of platinum complex/Zn-porphyrinato assembled macrosystems, related precursors and model molecules, as probed by X-ray absorption spectroscopy (NEXAFS): theory and experiment|
|Data di pubblicazione:||2004|
|Appartiene alla tipologia:||01a Articolo in rivista|