Axial coordination nickel porphyrins

Axial Coordination in Nickel Porphyrins and Nickel-Reconstituted Heme Proteins Investigated by Raman-Difference and Transient-Raman Spectroscopy... 

Resonance Raman scattering provides a valuable method of determining the state of axial ligation in nickel-reconstituted heme proteins and Ni-porphyrin complexes. A pattern of shifts in the Raman coresize and oxidation-state marker lines can be used to monitor changes in axial coordination. The shifts in the core-size lines (e.g. indicate an expansion of the core from about 1.96 A for the 4-coordinate Ni porphyrin to 2.04 A for the 6-coordinate species,... 

The spectra presented in Figures 1-3 demonstrate that high quality, transient resonance Raman spectra can be obtained for Ni(OEP) and Ni(PP) solutions using Soret excitation. These spectra can be interpreted on a molecular level by comparison with the extensive theoretical and experimental data base that exists for ground state nickel porphyrin species (8-16 and refs, therein). The coordination state of nickel porphyrins can easily be detetmined from the resonance Raman spectrum of the sample (10.12). Several modes in the Raman spectrum of porphyrins are quite sensitive to the state of axial ligation (10.12). In particular, the marker lines V4, 11 2> 3 10 (porphyrin skeletal mode designations follow those of Abe et al., (I2a). The designation... 

Supramolecular systems assembled by peripheral and axial coordination were also thoroughly described. For example, heteroarrays held by axial coordination, particularly of zinc, nickel, ruthenium, tin, silicon, etc. porphyrins and phthalo-cyanines to peripheral pyridyl and 4,4-bipyridyl groups were described. Another interesting class of compounds are porphyrin dimers prepared by coordinative assembly of cw- icso-(4-pyridyl)porphyrins with PdCla forming two [PtCl2(pyP)2] complexes, and more complex tesselated structures by substitution of the platinum complex chloro ligands by 2,3-diamine(azaporphyrins), as depicted in Fig. 12. 

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