Piperidinate Complexes of Nickel and Copper Mesoporphyrin IX

Abstract

PlPERIDINATE COMPLEXES OF NICKEL AND COPPER MESOPORPHYRIN IX 4587 fully acknowledged. We wish to thank Professor D. H.Templeton and his associates for informing us of the results of their crystal structure determinations prior to publication. We also thank Mr. A. Kwok for engaging in many helpful discussions.

Unusual solvent dependent electronic absorption spectral properties of nickel(II) and copper(II) perhaloporphyrins

“…The equilibrium data was analyzed using reported literature methods and for all of the bases (L), the NiOBrTPP exhibited a 1:2 stoichiometry (Equation 2). Similar behavior was reported for the ligation of piperidine to NiTPP [65] and other Ni(II) porphyrins [64]. In the solid-state, the Ni(II) porphyrins are known to exhibit six coordinate geometry [96][97][98][99][100][101][102].…”

“…Inset shows the corresponding plot for CuTPP. The lines represent a least-squares regression analysis through the data points Similar complexation behavior was observed for the coordination of bases to CuTPP [75] and also to other Cu(II) porphyrins [64].…”

“…Electronic absorption spectral features of certain metalloporphyrins are sensitive to the coordination of a fifth or sixth ligand to the core metal ions [61][62][63][64][65][66][67][68][69][70][71][72][73][74][75] and were exploited in the formation of supramolecular coordination network solids [76]. Recently, the change in absorption spectral pattern of metallotetraphenylporphyrins in the presence of ligating bases has been employed as molecular sensors for the detection of chemical agents [77].…”

Core expansion and electronic structure of the porphyrin in the neutral pH form of copper cytochrome c

“…Because of the similarity of the EPR parameters of the low-pH monomer to monomeric Cu porphyrins in noncoordinating solvents, the pH 4-6 monomer is thought to be 4-coordinate. The neutral pH monomeric form is 5coordinate on the basis of similarity of the EPR parameters to those of the reported pyrrolidine monoadduct of Cu(II) octaethylporphyrin (Chikira et al, 1979;Baker et al, 1964) and Cu(II) myoglobin (CuMb), in which Cu is bound only to the imidazole of proximal histidine (Alston & Storm, 1979).…”

Luminescence Quenching of Copper(II) Porphyrins with Lewis Bases

“…However, there is no indication of a significant change in the energy of the -* excited state of the copper(II) porphyrins because the visible spectrum changes very little upon formation of the ground state adduct. 31 As suggested in the literature,3-4 a more likely possibility is that addition of a fifth ligand stabilizes another short-lived excited state that efficiently quenches the trip-doublet and trip-quartet excited states. We will consider the identity of the quenching state below; for now, we will simply call it the 2X state.…”