16999-25-0Relevant articles and documents
Spectroscopic Evidence of Pore Geometry Effect on Axial Coordination of Guest Molecules in Metalloporphyrin-Based Metal Organic Frameworks
Kucheryavy, Pavel,Lahanas, Nicole,Lockard, Jenny V.
, p. 3339 - 3347 (2018)
A systematic comparison of host-guest interactions in two iron porphyrin-based metal-organic frameworks (MOFs), FeCl-PCN222 and FeCl-PCN224, with drastically different pore sizes and geometries is reported in this fundamental spectroscopy study. Guest molecules (acetone, imidazole, and piperidine) of different sizes, axial binding strengths, and reactivity with the iron porphyrin centers are employed to demonstrate the range of possible interactions that occur at the porphyrin sites inside the pores of the MOF. Binding patterns of these guest species under the constraints of the pore geometries in the two frameworks are established using multiple spectroscopy methods, including UV-vis diffuse reflectance, Raman, X-ray absorption, and X-ray emission spectroscopy. Line shape analysis applied to the latter method provides quantitative information on axial ligation through its spin state sensitivity. The observed coordination behaviors derived from the spectroscopic analyses of the two MOF systems are compared to those predicted using space-filling models and relevant iron porphyrin molecular analogues. While the space-filling models show the ideal axial coordination behavior associated with these systems, the spectroscopic results provide powerful insight into the actual binding interactions that occur in practice. Evidence for potential side reactions occurring within the pores that may be responsible for the observed deviation from model coordination behavior in one of the MOF/guest molecule combinations is presented and discussed in the context of literature precedent.
Richman, Robert M.,Peterson, Mark W.
, p. 5795 - 5796 (1982)
Electron density studies of porphyrins and phthalocyanines. 7. Electronic ground state of bis(pyridine)(meso-tetraphenylporphinato)iron(II)
Li, Naiyin,Coppens, Philip,Landrum, John
, p. 482 - 488 (2008/10/08)
The structure and electron density distribution of bis(pyridine)(meso-tetraphenylporphinato)iron(II), FeN6C54H38, have been determined by using two sets of X-ray diffraction data collected at 110-120 K. Crystal data: Mr = 826.79, triclinic, P1, Z = 1, a = 9.423 (1) ?, b = 10.560 (2) ?, c = 11.998 (2) ?, α = 101.70 (1)°, β = 104.96 (1)°, γ = 111.95 (2)°, V = 1008.50 (2) ?3, dcalcd = 1.361 g/cm3, μ = 4.17 cm-1, λ(Mo Kα) = 0.71073 ?. R factors of the final aspherical atom refinements: R = 2.44%, Rw = 2.41% for data set 1 [(sin θ)/λmax = 0.91 ?-1]; R = 3.98%, Rw = 2.85% for data set 2 [(sin θ)/λmax = 1.15 ?-1]. The Fe-N(pyridine) distance is 2.037 (2) ?, while the average Fe-N(porphinato) distance is 2.001 (1) ?. Bond lengths and electron density distribution indicate that the iron atom is in the low-spin state. The experimental populations of the iron d orbitals are close to those from an extended Hückel calculation, with significant population of the crystal field destabilized orbitals, indicating σ-donation from the coordinated ligands. Covalency parameters derived from the dx2-y2 populations in three complexes correlate with bond lengths. π-Back-bonding is suggested by the less-than-six total electron population of the dxz, dyz, and dxy orbitals. The calculated M?ssbauer shift is equal within experimental error to the spectroscopically observed value and has a negative sign.
Dioxygen Activation in the Photochemistry of some Oxo-metalloporphyrin Complexes
Bergamini, Paola,Sostero, Silvana,Traverso, Orazio,Deplano, Paola,Wilson, Lon J.
, p. 2311 - 2314 (2007/10/02)
Ultraviolet irradiation of the peroxo-complexes and (tpp = 5,10,15,20-tetraphenylporphyrinate) induces elimination of O2 and generation of the corresponding oxometalloporphyrins and .Reductive elimination o
