Interaction of diatomic ligands with Fe(II) meso-mono-4-pyridyl-tri-phenyl-porphyrinate. Spectral evidence of self-assembly in sublimed layers

Abstract

The interaction of CO, NO and O 2 gases with thin layers of meso-mono-4-pyridyltri-phenylporphyrinatoiron(II) (FeMPyTPP) obtained by sublimation onto low-temperature (T = 77 K) substrates has been investigated by means of IR and UV-visible spectroscopy. In contrast to the closely-related meso-tetraphenylporphyrinatoiron(II) (FeTPP), the formation of two types of axial complexes has been observed. In one of these the 5th coordination site is occupied by the pyridyl group of an adjacent molecule indicating the self-assembly of Fe(MPyTPP) in layers with formation of coordinatively linked oligomers. The degree of oligomerisation depends on the nature of the interacting gas. Due to the specificity of the supramolecular structure, the layers are fairly stable in ambient conditions and conserve their microporosity to bind reversibly with the aforementioned ligands.

FTIR and optical spectroscopic studies of the reactions of heme models with nitric oxide and other NOx in porous layered solids

“…Despite this, the observation that the 15 NO 2 reaction with unlabeled Fe(Por)(ONO) gives some unlabeled nitrato product initially argues for the operation of the first mechanism, at least partially. where L is a pyridyl from an adjacent Fe(MPyTPP) [68]. Addition of labeled NO to this mixture gave exchange only with the five-coordinate species, thus an empty coordination site is necessary to access the dinitrosyl intermediate trans-Fe(Por)(NO) 2 [35,36].…”

Low-Temperature Interaction of Dioxygen and Carbon Monoxide with Microporous Films of Co(II) Porphyrins Containing Bulky tert-Butyl Substituents

“…Sublimed layers of Co(II) complex of 5,10,15,20-tetrakis(3',5'-di-tert-butylphenyl)porphyrin (I), in contrast to the layers of [5,10,15,20-tetraphenylporphyrinato]cobalt(II) Co(TPP) that lose their porosity and ligand-binding ability upon standing at ambient conditions, conserve these properties for a long time. Obviously, the bulky tert-butyl groups of I slow down the close packing of molecules in the films making metal ions accessible to different ligands for a long period.…”

“…The same pattern was observed upon interaction of O 2 with sublimed layers of Fe(M4PyTPP). [20] Hence despite the presence of bulky tert-butyl groups the same type of oligomers (Scheme 2) is formed in the films of II too. The six-coordinate dioxygen complexes formed by oligomeric units are thermally much more stable than five-coordinate dioxygen complexes that terminate the oligomers.…”

Interaction of dioxygen with nitrosyl complexes of meso-mono-4(3)-pyridyl-triphenylporphyrinato cobalt in sublimed layers

“…In contrast to metal complexes of meso-tetraarylporphyrins, sublimed layers of meso-pyridyl substituted derivatives with metal ion capable of axial coordination retain a microporous structure and the ability of reversible coordination of various ligands during storage. [2,3] This is due to the formation of zigzag type oligomeric structures by coordinating pyridyl group of one molecule with the metal ion of the adjacent molecule in the layer. For complexes with metals prone to octahedral coordination, such supramolecular organization leads to the formation of a penta-or hexacoordinated complexes.…”

“…For complexes with metals prone to octahedral coordination, such supramolecular organization leads to the formation of a penta-or hexacoordinated complexes. [2][3][4][5] Nitrosyl complexes of metalloporphyrins are of considerable interest in biology and in medicine as potential sources of NO. [6] It has been previously shown, [4] that the reaction of NO with sublimed layers of I and II leads to the formation of two types of nitrosyl complexes: pentacoordinated -with molecules at the end of the oligomers and those not involved in the oligomeric structures; and hexacoordinated -with the sixth coordination site occupied by the pyridyl group of adjacent molecule in the layer.…”