Molecular Structure of Nickel Octamethylporphyrin—Rare Experimental Evidence of a Ruffling Effect in Gas Phase

The structure of a free nickel (II) octamethylporphyrin (NiOMP) molecule was determined for the first time through a combined gas-phase electron diffraction (GED) and mass spectrometry (MS) experiment, as well as through quantum chemical (QC) calculations. Density functional theory (DFT) calculations do not provide an unambiguous answer about the planarity or non-planar distortion of the NiOMP skeleton. The GED refinement in such cases is non-trivial. Several approaches to the inverse problem solution were used. The obtained results allow us to argue that the ruffling effect is manifested in the NiOMP molecule. The minimal critical distance between the central atom of the metal and nitrogen atoms of the coordination cavity that provokes ruffling distortion in metal porphyrins is about 1.96 Å.

Study of bioactive molecular systems by gas-phase electron diffraction: examples, limitations and possibilities

The paper is aimed to the development of structural chemistry of biomolecules, which play essential role for living systems. The structures of biogenic amine, adrenaline, was determined using gas phase electron diffraction (GED) technique in comparison with tryptamine and noradrenaline investigation. Possibilities of method and its limitations are shown in application to bioactive molecular systems. The investigations of the molecules in gas phase allows us to find and describe details of their structures, molecular dynamic which leads to the behavior of the substances in the various processes.