Журнал "Макрогетероциклы"

^aMolecule Structure Research Center of Scientific and Technological Center of Organic and Pharmaceutical Chemistry NAS, 0014 Yerevan, Armenia

^bResearch Institute of Macroheterocycles, Ivanovo State University of Chemical Technology, 153000 Ivanovo, Russia

^@Corresponding author E-mail: kurto@netsys.am

 

DOI: 10.6060/mhc160538k

Macroheterocycles 2016 9(2) 156-162

 

The low-temperature interaction of O₂, CO and their mixtures with sublimed layers of Co(II) complexes of 5,10,15,20-tetrakis(3’,5’-di-tert-butylphenyl)porphyrin (I) and 5-(pyridin-4’-yl)-10,15,20-tris(3’,5’-di-tert-butylphenyl)porphyrin (II) has been studied by FTIR and optical spectroscopy. 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 overnight, the films of I conserve these properties for a long time. Thus the bulky tert-butyl groups of I substantially slow down the close packing of molecules in the films making metal ions accessible to different ligands. It is shown that the films of II consist of coordination oligomers, the sixth coordination site of which is occupied by the pyridyl group of an adjacent molecule in the film. The reaction of O₂ gas with these films leads to the formation of two types of complexes: six-coordinate dioxygen complexes, in which the fifth site is occupied by the pyridyl group of the neighboring molecule in the film and the five-coordinate dioxygen complexes that terminate the oligomers. Upon storage of the films, the concentration of six-coordinate complexes increases at the expense of the five-coordinate indicating increasing degree of oligomerization. In contrast, only the end group of oligomers is able to coordinate carbon monoxide CO. No six-coordinate complexes of CO with trans pyridyl group are formed in the films of II and the 6-coordination sites of oligomers remain free. When CO/O₂ mixture is admitted into the cryostat with films of II these sites selectively bind O₂. This phenomenon allows eliminating O₂  from the CO/O₂ mixture containing very low concentrations of O₂ and can be used for CO purification of trace quantities of dioxygen. .