The aims of the project were the development of fundamental approaches to construction of a new generation of materials based on porous crystalline coordination compounds in order to their use for hydrogen accumulation and storage, as well as the establishment the possibilities and the ways of the modification of chemical nature of pore interior in these materials.
Using the macrocyclic complexes as cationic components and anions of aromatic oligocarboxylates the new porous crystalline materials of ionic and coordination-polymeric nature have been obtained. The crystal structures more than 20 crystalline hydrates of this type have been established by X-ray crystallography. Thermogravimetric studies have revealed that the desolvatation/solvatation processes for the majority of materials obtained are reversible and proceed with the retention of the main structural peculiarities of the crystal lattices. Based on structural data obtained the factors leading to the appearance of porosity of crystal lattices have been established. It was shown that the variation of the substituents in the macrocyclic ligands is a convenient way to control the chemical nature of pore walls, in particular their hydrophobicity.
The porosity of desolvated materials has been established by nitrogen adsorption. It was shown that depending of the nature of constituents and the topology of lattices the specific surfaces of the samples lie between 4 - 614 m2/g with the pore volumes of 0.02 – 0.26 cm3/g. For many compounds the distribution of the pore diameters is narrow and corresponds to that estimated by X-ray crystallography.
Sorption characteristics of porous materials obtained relative hydrogen have been estimated by volumometric method. It was shown that, despite similar chemical structure, the sorbents display different behaviour – some of them do not interact with the adsorbate while other absorb 0.05 - 0.68 percent of Н2 by weight (77 К, 1 bar). No correlation has been found between the nature of crystal lattices and pore sizes on the one hand and sorption capacity on the other. The later was shown to depend essentially on the conditions of preliminary desolvatation and the optimal regime of desolvatation of sorbents was developed based on the results obtained.
Keywords: molecular hydrogen, porous naterials, nickel(II), copper(II), macrocyclic complexes, aromatic carboxylates, thermal stability, X-ray structural analysis, adsorption properties