The rate of adsorption of water vapor by compounds obtained from cationic copper(II) and nickel(II) ammine complexes and polyoxometallate anions may be described by the linear driving force mass transfer model as one or two parallel processes. The differences observed were attributed to differences in the crystal structure of the adsorbents.Polyoxometallates (POM) are a large family of anionic metal-oxygen cluster species with highly variable composition, structure, and electronic structure. These features impart POM with many valuable properties and may permit their use in catalysis, materials science, medicine, etc. [1][2][3][4]. In light of their fixed nanodimensional size, POM anions are also suitable building blocks for obtaining structurized materials (organometallic framework materials, OMF), which may be expected to have specific adsorption properties. However, this aspect of the chemistry of these compounds has hardly been studied.Recent investigations have shown that ionic OMF with the general formula M n [Cr 3 O(OOCR) 6 (H 2 O) 3 ][XW 12 O 40 ]·mH 2 O (M = K + or Cs + , R = H or Et, X = Si IV or Co II ) [5-9] and the complex [Pd(en)(bpy)] 2 [SiW 12 O 40 ]·8DMSO·4DMF (en = ethylenediamine, bpy = 4,4¢-bipyridyl) [10] have a number of features distinguishing them from other adsorbents derived from organometallic compounds without POM.Firstly, the hydrophilic nature of the oxometallate building blocks leads to high selectivity of these adsorbents relative to polar molecules such as water, acetone, alcohols, and nitriles and their virtual inability to adsorb nonpolar adsorbates or molecules, which interact with the adsorbent by means of van der Waals forces [5-10]. Such molecules include nitrogen [7,8,10], which makes the use of the traditional adsorption chemistry methods for analyzing the porous structure of these compounds impossible. Secondly, as noted for compounds with M n [Cr 3 O(OOCR) 6 (H 2 O) 3 ] (n+1)+ cations, variation of the alkali metal and organic fragment permit fine control of the selectivity of the adsorption processes due to slight changes in the crystal lattice parameters. Thus, the complex Cs 5 [Cr 3 O(OOCH) 6 (H 2 O) 3 ][CoW 12 O 40 ] selectively adsorbs water in the presence of methanol and ethanol [6], while K 2 [Cr 3 O(OOCH) 6 (H 2 O) 3 ][CoW 12 O 40 ] also binds alcohols and nitriles with two or less carbon atoms in addition to water [7]. Similar behavior is found for K 2 [Cr 3 O(OOCC 2 H 5 ) 6 (H 2 O) 3 ][SiW 12 O 40 ] with the distinction that this compound also adsorbs alcohols with four or more carbon atoms [8]. The replacement of the potassium ions in this complex by cesium ions leads to the appearance of additional hydrophobic channels in its lattice, capable of binding dichloromethane molecules. This process occurs independently of the adsorption of water molecules in the hydrophilic channels [9].In light of the very limited number of compounds studied and their interesting properties, we investigated the adsorption characteristics of other compounds containing POM. For thi...

It was established that the compounds formed by the cations in amine complexes of nickel(II) and copper (II) and the anions of polyoxometallates are capable of reacting stoichiometrically with gaseous ammonia when in the hydrated state. Some of the studied compounds are characterized by high sorption capacity (up to 40 molecules of adsorbate to a formula unit of the complex) and exhibit selectivity in the sorption of ammonia in the presence of water vapor.The anions of polyoxometallates (POM) are convenient building blocks for the creation of substances with promising oxidation-reduction, catalytic, magnetic, optical, and other functional characteristics [1][2][3][4]. In the light of their fixed dimensions, ranging from tenths of a nanometer to several nanometers, they can also be used for the design of materials with a porous structure, from which specific sorption characteristics can be expected. However, in spite of the obvious nature of this proposition, this aspect of the physical chemistry of polyoxometallate compounds has hardly been studied at all.Recent investigations have shown that materials constructed from the complex cations of chromium [5-9] or palladium(II) [10] and anions of the Keggin type [XW 12 O 40 ] n-(X = Si IV or Co II ) have interesting sorption behavior. This shows up primarily in their high and finely regulated (on account of the change in the size of the additional alkali-metal cation) selectivity toward polar molecules (water, acetone, alcohols, or nitriles). The materials do not interact with nonpolar adsorbates [5-10], including molecular nitrogen [7,8,10]. This feature makes it impossible to use traditional adsorption-chemical methods to analyze the porous structure of the compounds.We recently showed [11] that the crystal solvates formed by various molybdates (tungstates) and the amine complexes of copper(II) and nickel(II) undergo reversible and stoichiometric dehydration/rehydration. The observed fact that the kinetic curves for the hydration reactions are described by both one-and two-exponential relationships was explained by the presence of one or two types of energy barriers respectively for the diffusion of water molecules into the solid. The structural factors leading to the appearance of such barriers may be, for example, the pore sizes of the various bonding centers of the adsorbate. This suggestion agrees well with the fact that the two complexes having only one type of channel in the crystal are characterized by almost identical kinetic parameters for the water sorption processes [11].In order to obtain new information on the sorption characteristics of materials based on POM and to study their bonding to various molecules we studied the heterophase reaction of a series of such compounds with another polar adsorbate -gaseous ammonia. As subjects for the investigation we used the compounds, presented in Table 1, constructed on the basis of the cationic components [M(L n )] 2+ (M = Cu, Ni; L n = L 1 or L 2 ) and POM anions with various structures. 2040040-5760/07/4303-...

Four new coordination polymer frameworks, namely [(NiL(1))(3)(BTB)(2)]·6H(2)O, [(NiL(2))(3)(BTB)(2)]·6H(2)O, [(NiL(3))(3)(BTB)(2)]·6H(2)O and [(NiL(2))(3)(BTC)(2)]·10.25H(2)O (L(1) = 1,4,8,11-tetraazacyclotetradecane, L(2) = 3-methyl-1,3,5,8,12-pentaazacyclotetradecane, L(3) = 3,10-dimethyl-1,3,5,8,10,12-hexaazacyclotetradecane, BTC(3-) = benzene-1,3,5-tricarboxylate, BTB(3-) = 4,4',4''-benzene-1,3,5-triyl-tribenzoate) were prepared in water-N,N-dimethylformamide solutions. The molecular and crystal structures of these compounds are compared to the related coordination polymers formed by nickel(II) macrocyclic cations to examine the effect of carboxylate linker size on the framework architecture. Luminescent properties of the complexes based on the BTB(3-) bridging ligand are also discussed.