Electrotransport, sorption, and photochemical properties of nanocluster polyoxomolybdates with a toroidal structure

Abstract

The electrotransport, sorption, and photochemical properties of polyoxometalateO 416 H 6 (H 2 O) 58 (CH 3 CO 2 ) 6 ] · xH 2 O (x ~ 250) with a toroidal structure are studied. Con ditions for studying these characteristics are selected on the basis of data on the stability of POM, in depen dence on the concentration and acidity of the medium and the processes of thermal decomposition. A set of independent physical and chemical methods of analysis is used. The possibility of the complexation of toroi dal POM with polymer molecules is established. The photostabilizing effect of this POM on polymer mole cules is revealed.

Interaction between nanocluster polyoxometallates and low-molecular-weight organic compounds

“…This difference in the character of sorption could be due to the internal holes being fairly large (diameter, ~2.0 nm) in a toroidal molecule, compared to the windows in a keplerate structure (diameter, ~0.6 nm for Мо 132 ). All active sites on external and internal torus surfaces are therefore more or less equivalent, compared to those of keplerate, whose outer and inner sites can differ substantially in terms of accessibility [20]. The shape of the isotherm for Mo 72 Fe 30 is likely related to its instability in organic solvents, unlike the two other polyoxometallates.…”

Physicochemical and biochemical properties of the Keplerate-type nanocluster polyoxomolybdates as promising components for biomedical use

“…The literature indicates a similar effect of cations on the formation of aggregates [291]. At the same time, the existence of singlet POMs in a solution is not typical for the toroid-like Mo 138 [286]; therefore, its destruction is a one-step process in a certain time interval.…”

“…The results of studies of thermal stability and destruction of the Keplerate and toroidal type POMs in the solid state using spectroscopic methods are given in [280][281][282][283][284][285][286]. At the same time, it was shown that a thorough spectroscopic analysis and a comprehensive interpretation of the results are necessary [280,286] in order to avoid unreliable conclusions [284] about the POMs' thermal stability. The features of the processes of POMs destruction in solutions have been considered in the earlier performed works [135,198].…”

“…The time dependencies (τ ) of the optical density A (directly proportional to the current POM concentration) obtained [135] In [135], a supposition was made concerning the possible differences in the process of Mo 72 Fe 30 POM destruction at different concentrations. The mentioned POMs tend to form aggregates or hollow globules in solutions [89,199,[286][287][288][289][290][291][292]. In solutions with high concentrations, aggregation proceeds in such a way that a significant part of the available POM molecules (ions) happens to be bound into aggregates within a relatively short time.…”

Formation of Molybdenum Blue Nanoparticles in the Organic Reducing Area

“…Molybdenum-oxygen nanoclusters represent a large class of polyoxometalates (POM) [ 1 , 2 , 3 , 4 , 5 ]. The modern chemistry of polyoxometalates is very extensive and includes clusters of various chemical composition, size and shape [ 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 ]. Usually disperse phase of molybdenum blue dispersions is presented by giant clusters, which are formed as a result of self-assembly from the original building blocks, which are Mo 1 , Mo 2 , Mo 8 , etc.…”