Novel silica-coated Tb(III) nanoparticles with high luminecsence were synthesized using the reverse microemulsion procedure. The quenching of luminescent properties of these nanoparticles can be achieved by ion exchange and energy transfer mechanisms. The quenching through the ion exchange of Tb(III) by H+ or La(III) is time dependent, indicating that the ion exchange is probably diffusion controlled. The quenching by Co(III) complex cations is achieved by the energy transfer mechanism and thus is not time dependent. The analysis of quenching data in Stern-Volmer cooordinates reveal the negative charge of the silica-coated Tb(III)-TCAS nanoparticles and several types of luminophoric species, located within the core and close to the surface of silica nanoparticles.

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Aggregation, catalytic activity, and the influence of alkylated p sulfonatocalix[n]arenes (SCA; n = 4, 6, 8) on the energy exchange in cells of wheat roots were studied. In water SCA are surfactants, and their efficiency changes with an increase in the number of aromatic rings (n) and the length of hydrocarbon substituents (R) in the molecule. In the range of critical micelle concentration, SCA form micelles with an effective hydrodynamic diameter of ~200 nm. The catalytic activity of micellar solutions of SCA (n = 4, 8; R = C 12 H 25 ) in hydrolysis of ethyl 4 nitrophenyl chloromethylphosphonate (ENCP) decreases with an increase in n, whereas the binding constant of ENCP increases. The modifying effect of SCA on the membranes and the energy exchange in cells of wheat roots was revealed: the membranotropic activity of SCA increases with an increase in the hydrophobicity of substituents R and the macrocycle size.Considerable attention is recently given to the study of methods for synthesis, properties, and the scope of application of p sulfonatocalix[n]arenes (SCA) and their derivatives. 1-16 One of the most promising and interest ing directions of using SCA is the medical biological area, 17 which is caused by high solubility of SCA in water, low toxicity, 17 and accessibility of functionalization, which makes it possible to control physicochemical properties of these compounds by changing the nature of substituents and the number of aromatic rings. For instance, the in troduction of alkyl radicals into the SCA molecule favors the change in its hydrophilic lipophilic balance and the appearance of surfactant properties. 1,4 A consequence of an increase in the number of aromatic rings is the confor mational mobility of the macrocycle, 5,6,9-11,17 resulting in the appearance of the adaptive ability to substrate binding (flexible "tuning"). 18 Although many publications are de voted to p sulfonatocalix[n]arenes, the aggregation be havior of SCA modified by alkyl radicals was not system atically studied.The mechanism of interaction of biologically active compounds with the cell membrane surface depends, to a great extent, on hydrophobicity of these compounds and their aggregation state. 19-22 Many micelle forming sur factants possess antimicrobial activity and can enhance the effect of sulfamide drugs and solubilize hydrophobic drugs by transforming them into the soluble form. 19,23 It is known that the energy processes in cells are tightly related to the phosphorylation dephosphorylation reactions of membrane proteins. 24 The study of biological aspects of application of nonmodified p sulfonatocalix[n]arenes showed that unsubstituted SCA (n = 4, R = Н) manifest supramolecular catalytic activity in hydrolysis of ATP, 17 which can change substantially in the case of alkylated SCA. Therefore, the complex study of the aggregation properties of alkylated SCA, their catalytic activity in the model reaction of hydrolysis of phosphorus acid esters, and the influence on biosystems is an urgent problem, whose solution will hel...

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