A variety of physicochemical methods were used to examine the self-organization, physicochemical, UV absorption, and fluorescent properties of diluted aqueous solutions (calculated concentrations from 1·10 −20 to 1·10 −2 M) of the membrane voltage-dependent potassium channels blocker 4-aminopyridine (4-AP). Using the dynamic light scattering method, it was shown that 4-AP solutions at concentrations in the range of 1·10 −20 –1·10 −6 M are dispersed systems in which domains and nanoassociates of hundreds of nm in size are formed upon dilution. An interrelation between the non-monotonic concentration dependencies of the size of the dispersed phase, the fluorescence intensity ( λ ex 225 nm, λ em 340 nm), specific electrical conductivity, and pH has been established. This allows us to predict the bioeffects of the 4-AP systems at low concentrations. The impact of these diluted aqueous systems on the electrical characteristics of identified neurons of Helix lucorum snails was studied. Incubation of neurons in the 4-AP systems for which the formation of domains and nanoassociates had been established lead to a nonmonotonic decrease of the resting potential by 7–13%. An analysis of the obtained results and published data allows for a conclusion that a consistent change in the nature and parameters of the dispersed phase, as well as the pH of the medium, apparently determines the nonmonotonic nature of the effect of the 4-AP systems in a 1·10 −20 –1·10 −6 M concentration range on the resting membrane potential of neurons. It was found that the pre-incubation of neurons in the 4-AP system with a concentration of 1·10 −12 M led to a 17.0% synergistic decrease in the membrane potential after a subsequent treatment with 1·10 −2 M 4-AP solution. This finding demonstrates a significant modifying effect of self-organized dispersed systems of 4-AP in low concentrations on the neurons’ sensitivity to 4-AP.

The interest in functional supramolecular systems for the design of innovative materials and technologies, able to fundamentally change the world, is growing at a high pace. The huge array of publications that appeared in recent years in the global literature calls for systematization of the structural trends inherent in the formation of these systems revealed at different molecular platforms and practically useful properties they exhibit. The attention is concentrated on the topics related to functional supramolecular systems that are actively explored in institutes and universities of Russia in the last 10–15 years, such as the chemistry of host–guest complexes, crystal engineering, self-assembly and self-organization in solutions and at interfaces, biomimetics and molecular machines and devices. The bibliography includes 1714 references.

The issue of protecting aquatic ecosystems from biologically active compounds (BACs) such as pesticides and pharmaceuticals detected in aquatic environments at low concentrations has become urgent. Presently, literature provides much information about BACs that at low concentrations cause significant damage to hydrobionts, but a physicochemical explanation for these phenomena has appeared only relatively recently. Experimental findings have shown that diluted aqueous solutions of BACs are self-organized disperse systems, whose disperse phase (nanoassociates) rearranges upon dilution, which is accompanied by nonmonotonous changes in the physicochemical and biological properties of the system. This work introduces the study of fluorescence and UV absorption of aqueous diluted systems of a biogenic succinic acid (SA), used as an antihypoxic and antioxidant pharmaceutical. It is shown for the first time that the fluorescence spectra (A ex at 225 nm) of SA systems are informative at the calculated concentrations range from 1.10(-17) to 1.10(-5) M. The nonmonotonous concentration dependence of fluorescence intensity (lambda(ex) at 225 nm, lambda(em) at 350 nm) is in good agreement with the data on nanoassociates' size, as well as with both the physicochemical properties of SA systems and their biotesting results, which were obtained using the certified procedures for monitoring the toxicity of natural waters and wastewater. The observed coherence between the fluorescence intensity of SA systems and the nanoassociates' size allows for the conclusion that it may be possible to consider fluorescence as a potential marker of self-organization and bioeffects of diluted aqueous BACs systems. (C) 2020 Elsevier B.V. All rights reserved.

Diclofenac sodium (DS) is a widely used nonsteroidal anti-inflammatory drug (NSAIDs). NSAIDs are poorly removed during standard wastewater treatment. The consequences of the presence of NSAIDs in rivers and lakes at 10(-11)-10(-8) mol/L are not yet established; therefore, ecotoxicologists have focused their efforts on studying the effect of low-concentration NSAIDs on fish and hydrobionts, and also on predicting the potential risks to humans. Literature provides some information about the bioeffects of some NSAID solutions in low concentrations but there is no physicochemical explanation for these phenomena. Studying the physicochemical patterns of DS solutions in the low range of concentrations and establishing an interconnection between the solutions' physicochemical properties and bioeffects can provide a conceptually new and important source of information regarding the unknown effects of DS. The physicochemical properties and action of DS solutions on Ceriodaphnia affinis cladocerans, Paramecium caudatum infusoria, Chlorella vulgaris unicellular green algae, as well as on the growth of the roots of Triticum vulgare wheat seeds, were studied in the calculated concentration range of 1 x 10(-3)-1 x 10(-18) mol/L. The relationship between these phenomena was established using the certified procedures for monitoring the toxicity of natural water and wastewater. It was shown for the first time that water solutions of DS are dispersed systems in which the dispersed phase undergoes a rearrangement with dilution, accompanied by changes in its size and properties, which affects the nonmonotonic dependences of the system's physicochemical properties and could cause nonmonotonic changes in action on hydrobionts in the low concentration range. (C) 2019 The Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences. Published by Elsevier B.V.

The self-organization and physicochemical properties of aqueous solutions of the sodium salt of azosulfimate calix[4] arene (1) were studied in a wide range of concentrations 1.10(-10)-1.10(-1) M using a complex of methods. It has been found that the solutions of macrocycle 1 are in fact complex disperse systems, the nature of disperse phase in which changes with dilutions -from micelles (CMC = 2.5.10(-2) M) and premicellar aggregates (1.10(-2)-1.10(-3) M) of the size of 1 nm to supramolecular domains (1 .10(-3)-1. 10(-6) M) with sizes of tens and hundreds of nm. Jointly using the methods of dynamic light scattering and UV spectroscopy it was shown for the first time that the nonlinear character of the concentration dependence of the optical absorbance (A(360)) in the concentration range 1.10(-6)-1.5.10(-5) M is a result of the rearrangements of supramolecular domains of 1, accompanied by the transition from bi- to monomodal pattern of particles' size distribution, as well as by non-monotonic change in their size and zeta-potential. It was established that molecules of 1 are not capable of photoisomerization of the azobenzene group, which may be due to steric hindrances to the process of isomerization of closely located azoarylsulfonate groups located on one side of the plane of macrocycle 1.

The synthesis and study of self-association and encapsulation ability of new low toxic conjugate of tetraphenyleneoxypentylcalix[4]resorcinarene and methoxy-poly(ethylene glycole) (C5OPh-mPEG) were described. The conjugate is characterized by 1H, 13C NMR, FT-IR, MS, SLS methods. In an aqueous solution the conjugate form multimicellar nanoparticles with low polydispersity value (0.1, DLS method). The self-association of the conjugate was studied by DLS, fluorescence, fluorescence anisotropy method, TEM, and SAXS methods. The SAXS data were detailed analyzed, and the conjugate associates structure as ellipsoidal core-shell particles was proposed. The encapsulation efficiency is a result of the affinity of the conjugate low rim substituents to substrates and reaches of 39.8, 26.7, and 28.9% toward naproxen, ibuprofen and doxorubicin drugs, respectively.

The reasons for the very high reactivity and variability of reactivity of two dienophiles, tetracyanoethylene (1) and 4-phenyl-1,2,4-triazoline-3,5-dione (2), in the Diels–Alder reactions were considered. The data on the rate of reactions with anthracene (3), benzanthracene (4) and dibenzanthracene (5) in 14 solvents over a range of temperatures and high pressures, data on the change in the enthalpy of solvation of reagents, transition state, and adducts in the forward and backward reactions, and the enthalpies of these reactions in solution were obtained. Strong π-acceptor dienophile 1 has sharply reduced reactivity in reactions in π-donor aromatic solvents. It was observed that the π-acceptor properties of dienophile 1 disappear upon passage to the transition state and adduct. Large solvent effects on the reaction rate can be predicted for all types of reactions involving tetracyanoethylene. Very high reactivity of dienophiles 1 and, especially, 2 can be useful to catch such carcinogenic impurities such as 3–5 and neutralize them by transformation into less dangerous adducts.

Kinetic parameters of the unusual [2+2 sigma+2 sigma]-cycloaddition reactions of quadricyclane (1) with tetracyanoethylene (2), 4-phenyl-1,2,4-triazoline-3,5-dione (3), N-phenylmaleimide (4), and diethyl azodicarboxylate (5) are determined experimentally. Additionally, the enthalpies of 1+2 reaction in 1,4-dioxane solution (-236.6 +/- 1.0kJmol(-1)) and 1+3 reaction in toluene (-255.0 +/- 2.8kJmol(-1)) are determined calorimetrically and shown to be the largest in absolute magnitude among all known cycloaddition reactions involving these dienophiles. Solvent effect on the rate of 1+3 reaction in 11 solvents is studied and found to be moderate and similar to that of the conventional Diels-Alder and ene reactions. The difference in the reaction rate constants of 1 with different dienophiles can be up to 9 orders of magnitude and is mainly caused by the difference in activation enthalpies. This difference is not correlated with the standard enthalpies of reactions and is likely the result of high sensitivity of the [2+2 sigma+2 sigma] reaction rates to the energy of donor-acceptor interactions between the reactants.

Here we present the supramolecular surfactant-macrocycle system which properties are independent on system composition in the wide range of components concentrations. The study of the interaction of octacarboxy-tetra(p-phenylene-oxy-pentyl)calixresorcinarene (C5R) and cetylpyridinuim chloride (CPC) in mixed aqueous solutions were performed by dynamic light scattering and electrophoretic methods, 1H and FT-PGSE NMR methods, absorption and fluorescence spectroscopy, and TEM. The variation of CPC/C5R molar ratio from 30/1 to 10/1 leads to the formation of nanoassociates with similar composition, size, surface potential value, and improved (in compare with CPC) solubilizing properties. The preparation of mixed supramolecular systems which properties are independent on system composition in the wide range of components concentrations is an elegant example of the producing of colloidal materials with the required morphology and properties.

Novel polymer nanospheres (p(SRA-B)) were prepared by cross-linking a sulfonated resorcinarene (SRA) with phenylboronic acid. p(SRA-B) shows good stability in water and can be used as a nanocontainer for the pH- and glucose-controlled substrate release. Fluorescent dyes (fluorescein, pyrene and 1,3,6,8-pyrenetetrasulfonic acid tetrasodium salt) were successfully loaded into p(SRA-B). The release of dye is achieved by lowering the pH value to 3 or by adding glucose.

Four new tetrasubstituted [1.1.1.1]metacyclophanes (4-7), that are inherently adopting a 1,3-Alternate conformation, bearing four or eight peripheral carboxylic binding sites, and appended with spacers group (alkyl or phenyl) differing by the flexibility, have been synthesised in high yields. The structures of the obtained compounds have been investigated in solution as well as in the solid state, for three of them, by using single-crystal X-ray analysis. (C) 2018 Elsevier Ltd. All rights reserved.

In a concentration range of 1.0–1.0 × 10–17 mol dm–3, aqueous systems based on (S)-and (R)-lysine vary in the ability to form a dispersed phase (domains and nanoassociates) hundreds nanometers in size with different UV absorption spectra of these systems.

In order to obtain a non-toxic amphiphilic calixresorcinarene capable to form nanoconjugates for drug encapsulation, tetraundecylcalixresorcinarene functionalized by methoxy poly(ethylene glycol) chains has been synthesized. The macrocycle obtained is characterized by low hemotoxicity. In aqueous solution it forms nanoassociates that are able to encapsulate organic substrates of different hydrophobicity, including drugs (doxorubicin, naproxen, ibuprofen, quercetin). The micelles of the macrocycle slowed down the release of the hydrophilic substrates in vitro. In physiological sodium chloride solution and phosphate-buffered saline, the micelles of the macrocycle acquire thermoresponsive properties and exhibit a temperature-controlled release of doxorubicin in vitro. The combination of the low toxicity and the encapsulation properties of the obtained calixresorcinarene–mPEG conjugate shows promising potential for the use as a supramolecular drug-delivery system.

Here we present the consecutive study of colloid systems formed by novel isatin derivative as compound with high pharmacological potential and series of carboxyresorcinarenes. The azo-modified isatin derivative bearing ammonium moiety (I-3) was synthesized and its antimicrobial activity was investigated. To increase its solubility the solubilization experiment using amphiphilic carboxyresorcinarenes, characterized by low hemolytic activity, was carried out. The I-3 – macrocycles systems were studied by NMR, UV–vis, DLS and TEM. The FT PGSE and 2D NOESY NMR methods demonstrated, that solubilization of I-3 is caused by the incorporation of its molecules in the hydrophobic part of the macrocycles associates. Herewith the loading efficiency of I-3 into the macrocycles associates was reached of 20–30% due to the change of the volume of hydrophobic part of associates by varying the length and structure of hydrophobic substituents of macrocyclic amphiphiles.

The data on temperature, solvent, and high hydrostatic pressure influence on the rate of the ene reactions of 4-phenyl-1,2,4-triazoline-3,5-dione (1) with 2-carene (2), and -pinene (4) have been obtained. Ene reactions 1+2 and 1+4 have high heat effects: Hr-n (1+2) -158.4, Hr-n(1+4) -159.2kJ mol(-1), 25 degrees C, 1,2-dichloroethane. The comparison of the activation volume (V(1+2) -29.9 cm(3) mol(-1), toluene; V(1+4) -36.0 cm(3) mol(-1), ethyl acetate) and reaction volume values (Vr-n(1+2) -24.0 cm(3) mol(-1), toluene; Vr-n(1+4) -30.4 cm(3) mol(-1), ethyl acetate) reveals more compact cyclic transition states in comparison with the acyclic reaction products 3 and 5. In the series of nine solvents, the reaction rate of 1+2 increases 260-fold and 1+4 increases 200-fold, respectively, but not due to the solvent polarity.

New lower rim functionalized thiacalix[4]arenes 7 and 8 in 1,3-alternate conformation containing photoswitchable azobenzene fragments and carboxyl groups as cation binding sites were obtained. The structure of the obtained compounds was established by ID and 2D NMR H-1 spectroscopy and MALDI-TOF mass spectrometry The ability of compounds 7 and 8 to form nanoaggregates in solution was studied by dynamic light scattering (DLS) both in the presence of cations of d/f elements and without them. Compound 7 forms in the solution time-stable nanoparticles with a diameter of about 3.5 nm, which, according to molecular modeling, are monomers. A similar result has been obtained for complexes based on Zn (II) and Tb(III) cations in different metal/ligand ratios (from 1:1 to 4:1). The metal/ligand=2: 1 stoichiometry determined by the UV -titration method for the complexes based on compound 7 indicates the formation of intramolecular chelate complexes typical for calixarenes in the 1,3-alternate conformation. Irradiation of macrocycle 7 solutions at a wavelength of 254 nm (8 W) for 30 minutes resulted in a small decrease of size of the nanoparticles till 2-2.5 nm. Obviously, compound 7 in cis form becomes more compact, which was confirmed by quantum-chemical modeling. A similar result is observed for the complexes with Zn(II) cations. For the Tb(III) ions which are considered as harder acids relative to Zn(II) cations, accordingly to HSAB theory, the aggregation process leads to increasing of nanoparticle size due to the interaction of Tb(III) cations with peripheral cis-N=N groups of compound 7. In contrast to macrocycle 7, compound 8 with Zn(II) and Tb(III) cations forms complexes of 1:1 stoichiometry. This leads to dramatic changing of aggregation behaviour of compound 8 compared to compound 7 either in the absence or in the presence of metal ions in the solution. Photoisomerization of the macrocycle 8 afforded an increasing (up to 2000 nm) of the size of the nanoaggregates observed in the solution. Thus, the formation of nanoscaled aggregates based on synthesized macrocycles and their complexes with Zn(II) and Tb(III) cations depends significantly on the availability of carboxyl groups for intermolecular interactions and the ability of metal ions to bind peripheral cis-azo groups. So, it has been shown that on the basis of synthesized macrocycles and their complexes with Zn(II) and Tb(III) cations, the photoswitchable supramolecular systems able to be controlled by the light irradiation can be created.

The kinetics of the Diels–Alder (DA) reactions of 4-phenyl-1,2,4-triazoline-3,5-dione 1, trans-diethyl azodicarboxylate 2, and tetracyanoethene 3 with 1,3-cyclohexadiene 4, cycloheptatriene 5, 1,3-cycloheptadiene 6, cyclooctatetraene 7, and 1,3-cyclooctadiene 8 in a range of temperatures and pressures has been studied. Values of the enthalpy, entropy, and volume of activation, as well as the enthalpy and volume of reaction have been obtained. Observed reaction rates of 5+1 and 7+1 have been compared with the known rate of norcaradiene 17 formation in the equilibrium , and that of bicyclo[4,2,0]-octa-2,4,7-triene 20 in the equilibrium . The kinetic data show that the rate of formation of 17 from 5 is much greater than the loss rate of dienophile 1 in reaction of 5+1. In contrast, the formation rate of tautomer 20 is less than the loss rate of dienophile 1 in reaction of 7+1. This reflects that the consecutive reaction of 5 → 17 (+1) → 15 is possible whereas the consecutive reaction of 7 → 20 (+1) → 22 does not occur as the only way.

In this article, we report the synthesis of mono- and bimetallic Pd–Ni nanocomposites supported on a multicharged polymeric matrix for catalytic applications.

The rates of the Diels–Alder reaction of 9-(hydroxymethyl)anthracene and 9,10-bis(hydroxymethyl)anthracene with maleic anhydride and two maleimides, N -ethyl- and N -phenylmaleimide, have been studied at various temperatures and pressures in different solvent media. A rate acceleration in water in comparison with organic solvents is observed. Thermodynamic functions of activation for the reaction of 9,10-bis(hydroxymethyl)anthracene with N -ethylmaleimide in binary 1,4-dioxane–water mixtures are determined. From the observed tendencies, it can be concluded that acceleration of the Diels–Alder reactions in water is linked with an energetically favorable dehydration of the reaction centers of the reactants on the way to the activated complex. Addition of an organic cosolvent makes the desolvation of these centers less favorable.

Using a complex of physicochemical methods it has been shown for the first time that the diluted solutions (10-11-10-3.) of dodecyl derivative of p-sulfonatocalix[6] arene are disperse systems, where the role of a disperse phase is played by the supramolecular structures of different nature - micelles (above 6.10(-4).), domains (1.10(-4)-1.10(-7).) and nanoassociates (1.10(-9)-1.10(-8).). The disperse phase's parameters change nonmonotonically as systems dilution, what results in the decrease of surface tension at concentrations lower than the critical micelle concentration and determines the differences in systems' behaviour at various temperatures (15-60 degrees C) and hold up times (after 8 months).