The study of supramolecular “host-guest” complexes in solutions is of fundamental and practical significance. The structures and formation enthalpy of supramolecular complexes for the 4-DASPI dye with two cavitands (cucurbit[6]uril and cucurbit[7]uril) have been obtained by the TDDFT quantum chemistry method with a camb3lyp basis. It was shown by visualization of the structures that the size of cucurbit[6]uril is too small and doesn’t allow the dye chromophore to penetrate into the cavitand cavity while the dye stays in the ground state, but the formation of an external complex is possible. On the contrary, formation of an inclusion complex with the cucurbit[7]uril is energetically favorable, and the dye chromophore penetrates into the cavity. Visualization of the complex structure allows us to determine the chromophore position relative to the given cavitand cavity, and thus we can predict the changes in the dye spectra due to complexation. The theoretical results of the work are in good correlation with the experiment.

The solvatochromic shifts of the maxima of the absorption spectra of a 4-DASPI dye (4-[4-(dimethylamino)styryl]-1-methylpyridinium iodide) in a water–ethylene glycol binary solvent in a range of concentrations of 0–100% are experimentally studied. The dependence of the solvatochromic shift on the macroscopic permittivity (dielectric constant) of the solution and concentration of ethylene glycol is constructed. The Onsager–Liptay model is applied for the theoretical interpretation which makes it possible to estimate the effective permittivity in the microscopic region directly adjacent to the chromophore based on the values of the measured solvatochromic shifts. It is found that the value of the permittivity in the solvate shell of this dye substantially differs from the macroscopic value of this quantity, which means that the shell is significantly enriched with ethylene glycol (specific solvation) throughout the entire range of concentrations, and the enrichment reaches a maximum approximately in the middle of the specified range. The composition of the solvate shell of the dye at different values of the concentration is discussed.

A hydrogel with gold nanoparticles stabilized in a citrate buffer is obtained by dehydration from a solution (sol-gel transition). The morphological characteristics of the hydrogel are studied using cryogenic transmission electron microscopy, in particular cryoelectron tomography. The spatial structure of the hydrogel is studied in three dimensions. The dimensional parameters of the nanoparticles and distances to nearest neighbors are determined. It is found that most of the nanoparticles are in a bound state and form clusters in the process of hydrogel formation.

We investigated the preferential solvation effect of pyridinium-N-phenolate betaine (organic dye) taken as a molecular probe in two binary solvents (water-BuOH and water-BuNH 2 ) in concentration range 0-100%. The Onsager-Liptay model was used to connect the spectral solvatochromic shift in solvation shell of the dye with the dielectric permittivity of the environment around its chromophore. That makes it possible to estimate the effective dielectric constant in the microscopic region of the probe, based on the values of the experimentally measured solvatochromic shifts. It was shown that the solvation shell of the dye is significantly depleted with the second component of binary solvent in water solution. It is true both for the water-BuOH and water-BuNH 2 solvents. The absolute spectral shift in case of water-BuNH 2 solvent is greater than in the second case. However, the relative depletion is stronger in case of water-BuOH. The innovative potential of the method is in the development the nanoprobe devices to measure the dielectric constant of small objects and nano-regions, to control instantaneous solvent concentration into evaporating sessile droplet of binary solvent in different zones of the droplet.

A comprehensive analysis of an aqueous solution of gold nanoparticles with an average size of 6 nm in a citrate buffer has been carried out, with investigation of the solution rheology and structure by electron and atomic force microscopy. A deviation of the rheological behavior of hydrosol from the Newtonian properties is found even at low gold nanoparticle concentrations. The specific features of the rheological behavior of hydrosol are explained based on the transmission electron microscopy (TEM) data.

The results of studies of the growth of p -quaterphenyl crystalline films under conditions of physical vapor transport (PVT) are presented. The surface energy of the most developed (001) face was studied experimentally by the contact angle method. The surface energies of the (100), (010), (110), and (001) faces of p ‑quaterphenyl (100) crystals were determined in the approximation of the OPLS atomic force field method. The crystal morphology was analyzed taking into account the crystal structure and the obtained surface energies of faces. The parameters of nucleation of p -quaterphenyl crystals were studied under experimental conditions of growth from solutions at the solution–air interface and from the vapor phase (PVT method) within the framework of the classical nucleation theory.

The influence of different solvents on the growth of anthracene crystals from solutions and on their morphological quality has been investigated. The dependence of the surface tension of solutions of anthracene in toluene on the anthracene concentration has been determined using the hanging drop method under conditions similar to the crystal growth conditions at the solution–air interface in an atmosphere saturated with solvent and precipitant vapors. The surface energies of the (100), (010), and (001) faces of anthracene crystal are calculated based on the structural data using the OPLS all-atom force field method. The surface energy value $${{\sigma }}_{{001}}^{V}$$ at the air interface is estimated experimentally by measuring the contact water-drop wetting angle for the most developed (001) face. The thermodynamic analysis of the nucleation parameters for anthracene crystals at the solution–air interface has been carried out based on the obtained data on the surface energy.

Solvatochromic shifts of the absorption spectra maxima of the dye 4-DASPI (4- [4- (dimethylamino) styryl] -1-methylpyridinium iodide) in a binary solvent water-ethyleneglycol in the concentration range 0-100% were experimentally investigated. The dependence of the solvatochromic shift on the macroscopic dielectric constant of the solution and the concentration of ethyleneglycol was determined. The Onsager-Liptay model was used for the theoretical interpretation of the experimental data. It made it possible to estimate the effective dielectric constant in the microscopic area that contacts with dye chromophore taking into account the measured solvatochromic shifts. It was found that the value of the dielectric constant in the solvation shell of this dye differs significantly from the macroscopic value. The solvation shell is significantly enriched by ethyleneglycol (preferential solvation) over the components’ concentration range. The enrichment reaches its maximum approximately in the middle of this range. The composition of the dye solvation shell at different concentration is discussed.

Crystals of linear oligophenyls p-nP (n is the number of phenyl groups) are of interest for organic electronics and photonics as effective blue emitters and scintillators. The surface properties and external conditions of the growth medium are the determining factors in the nucleation and formation of crystals. However, the crystallization processes of conjugated linear molecules are still understudied and there is practically no experimental data on the surface properties of solutions and crystals. At the same time, there are few studies in the literature on modeling the surface energy of the crystal faces of these substances [1]. This work presents the results of studying of the linear oligophenyls (n = 2..6) crystals growth from solutions and the vapor phase. In the approximation of the OPLS atomic force field method, the values of the surface energy of the (100), (010), (110), and (001) faces of the crystals are determined. Based on the data on the crystal structure and the obtained values of the surface energy of the faces, the morphology of the crystals is analyzed and their equilibrium shapes are predicted. Within the framework of the classical nucleation theory, the parameters of crystal nucleation under experimental conditions of growth from solutions and physical vapor transport are studied. References 1. Nabok D., Puschnig P. and Ambrosch-Draxl C. Phys. Rev. B 2008, B 77, 245316. Studies in part on crystals growth from solution and modeling the surface energy of crystal faces were made with financial support from the Ministry of Science and Higher Education of the Russian Federation within the State assignment FSRC “Crystallography and Photonics” RAS using the equipment of Collaborative Access Center “Structural diagnostics of materials” (project # RFMEF162119X0035); studies in part on crystals growth by the PVT method, their crystal structure and nucleation thermodynamic analysis were made under the support of the Russian Foundation for Basic Research (grant no. 19-32-90145); development of the approaches to purification of the conjugated oligomers was supported by the Russian Science Foundation (grant no. 18-73-10182).

The morphology of photonic-crystal structures formed by the self-assembly of fluorescent marker nanoparticles from evaporating droplets of a binary water–glycerol solvent, the components of which differ appreciably from each other in the viscosity and evaporation rate, being infinitely mutually soluble under normal conditions, was has been studied experimentally for the first time. It has been shown that the main self-assembly disordering factor is Marangoni vortex flows, and the change in the initial concentration ratio between binary mixture components enables the control over the degree of disordering in the solid phase, which is formed after the solvent is evaporated from a droplet and distributed over the substrate. A low initial concentration of any component corresponds to the most ordered distribution, whereas their medium concentrations correspond to the most disordered distribution. The characteristic values of Marangoni numbers in experiments have been calculated. It has been demonstrated that the average radius of the distribution of an ensemble of marker particles over a substrate may serve as a descriptor for the degree of ordering.

An analysis of the change in the Gibbs free energy ∆G upon the formation of a flat nucleus of a p-terphenyl crystal at the liquid – air interface is presented, taking into account the anisotropy of the surface energy of the faces. The surface energy values of the p-terphenyl crystal faces were calculated by the atomic force field method OPLS, based on structural data. Experimental information on crystal growth from solutions and their surface properties was used to analyze the model.

Computer modeling the dielectric properties of the cucurbit [7]uril (CB [7]) cavity based on the Onsager-Liptay model was carried out by analyzing the solvatochromic shift of the absorption spectrum of 1-(3ammoniumpropyl) -4-[(E) -2-(3,4-dimethoxyphenyl) ethynyl]pyridinium upon the formation of the inclusion complex with CB [7] in a water solution. The CB [7] cavity was considered as a polar environment into which the dye chromophore is placed. Positions of the maxima of the dye absorption spectra were measured experimentally in the following solvents: methanol, ethanol, i-propanol, n-butanol and water with known dielectric and optical properties. These values were used for parametrization of the Onsager-Liptay equation. Quantum-chemical calculations were used to determine molecular structures, dipole moments of the ground and excited states, and polarizability of the dye. Theoretical value of the effective dielectric permittivity of the cavity is in good agreement with the literature data derived by another method. Thus, we propose a new method for investigation the dielectric constant both in bulk liquids and in very small liquid volumes, for example, into picoliter droplets.

An analysis of the variation of Gibbs free energy Δ G upon the formation of a plane nucleus of the p -terphenyl crystal at the liquid–air interface is presented, in which the anisotropy of the surface energy of faces are considered. The values of the surface energy of faces of the p -terphenyl crystal are calculated using the OPLS atomic force field method based on structural data. Experimental data on the growth of crystals from solutions and their surface properties are used in the analysis of the model.

Study of dielectric properties of the macrocyclic molecules cavity that can form inclusion complexes with dye molecules is an important problem. Changes in absorption spectra of chromophore inserted into macrocyclic cavity with the formation of the supramolecular complex can be considered as solvatochromic shift. This shift caused by changes of dielectric properties of the environment around the chromophore when it moves from water solution to macrocyclic cavity. Theoretical model that can describe the effective dielectric permittivity of the cavity allows predicting solvatochromic spectral shift of dye molecules due to non-covalent supramolecular complexation. Such a dye molecule could apply as a nano-probe for measurement of the effective dielectric constant of any local surrounding media in which its chromophore can be inserted.

A new approach to the theoretical evaluation of the local dielectric properties of media that contain an organic dye acting as a nanoprobe is proposed. The method is checked so as to evaluate the dielectric properties of the host molecule in a supramolecular inclusion complex from the experimentally measured shift of the optical absorption spectrum of the guest molecules (dye) after the complex formation. Using the Onsager–Liptay model, the dielectric properties of the cucurbit[7]uril cavity was theoretically estimated by analyzing the experimentally measured shift of the absorption spectrum of 1-(3-ammoniopropyl)-4-[(E)-2-(3,4-dimethoxyphenyl)-ethenyl]-pyridinium dication of the dye after it forms a complex with cucurbit[7]uril in an aqueous solution. To parameterize the Onsager–Liptay equation, the positions of the absorption spectral maxima of the dye under study were experimentally measured in the following solvents with known dielectric and optical properties: methanol, ethanol, 1-propanol, 1-butanol, and water. When calculating molecular structures, dipole moments of the ground and excited states, and polarizability, the TD-DFT quantum chemical method with the CAM-B3LYP functional in the 6-311G(d,p) basis set was used within the Gamess (United States) software package. The obtained theoretical value of the effective dielectric permittivity of the cavity (about 13) is in good agreement with the published value.