Proceedings, 2018, IOCC 2018

The lighter group-V element phosphorus forms the As-type (hR2) structure under pressure, above 5 GPa, and at 10 GPa transforms to the simple cubic structure (cP1), similar to arsenic. Despite its low packing density, the simple cubic structure is stable in phosphorus over a very wide pressure range up to 103 GPa. On further pressure increase, the simple cubic structure transforms into a simple hexagonal structure (hP1) via a complex phase that was solved recently as incommensurately modulated. Structural transformations of phosphorus are connected with the changes of physical properties. Above 5 GPa phosphorus shows superconductivity with T_c reaching ~9.5 K at 32 GPa. The crystal structures and properties of high-pressure phases for phosphorus are discussed within the model of the Fermi sphere and Brillouin zone interactions. Full article

Features of solute-solvent intermolecular interaction establishing hydrogen bonds were studied in view of proton sharing in the O---H⁺–O moiety that is the prerequisite for proton moving through water. Liquid microcrystals are expected to be formed due to the protons moving through water confined in their precursors. Among the different oxygen-containing organic solvents well-dissolved in water, tetrahydrofuran (THF) has been found the most suitable since it forms a molecular complex with carbon dioxide dissolved in water producing the ions H⁺ and (HCO₃)⁻. This three-component complex exhibits in infrared spectra vibrational bands characterizing the complex and the proton sharing in the O---H⁺–O moiety. Assemblies consisting of mono- protonated meso-tetraphenylporphine (TPP) dimers self-organized into submicroscopic particles in solution and water with 0.86 mol·L⁻¹ THF have been investigated by infrared spectroscopy, SEM, and AFM in thin layers. Earlier found tight water covering the submicroscopic particles is proved to exhibit an ordered and non-ordered local areas on the surface. Molecular characteristics estimated for the three-component complex involving THF suggest that the complex together with the TPP dimers partakes in the crystallization process providing protons moving through water. Full article

Microscopic properties of nanocrystal Aluminum thin film have been simulated using the quasicontinuum method in order to study the surface defect influence in nanoindentation. Various distances between the surface defect and indenter have been taken into account. The results show that as the distance between the pit and indenter increases, the nanohardness increases in a wave pattern associated with a cycle of three atoms, which is closely related to the crystal structure of periodic atoms arrangement on {111} atomic close-packed planes of face-centered cubic metal; when the adjacent distance between the pit and indenter is more than 16 atomic spacing, there is almost no effect on nanohardness. In addition, the theoretical formula for the necessary load for the elastic-to-plastic transition of Al film has been modified with the initial surface defect size, which may contribute to the investigation of material properties with surface defects. Full article

We report the crystal structure of [Zn^II₂Ho^III(L)(ald)(HO)(H₂O)₃(MeCN)](NO₃)₂·EtOH [H₃L = 2-(5-bromo-2-hydroxy-3-methoxyphenyl)-1,3-bis[4-(5-bromo-2-hydroxy-3-methoxyphenyl)-3-azabut-3-enyl]-1,3-imidazolidine) and Hald = 5-bromo-2-hydroxy-3-methoxy-benzaldehyde]. Despite the presence of two bulky multidentate ligands, as well as several monodentate ligands surrounding the nonacoordinate holmium cation, and the two pseudooctahedral zinc ions, the intricate H-bonded system formed by this chiral heterotrinuclear complex is only expanded in a 2D supramolecular structure. The interactions involve the nitrate counterions and the solvated ethanol, in such way that each complex unit is connected to an identical enantiomer, and to two units of inverted chirality through H bonds. Full article

Reaction of 2-cyanopyridine with N-phenylthiosemicarbazide afforded the 4-phenyl-5-(pyridin-2-yl)-2,4-dihydro-3H-1,2,4-triazole-3-thione. Methyl 2-((4-phenyl-5-(pyridin-2-yl)-4H-1,2,4-triazol-3-yl)thio)acetate (phpy2NS, 1), derived from this 1,2,4-triazole-3-thione, was obtained by reaction with chloroacetic acid followed by an acid-catalyzed esterification of the carboxylic acid with methyl alcohol. Synthesis of a Hg(II) complex, [Hg(phpy2NS)Cl₂] (2), has been performed using the ligand (1) and HgCl₂. The molecular and supramolecular structures of the ligand and the complex were studied by X-ray diffractometry. Full article

A new technique of liquid phase epitaxy has been proposed in this work. It allows to eliminate known disadvantages of liquid phase epitaxy by creating short-time contact between a substrate and a solution-melt, as well as due to segmental deposition of an epitaxial layer over the working substrate surface. The short-time of the contact is achieved by the means of Ampere force acting on the solution-melt. And the contact itself between the substrate and the solution-melt is realized pointwise (or segmentally) over the substrate surface using the scanning principle. The new technique was named “scanning liquid phase epitaxy”. One of the modifications of device realization of the technique proposed has been considered and its principle of operation has been described. Preliminary theoretical investigations and experimental processes of semiconductor epitaxial layers obtaining have proved principal operational capability of the new technique. The technique developed allows to obtain thin and ultrathin epitaxial layers on the substrates of very large area which is limited only by the growth equipment size. Full article

Order to disorder transitions are important for 2D objects such as oxide films with a cellular porous structure, honeycomb, graphene, and Bénard cells in liquid and artificial systems consisting of colloid particles on a plane. For instance, solid films of the porous alumina represent an almost regular quasicrystal structure (perfect aperiodic quasicrystals discovered in 1991 is not implied here). We show that, in this case, the radial distribution function is well described by the quasicrystal model, i.e., the smeared hexagonal lattice of the two-dimensional ideal crystal by inserting a certain amount of defects into the lattice. Another example is a system of hard disks in a plane, which illustrates the order to disorder transitions. It is shown that the coincidence with the distribution function, obtained by the solution of the Percus-Yevick equation, is achieved by the smoothing of the square lattice and injecting the defects of the vacancy type into it. However, a better approximation is reached when the lattice is a result of a mixture of the smoothened square and hexagonal lattices. Impurity of the hexagonal lattice is considerable at short distances. Dependences of the lattices constants, smoothing widths, and impurity on the filling parameter are found. Transition to the order occurs upon an increasing of the hexagonal lattice contribution and decreasing of smearing. Full article

The structure of metallomesogen complexes differs essentially from that of calamitic liquid crystals, which emerges in their physical properties. We studied anomalous features of the transition from the nematic to isotropic phase in the ytterbium-based liquid crystal complex. For this, two approaches were used. In the first approach, we showed that the experimental values of the dielectric and optical anisotropies measured near the phase transition turned out to be substantially smaller than their calculated values. This evidently occurs because the phase transition temperature in the deep region of the experimental cell differs from that near the surface of the cell. Secondly, the temperature of N–I transitions in metallomesogenic layers within glass sandwich cells is obtained directly by means of the polarization microscope method. It was found that the phase transition temperature drops in more than ten degrees when reducing the metallomesogenic layer thickness from 200 to 5 microns. The calamite liquid crystals show the confinement effect only within the interstice of the specific size smaller than one micron. An anomalous confinement effect can be caused by a strong interaction of the molecular complexes with each other. Full article

A new Z = 8, Z′ = 2 polymorph of 4-oxo-4-phenylbutanoic (β-benzoylpropionic) acid, C₁₀H₁₀O₃, was obtained. The previously published two polymorphs with CCDC codes VERMAG and VERMAG01 crystallize with Z = 4, Z′ = 1 in monoclinic space groups P2₁/c [a = 15.071(10), b = 5.435(9), c = 16.058(10), β = 129.57(10)°] and P2₁/n [a = 12.728(6), b = 5.200(3), c = 14.426(6), β = 111.33(3)°], respectively. Reported herein, polymorph crystallizes in monoclinic space group P2₁/c and has significant larger cell volume of 1754.51 ų [a = 15.2673(6), b = 5.2028(2), c = 22.3063(8), β = 98.0217(7)°]. Structurally, new polymorph differs from two known other slightly (RMSD of about 0.112–0.183 Å). All polymorphs contain dimers of molecules bounded by intermolecular hydrogen bonds leaving carbonyl groups at Position 4 unaffected. Full article

Compounds containing benzimidazole moiety in solid state often demonstrate the ability to the formation of π-π stacking interactions. In this work, we focused on the investigation of intermolecular hydrogen bonds and parallel displaced (PD) π-π stacking interactions found in the crystals of titled molecules, both crystallize with Z = 2 in the space group P-1. Differences of the π-π stacking interactions parameters depending on the volume of side aromatic substituent in a homologous series, as well as a theoretical estimation of the energy of these interactions using DFT at two different functionals (M06-2X, MPWB95) and three basis sets [6-31G(d), 6-31++G, and 6-31++G(d)] were shown. Full article

The crystal structure and the structural features of the 8a-phenylhexahydropyrrolo[1,2-a]pyrimidine-6(2H)-one, C₁₃H₁₆N₂O, obtained by condensation of 4-phenyl-4-oxobutanoic acid with 1,3-diaminopropane. Molecules are weakly linked by the intermolecular hydrogen bonds C=O···H–N into the chains. These chains are weakly linked by π-π stacking interactions to form a three-dimensional framework. Full article

The majority of tunable liquid crystal devices are driven by electric fields. The performance of such devices can be altered by the presence of small amounts of ions in liquid crystals. Therefore, the understanding of possible sources of ions in liquid crystal materials is very critical to a broad range of existing and future applications employing liquid crystals. Recently, nanomaterials in liquid crystals have emerged as a hot research topic, promising for its implementation in the design of wearable and tunable liquid crystal devices. An analysis of published results revealed that nanodopants in liquid crystals can act as either ion-capturing agents or ion-generating objects. In this presentation, a recently developed model of contaminated nanomaterials is analyzed. Nanoparticle-enabled ion capturing and ion generation regimes in liquid crystals are discussed within the framework of the proposed model. This model is in very good agreement with existing experimental results. Practical implications and future research directions are also discussed. Full article

Metallomesogenic lanthanide complexes can be used as a basis for developing magneto- and electro-optical devices. The magnitude and sign of the dielectric anisotropy both play a leading role in this case. However, any direct measurements of the dielectric anisotropy for the most part of the metallomesogenic complexes are highly problematic since they only have a smectic phase, and therefore there is no way to produce macroscopic homogeneous samples. This problem can be solved due to the similarity between the mechanism of the dielectric polarization in the liquid crystal phase and that of the electrical birefringence in the isotropic phase. Thereby, one can estimate the dielectric anisotropy in the liquid crystal phase by studying the electrical birefringence in the isotropic melt. We have studied complexes consisting of ions of rare-earth metals such as Dy, Er, Gd, Tb, and of alkylsulfate counterions and Schiff bases as being ligands. The number of methylene groups in aliphatic chains of counterions was varied between 0 and 12. It was found that in the series of the substances under investigation the magnitude as well as the sign of electro- optical effect in the isotropic phase depended on length of the counterions, but not depended on the metal ions used. Thus, dielectric anisotropy of smectic lanthanide complexes can be widely changed by variations of chemical structure of the counterions. Full article

A₈Tl₁₁ (A = alkali metal) compounds have been known since the investigations of Corbett et al. in 1995 and still are matter of current discussions as the compound includes one extra electron referred to the charge of the Tl₁₁⁷⁻ cluster. Attempts to substitute the charge by incorporation of a halide atom succeeded for the lightest homologue of the group, Cs₈Ga₁₁Cl, and powder diffraction experiments for the heavier homologues also suggested the formation of analogous compounds. However, X-ray single crystal studies on A₈Tl₁₁X to prove this substitution and to provide a deeper insight into the influence on the thallide substructure have not yet been performed, probably due to severe absorption combined with air and moisture sensitivity for this class of compounds. In our contribution we present single crystal X-ray analyses of the new compounds Cs₈Tl₁₁Cl_0.8, Cs₈Tl₁₁Br_0.9 and Cs₅Rb₃Tl₁₁Cl_0.5. It is shown that a (partial) incorporation of halide can also be indirectly determined by examination of the Tl-Tl distances for low resolved data sets, e.g., for Cs_5.7K_2.3Tl₁₁Cl_?. Mixed occupied sites by two different alkali metals indicate a dependence on the cesium content, the systems K/Rb–Tl–Br and K/Rb–Tl–Cl only gave rise to the formation of the higher reduced (K/Rb)₈Tl₁₁ and the less reduced by-product (K/Rb)₁₅Tl₂₇. We have not been able to prove the formation of halide including thallides in the absence of cesium. Full article