Landau Model for Commensurate-Commensurate Phase Transitions in Uniaxial Improper Ferroelectric Crystals

We propose the Landau model for lock-in phase transitions in uniaxially modulated improper ferroelectric incommensurate-commensurate systems of class I. It includes Umklapp terms of third and fourth order and secondary order parameter representing the local polarization. The corresponding phase diagram has the structure of harmless staircase, with the allowed wave numbers obeying the Farey tree algorithm. Among the stable commensurate phases only those with periods equal to odd number of lattice constants have finite macroscopic polarizations. These results are in excellent agreement with experimental findings in some A2BX4 compounds.Comment: 9 pages, 5 figures, revtex, to be published in Journal of Physics: Cond. Matter as a Letter to the Edito

Zn(II) Based Potential Drug Containing Sertraline as a Strong Antidepressant Agent

A novel compound for depression treatment and other psychiatric disorders has been obtained being capable of displaying the combined benefits of sertraline and an essential element such as zinc in order to get better antidepressant and negative side effects. Our working group has synthesized a salt formulation (SerH2 ) 2 +[ZnCl4 ] 2- (C34H36N2 Cl8 Zn, sertralonium tetrachlorozincate(II)). The crystal structure was determined by X-ray diffraction methods. It crystallizes in the monoclinic P21 space group with a=7.3869(2) Å, b=13.2888(4) Å, c=19.3541(6) Å, β=96.596(3)° Å, β=91.792(4)°, and Z=2 molecules per unit cell. Their antidepressant activity in the forced swimming test (FST) proved to be stronger than the one shown by the commercial drug sertraline hydrochloride per se. Furthermore, this compound suppressed the anorexigenic effect caused by the antidepressant and showed an improvement in the assimilation time during in vitro fluorescence studies with bovine serum albumin. The results of this work have led to a patent application which was filed (Nº 20150103320) in Argentine country.Centro de Química InorgánicaFacultad de Ciencias ExactasInstituto de Física La Plat

Zn(II) Based Potential Drug Containing Sertraline as a Strong Antidepressant Agent

A novel compound for depression treatment and other psychiatric disorders has been obtained being capable of displaying the combined benefits of sertraline and an essential element such as zinc in order to get better antidepressant and negative side effects. Our working group has synthesized a salt formulation (SerH2 ) 2 +[ZnCl4 ] 2- (C34H36N2 Cl8 Zn, sertralonium tetrachlorozincate(II)). The crystal structure was determined by X-ray diffraction methods. It crystallizes in the monoclinic P21 space group with a=7.3869(2) Å, b=13.2888(4) Å, c=19.3541(6) Å, β=96.596(3)° Å, β=91.792(4)°, and Z=2 molecules per unit cell. Their antidepressant activity in the forced swimming test (FST) proved to be stronger than the one shown by the commercial drug sertraline hydrochloride per se. Furthermore, this compound suppressed the anorexigenic effect caused by the antidepressant and showed an improvement in the assimilation time during in vitro fluorescence studies with bovine serum albumin. The results of this work have led to a patent application which was filed (Nº 20150103320) in Argentine country.Centro de Química InorgánicaFacultad de Ciencias ExactasInstituto de Física La Plat

Phase transitions and related properties of organic-inorganic hybrid materials

Organic-inorganic hybrid perovskite materials incorporate inorganic as well as organic moieties into a single monolithic nanocomposite structure. Generally the crystals adopt a high degree of order through self-assembly which results from the various bonding interactions.Organic-inorganic aliphatic hybrid crystals are generally represented by the formula: [(CnH2n+1)NH3]2 MX4. These hybrid structures are characterized by an alternating structure where the ionic, inorganic metal halide layers are sandwiched between paraffinic alkylammonium chains (Ciajoloet al.1977; Zuniga et al. 1983; Guoet al. 1995). This study was based around hybrid materials containing a range of aliphatic amines and the divalent metals:Copper, Cobalt, Zinc, Mercury and Lead. The hybrid crystals that were synthesized in this study were structurally and thermally characterized as a majority of the structures were novel. The coordination of the inorganic metal-halide component was determined by the divalent metal centre. The divalent zinc, mercury and cobalt centers which were ionically bonded to chlorine, bromine or iodine tended to form isolated tetrahedral units. The zinc (II) chloride hybrid crystals however had the ability to coordinate as either isolated octahedral or isolated tetrahedral units. The lead and cadmium hybrid crystals coordinated as corner sharing octahedral units which extended along two dimensions. The packing characteristics of the cationic organic chains were directly influenced by the coordination and dimensionality of the inorganic component. The hybrid crystals were thermally characterized as they tend to exhibit a number of phase transitions such as solid-solid phase transitions and order-disorder transitions. Some hybrid crystals proved to be more stable than others when exposed to various atmospheric conditions. Overall the iodine containing crystals were not as stable as they tended to oxidized and degraded easily. The mercury containing crystals were also quite unstablewhen exposed to the atmosphere

Characterisation of the REACH Pre-Registered Substances List by Chemical Structure and Physicochemical Properties

In the European Union, the registrants of chemical substances under the REACH legislation are explicitly encouraged, and even required, to use non-testing methods as a means of identifying the presence or absence of hazardous properties of substances in order to meet the information requirements of REACH while at the same time minimising testing on vertebrate animals. The need to use non-testing methods or other alternative (non-animal) methods such as in vitro tests, has led to the development and implementation of Integrated Testing Strategies based as far as possible on the integrated use of non-animal data. The use of non-testing methods within such strategies implies the need for computational tools and a structured workflow to facilitate their application. The list of pre-registered substances (PRS) published by the European Chemicals Agency includes chemicals that industry may to register in accordance with the deadlines specified in the REACH legislation. The PRS list does not include information on chemical structures, which are a prerequisite for the development and application of non-testing methods. Therefore, in order to facilitate the implementation of non-testing methods for the regulatory assessment of REACH chemicals, the Computational Toxicology Group within the Joint Research Centre (JRC) has: ¿ generated structures for the PRS were by using the ACDLabs Name-to-Structure (NTS) software and validated them with a random sample ¿ processed the structures to generate substance identifiers such as IUPAC name, InChI codes and SMILES strings ¿ processed the structures to obtain information on chemical characteristics suitable for a preliminary assessment of the hazard and exposure ¿ indicated the availability of experimental toxicological data with DSSTOX and FOOTPRINT tags ¿ created a ¿QSAR-ready¿ data file to support the application of non-testing methods, such as QSARs The application of ACD NTS resulted in a high rate of yield for the generation of structures (85%) for mono-constituent substances with a high reliability ¿ in total, about 80,000 structures were generated. By comparing these results with inventories of structures available from other publicly available sources of information, additional high quality structures including precise information on stereochemistry were generated. A quality review resulted in the assignment of quality labels to the structures and in the further checking of about 5500 structures. To support QSAR predictions and to estimate key physicochemical properties of the substances, these structures were processed to obtain an inventory of PRS parent substances, which serves as a standardised input for computational tools containing about 62,000 records. For these parent compounds the key features of the structures were calculated and key physicochemical properties were estimated using EPISUITE, Pipeline Pilot and ADMET Predictor. This chemical characterisation of the parent substances can be used to support a preliminary assessment of hazard and exposure. The data highlight the importance of ionisation to predict hazard and exposure for about 40% of the substances in the inventory.JRC.DDG.I.6-Systems toxicolog

Single-crystal-to-single-crystal transformation and catalytic properties of new hybrid perhalidometallates

Two new organic–inorganic salts of perhalidometallates with protonated organic amine cations have been synthesized and characterized by X-ray diffraction and thermal analysis. (CHBMAH2) ZnBr4·3/2H2O 1 and (CHBMAH2 )ZnCl4 4 [(CHBMAH2 )2+: 1, 3-cyclohexanebis(methylammonium)] were obtained in single-crystal form. The crystal packing in all of the obtained compounds is governed by the formation of various non-covalent intermolecular forces between tetrahalidometallate anions and organic cations, assisted by water molecules in the hydrates. Hirshfeld surface analysis denotes that the most important contributions to the crystal packing are X···H/H···X (X: Cl, Br, I) and H···H interactions. Interestingly, the compound 1, 3-cyclohexanebis(methylammonium)tetrachlorido-zincate (II) dihydrate, (CHBMAH2 )ZnCl4·2H2O 2, undergoes thermally-triggered single-crystal-to-single-crystal (SCSC) transformation upon dehydration to produce a supramolecular solid compound, 1, 3-cyclohexanebis(methylammonium) tetrachloridozincate (II), (CHBMAH2 )ZnCl4 4. The SCSC transformation causes changes in the lattice parameters and a structural rearrangement. Furthermore, the catalytic properties of (CHBMAH2 )ZnCl4·2H2O 2 and (CHBMAH2 )CdI4·2H2O 3 have been explored in the acetalization process using various uncommon alcohols, beyond methanol or ethanol, for the first time in the literature, with outstanding results, and opening the door to the formation of alternative acetals. © 2021 by the authors. Licensee MDPI, Basel, Switzerland

Crystal structure of ammonium tetrachloromercurate(II) monohydrate, (NH₄)₂HgCl₄ · H₂O

Cl₄H₁₀HgN₂₀, orthorhombic, Pbam (No. 55), a = 8.473(3) Å, b= 11.929(3) Å, c = 9.197(3) Å, V = 929.6 ų, Z = 4, Rgt(F) = 0.048, wRref(F²) = 0.101, T = 299 K

Heat capacities of bis-tetraethylammonium tetrachloronickelate and tetrachlorozincate I. Structural transitions and thermophysical results

The heat capacities of bis-tetraethylammonium tetrachloronickelate () and tetrachlorozincate () were measured over the temperature range 5 to 350 K by adiabatic calorimetry. Bifurcated anomalies were found for both compounds with the temperatures of the maxima occurring at (222.1 +/- 0.1) K and (222.7 +/- 0.1) K for and at (227.9 +/- 0.2) K and (228.9 +/- 0.2) K for . The excess entropies associated with the transition regions were 9.16 and 9.96 calth K-1 mol-1 respectively. Both transition regions were characterized by equilibrium times of several days. Selected thermal functions Cpo, So, and -{Go(T) - Ho(0)}/T at 298.15 K are, respectively, 151.7, 185.33, and 92.16 calth K-1 mol-1 for and 153.0, 181.52, and 88.53 calth K-1 mol-1 for .Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/23707/1/0000679.pd

Ionic Liquid Crystals Based on Pyridinium Salts

This chapter describes the liquid crystalline properties of the ionic liquid crystals (ILC) based on pyridinium salts as well as their metal-containing compounds with an emphasis on the recent systems described in literature. The main factors that influence the liquid crystalline properties of pyridinium ILC are discussed. Selected thermal data are given according to mesogenic group employed and its position (either N-substitution or pyridinium ring substitution) and the number of structural cationic units (mono-, di-, or polycationic pyridinium ILC)