Dense Hydrated Magnesium Carbonate MgCO·3HO Phases.

The study of the structural stability of carbonates under different pressure and temperature conditions is important for modeling the carbon budget in the Earth's interior and the stability of carbonation products of carbon capture and storage (CCS) solutions. In this work, we confirm the existence of the two dense polymorphs of the hydrated magnesium carbonate MgCO·3HO nesquehonite mineral previously reported, and we characterize their structures using synchrotron single-crystal X-ray diffraction at 3.1 and 11.

Polymorphism and Phase Stability of Hydrated Magnesium Carbonate Nesquehonite MgCO·3HO: Negative Axial Compressibility and Thermal Expansion in a Cementitious Material.

The - phase diagram of the hydrated magnesium carbonate nesquehonite (MgCO·3HO) has not been reported in the literature. In this paper, we present a joint experimental and computational study of the phase stability and structural behavior of this cementitious material at high-pressure and high-temperature conditions using single-crystal and synchrotron powder X-ray diffraction measurements in resistive-heated diamond anvil cells plus density functional theory calculations. Our results show that nesquehonite undergoes two pressure-induced phase transitions at 2.

Joint experimental and theoretical study of PbGaS under compression.

The effect of pressure on the structural, vibrational, and optical properties of lead thiogallate, PbGaS, crystallizing under room conditions in the orthorhombic EuGaS-type structure (space group ), is investigated. The results from X-ray diffraction, Raman scattering, and optical-absorption measurements at a high pressure beyond 20 GPa are reported and compared not only to calculations, but also to the related compounds α'-GaS, CdGaS, and HgGaS. Evidence of a partially reversible pressure-induced decomposition of PbGaS into a mixture of PbGaS and GaS above 15 GPa is reported.

Isoreticular Expansion and Linker-Enabled Control of Interpenetration in Titanium-Organic Frameworks.

Titanium-organic frameworks offer distinctive opportunities in the realm of metal-organic frameworks (MOFs) due to the integration of intrinsic photoactivity or redox versatility in porous architectures with ultrahigh stability. Unfortunately, the high polarizing power of Ti cations makes them prone to hydrolysis, thus preventing the systematic design of these types of frameworks. We illustrate the use of heterobimetallic cluster TiCa as a persistent building unit compatible with the isoreticular design of titanium frameworks.

2D Cu(I)-I Coordination Polymer with Smart Optoelectronic Properties and Photocatalytic Activity as a Versatile Multifunctional Material.

This work presents two isostructural Cu(I)-I 2-fluoropyrazine (Fpyz) luminescent and semiconducting 2D coordination polymers (CPs). Hydrothermal synthesis allows the growth of -1 space group single crystals, whereas solvent-free synthesis produces polycrystals. Via recrystallization in acetonitrile, 2 space group single crystals are obtained.

Reassigning the Pressure-Induced Phase Transitions of Methylammonium Lead Bromide Perovskite.

The high-pressure crystal structure evolution of CHNHPbBr (MAPbBr) perovskite has been investigated by single-crystal X-ray diffraction and synchrotron-based powder X-ray diffraction. Single-crystal X-ray diffraction reveals that the crystal structure of MAPbBr undergoes two phase transitions following the space-group sequence: 3̅ → 3̅ → 2, unveiling the occurrence of a nonpolar/polar transition (3̅ → 2). The transitions take place at around 0.

Pressure-Induced Phase Transition and Band Gap Decrease in Semiconducting β-CuVO.

The understanding of the interplay between crystal structure and electronic structure in semiconductor materials is of great importance due to their potential technological applications. Pressure is an ideal external control parameter to tune the crystal structures of semiconductor materials in order to investigate their emergent piezo-electrical and optical properties. Accordingly, we investigate here the high-pressure behavior of the semiconducting antiferromagnetic material β-CuVO, finding it undergoes a pressure-induced phase transition to γ-CuVO below 4000 atm.

A self-consistent approach to describe unit-cell-parameter and volume variations with pressure and temperature.

A method for the self-consistent description of the large variations of unit-cell parameters of crystals with pressure and temperature is presented. It employs linearized versions of equations of state (EoSs) together with constraints to ensure internal consistency. The use of polynomial functions to describe the variation of the unit-cell angles in monoclinic and triclinic crystals is compared with the method of deriving them from linearized EoSs for spacings.

Permanent Porosity in Hydroxamate Titanium-Organic Polyhedra.

Following the synthesis of hydroxamate titanium-organic frameworks, we now extend these siderophore-type linkers to the assembly of the first titanium-organic polyhedra displaying permanent porosity. Mixed-linker versions of this molecular cage (cMUV-11) are also used to demonstrate the effect of pore chemistry in accessing high surface areas of near 1200 m·g.

Dry needling for treating spasticity in multiple sclerosis.

[Purpose] The aim of the study is to evaluate the efficacy of dry needling (DN) in the treatment of spasticity in patients with multiple sclerosis (MS). [Participants and Methods] Twelve participants (3 males and 9 females) with MS, with no evidence of a relapse in the last four weeks and with an EDSS (Expanded Disability Status Scale) greater than 2.5 points (related with pyramidal score) were recruited.

Effect of Linker Distribution in the Photocatalytic Activity of Multivariate Mesoporous Crystals.

The use of Metal-Organic Frameworks as crystalline matrices for the synthesis of multiple component or multivariate solids by the combination of different linkers into a single material has emerged as a versatile route to tailor the properties of single-component phases or even access new functions. This approach is particularly relevant for Zr-MOFs due to the synthetic flexibility of this inorganic node. However, the majority of materials are isolated as polycrystalline solids, which are not ideal to decipher the spatial arrangement of parent and exchanged linkers for the formation of homogeneous structures or heterogeneous domains across the solid.

Cu(I)-I-2,4-diaminopyrimidine Coordination Polymers with Optoelectronic Properties as a Proof of Concept for Solar Cells.

Two coordination polymers with formulas [CuI(dapym)] and [CuI(dapym)] (dapym = 2,4-diaminopyrimidine) have been synthesized in water at room temperature. According to the stoichiometry used, mono (1D) and the two-dimensional (2D) structures can be obtained. Both are made up of CuI double chains.

Precise Characterization of the Rich Structural Landscape Induced by Pressure in Multifunctional FeVO.

We have studied the high-pressure behavior of FeVO by means of single-crystal X-ray diffraction (XRD) and density functional theory (DFT) calculations. We have found that the structural sequence of FeVO is different from that previously assumed. In particular, we have discovered a new high-pressure phase at 2.

Phase Behavior of TmVO under Hydrostatic Compression: An Experimental and Theoretical Study.

We present a structural and optical characterization of magnetoelastic zircon-type TmVO at ambient pressure and under high pressure. The properties under high pressure have been determined experimentally under hydrostatic conditions and theoretically using density functional theory. By powder X-ray diffraction we show that TmVO undergoes a first-order irreversible phase transition to a scheelite structure above 6 GPa.

Influence of the / configuration on the supramolecular aggregation of aryltriazoles.

The ability of - and -1,2-glucopyranosyl and cyclohexyl ditriazoles, synthesized by CuAAC "click" chemistry, to form gels was studied, their physical properties determined, and the self-aggregation behavior investigated by SEM, X-ray, and EDC studies. The results revealed that self-assembly was driven mainly by π-π stacking interactions, in addition to hydrogen bonding, with the aromatic rings adopting a high degree of parallelism, as seen in crystal packings and ECD data. Furthermore, π-bromine interactions between the bromine atom of the aryl substituents and the triazole units might also contribute to an overall stabilization of the supramolecular aggregation of bis(4-bromophenyl)triazoles.

High-Pressure Single-Crystal X-ray Diffraction of Lead Chromate: Structural Determination and Reinterpretation of Electronic and Vibrational Properties.

We have investigated the high-pressure behavior of PbCrO. In particular, we have probed the existence of structural transitions under high pressure (at 4.5 GPa) by single-crystal X-ray diffraction and density functional theory calculations.

Smart composite films of nanometric thickness based on copper-iodine coordination polymers. Toward sensors.

One-pot reactions between CuI and methyl or methyl 2-amino-isonicotinate give rise to the formation of two coordination polymers (CPs) based on double zig-zag CuI chains. The presence of a NH group in the isonicotinate ligand produces different supramolecular interactions affecting the Cu-Cu distances and symmetry of the CuI chains. These structural variations significantly modulate their physical properties.

Chemical Engineering of Photoactivity in Heterometallic Titanium-Organic Frameworks by Metal Doping.

We report a new family of titanium-organic frameworks that enlarges the limited number of crystalline, porous materials available for this metal. They are chemically robust and can be prepared as single crystals at multi-gram scale from multiple precursors. Their heterometallic structure enables engineering of their photoactivity by metal doping rather than by linker functionalization.

Peptide metal-organic frameworks under pressure: flexible linkers for cooperative compression.

We investigate the structural response of a dense peptide metal-organic framework using in situ powder and single-crystal X-ray diffraction under high-pressures. Crystals of Zn(GlyTyr) show a reversible compression by 13% in volume at 4 GPa that is facilitated by the ability of the peptidic linker to act as a flexible string for a cooperative response of the structure to strain. This structural transformation is controlled by changes to the conformation of the peptide, which enables a bond rearrangement in the coordination sphere of the metal and changes to the strength and directionality of the supramolecular interactions specific to the side chain groups in the dipeptide sequence.

Integrative Pericyclic Cascade: An Atom Economic, Multi C-C Bond-Forming Strategy for the Construction of Molecular Complexity.

An all-pericyclic manifold is developed for the construction of topologically diverse, structurally complex and natural product-like polycyclic chemotypes. The manifold uses readily accessible tertiary propargyl vinyl ethers as substrates and imidazole as a catalyst to form up to two new rings, three new C-C bonds, six stereogenic centers and one transannular oxo-bridge. The manifold is efficient, scalable and instrumentally simple to perform and entails a propargyl Claisen rearrangement-[1,3]H shift, an oxa-6π-electrocyclization, and an intramolecular Diels-Alder reaction.

Experimental and ab Initio Study of Catena(bis(μ2-iodo)-6-methylquinoline-copper(I)) under Pressure: Synthesis, Crystal Structure, Electronic, and Luminescence Properties.

Copper(I) iodine compounds can exhibit interesting mechanochromic and thermochromic luminescent properties with important technological applications. We report the synthesis and structure determination by X-ray diffraction of a new polymeric staircase copper(I) iodine compound catena(bis(μ2-iodo)-6-methylquinoline-copper(I), [C10H9CuIN]. The structure is composed of isolated polymeric staircase chains of copper-iodine coordinated to organic ligands through Cu-N bonds.

Low Prevalence of Sleep Disorders in Demyelinating Disease in a Northern Tenerife Population.

Study Objectives: Sleep disorders are seen in patients with demyelinating disease (DD) more often than in the general population. Combination of physical and psychological factors such as pain, spasms, nocturia, depression, anxiety, or medication effects could contribute to sleep disruption. Frequently, these disturbances have a major impact on health and quality of life of patients.

The crystal structure and magnetic properties of 3-pyridinecarboxylate-bridged Re(II)M(II) complexes (M = Cu, Ni, Co and Mn).

The novel Re(II) complex NBu4[Re(NO)Br4(Hnic)] (1) and the heterodinuclear compounds [Re(NO)Br4(μ-nic)Ni(dmphen)2]·½CH3CN (2), [Re(NO)Br4(μ-nic)Co(dmphen)2]·½MeOH (3), [Re(NO)Br4(μ-nic)Mn(dmphen)(H2O)2]·dmphen (4), [Re(NO)Br4(μ-nic)Cu(bipy)2] (5) [Re(NO)Br4(μ-nic)Cu(dmphen)2] (5') (NBu4(+) = tetra-n-butylammonium cation, Hnic = 3-pyridinecarboxylic acid, dmphen = 2,9-dimethyl-1,10-phenanthroline, bipy = 2,2'-bipyridine) have been prepared and the structures of 1-5 determined using single crystal X-ray diffraction. The structure of 1 consists of [Re(NO)Br4(Hnic)](-) anions and NBu4(+) cations. Each Re(II) is six-coordinate with four bromide ligands, a linear nitrosyl group and a nitrogen atom from the Hnic molecule, in a distorted octahedral surrounding.

Synthesis and conformational analysis of cyclic homooligomers from pyranoid ε-sugar amino acids.

New pyranoid ε-sugar amino acids were designed as building blocks, in which the carboxylic acid and the amine groups were placed in positions C2 and C3 with respect to the tetrahydropyran oxygen atom. By using standard solution-phase coupling procedures, cyclic homooligomers containing pyranoid ε-sugar amino acids were synthesized. Conformation analysis was performed by using NMR spectroscopic experiments, FTIR spectroscopic studies, X-ray analysis, and a theoretical conformation search.

Synthesis, crystal structure and magnetic properties of the Re(II) complexes NBu4[Re(NO)Br4(L)] (L = pyridine and diazine type ligands).

Four novel Re(II) complexes of formula NBu4[Re(NO)Br4(L)] [NBu4(+) = tetra-n-butylammonium cation and L = pyridine (1), pyrazine (2), pyrimidine (3), pyridazine (4)] have been prepared by a substitution reaction involving NBu4[Re(NO)Br4(EtOH)] and L. Their crystal structures have been determined by single crystal X-ray diffraction. They are all mononuclear complexes whose structure is made up of [Re(NO)Br4L](-) anions and NBu4(+) cations.