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The crystal structure of glycinium phosphite (GPI) was studied in the pressure range from ambient to 6.5 GPa at 293 K using single-crystal X-ray diffraction. The changes in the unit-cell volume and parameters were continuous and anisotropic. The major compression was observed normal to the direction of the spontaneous polarization that occurs in this structure during a ferroelectric phase transition on cooling, whereas the structural compression along the b axis coinciding with the 21 axis was almost zero. The effect of pressure on the hydrogen bonds linking the H2PO3 tetrahedra into zigzag chains along the c axis was different from that on the hydrogen bonds connecting the glycinium cations with the H2PO3 tetrahedra in the (b × c) plane. The discontinuous changes in the geometries of selected hydrogen bonds at about 1.21 GPa may be evidence of a phase transition, e.g. into an ordered ferroelectric phase (with ordered positions of protons). The anisotropy of compression of GPI in the ferroelectric state (at 0 K) was studied using DFT calculations taking into account dispersive van der Waals interactions. The calculations predicted negative linear compressibility along the b axis.

This note reports a study of the coating of a crystal with `ice' at temperatures below 45 K during single-crystal in-house diffraction experiments when using an open-flow helium cryostat. The `ice' consists mainly of crystalline oxygen and nitrogen. This suggests completely different techniques for avoiding this type of icing compared with water icing. With appropriate choices of crystal mount, crystal position with respect to the nozzle and gas flow conditions, it is possible to avoid detectable condensation. However, sometimes this cannot be achieved in practice (poor diffraction from a smaller crystal, necessity of positioning the crystal in certain orientations to achieve desired data completeness, need to reduce helium consumption etc.). The problem of icing seems to be less common for powder experiments where the laminar gas flow is parallel to the capillary containing the sample, and for synchrotron experiments where the sample is comparatively small and almost continuously rotated, which facilitates the ice covering being removed by the gas flow. This last technique can in principle also be applied to single-crystal X-ray diffraction using laboratory diffractometers – periodic rapid rotation of the crystal can help to minimize any icing, but this technique will not work when the condensation rate is comparable to or faster than one frame of data collection. The coating around a sample crystal reduces the quality of the diffraction data, and the temperature at the sample below the coating may differ significantly from that at the cryostat nozzle reported by the instrument.

Thermal evolution of an organic ferroelectric, namely, glycinium phosphite, was probed by multi-temperature single-crystal diffraction using synchrotron radiation and also by a similar experiment with a laboratory X-ray diffractometer. Both series of measurements showed a transition from the paraelectric to the ferroelectric state at nearly the same temperature,Tc = 225 K. Temperature evolution of the unit-cell parameters and volume are drastically different for the synchrotron and laboratory data. The latter case corresponds to previous reports and shows an expected contraction of the cell on cooling. The data collected with the synchrotron beam show an abnormal nonlinear increase in volume on cooling. Structure analysis shows that this volume increase is accompanied by a suppression of scattering at high angles and an apparent increase of the anisotropic displacement parameters for all atoms; we therefore link these effects to radiation damage accumulated during consecutive data collections. The effects of radiation on the formation of the polar structure of ferroelectric glycinium phosphite is discussed together with the advantages and drawbacks of synchrotron experimentation with fine temperature sampling.

A series of polyhalogenated diaminobenzonitriles and 18-crown-6 ether were used to reveal the dependence of the stoichiometry and supramolecular structure of co-crystals on various factors. 2,6-Diamino-3,5-difluoro-, 2,6-diamino-4-chloro-3,5-difluoro-, and 2,6-diamino-4-chloro-3-fluorobenzonitriles, as well as 2,4-diamino-3,5-difluorobenzonitrile give 1 : 1 co-crystals regardless of the diamine : crown ratio in the crystallization solution (from 2.5 : 1 to 1 : 2.5) and the nature of the solvent. According to X-ray diffraction data, the supramolecular structures of these co-crystals can be considered as 1D assemblies with the only structure-forming N–H⋯Ocr hydrogen bond. 2,4-Diamino-3,5,6-triflurobenzonitrile forms no 1 : 1 co-crystal, but yields co-crystals of 4 : 3 (under most of the studied conditions) and 2 : 1 (in CCl4 solution) stoichiometry. The N–H⋯NC hydrogen bond and p⋯π electron interactions, along with the N–H⋯Ocr H-bond, participate in the formation of the 3D supramolecular structures of these co-crystals. The effect of the number of F atoms on the co-crystallization behaviour of difluoro- and trifluoro-2,4-diaminobenzonitriles was rationalized using quantum-chemical computations of the interaction energies of N–H⋯NC bonded pairs of these diamines in the experimental crystals and DFT simulated models. The DSC curves of each co-crystal contain a single peak corresponding to a crystal-to-liquid phase transition (melting), which does not change in melting–crystallization cycles, indicating that the stoichiometry and crystal structure are reproducible.

While proteins can often be stabilized by maintaining them in the frozen state, water-to-ice transformation can also lead to degradation of protein molecules. A new method to study protein/ice interaction is presented herein, which is based on measuring the characteristic features of X-ray diffraction (XRD) patterns of hexagonal ice (Ih). Aqueous solutions of four different proteins and several small molecular weight solutes are studied using high-resolution synchrotron X-ray diffraction at the ID22 beamline at the European Synchrotron Radiation Facility. The beamline is optimized to eliminate the instrumental broadening of diffraction lines and reduce the preferred orientation effects, thereby enabling quantitative analysis of the XRD data. The analysis demonstrates that two pharmaceutical proteins, recombinant human albumin (rHA) and monoclonal antibody (mAb), have a pronounced effect on the properties of ice crystals. In particular, the size of the crystalline domains is significantly smaller, and the microstrain is larger, in the solutions of the pharmaceutical proteins, when compared with a model protein (lysozyme), an antifreeze protein, and sucrose and histidine. Neither of the proteins studied exhibit preferred interaction with specific crystalline faces of Ih. The results are consistent with indirect interaction of the pharmaceutical proteins with ice, in which protein molecules are accumulated in the quasi-liquid layer next to growing ice crystallization front. Direct interaction would indicate a sorption of protein molecules on ice crystals, whereas “indirect interaction” terminology is used to describe any interference of proteins with ice crystals without sorption involved. Lysozyme molecules, on the other hand, do not exhibit any evidence of interaction (either direct or indirect) with ice crystals. This is the first report, to the best of our knowledge, of major difference in protein/ice interaction between different types of non-antifreeze proteins. In addition, we report an unexpected finding of a second population of ice crystals, with a much smaller (a few nm) size of crystalline domains. The second (minor) population is tentatively identified as a high-pressure form of ice, possibly IceIII or IceIX. This observation highlights a potential role of mechanical stresses and local pressure in freeze-induced destabilization of proteins.

The crystal structure of a hydrate of the sodium salt of guanine (2Na+·C5H3N5O2−·7H2O) was studied using single-crystal X-ray diffraction and Raman spectroscopy up to ∼2.5 GPa, after which the structure distorted and the diffraction pattern from single crystal fragments disappeared along with the appearance of powder ring fragments. On increasing the pressure the distances between the double walls of the slit channels formed by the guanine moieties became more equal, with the longer one shortening and the shorter one expanding. The topology of the Na+–water intra-channel infinite clusters was preserved, although these clusters became distorted on compression. Among several types of OH⋯O and OH⋯N hydrogen bonds, only two practically did not change with increasing pressure, namely the bonds connecting the guanine walls to the intra-channel water molecules. A possible relationship to the interactions in the ion channels with the walls formed by the guanine species in biological systems is discussed.

Since the early days of X-ray diffraction, researchers have tried to follow the evolution of crystal structures under extremes of pressure. Recently, interest in this area has exploded, attracting scientists from backgrounds across the physical and life sciences. Much of this rapid expansion has been due to the enhancement of diffraction equipment, including detectors, goniometers, and high-pressure cells, and the development of synchrotron radiation and neutron sources. The high-pressure research generally focuses on the direct effects of pressure on the structural evolution of a system. The present contribution describes examples of a less common application: hydrostatic compression of crystals of organic and coordination compounds can be used as a complementary tool in order to rationalise the mechanisms of the transformations in these solids that take place at atmospheric pressure. The data on the compressibility, equations of state, phase changes, or the effects of pressure on intermolecular distances, molecular conformations and chemical bonds can shed light on the factors that are important for thermal and photochemical reactions in the same crystals without an external load as well as on their solid-state or solvent-assisted polymorphic transformations. The manuscript also discusses how structural studies under extreme conditions can help to rationalise the thermo- and photosalient effects that accompany some solid-state transformations. This knowledge is currently of great importance for materials science since mechanically responsive materials have the potential to be used for the design and manufacture of new supramolecular devices.

The methodology of the quantification of photoinduced bending of crystals is described and illustrated by the case study of [Co(NH3)5NO2]Cl(NO3) crystal bending caused by the reversible photochemical isomerization. The measurement technique is combined with the quantitative model to give an effective method for assessing of the key material properties defining the characteristics of the potential light-driven actuators.

The effects of temperature (100–370 K) and pressure (0–6 GPa) on the non-localized two-electron multicentric covalent bonds (`pancake bonding') in closely bound radical dimers were studied using single-crystal X-ray diffraction on a 4-cyano-N-methylpyridinium salt of 5,6-dichloro-2,3-dicyanosemiquinone radical anion (DDQ) as the sample compound. On cooling, the anisotropic structural compression was accompanied by continuous changes in molecular stacking; the discontinuities in the changes in volume and b and c cell parameters suggest that a phase transition occurs between 210 and 240 K. At a pressure of 2.55 GPa, distances between radical dimers shortened to 2.9 Å, which corresponds to distances observed in extended π-bonded polymers. Increasing pressure further to 6 GPa reduced the interplanar separation of the radicals to 2.75 Å. This may indicate that the covalent component of the interaction significantly increased, in accordance with the results of DFT calculations reported elsewhere [Molčanov et al. (2019), Cryst. Growth Des. 19, 391–402].

The Mx H y (AO4) z acid salts (M = Cs, Rb, K, Na, Li, NH4; A = S, Se, As, P) exhibit ferroelectric properties. The solid acids have low conductivity values and are of interest with regard to their thermal properties and proton conductivity. The crystal structure of caesium dihydrogen orthophosphate monohydrogen orthophosphate dihydrate, Cs3(H1.5PO4)2·2H2O, has been solved. The compound crystallizes in the space group Pbca and forms a structure with strong hydrogen bonds connecting phosphate tetrahedra that agrees well with the IR spectra. The dehydration of Cs3(H1.5PO4)2·2H2O with the loss of two water molecules occurs at 348–433 K. Anhydrous Cs3(H1.5PO4)2 is stable up to 548 K and is then converted completely into caesium pyrophosphate (Cs4P2O7) and CsPO3. Anhydrous Cs3(H1.5PO4)2 crystallizes in the monoclinic C2 space group, with the unit-cell parameters a = 11.1693 (4), b = 6.4682 (2), c = 7.7442 (3) Å and β = 71.822 (2)°. The conductivities of both compounds have been measured. In contrast to crystal hydrate Cs3(H1.5PO4)2·2H2O, the dehydrated form has rather low conductivity values of ∼6 × 10−6–10−8 S cm−1 at 373–493 K, with an activation energy of 0.91 eV.

A comparison is made of information on the structural aspects of the displacive dehydration of samarium oxalate decahydrate obtained from optical microscopy observations and X-ray diffraction studies., For martensitic transformations the macroscopic crystal strain is directly related to the corresponding structural rearrangement at the microscopic level. In situ optical microscopy observations of the interface migration and the change in crystal shape during a displacive single crystal to single crystal transformation can contribute significantly to understanding the mechanism of the process at the atomic scale. This is illustrated for the dehydration of samarium oxalate decahydrate in a study combining optical microscopy and single-crystal X-ray diffraction.

The crystal structures of a series of isostructural rare-earth metal oxalates, (REE)2(C2O4)3·10H2O (REE=Sm, Y) and a 1:1 YSm(C2O4)3·10H2O solid solution, have been studied in situ by single-crystal X-ray diffraction and optical microscopy. The structures were followed from ambient pressure to 6 GPa in a DAC with paraffin as the hydrostatic fluid. Bulk compressibilities, anisotropic lattice strain on hydrostatic compression and the corresponding changes in the atomic coordinates were followed. Discontinuities/sharp changes in the slopes of the pressure dependences of volume and selected cell parameters have been observed for yttrium-containing salts at ~3.5 GPa. This may be related to the re-distribution of water molecules within the crystal structure. Y2(C2O4)3·10H2O undergoes a partial dehydration at 1 GPa, forming monoclinic Y2(C2O4)3·6H2O as single-crystalline inclusions in the original phase.

Two polymorphs of tolazamide, N-[(azepan-1-ylamino)carbonyl]-4-methylbenzenesulfonamide, a sulfonylurea anti-diabetic drug, have different densities and molecular packings. Polymorph II converts into polymorph I in the solid state on heating or via recrystallization if solvent-assisted. The effect of pressure on the two forms and the possibility of a transformation to a denser form on compression have been studied. No phase transitions have been observed in either of the forms in a pentane–isopentane mixture (when no recrystallization is possible). Polymorph II recrystallized partly into a denser polymorph I in methanol at 0.1 GPa, but the transformation stopped at an early stage. Solid state DFT calculations of the two forms as well as conformational landscape investigation in the gas phase were used to rationalize this result. The anisotropic pressure-induced strain of the two polymorphs has been compared in relation to changes in the hydrogen bond geometry and the behavior of stacking interactions.

The study of structure and morphology changes during thermal decomposition of yttrium oxalate decahydrate Y 2 (C 2 O 4 ) 3 ·10H 2 O was presented in this paper. Thermal decomposition was found to include two main stages: dehydration and oxalate thermolysis. The effect of different dehydration conditions at hexahydrate formation stage on its structure and morphology was studied. Two polymorphic hexahydrate phases are shown to form. Structural transformations during dehydration were assumed to proceed by martensitic mechanism in both cases. Structural transformation mechanisms were suggested. The stages of oxalate thermolysis were determined and products at each stage were identified. Yttrium oxide as final product of decomposition was obtained.

The hydrostatic compression of β-chlorpropamide gives different high-pressure phases, depending on the choice of pressure-transmitting fluid (paraffin, neon and helium). This is particularly surprising as none of these fluids interact obviously with the solid at ambient pressure. This phenomenon is not related to dissolution and recrystallization, in contrast to what has been previously observed for β-chlorpropamide in a 1:1 pentane-isopentane mixture.

The effects of temperature and pressure on the co-crystals of glycine with DL-tartaric and phthalic acids (GTa and GPh, respectively) have been studied by X-ray diffraction and Raman spectroscopy in comparison with those on glycine–glutaric acid (GGa). On cooling, no phase transitions were observed in GTa or GPh, in contrast to the situation with GGa. On hydrostatic compression, both GTa and GPh underwent reversible phase transformations, accompanied by fracture. In the high-pressure phases, the main structural framework was preserved, and the number of crystallographically independent molecules in the unit cell increased. In GTa, dimers are squeezed together so that some hydrogen bonds get a three-centered character, and the interactions of one of the two glycine molecules change dramatically.

The effect of anisotropic structural strain resulting from thermal expansion on linkage photoisomerisation in crystals of [Co(NH3)5NO2]Cl(NO3) was studied. The quantum yield of the photoisomerisation was qualitatively correlated with the bending of needle-shaped crystals across a series of temperatures from 80–363 K. The thermal evolution of the crystal structure was also studied across the same temperature range by single-crystal X-ray diffraction. A qualitative correlation was found between the photo-reaction rate and both the cell volume and the volume of void space around the nitro groups. However, this correlation was found to be non-linear. The effect of the anisotropic structural strain resulting from temperature variations on the rate of photoisomerisation is qualitatively different from the effect of strain that is generated by elastic external loading. If strain is induced by external load, the reaction rate correlates linearly with compression along the crystallographic b direction. In contrast, if strain results from temperature variations, then the reaction rate correlates linearly with changes along the crystallographic a direction. This effect is measured quantitatively and its rationalisation is attempted.

The coordination compounds of Cu(II), Co(II), Ni(II) and Pd(II) with 2-anilinomethylidene-5,5-dimethylcyclohexane-1,3-dione (HL) of the composition [ML2(C2H5OH)2]·nH2O (M = Co (n = 1), Ni (n = 0)) and [ML2] (M = Cu, Pd) have been prepared and investigated by elemental analysis, IR-spectroscopy, NMR spectroscopy, powder X-ray diffraction analysis. Single-crystal X-ray diffraction analysis shows that HL serves as a chelate bidentate ligand coordinated to the metal ion through the N and O atoms forming a six-membered chelate ring. The coordination polyhedron of the metal atoms is a square bipyramid [ML2(C2H5OH)2] or square planar [ML2]. The Cu(II) and Pd(II) complexes stability in solution has been shown by NMR spectroscopy. The results of the cell viability study on Hep2 (human larynx carcinoma) cells demonstrate that the complexes don’t exhibit strong cytotoxic effect against Hep-2 cell line compared to cisplatin (IC50 = 9,2 ± 0,5 μM). Palladium(II) complex is the most cytotoxic among all complexes and shows IC50 value of 68,7 ± 5,3 μM.

The thermosalient effect (crystal jumping on heating) attracts much attention as both an intriguing academic phenomenon, as well as in relation to its potential for the development of molecular actuators. This effect has been documented in many papers. Still, its mechanism remains unclear. 1,2,4,5-Tetrabromobenzene (TBB) is one of the most extensively studied thermosalient compounds that has been shown previously to undergo a phase transition on heating, accompanied by crystal jumping and cracking. The difference in the crystal structures and intermolecular interaction energies of the low- and high-temperature phases is, however, too small to account for the large stress that arises over the course of the transformation. The energy is released spontaneously, and crystals jump across distances that exceed the crystal size by orders of magnitude. In the present work, the anisotropy of lattice strain is followed across the phase transition by single-crystal X-ray diffraction, focusing on the structural evolution from 273 to 343 K. A pronounced lattice softening is observed close to the transition point, with the structure becoming more rigid immediately after the phase transition. The diffraction studies are further supported by theoretical analysis of pairwise intermolecular energies and zone-centre lattice vibrations. Only three modes are found to monotonically soften up to the phase transition, with complex behaviour exhibited by the remaining lattice modes. The thermosalient effect is delayed with respect to the structural transformation itself. This can originate from the martensitic mechanism of the transformation, and the accumulation of stress associated with vibrational switching across the phase transition. The finding of this study sheds more light on the nature of the thermosalient effect in 1,2,4,5-tetrabromobenzene and can be applicable also to other thermosalient compounds.

Two crystalline salts have been obtained from the system l -serine - picric acid - H2O: l -serinium picrate monohydrate (I) and tris( l -serine) bis( l -serinium) dipicrate trihydrate (II). The salt (I) crystallizes in monoclinic system (space group P21, Z = 4). Asymmetric unit of (I) contains two formula units. Carboxyl groups of both l -serinium cations form hydrogen bonds with picrate anions with O···O distances: 2.595 (6) A and 2.638 (5) A. The salt (II) crystallizes in orthorhombic system (space group P212121, Z = 4). Asymmetric unit of (II) contains one formula unit. Carboxyl groups of both l -serinium cations form short O–H···O hydrogen bonds with two of three zwitterionic moieties, forming two dimeric ( l -serine l -serinium) cations with O···O distances: 2.485 (3) A and 2.487 (3) A. The infrared and Raman spectra of obtained salts are recorded and discussed.

In the present case study of tolazamide we illustrate how many seemingly contradictory results that have been obtained from experimental observations and theoretical calculations can finally start forming a consistent picture: a "puzzle put together". For many years, tolazamide was considered to have no polymorphs. This made this drug substance unique among the large family of sulfonylureas, which was known to be significantly more prone to polymorphism than many other organic compounds. The present work employs a broad and in-depth analysis that includes the use of optical microscopy, single-crystal and powder X-ray diffraction, IR and Raman spectroscopies, DSC, semiempirical PIXEL calculations and DFT of three polymorphs of tolazamide. This case study shows how the polymorphs of a molecular crystal can be overlooked even if discovered serendipitously on one of numerous crystallizations, and how very different molecular packings can be practically isoenergetic but still crystallize quite selectively and transform one into another irreversibly upon heating.

Previous study of the setae covering the opisthosoma of ground spiders shows that the morphology of the covering setae is genus-specific. The present study pursues the description of covering setae across the whole Gnaphosidae family using SEM. A detailed morphology of the setae of ground spiders (Araneae, Gnaphosidae) is presented. The six major types of covering setae recognized among gnaphosid spiders are squamose, plumose, lanceolate, pinnate, arborate and sicate setae. Squamose setae are characteristic for Micaria lenzi and Nauhea tapa. Plumose setae are more common in ground spiders and occur in the genera Drassodes, Haplodrassus, Anagraphis, Nodocion, Zelotes and the species Berlandina caspica, Nomisia aussereri, Minosiella intermedia, Sosticus loricatus, Leptodrassus memorialis, Intruda signata, Parasyrisca caucasica, Scopoides catharius, Echemoides tofo, Zimiromus medius, Encoptarthria echemophthalma, Apodrassodes trancas, Apopyllus silvestri, Hemicloea sundevalli, Zelanda erebus, Orodrassus assimilis, Callilepis nocturna and Synaphosus turanicus. The species Matua valida, Anzacia gemmea, Hypodrassodes maoricus, Homoeothele micans and Scotophaeus blackwalli have lanceolate setae. Spiders of the genus Gnaphosa have pinnate setae. Fedotovia uzbekistanica has arborate setae. The species Cesonia bilineata, Herpyllus propinquus, Litopyllus temporarius, Aphantaulax seminigra and Kishidaia conspicua have sicate setae. Some genera, such as Drassodes and Synaphosus, have a combination of different types of setae on their opisthosoma, whereas others, like Eilica sp., Laronius erawan, Urozelotes rusticus, have no covering setae on their opisthosoma at all. This study reveals the existence of different types of covering setae and provides a set of characteristics important for the classification and phylogenetic analysis of Gnaphosidae.

A series of new quaternary 1,4-diazabicyclo[2.2.2]octane derivatives was synthesized and evaluated for activity against several strains of both Gram positive and Gram negative bacteria and one strain of fungus under different inoculum size. Minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) against six species of microorganisms were tested. Results show a clear structure–activity relationship between alkyl chain length of substitutions of 1,4-diazabicyclo[2.2.2]octane tertiary amine sites and antimicrobial activity. In the case of compounds 4a–4k, MIC was found to decrease with the increase of the alkyl chain length from ethyl to dodecyl and then to increase at higher chain length (n > 14). The MIC values were found to be low for the compounds 4f and 4g with alkyl chains ranging from 10 to 12 carbons in length (1.6 μg/ml) and were comparable to the reference drug Ciprofloxacin. Also, time-kill assay was performed to examine the bactericidal kinetics. Results indicated that 4f and 4g had rapid killing effects against Staphylococcus aureus, and eliminated 100% of the initial inoculum of bacteria in 2.5 h at the concentration of 10 μg/ml. In addition, compound 4g eliminate more than 99.9% of the initial inoculum of Ps. aeruginosa after 2.5 h of interaction but the activity of compound 4f against this species seems to be weak. Thus, 4g had strong bactericidal activity and could rapidly kill Gram positive S. aureus, as well as Gram negative Ps. aeruginosa at low and high inoculum size.

In order to investigate the possibility of salt formation in the L-Arg–H3PO3–H2O system, single crystals of L-argininium phosphite, C6H15N4O2+·H2PO3−, were prepared by evaporation of an aqueous solution containing equimolar quantities of L-arginine and phosphorous acid. The asymmetric unit contains one L-argininium(+) cation and one phosphite [HPO2(OH)]−anion. The phosphite anions form chains parallel to [010] by O—H...O hydrogen bonding, with an O...O distance of 2.630 (3) Å. The protonated amine and guanidyl groups of the L-argininium(+) cations form N—H...O hydrogen bonds with the carboxylate groups and anions. The IR and Raman spectra are discussed in relation to the crystal structure. The salt displays nonlinear optical (NLO) properties. Another salt was obtained from a solution with a 1:2 molar ratio of components, but was characterized by vibrational spectra only.

We report the unusual behavior of β-alanine under pressure. Depending on the protocol with which pressure was increased, the crystals of β-alanine I after transition to phase II either transformed into monoclinic phase V at approximately 6 GPa or remained orthorhombic at least up to 8 GPa in phase II with a molecular packing very similar to that of phase I.

Multi-component crystals – salts, co-crystals, or solvates – are usually designed based on the analysis of the complementarity of functional groups and intermolecular interactions of the components. However, no crystal design can do without a practical method of crystal growth. Not all compounds that should be expected to exist based on the “synthon approach” can be prepared in real experiments. This paper aims to illustrate that, in addition to the synthon approach, it is equally important to take into account phase diagrams when searching for practical methods of crystallising multi-component crystals, either as single crystals or as fine particles. Here, we describe the crystallization of a bis(paracetamol) pyridine solvate from a glass-like metastable phase produced by quench-freezing of a paracetamol–pyridine solution with subsequent low-temperature annealing. These procedures must be carried out strictly within the boundaries of the two-phase region “solid solvate + liquor”, which was found only as a result of modelling the phase diagram. The crystal structure was solved by single-crystal X-ray diffraction and compared with co-crystals of paracetamol found in the Cambridge Structural Database. The structure-forming role of the intermolecular interactions and their characteristics were studied by variable-temperature experiments over the range of 100–275 K. This was compared with the structures of pure paracetamol polymorphs and other solvates and co-crystals at ambient and non-ambient conditions.

Changes in the crystal structure of [Co(NH3)5NO2]Br2 – including a previously unknown single-crystal to single-crystal phase transition above 6.0 GPa – were followed from ambient pressure to 6.9 GPa and discussed in relation to the structural mechanism of homogeneous linkage photoisomerisation that is accompanied by photomechanical effects in the same compound.

Precise measurement of bending kinematics induced by a photochemical reaction in a single crystal can be used to extract the kinetic parameters of the underlying reaction with high accuracy., Photomechanically reconfigurable elastic single crystals are the key elements for contactless, timely controllable and spatially resolved transduction of light into work from the nanoscale to the macroscale. The deformation in such single-crystal actuators is observed and usually attributed to anisotropy in their structure induced by the external stimulus. Yet, the actual intrinsic and external factors that affect the mechanical response remain poorly understood, and the lack of rigorous models stands as the main impediment towards benchmarking of these materials against each other and with much better developed soft actuators based on polymers, liquid crystals and elastomers. Here, experimental approaches for precise measurement of macroscopic strain in a single crystal bent by means of a solid-state transformation induced by light are developed and used to extract the related temperature-dependent kinetic parameters. The experimental results are compared against an overarching mathematical model based on the combined consideration of light transport, chemical transformation and elastic deformation that does not require fitting of any empirical information. It is demonstrated that for a thermally reversible photoreactive bending crystal, the kinetic constants of the forward (photochemical) reaction and the reverse (thermal) reaction, as well as their temperature dependence, can be extracted with high accuracy. The improved kinematic model of crystal bending takes into account the feedback effect, which is often neglected but becomes increasingly important at the late stages of the photochemical reaction in a single crystal. The results provide the most rigorous and exact mathematical description of photoinduced bending of a single crystal to date.

We report the study of a reversible phase transition accompanied by pressure-induced disordering in bis ( dl -serinium) oxalate dihydrate which was observed at hydrostatic pressures of ∼4 GPa. The disordering manifested itself as a strong diffuse scattering in diffraction patterns and as a similarity of low-wavenumber Raman spectra measured for different polarizations. Several domains were formed, though the single crystals remained intact. On releasing pressure, both the order in the crystal structure and the mono-domain single crystal were restored. Structural strain on increasing pressure prior to the phase transition was studied by single-crystal X-ray diffraction and Raman spectroscopy and compared with that on cooling, as well as with the pressure-induced strain of dl -serine, in which no pressure-induced disordering or structural transitions could be observed.

Structural changes in nickel dimethylglyoxime (Ni(dmg)2) were followed by single-crystal X-ray diffraction in a diamond-anvil cell (DAC) at pressures up to 5.1 GPa, that is, in the pressure range through the major color change point (2 GPa), but before the phase transition at 7.4 GPa. Significant average compression (∼4%/GPa) was observed, with anisotropic, but continuous and monotonic lattice strain. The maximum compression was observed for the direction perpendicular to planar layers of Ni(dmg)2 and thus corresponds to decreasing the shortest contacts between nickel cations. Compression within the layers was not so pronounced as the compression between the layers. The structure and dynamics of the short O–H···O hydrogen bond connecting the adjacent dimethylglyoxime ligands were investigated by periodic DFT calculations and showed evidence of a flat, asymmetric single-well proton potential facilitating large-amplitude proton oscillations. The proton motion appears to be coupled to the dynamics of the adj...

The survey results of the spider fauna of Black Rock Forest (BRF), Orange County, New York for 12 years are presented. The BRF spider fauna includes 27 families, 121 genera, and 279 species. Most numerous are the Linyphiidae, which make up 26.9% of all spider fauna. Pityohyphantes subarcticus Chamberlin et Ivie, 1943, Tenuiphantes tenuis (Blackwall, 1852), and Erigone dentosa O.Pickard-Cambridge, 1894 were found for first time in the New York State region. The most diverse community was that of the deciduous forest, where 201 species were found. We also found 83 species in swamp areas; 111 species in the coniferous forest; 141 meadow species and 95 species near rivers and ponds. The most unique spider fauna were in the deciduous forest, whereas it had been previously thought the most unique fauna occurred in meadows. The richness and uniqueness of spider faunas in natural ecosystems strongly depend on the type and state of wild vegetation, which may be used for monitoring the health of the landscape.

A detailed morphology of the male and female copulatory organs of the Australian ground spider Hemicloea sundevalli Thorell, 1870 is presented. The genitalia of the female are characterized by a pair of spermathecae on both sides of vulva. On one side, each spermatheca is connected with the bursa copulatrix, and on the other side, they are connected with the uterus externus that leads to the genital opening. The female epigynum of the genus Hemicloea have a peculiar, folded scapus, which expands during copulation. The structure of the male copulatory bulb was compared with bulbs of other gnaphosid spiders. The embolar part of the male bulb has only an embolus. The embolus is attached to the tegulum by a flexible membrane. This kind of male bulb organization is also characteristic in spiders of the genus Zelanda. During copulation, the male inserts completely the right palp embolus into the right bursa copulatrix of the female. The male tibial retrolateral apophysis is used as a lock mechanism to ...

Crystals on the move: If they are subjected to a strong light stimulus, crystals of the cobalt coordination compound [Co(NH3)5(NO2)]Cl(NO3) undergo sudden jumps and leap over distances 10(2)-10(5) times their own size to release the strain that accumulates in their interior. The first quantitative kinematic analysis of this phenomenon is reported. The observed effect could be employed for actuation on the macroscopic scale.

doi: 10.5431/aramit4504 Abstract. A detailed morphological account of the male copulatory organs of three species of ground spiders, Sergiolus capulatus, Herpyllus propinquus and Callilepis pluto (Araneae, Gnaphosidae), is presented. The large sclerites (subtegulum, tegulum and embolus) appear to be homologous in all spiders. Sergiolus and Zelanda have a plesio - morphic palp organization. The increased complexity in the male bulb organization creates a locking mechanism that fixes the male palp position during intercourse in Callilepis, as well as in Encoptarthria, Trachyzelotes and Zelotes. The palp of Herpyllus, together with Anzacia, Drassodes and Intruda, demonstrates progressive modification of the male bulb.

L-Serinium semi-maleate, (I), and DL-serinium semi-maleate, (II), both C3H8NO3+·C4H3O4−, provide the first example of chiral and racemic anhydrous serine salts with the same organic anion. A comparison of their crystal structures with each other, with the structures of the pure components (L-serine polymorphs, DL-serine and maleic acid) and with other amino acid maleates is important for understanding the formation of the crystal structures, their response to variations in temperature and pressure, and structure–property relationships. As in other known crystal structures of amino acid maleates, there are no direct links between the semi-maleate anions in the two new structures. The serinium cations have different conformations in (I) and (II). In (I), they are linked into infinite chainsviahydrogen bonds between carboxylic acid and hydroxy groups. In (II), there are no such chains formed by the serinium cations. In both (I) and (II), there areC22(12) chains consisting of alternating semi-maleate anions and serinium cations. Two types of such chains are present in (I) and (II), termedC22(12) andC22(12)′. In (I), these chains, lying in the same plane, are further linked to each otherviahydrogen bonds, whereas in (II) they are not.

The occurrence of a first-order reversible phase transition in glycine–glutaric acid co-crystals at 220–230 K has been confirmed by three different techniques – single-crystal X-ray diffraction, polarized Raman spectroscopy and differential scanning calorimetry. The most interesting feature of this phase transition is that every second glutaric acid molecule changes its conformation, and this fact results in the space-group symmetry change from P21/c to P\bar 1. The topology of the hydrogen-bonded motifs remains almost the same and hydrogen bonds do not switch to other atoms, although the hydrogen bond lengths do change and some of the bonds become inequivalent.

Information on the effect of pressure on hydrogen bonds, which could be derived from single-crystal X-ray diffraction at a laboratory source and polarized Raman spectroscopy, has been compared. L-Serine and DL-serine were selected for this case study. The role of hydrogen bonds in pressure-induced phase transitions in the first system and in the structural stability of the second one are discussed. Non-monotonic distortion of selected hydrogen bonds in the pressure range below ∼ 1–2 GPa, a change in the compression mechanism at ∼ 2–3 GPa, and the evidence of formation of bifurcated N—H...O hydrogen bonds in DL-serine at ∼ 3–4 GPa are considered.

Detailed morphologies of the male copulatory organs of the Australian genera Anzacia, Intruda, Encoptarthria and Zelanda and the Holarctic genus Drassodes are presented. The homology of several palpal elements within the family Gnaphosidae is established. The possible homology of these structures with those in other spider families is discussed. The ground plan of the gnaphosoid genital bulb is compared with the bulb of other Entelegynae genera. Australasian spider genera have a peculiar organization of the male palpal organs. Thus, the Holarctic genus Drassodes was also analyzed for comparison. The analysis of the male copulatory organs is presented and its implication for classification of these groups is discussed. The taxonomic changes we make here are the transfer of four species from the genus Megamyrmaekion to genus Encoptarthria: E. echemophthalma (Simon 1908), E. penicillata (Simon 1908), E. perpusilla (Simon 1908), and E. vestigator (Simon 1908). One species is transferred from genus Echemus to genus Encoptarthria: E. grisea (L. Koch 1873). New synonymy established: Encoptarthria echemophthalmum (Simon 1908) 5 Encoptarthria serventyi Main 1954, syn. n.

The structure of the title compound, C(3)H(8)NO(2)(+)·C(2)HO(4)(-)·H(2)O, is formed by two chiral counterparts (L- and D-alaninium cations), semi-oxalate anions and water molecules, with a 1:1:1 cation-anion-water ratio. The structure is compared with that of the previously known anhydrous DL-alaninium semi-oxalate [Subha Nandhini, KrishnakumarNatarajan (2001). Acta Cryst. E57, o666-o668] in order to investigate the role of water molecules in the crystal packing. The structure of the hydrate resembles that of anhydrous alaninium semi-oxalate, with the water molecule incorporated into the general three-dimensional network of hydrogen bonds where it forms four hydrogen bonds with neighbours disposed tetrahedrally about it. Although the main structural motifs in the hydrate and in the anhydrous form are topologically similar, the incorporation of water molecules in the network results in significant geometric distortion. There are several types of hydrogen bond in the crystal structure of the hydrate, two of which (O-H···O bonds between the semi-oxalate anions and O-H···O hydrogen bonds between water and alaninium cations) are very short. Such hydrogen bonds between semi-oxalate anions are also present in the anhydrous form of this compound. Short distances between semi-oxalate anions in neighbouring chains in the hydrate alternate with longer ones, whereas in the anhydrous structure they are equidistant. Despite the similarity of these compounds, dehydration of the hydrate on storage is not of a single-crystal to single-crystal type, but gives a polycrystalline pseudomorph, preserving the crystal habit. This transformation proceeds through the formation of an intermediate compound, presumably a hemihydrate.

A new compact laboratory device for loading diamond anvil cells with low-boiling pressure-transmitting media is described. This device allows, in particular, the easy loading of diamond anvil cells with pentane–isopentane (1:1) mixture at environmental temperatures up to 303 K and relative humidity at least up to 75–80%. The relatively simple design, the easy availability of materials used for the device and the application of liquid nitrogen as cooling agent allow the manufacture of such a device in a short time at almost any laboratory.