Sharma was taking part in an Instagram Live session with Australian opener David Warner recently, where he was questioned about his hat-trick.

(This story originally appeared in AhmedabadMirror on May 10, 2020)

But still we have prepared the whole country for the worst situation, the Union health minister said.

This is the Indian Navy's first massive evacuation exercise from foreign soil during the COVID-19 lockdown.

Calibration of area detectors from powder diffraction standards is widely used at synchrotron beamlines. From a single diffraction image, it is not possible to determine both the sample-to-detector distance and the wavelength, but, with images taken from multiple positions along the beam direction and where the relative displacement is known, the sample-to-detector distance and wavelength can both be determined with good precision. An example calibration using the GSAS-II software package is presented.

Serial synchrotron crystallography (SSX) is an emerging technique for static and time-resolved protein structure determination. Using specifically patterned silicon chips for sample delivery, the `hit-and-return' (HARE) protocol allows for efficient time-resolved data collection. The specific pattern of the crystal wells in the HARE chip provides direct access to many discrete time points. HARE chips allow for optical excitation as well as on-chip mixing for reaction initiation, making a large number of protein systems amenable to time-resolved studies. Loading of protein microcrystals onto the HARE chip is streamlined by a novel vacuum loading platform that allows fine-tuning of suction strength while maintaining a humid environment to prevent crystal dehydration. To enable the widespread use of time-resolved serial synchrotron crystallography (TR-SSX), detailed technical descriptions of a set of accessories that facilitate TR-SSX workflows are provided.

Pressure can play a key role in probing the structure and dynamics of membrane assemblies, and is also critical to the biology and adaptation of deep-sea organisms. This article presents an overview of the effect of pressure on the structure of membranes and recent developments in high-pressure instrumentation.

Ripon sinkhole concerns halt Harrogate council homes plans  BBC News

Ripon sinkhole: British Geological Survey says area susceptible to holes  BBC News

The enzyme 4-hydroxy-tetrahydrodipicolinate synthase (DapA) is involved in the production of lysine and precursor molecules for peptidoglycan synthesis. In a multistep reaction, DapA converts pyruvate and l-aspartate-4-semialdehyde to 4-hydroxy-2,3,4,5-tetrahydrodipicolinic acid. In many organisms, lysine binds allosterically to DapA, causing negative feedback, thus making the enzyme an important regulatory component of the pathway. Here, the 2.1 Å resolution crystal structure of DapA from the thermoacidophilic methanotroph Methylacidiphilum fumariolicum SolV is reported. The enzyme crystallized as a contaminant of a protein preparation from native biomass. Genome analysis reveals that M. fumariolicum SolV utilizes the recently discovered aminotransferase pathway for lysine biosynthesis. Phylogenetic analyses of the genes involved in this pathway shed new light on the distribution of this pathway across the three domains of life.

The title compound [systematic name: 4-(2,3-Dichlorophenyl)benzene-1,2-diol], C12H8Cl2O2, is a putative di­hydroxy­lated metabolite of 2,3-di­chloro­biphenyl (PCB 5). The title structure displays intra­molecular O—H⋯O hydrogen bonding, and the π–π stacking distance between inversion-related chlorinated benzene rings of the title compound is 3.371 (3) Å. The dihedral angle between two benzene rings is 59.39 (8)°.

In the crystal structure of the title compound, [Sn(C42H26N6)(C7H5O2)2], the SnIV ion is located on a crystallographic inversion centre and is octa­hedrally coordinated with an N4O2 set. Four N atoms of the porphyrin ring form the equatorial plane while the axial positions are occupied by two O atoms from benzoate anions. The molecular packing of the title complex involves non-classical hydrogen bonds of the types C—H⋯O and C—H⋯N, leading to a three-dimensional network structure.

The title compound, C21H16O2, was isolated from the reaction of 1-(2-meth­oxy­eth­oxy)-1-vinyl­cyclo­propane, 4-ethynylbiphenyl, and CO in a [5 + 1 + 2 + 1] cyclo­addition reaction catalysed by [Rh(CO)2Cl]2. The crystals precipitated directly from the crude reaction mixture. A hydrogen-bonding framework between the hy­droxy and carbonyl groups of a symmetry-related neighbour connects the mol­ecules into chains running parallel to the crystallographic c axis. A minor non-merohedral twin component was included in the refinement.

The mol­ecular structure of the title compound, C18H15ISi, which crystallizes in the space group C2/c, does not exhibit any unusual features. Two weak C—H⋯π inter­actions may help to consolidate the packing. The present structure is not isostructural with the known Ph3SiX (X = F, Cl or Br) compounds.

The asymmetric unit of the title compound, C17H20O5, contains two independent mol­ecules, A and B, with similar geometries [dihedral angles between the phenyl rings = 56.19 (8) and 54.98 (7)°, respectively]. Intra­molecular O—H⋯O hydrogen bonds occur in both mol­ecules. In the crystal, the A mol­ecules form [1overline{1}0] chains linked by O—H⋯O hydrogen bonds from the hydroxyl group to one of the meth­oxy O atoms. The B mol­ecules form O—H⋯O hydrogen bonds to the hydroxyl O atoms of the A mol­ecules and thus act as fixed spacers between the chains of mol­ecule A. Some weak C—H⋯O contacts are also present.

The title compound, C18H20N4O4, was synthesized via the base-assisted reaction of piperazine and 2-nitro­benyl bromide in toluene: the complete mol­ecule is generated by a crystallographic inversion centre in the solid state.

The crystal structure of the benzene monosolvate of the well known organic diphosphite ligand BIPHEPHOS, C46H44O8P2·C6H6, is reported for the first time. Single crystals of BIPHEPHOS were obtained from a benzene solution after layering with n-heptane at room temperature. One specific property of this type of diphosphite structure is the twisting of the biphenyl units. In the crystal, C—H⋯π contacts and π–π stacking inter­actions [centroid-to-centroid distance = 3.8941 (15) Å] are observed.

In the title compound, C29H26ClNO4, the di­hydro­pyridine ring adopts a shallow boat conformation. The mean plane of the di­hydro­pyridine ring (all atoms) subtends dihedral angles of 66.54 (1), 73.71 (1) and 79.47 (1)° with the two phenyl rings and the chloro­phenyl ring, respectively. In the crystal, N—H⋯O hydrogen bonds link the mol­ecules into [001] chains.

In the title compound, C29H23ClN2O, the 5-chloro­phenol ring and the imidazole ring are nearly coplanar, with a dihedral angle of 15.76 (9)° between them. The ethyl­phenyl ring and the two phenyl rings subtend angles of 71.09 (7), 43.95 (5) and 36.53 (9)°, respectively, with the imidazole plane. An intra­molecular O—H⋯N hydrogen bond supports the mol­ecular conformation, and an inter­molecular C—H⋯O inter­action, originating from an ortho-phenyl H atom, stabilizes the packing arrangement. In addition, a weak C—H⋯π inter­action, also involving an ortho-phenyl H atom, is observed.

The title salt, (PMIM)2[Ni(P2S8)2] (PMIM = 3-methyl-1-propyl-1H-imidazol-3-ium, C7H13N2+), consists of a nickel–thio­phosphate anion charge-balanced by a pair of crystallographically independent PMIM cations. It crystallizes in the monoclinic space group P21/n. The structure exhibits the known [Ni(P2S8)2]2− anion with two unique imidazolium cations in the asymmetric unit. Whereas one PMIM cation is well ordered, the other is disordered over two orientations with refined occupancies of 0.798 (2) and 0.202 (2). The salt was prepared directly from the elements in the ionic liquid [PMIM]CF3SO3. Whereas one of the PMIM cations is well behaved (it does not exhibit disorder even in the propyl side chain), the other is found in two overlapping positions. The refined occupancies for the two orientations are roughly 80:20. Here, too, there appears to be little disorder in the propyl arm.

In the title compound, C10H13N5, the piperidine ring adopts a chair conformation with the exocyclic N—C bond in an axial orientation, and the dihedral angle between the mean planes of piperidine and pyrimidine rings is 49.57 (11)°. A short intra­molecular C—H⋯N contact generates an S(7) ring. In the crystal, N—H⋯N hydrogen bonds link the mol­ecules into (100) sheets and a weak aromatic π-π stacking inter­action is observed [centroid–centroid separation = 3.5559 (11) Å] between inversion-related pyrimidine rings.

In the title compound, C20H21NO, the dihedral angle between the phenyl ring is 47.5 (1)° and the piperidine ring adopts a chair conformation. In the crystal, mol­ecules are linked by C—H⋯π inter­actions into dimers with the mol­ecules related by twofold symmetry.

The title compound, C52H40N2, is disposed about a centre of inversion and the conformation about the imine bond [1.268 (3) Å] is E. The terminal benzene ring is approximately perpendicular to the central 1,4-di­aza­butadiene mean plane, forming a dihedral angle of 81.2 (3)°. Weak C—H⋯π and π–π [inter-centroid distance = 4.021 (5) Å] inter­actions help to consolidate the packing.

The synthesis and crystal structures of a series of 6-aryl­fuvlenes (fulvene is 5-methyl­idene­cyclo­penta-1,3-diene) with varying methyl­ation patterns on the 6-phenyl substituent are reported, namely 6-(3-methyl­phen­yl)-1,3-di­phenyl­fulvene (C25H20), 6-(4-methyl­phen­yl)-1,3-di­phenyl­fulvene (C25H20), 6-mesityl-3-di­phenyl­fulvene (C27H24) and 6-(2,3,4,5,6-penta­methyl­phen­yl)-1,3-di­phenyl­fulvene (C29H28). The bond lengths are typical of those observed in related fulvenes. A network of C—H⋯π ring inter­actions consolidates the packing in each structure.

The title compound, C21H16N2O2, consists of an imidazolidine unit linked to two phenyl rings and two prop-2-yn-1-yl moieties. The imidazolidine ring is oriented at dihedral angles of 79.10 (5) and 82.61 (5)° with respect to the phenyl rings, while the dihedral angle between the two phenyl rings is 62.06 (5)°. In the crystal, inter­molecular C—HProp⋯OImdzln (Prop = prop-2-yn-1-yl and Imdzln = imidazolidine) hydrogen bonds link the mol­ecules into infinite chains along the b-axis direction. Two weak C—HPhen⋯π inter­actions are also observed. The Hirshfeld surface analysis of the crystal structure indicates that the most important contributions for the crystal packing are from H⋯H (43.3%), H⋯C/C⋯H (37.8%) and H⋯O/O⋯H (18.0%) inter­actions. Hydrogen bonding and van der Waals inter­actions are the dominant inter­actions in the crystal packing. Computational chemistry indicates that the C—HProp⋯OImdzln hydrogen-bond energy in the crystal is −40.7 kJ mol−1. Density functional theory (DFT) optimized structures at the B3LYP/6–311G(d,p) level are compared with the experimentally determined mol­ecular structure in the solid state. The HOMO–LUMO behaviour was elucidated to determine the energy gap.

The coordination of the ligands with respect to the central atom in the complex bromido­tricarbon­yl[diphen­yl(pyridin-2-yl)phosphane-κ2N,P]rhenium(I) chloro­form disolvate, [ReBr(C17H14NP)(CO)3]·2CHCl3 or [κ2-P,N-{(C6H5)2(C5H5N)P}Re(CO)3Br]·2CHCl3, (I·2CHCl3), is best described as a distorted octa­hedron with three carbonyls in a facial conformation, a bromide atom, and a biting P,N-di­phenyl­pyridyl­phosphine ligand. Hirshfeld surface analysis shows that C—Cl⋯H inter­actions contribute 26%, the distance of these inter­actions are between 2.895 and 3.213 Å. The reaction between I and piperidine (C5H11N) at 313 K in di­chloro­methane leads to the partial decoord­ination of the pyridyl­phosphine ligand, whose pyridyl group is replaced by a piperidine mol­ecule, and the complex bromido­tricarbon­yl[diphen­yl(pyridin-2-yl)phosphane-κP](piperidine-κN)rhenium(I), [ReBr(C5H11N)(C17H14NP)(CO)3] or [P-{(C6H5)2(C5H5N)P}(C5H11N)Re(CO)3Br] (II). The mol­ecule has an intra­molecular N—H⋯N hydrogen bond between the non-coordinated pyridyl nitro­gen atom and the amine hydrogen atom from piperidine with D⋯A = 2.992 (9) Å. Thermogravimetry shows that I·2CHCl3 losses 28% of its mass in a narrow range between 318 and 333 K, which is completely consistent with two solvating chloro­form mol­ecules very weakly bonded to I. The remaining I is stable at least to 573 K. In contrast, II seems to lose solvent and piperidine (12% of mass) between 427 and 463 K, while the additional 33% loss from this last temperature to 573 K corresponds to the release of 2-pyridyl­phosphine. The contribution to the scattering from highly disordered solvent mol­ecules in II was removed with the SQUEEZE routine [Spek (2015). Acta Cryst. C71, 9-18] in PLATON. The stated crystal data for Mr, μ etc. do not take this solvent into account.

The title compounds, 8-amino-6-methyl-3,4-diphenyl-1H-isochromen-1-one, C22H17NO2, (I), and 8-amino-3,4-diethyl-6-methyl-1H-isochromen-1-one, C14H17NO2, (II), are new isocoumarin derivatives in which the isochromene ring systems are planar. Compound II crystallizes with two independent mol­ecules (A and B) in the asymmetric unit. In I, the two phenyl rings are inclined to each other by 56.41 (7)° and to the mean plane of the 1H-isochromene ring system by 67.64 (6) and 44.92 (6)°. In both compounds, there is an intra­molecular N—H⋯O hydrogen bond present forming an S(6) ring motif. In the crystal of I, mol­ecules are linked by N—H⋯π inter­actions, forming chains along the b-axis direction. A C—H⋯π inter­action links the chains to form layers parallel to (100). The layers are then linked by a second C—H⋯π inter­action, forming a three-dimensional structure. In the crystal of II, the two independent mol­ecules (A and B) are linked by N—H⋯O hydrogen bonds, forming –A–B–A–B– chains along the [101] direction. The chains are linked into ribbons by C—H⋯π inter­actions involving inversion-related A mol­ecules. The latter are linked by offset π–π inter­actions [inter­centroid distances vary from 3.506 (1) to 3.870 (2) Å], forming a three-dimensional structure.

The crystal structure of the title compound, [Ni(C63H31F10N5S2)]·xCH2Cl2 (x > 1/2), consists of Ni–porphyrin complexes that are located in general positions and di­chloro­methane solvent mol­ecules that are disordered around centers of inversion. The NiII ions are in a square-pyramidal (CN5) coordination, with four porphyrin N atoms in the equatorial and a pyridine N atom in the apical position and are shifted out of the porphyrine N4 plane towards the coordinating pyridine N atom. The pyridine substituent is not exactly perpendicular to the N4 plane with an angle of inter­section between the planes planes of 80.48 (6)°. The di­chloro­methane solvent mol­ecules are hydrogen bonded to one of the four porphyrine N atoms. Two complexes are linked into dimers by two symmetry-equivalent C—H⋯S hydrogen bonds. These dimers are closely packed, leading to cavities in which additional di­chloro­methane solvent mol­ecules are embedded. These solvent mol­ecules are disordered and because no reasonable split model was found, the data were corrected for disordered solvent using the PLATON SQUEEZE routine [Spek (2015). Acta Cryst. C71, 9–18].

The isostructural title compounds, poly[piperazin-1-ium [di-μ-bromido-caesium]], {(C4H11N2)[CsBr2]}n, and poly[piperazin-1-ium [di-μ-bromido-rubidium]], {(C4H11N2)[RbBr2]}n, contain singly-protonated piperazin-1-ium cations and unusual ABr6 (A = Cs or Rb) trigonal prisms. The prisms are linked into a distinctive `curtain wall' arrangement propagating in the (010) plane by face and edge sharing. In each case, a network of N—H⋯N, N—H⋯Br and N—H⋯(Br,Br) hydrogen bonds consolidates the structure.

Six new 1-aroyl-4-(4-meth­oxy­phen­yl)piperazines have been prepared, using coupling reactions between benzoic acids and N-(4-meth­oxy­phen­yl)piperazine. There are no significant hydrogen bonds in the structure of 1-benzoyl-4-(4-meth­oxy­phen­yl)piperazine, C18H20N2O2, (I). The mol­ecules of 1-(2-fluoro­benzo­yl)-4-(4-meth­oxy­phen­yl)piperazine, C18H19FN2O2, (II), are linked by two C—H⋯O hydrogen bonds to form chains of rings, which are linked into sheets by an aromatic π–π stacking inter­action. 1-(2-Chloro­benzo­yl)-4-(4-meth­oxy­phen­yl)piperazine, C18H19ClN2O2, (III), 1-(2-bromo­benzo­yl)-4-(4-meth­oxy­phen­yl)piperazine, C18H19BrN2O2, (IV), and 1-(2-iodo­benzo­yl)-4-(4-meth­oxyphen­yl)piperazine, C18H19IN2O2, (V), are isomorphous, but in (III) the aroyl ring is disordered over two sets of atomic sites having occupancies of 0.942 (2) and 0.058 (2). In each of (III)–(V), a combination of two C—H⋯π(arene) hydrogen bonds links the mol­ecules into sheets. A single O—H⋯O hydrogen bond links the mol­ecules of 1-(2-hy­droxy­benzo­yl)-4-(4-meth­oxy­phen­yl)piperazine, C18H20N2O3, (VI), into simple chains. Comparisons are made with the structures of some related compounds.

The title compound, [Ni(C64H33F10N5S2)]·xCH2Cl2, consists of discrete NiII porphyrin complexes, in which the five-coordinate NiII cations are in a distorted square-pyramidal coordination geometry. The four porphyrin nitro­gen atoms are located in the basal plane of the pyramid, whereas the pyridine N atom is in the apical position. The porphyrin plane is strongly distorted and the NiII cation is located above this plane by 0.241 (3) Å and shifted in the direction of the coordinating pyridine nitro­gen atom. The pyridine ring is not perpendicular to the N4 plane of the porphyrin moiety, as observed for related compounds. In the crystal, the complexes are linked via weak C—H⋯F hydrogen bonds into zigzag chains propagating in the [001] direction. Within this arrangement cavities are formed, in which highly disordered di­chloro­methane solvate mol­ecules are located. No reasonable structural model could be found to describe this disorder and therefore the contribution of the solvent to the electron density was removed using the SQUEEZE option in PLATON [Spek (2015). Acta Cryst. C71, 9–18].

Twelve 4-(4-meth­oxy­phen­yl)piperazin-1-ium salts containing organic anions have been prepared and structurally characterized. The monohydrated benzoate, 4-fluoro­benzoate, 4-chloro­benzoate and 4-bromo­benzoate salts, C11H17N2O+·C7H5O2−·H2O (I), C11H17N2O+·C7H4FO2−·H2O (II), C11H17N2O+·C7H4ClO2−·H2O (III), and C11H17N2O+·C7H4BrO2−·H2O (IV), respectively, are isomorphous and all exhibit disorder in the 4-meth­oxy­phenyl unit: the components are linked by N—H⋯O and O—H⋯O hydrogen bond to form chains of rings. The unsolvated 2-hy­droxy­benzoate, pyridine-3-carboxyl­ate and 2-hy­droxy-3,5-di­nitro­benzoate salts, C11H17N2O+·C7H5O3− (V), C11H17N2O+·C6H4NO2− (VI) and C11H17N2O+·C7H3N2O7− (VII), respectively, are all fully ordered: the components of (V) are linked by multiple N—H⋯O hydrogen bonds to form a chain of rings; those of (VI) are linked into a three-dimensional framework by a combination of N—H⋯O, C—H⋯O and C—H⋯N hydrogen bonds and those of (VII), where the anion has a structure reminiscent of the picrate anion, are linked into a three-dimensional array by N—H⋯O and C—H⋯O hydrogen bonds. The hydrogensuccinate and hydrogenfumarate salts, C11H17N2O+·C4H5O4− (VIII) and C11H17N2O+·C4H3O3− (IX), respectively, are isomorphous, and both exhibit disorder in the anionic component: N—H⋯O and O—H⋯O hydrogen bonds link the ions into sheets, which are further linked by C—H⋯π(arene) inter­actions. The anion of the hydrogenmaleate salt, C11H17N2O+·C4H3O3− (X), contains a very short and nearly symmetrical O⋯H⋯O hydrogen bond, and N—H⋯O hydrogen bonds link the anions into chains of rings. The ions in the tri­chloro­acetate salt, C11H17N2O+·C2Cl3O2− (XI), are linked into simple chains by N—H⋯O hydrogen bonds. In the hydrated chloranilate salt, 2C11H17N2O+·C6Cl2O42−·2H2O (XII), which crystallizes as a non-merohedral twin, the anion lies across a centre of inversion in space group P21/n, and a combination of N—H⋯O and O—H⋯O hydrogen bonds generates complex sheets. Comparisons are made with the structures of some related compounds.

The syntheses and crystal structures of three cyclo­triphosphazenes, all with fluorinated ar­yloxy side groups that generate different steric characteristics, viz. hexa­kis­(penta­fluoro­phen­oxy)cyclo­triphosphazene, N3P3(OC6F5)6, 1, hexa­kis­[4-(tri­fluoro­methyl)­phen­oxy]cyclo­triphosphazene, N3P3[OC6H4(CF3)]6, 2 and hexa­kis­[3,5-bis(­tri­fluoro­methyl)­phen­oxy]cyclo­triphosphazene, N3P3[OC6H3(CF3)2]6 3, are reported. Specifically, each phospho­rus atom bears either two penta­fluoro­phen­oxy, 4-tri­fluoro­methyl­phen­oxy, or 3,5-tri­fluoro­methyl­phen­oxy groups. The central six-membered phosphazene rings display envelope pucker conformations in each case, albeit to varying degrees. The maximum displacement of the `flap atom' from the plane through the other ring atoms [0.308 (5) Å] is seen in 1, in a mol­ecule that is devoid of hydrogen atoms and which exhibits a `wind-swept' look with all the aromatic rings displaced in the same direction. In 3 an intra­molecular C—H(aromatic)⋯F inter­action is observed. All the –CF3 groups in 2 and 3 exhibit positional disorder over two rotated orientations in close to statistical ratios. The extended structures of 2 and 3 are consolidated by C—H⋯F inter­actions of two kinds: (a) linear chains, and (b) cyclic between mol­ecules related by inversion centers. In both 1 and 3, one of the six substituted phenyl rings has a parallel-displaced aromatic π–π stacking inter­action with its respective symmetry mate with slippage values of 2.2 Å in 1 and 1.0 Å in 3. None of the structures reported here have solvent voids that could lead to clathrate formation.

In the title com­pound, C29H22N4O3, the carbazole system forms a dihedral angle of 68.45 (3)° with the mean plane of the bi­pyridine ring system. The bi­pyridine ring system, with two meth­oxy substituents, is approximately planar (r.m.s. deviation = 0.0670 Å), with a dihedral angle of 7.91 (13)° between the planes of the two pyridine rings. Intra­molecular C—H⋯O/N hydrogen bonds may promote the planarity of the bipyridyl ring system. In the pyridyl-substituted carbazole fragment, the pyridine ring is tilted by 56.65 (4)° with respect to the mean plane of the carbazole system (r.m.s. deviation = 0.0191 Å). In the crystal, adjacent mol­ecules are connected via C—H⋯O/N hydrogen bonds and C—H⋯π inter­actions, resulting in the formation of a three-dimensional (3D) supra­molecular network. In addition, the 3D structure contains inter­molecular π–π stacking inter­actions, with centroid–centroid distances of 3.5634 (12) Å between pyridine rings. The title com­pound exhibits a high energy gap (3.48 eV) and triplet energy (2.64 eV), indicating that it could be a suitable host material in organic light-emitting diode (OLED) applications.

The crystal and mol­ecular structures of the title CuII complex, isolated as a dihydrate, [Cu(C21H14N3O3)2]·2H2O, reveals a highly distorted coordination geometry inter­mediate between square-planar and tetra­hedral defined by an N2O2 donor set derived from two mono-anionic bidentate ligands. Furthermore, each six-membered chelate ring adopts an envelope conformation with the Cu atom being the flap. In the crystal, imidazolyl-amine-N—H⋯O(water), water-O—H⋯O(coordinated, nitro and water), phenyl-C—H⋯O(nitro) and π(imidazol­yl)–π(nitro­benzene) [inter-centroid distances = 3.7452 (14) and 3.6647 (13) Å] contacts link the components into a supra­molecular layer lying parallel to (101). The connections between layers forming a three-dimensional architecture are of the types nitro­benzene-C—H⋯O(nitro) and phenyl-C—H⋯π(phen­yl). The distorted coordination geometry for the CuII atom is highlighted in an analysis of the Hirshfeld surface calculated for the metal centre alone. The significance of the inter­molecular contacts is also revealed in a study of the calculated Hirshfeld surfaces; the dominant contacts in the crystal are H⋯H (41.0%), O⋯H/H⋯O (27.1%) and C⋯H/H⋯C (19.6%).

In the crystal structure of the title compound, (C5H6N)[Cr(NCS)4(C5H5N)2]·C5H5N, the CrIII ions are octa­hedrally coordinated by four N-bonding thio­cyanate anions and two pyridine ligands into discrete negatively charged complexes, with the CrIII ion, as well as the two pyridine ligands, located on crystallographic mirror planes. The mean planes of the two pyridine ligands are rotated with respect to each other by 90°. Charge balance is achieved by one protonated pyridine mol­ecule that is hydrogen bonded to one additional pyridine solvent mol­ecule, with both located on crystallographic mirror planes and again rotated by exactly 90°. The pyridinium H atom was refined as disordered between both pyridine N atoms in a 70:30 ratio, leading to a linear N—H⋯N hydrogen bond. In the crystal, discrete complexes are linked by weak C—H⋯S hydrogen bonds into chains that are connected by additional C—H⋯S hydrogen bonding via the pyridinium cations and solvent mol­ecules into layers and finally into a three-dimensional network.

A peptide biphenyl hybrid compound {systematic name: dimethyl 2,2'-[((2S,2'S)-2,2'-{[(2S,2'S)-1,1'-([1,1'-biphen­yl]-2,2'-dicarbon­yl)bis­(pyrrolidine-1,2-diyl-2-carbon­yl)]bis­(aza­nedi­yl)}bis­(3-phenyl­propano­yl))bis­(aza­nedi­yl)](2S,2'S)-dipropionate hemihydrate}, C50H56N6O10·0.5H2O, was prepared by coupling of [1,1'-biphen­yl]-2,2'-dicarbonyl dichloride, tri­ethyl­amine and the tripeptide Pro–Phe–Ala in CH2Cl2 at 273 K under an N2 atmosphere. In the crystal, the asymmetric unit contains the peptide biphenyl hybrid accompanied by one-half of a water mol­ecule. A C atom of one of the proline rings is disordered between two positions in a 0.746 (11):0.254 (11) ratio. An important structural aspect of peptide compounds is their capacity to self-associate mediated by inter­molecular and intra­molecular hydrogen bonding. This characteristic can be useful in understanding the inter­actions between peptides and biomacromolecular targets, as well as to explain peptide properties.

The title compound, C13H16ClNO, contains a methyl­piperidine ring in the stable chair conformation. The mean plane of the twisted piperidine ring subtends a dihedral angle of 39.89 (7)° with that of the benzene ring. In the crystal, weak C—H⋯O inter­actions link the mol­ecules along the a-axis direction to form infinite mol­ecular chains. H⋯H inter­atomic inter­actions, C—H⋯O inter­molecular inter­actions and weak dispersive forces stabilize mol­ecular packing and form a supra­molecular network, as established by Hirshfeld surface analysis.

In the title compound, C22H27NO, the piperidine ring adopts a chair conformation. The dihedral angles between the mean plane of the piperidine ring and the phenyl rings are 89.78 (7) and 48.30 (8)°. In the crystal, mol­ecules are linked into chains along the b-axis direction by C—H⋯O hydrogen bonds. The DFT/B3LYP/6–311 G(d,p) method was used to determine the HOMO–LUMO energy levels. The mol­ecular electrostatic potential surfaces were investigated by Hirshfeld surface analysis and two-dimensional fingerprint plots were used to analyse the inter­molecular inter­actions in the mol­ecule.

Crystal structures are reported for N-(4-meth­oxy­phen­yl)piperazine (MeOPP), (I), and for its 3,5-di­nitro­benzoate, 2,4,6-tri­nitro­phenolate (picrate) and 4-amino­benzoate salts, (II)–(IV), the last of which crystallizes as a monohydrate. In MeOPP, C11H16N2O, (I), the 4-meth­oxy­phenyl group is nearly planar and it occupies an equatorial site on the piperazine ring: the mol­ecules are linked into simple C(10) chains by N—H⋯O hydrogen bonds. In each of the salts, i.e., C11H17N2O+·C7H3N2O6−, (II), C11H17N2O+·C6H2N3O7−, (III), and C11H17N2O+·C7H6NO2−·H2O, (IV), the effectively planar 4-meth­oxy­phenyl substituent again occupies an equatorial site on the piperazine ring. In (II), two of the nitro groups are disordered over two sets of atomic sites and the bond distances in the anion indicate considerable delocalization of the negative charge over the C atoms of the ring. The ions in (II) are linked by two N—H⋯O hydrogen bonds to form a cyclic, centrosymmetric four-ion aggregate; those in (III) are linked by a combination of N—H⋯O and C—H⋯π(arene) hydrogen bonds to form sheets; and the components of (IV) are linked by N—H⋯O, O—H⋯O and C—H⋯π(arene) hydrogen bonds to form a three-dimensional framework structure. Comparisons are made with the structures of some related compounds.

The title compound, bis­(4-hy­droxy-N-isopropyl-N-methyl­tryptammonium) (4-HO-MiPT) fumarate (systematic name: bis­{[2-(4-hy­droxy-1H-indol-3-yl)eth­yl](meth­yl)propan-2-yl­aza­nium} but-2-enedioate), 2C14H21N2O+·C4H2O42−, has a singly protonated tryptammonium cation and one half of a fumarate dianion in the asymmetric unit. The tryptammonium and fumarate ions are held together in one-dimensional chains by N—H⋯O and O—H⋯O hydrogen bonds. These chains are a combination of R42(20) rings, and C22(15) and C44(30) parallel chains along (110). They are further consolidated by N—H⋯π inter­actions. There are two two-component types of disorder impacting the tryptammonium fragment with a 0.753 (7):0.247 (7) occupancy ratio and one of the fumarate oxygen atoms with a 0.73 (8):0.27 (8) ratio.

The title compound, C21H23F2NO, consists of two fluoro­phenyl groups and one butyl group equatorially oriented on a piperidine ring, which adopts a chair conformation. The dihedral angle between the mean planes of the phenyl rings is 72.1 (1)°. In the crystal, N—H⋯O and weak C—H⋯F inter­actions, which form R22[14] motifs, link the mol­ecules into infinite C(6) chains propagating along [001]. A weak C—H⋯π inter­action is also observed. A Hirshfeld surface analysis of the crystal structure indicates that the most significant contributions to the crystal packing are from H⋯H (53.3%), H⋯C/C⋯H (19.1%), H⋯F/F⋯H (15.7%) and H⋯O/O⋯H (7.7%) contacts. Density functional theory geometry-optimized calculations were compared to the experimentally determined structure in the solid state and used to determine the HOMO–LUMO energy gap and compare it to the UV–vis experimental spectrum.

The title compounds, 5-(2H-1,3-benzodioxol-5-yl)-N-cyclo­hexyl­penta-2,4-dienamide, C18H21NO3 (I), and 5-(2H-1,3-benzodioxol-5-yl)-1-(pyrrolidin-1-yl)penta-2,4-dien-1-one C16H17NO3 (II), are derivatives of piperine, which is known as a pungent component of pepper. Their geometrical parameters are similar to those of the three polymorphs of piperine, which indicate conjugation of electrons over the length of the mol­ecules. The extended structure of (I) features N—H⋯O amide hydrogen bonds, which generate C(4) [010] chains. The crystal of (II) features aromatic π–π stacking, as for two of three known piperine polymorphs.

Exact and approximate mathematical formulas of equatorial aberration for powder diffraction data collected with an Si strip X-ray detector in continuous-scan integration mode are presented. An approximate formula is applied to treat the experimental data measured with a commercial powder diffractometer.

A furnace that covers the temperature range from room temperature up to 2000 K has been designed, built and implemented on the D2AM beamline at the ESRF. The QMAX furnace is devoted to the full exploration of the reciprocal hemispace located above the sample surface. It is well suited for symmetric and asymmetric 3D reciprocal space mapping. Owing to the hemispherical design of the furnace, 3D grazing-incidence small- and wide-angle scattering and diffraction measurements are possible. Inert and reactive experiments can be performed at atmospheric pressure under controlled gas flux. It is demonstrated that the QMAX furnace allows monitoring of structural phase transitions as well as microstructural evolution at the nanoscale, such as self-organization processes, crystal growth and strain relaxation. A time-resolved in situ oxidation experiment illustrates the capability to probe the high-temperature reactivity of materials.

In this work, two methods of high-resolution X-ray data refinement: multipole refinement (MM) and Hirshfeld atom refinement (HAR) – together with X-ray wavefunction refinement (XWR) – are applied to investigate the refinement of positions and anisotropic thermal motion of hydrogen atoms, experiment-based reconstruction of electron density, refinement of anharmonic thermal vibrations, as well as the effects of excluding the weakest reflections in the refinement. The study is based on X-ray data sets of varying quality collected for the crystals of four quinoline derivatives with Cl, Br, I atoms and the -S-Ph group as substituents. Energetic investigations are performed, comprising the calculation of the energy of intermolecular interactions, cohesive and geometrical relaxation energy. The results obtained for experimentally derived structures are verified against the values calculated for structures optimized using dispersion-corrected periodic density functional theory. For the high-quality data sets (the Cl and -S-Ph compounds), both MM and XWR could be successfully used to refine the atomic displacement parameters and the positions of hydrogen atoms; however, the bond lengths obtained with XWR were more precise and closer to the theoretical values. In the application to the more challenging data sets (the Br and I compounds), only XWR enabled free refinement of hydrogen atom geometrical parameters, nevertheless, the results clearly showed poor data quality. For both refinement methods, the energy values (intermolecular interactions, cohesive and relaxation) calculated for the experimental structures were in similar agreement with the values associated with the optimized structures – the most significant divergences were observed when experimental geometries were biased by poor data quality. XWR was found to be more robust in avoiding incorrect distortions of the reconstructed electron density as a result of data quality issues. Based on the problem of anharmonic thermal motion refinement, this study reveals that for the most correct interpretation of the obtained results, it is necessary to use the complete data set, including the weak reflections in order to draw conclusions.

Efficient and reliable sample delivery has remained one of the bottlenecks for serial crystallography experiments. Compared with other methods, fixed-target sample delivery offers the advantage of significantly reduced sample consumption and shorter data collection times owing to higher hit rates. Here, a new method of on-chip crystallization is reported which allows the efficient and reproducible growth of large numbers of protein crystals directly on micro-patterned silicon chips for in-situ serial crystallography experiments. Crystals are grown by sitting-drop vapor diffusion and previously established crystallization conditions can be directly applied. By reducing the number of crystal-handling steps, the method is particularly well suited for sensitive crystal systems. Excessive mother liquor can be efficiently removed from the crystals by blotting, and no sealing of the fixed-target sample holders is required to prevent the crystals from dehydrating. As a consequence, `naked' crystals are obtained on the chip, resulting in very low background scattering levels and making the crystals highly accessible for external manipulation such as the application of ligand solutions. Serial diffraction experiments carried out at cryogenic temperatures at a synchrotron and at room temperature at an X-ray free-electron laser yielded high-quality X-ray structures of the human membrane protein aquaporin 2 and two new ligand-bound structures of thermolysin and the human kinase DRAK2. The results highlight the applicability of the method for future high-throughput on-chip screening of pharmaceutical compounds.

Functional materials are of critical importance to electronic and smart devices. A deep understanding of the structure–property relationship is essential for designing new materials. In this work, instead of utilizing conventional atomic coordinates, a symmetry-mode approach is successfully used to conduct structure refinement of the neutron powder diffraction data of (1−x)AgNbO3–xLiTaO3 (0 ≤ x ≤ 0.09) ceramics. This provides rich structural information that not only clarifies the controversial symmetry assigned to pure AgNbO3 but also explains well the detailed structural evolution of (1−x)AgNbO3–xLiTaO3 (0 ≤ x ≤ 0.09) ceramics, and builds a comprehensive and straightforward relationship between structural distortion and electrical properties. It is concluded that there are four relatively large-amplitude major modes that dominate the distorted Pmc21 structure of pure AgNbO3, namely a Λ3 antiferroelectric mode, a T4+ a−a−c0 octahedral tilting mode, an H2 a0a0c+/a0a0c− octahedral tilting mode and a Γ4− ferroelectric mode. The H2 and Λ3 modes become progressively inactive with increasing x and their destabilization is the driving force behind the composition-driven phase transition between the Pmc21 and R3c phases. This structural variation is consistent with the trend observed in the measured temperature-dependent dielectric properties and polarization–electric field (P-E) hysteresis loops. The mode crystallography applied in this study provides a strategy for optimizing related properties by tuning the amplitudes of the corresponding modes in these novel AgNbO3-based (anti)ferroelectric materials.