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An experimental investigation was conducted on two lengths of Roman lead water pipe excavated near Corbridge, Northumberland, England. The pipes date from approximately AD 80. One length of pipe contained a sleeve joint. The pipes were linked to a pump system using 3 D-printed connectors, and the hydraulic head loss along the pipe was measured. The pipe without a joint was used to determine a value for the wall roughness height, fitting the results to the Darcy-Weisbach equation. The wall roughness height obtained was assumed to apply to the pipe with the joint, and the additional head loss observed was then assumed to be due to the joint, allowing determination of a local loss coefficient. The pipes have a sinter encrustation, indicating that they had typically flowed partially full. Using this as an indication of water depth and deriving topographical information from the excavation report, the likely flow the pipes carried during their operational life was estimated. It was concluded that the pipe wall roughness coefficient ks was 0.9 mm, the joint local loss coefficient was 1.159, and that during operation the pipe probably carried around 17 litres/minute.

The “Pittsburgh renaissance” is a celebrated portrayal of transformation from a “rust belt” economy into a dynamic “brain belt” success story. Pittsburgh has been proffered as an aspiration...

To determine whether non-urgent referrals can be adequately assessed in a triage clinic, to determine the service outcome of these referrals, and whether triage was acceptable to families, referrers and CAMHS clinicians.Families, CAMHS clinicians and GPs were surveyed to ascertain the acceptability of triage. Non-attendance and outcome of triage were recorded.Ninety-two cases were included and the DNA rate fell by one-third.Overall, clinicians and families reported high rates of satisfaction with triage (93.7% and 95.2%) and multidisciplinary working improved.

The carboxylic acid dimer is a frequently observed intermolecular association used in crystal engineering and design, which can show proton disorder across its hydrogen bonds. Proton disorder in benzoic acid dimers is a dynamic, temperature-dependent process whose reported occurrence is still relatively rare. A combination of variable temperature X-ray and neutron diffraction has been applied to demonstrate the effect of local crystalline environment on both the degree and onset of proton disorder in 3,5-dinitrobenzoic acid dimers. Dimers which have significantly asymmetric local intermolecular interactions are found to have a higher onset temperature for occupation of a second hydrogen atom site to be observed, indicating a greater energy asymmetry between the two configurations. Direct visualization of the electron density of hydrogen atoms within these dimers using high resolution X-ray diffraction data to characterize this disorder is shown to provide remarkably good agreement with that derived from neutron data.

A new polymorph of 2,4-dihydroxybenzoic acid is reported. The structure was characterized by multiple-temperature X-ray diffraction and solid-state DFT computations. The material shows a geometric pattern of hydrogen bonding consistent with cooperativity between the intermolecular carboxylic acid dimer and intramolecular hydrogen bonds. The presence of proton disorder within this hydrogen-bond system, which would support such a cooperative model, was not fully ruled out by the initial X-ray studies. However, solid-state calculations on the three possible end-point tautomers indicate that the dominant crystallographically observed configuration is substantially lower in energy than the other tautomers (by at least 9 kJ mol−1), indicating that no disorder should be expected. It is therefore concluded that no disorder is observed either in the intra- or intermolecular hydrogen bonds of the title compound and that the cooperativity between the hydrogen bonds is not present within the temperature range studied.

A highly interactive research-led learning session for chemistry undergraduates is described, which aims to lead students to an awareness of the applications of crystallography technique through a mentored hands-on crystal structure solution and refinement session. The research-based environment is inherent throughout the 4.5 h program and is emphasized by several features in the learning experience.

The synthesis and crystal structures of three new metal organic frameworks of type [Zn(L-2H)] n (1), {[ZnLCl2](CH3CN)0.5(DMF)0.5(H2O)0.5} n (2) and {[CdL(DMF)(NO3)2]·DMF} n (3), all based on the dipyridyl-derivatised macrocycle, dipyridyldibenzotetraaza[14]annulene (L), are reported along with the X-ray structure of the protonated metal-free ligand as its perchlorate salt, [(HL)(ClO4)] n (4). In [Zn(L-2H)] n , the zinc ion occupies the macrocyclic cavity, being bound to the N4-donor set of the macrocyclic ring in its doubly deprotonated form. Each zinc atom is also axially bound by a pyridyl moiety from an adjacent complex, resulting in formation of an infinite one-dimensional chain of the ‘herringbone’ type in which pairs of macrocyclic complexes interact via face-to-face π–π stacking interactions. In contrast, the zinc ion in {[ZnLCl2](CH3CN)0.5(DMF)0.5(H2O)0.5} n does not occupy the macrocyclic cavity but is bound to a pyridyl nitrogen from two ligands such that it acts as a bridge between macrocyclic units and results in the generation of a one-dimensional chain. Two chloro ligands also bind to each zinc centre to yield a distorted tetrahedral coordination geometry. Offset π–π stacking occurs between adjacent chains involving alternate macrocycles in each chain, giving rise to a zig-zag arrangement. Pairs of interacting chains pass through the above-mentioned chains to generate further π–π stacking to yield an overall three-dimensional structure that contains large ellipsoidal-shaped channels. In {[CdL(DMF)(NO3)2]·DMF} n the cadmium ion again does not occupy the macrocyclic cavity but acts as a bridge between macrocycles to once again afford a linear chain structure. Each cadmium is bound to two pyridyl groups (arising from different molecules of L), two nitrato ligands and one oxygen-bound dimethylformamide molecule to yield a distorted pentagonal bipyramidal coordination geometry. The protonated ligand, [(HL)(ClO4)] n , adopts a linear chain structure in which one pyridyl group is protonated and interacts intermolecularly via a hydrogen bond with the non-protonated pyridyl group of an adjacent macrocyclic unit to yield a hydrogen-bonded linear chain structure.

A concise synthesis of the tricyclic core of the marine diterpene natural products labiatin A and australin A has been accomplished. The key ring-forming transformation is a cascade reaction comprising generation of a copper carbenoid from a diazo ketone, intramolecular reaction of the carbenoid with a cyclic ether, and rearrangement of the resulting free oxonium ylide or its metal-bound equivalent with ring expansion of the original cyclic ether.

An investigation into the creation of cocrystals of benzamide and substituted benzoic acids was undertaken and four new cocrystals were structurally characterized by single-crystal X-ray diffraction. The attempted cocrystallizations were only successful in those cases where electron-withdrawing functional groups were present as substituents on the benzoic acid. This experimental observation was supported by computational studies, which indicated that in these cases the intermolecular acid···amide interaction between the acid and benzamide was strengthened. A correlation between the interaction energy and the Hammett substitution constant in the applicable cases was displayed. The calculated energy of interaction between benzamide/salicylic acid dimers and benzamide/benzoic acid dimer are the same, yet only benzamide/salicylic acid forms a cocrystal. Lattice energy calculations on the salicylic acid/benzamide crystal structure and hypothetical benzoic acid/benzamide cocrystal structures indicate a differen...

The multicomponent ternary complex of 4-dimethylaminobenzoic acid (4-DABA), 3,5-dinitrobenzoic acid (3,5-DNBA), and 4,4′-bipyridine (BIPY) has been studied by variable temperature X-ray and neutron diffraction. Proton disorder is observed within the 4-DABA homodimers present and quantitatively evaluated from neutron data. The effect of the crystal environment and in particular the pyramidalization of the nitrogen atom within the 4-DABA molecule and the consequential effect on the presence of hydrogen atom disorder are discussed with reference to the previously determined pure 4-DABA structure and the binary cocrystal with 3,5-DNBA.

Multiple temperature single crystal neutron diffraction studies of a new polymorphic form of 2,4-dihydroxybenzoic acid, and of the isomer 2,5-dihydroxybenzoic acid, are presented, together with static and dynamic solid-state density functional theory calculations. The studies present an unambiguous analysis of the potential for cooperativity and hydrogen atom disorder in the hydrogen bond network of both materials. The neutron diffraction experiments establish clearly that there is no disorder, and hence that no hydrogen bond cooperativity is present in either system at temperatures up to 150 K. The findings are supported by DFT calculations, from which lattice and hydrogen bond configuration energies are also obtained, together with computed vibrational spectra.

Chloranilic acid (2,5-dichloro-3,6-dihydroxybenzoquinone, CA) readily forms molecular complexes with the three methylpyridine (picoline) isomers in both 1 : 1 and 1 : 2 ratios. In each case a predictable hydrogen-bonded supramolecular unit is formed consisting of a P:C:C:P or a P:C:P arrangement for each of the stoichiometric ratios, respectively. At least one proton is transferred from a chloranilic acid molecule to the nitrogen of the picoline in all the structures. The molecules are held together by a series of bifurcated hydrogen bonds in which a large degree of variation in the directionality can be observed. The proton depleted chloranilate ions show a delocalisation of charge across the entire molecule in the presence of highly bifurcated hydrogen bonds. The variation of the supramolecular units is discussed with particular reference to the degree of bifurcation in the hydrogen bonds.

The divergent syntheses of the trichloroacetamide derivatives of (2S,3R,8R,9R,4E,6E)-3-amino-9-methoxy-2,6,8-trimethyl-10-phenyl-decadenoic acid (enantio-iso-ADDA), and (2R,3R,8R,9R,4E,6E)-3-amino-9-methoxy-2,6,8-trimethyl-10-phenyl-decadenoic acid (enantio-ADDA), have been achieved. Our approach takes advantage of highly efficient non-aldol aldol, palladium catalysed aza-Claisen and cross-metathesis methodologies.

The formation of crystalline molecular complexes of benzoic acid and isonicotinamide with 1:1 and 2:1 compositions has been investigated through solution cocrystallization. The 1:1 complex was solely obtained from ethanol solutions, while either complex could be grown from aqueous and methanol solution by variation of the initial composition. The crystal structures of the 2:1 complex and a monohydrate of isonicotinamide were determined by single crystal X-ray diffraction. The intermolecular interactions in the crystal structure of the complex were compared with other published carboxylic acid:isonicotinamide molecular complexes, which highlights the robust nature of the acid···pyridine and acid···amide hydrogen bond, which exist in most cases. Complementary computational studies into the binding of pairs of these molecules by ab initio calculations were found to support the experimental observations and highlight the role of solvent in controlling the final crystalline form for multicomponent systems, through altering the hierarchy of intermolecular interactions.

The synthesis and characterization of ruthenium(II) arene complexes [(eta(6)-arene)Ru(N,N)Cl](0/+), where N,N = 2,2'-bipyridine (bipy), 2,2'-bipyridine-3,3'-diol (bipy(OH)(2)) or deprotonated 2,2'-bipyridine-3,3'-diol (bipy(OH)O) as N,N-chelating ligand, arene = benzene (bz), indan (ind), biphenyl (bip), p-terphenyl (p-terp), tetrahydronaphthalene (thn), tetrahydroanthracene (tha) or dihydroanthracene (dha), are reported, including the X-ray crystal structures of [(eta(6)-tha)Ru(bipy)Cl][PF(6)] (1), [(eta(6)-tha)Ru(bipy(OH)O)Cl] (2) and [(eta(6)-ind)Ru(bipy(OH)(2))Cl][PF(6)] (8). Complexes 1 and 2 exibit CH (arene)/pi (bipy or bipy(OH)O) interactions. In the X-ray structure of protonated complex 8, the pyridine rings are twisted (by 17.31 degrees). In aqueous solution (pH = 2-10), only deprotonated (bipy(OH)O) forms are present. Hydrolysis of the complexes was relatively fast in aqueous solution (t(1/2) = 4-15 min, 310 K). When the arene is biphenyl, initial aquation of the complexes is followed by partial arene loss. Complexes with arene = tha, thn, dha, ind and p-terp, and deprotonated bipyridinediol (bipy(OH)O) as chelating ligands, exhibited significant cytotoxicity toward A2780 human ovarian and A549 human lung cancer cells. Complexes [(eta(6)-bip)Ru(bipy(OH)O)Cl] (7) and [(eta(6)-bz)Ru(bipy(OH)O)Cl] (5) exhibited moderate cytotoxicity toward A2780 cells, but were inactive toward A549 cells. These activity data can be contrasted with those of the parent bipyridine complex [(eta(6)-tha)Ru(bipy)Cl][PF(6)] (1) which is inactive toward both A2780 ovarian and A549 lung cell lines. DFT calculations suggested that hydroxylation and methylation of the bipy ligand have little effect on the charge on Ru. The active complex [(eta(6)-tha)Ru(bipy(OH)O)Cl] (2) binds strongly to 9-ethyl-guanine (9-EtG). The X-ray crystal structure of the adduct [(eta(6)-tha)Ru(bipy(OH)O)(9-EtG-N7)][PF(6)] shows intramolecular CH (arene)/pi (bipy(OH)O) interactions and DFT calculations suggested that these are more stable than arene/9-EtG pi-pi interactions. However [(eta(6)-ind)Ru(bipy(OH)(2))Cl][PF(6)] (8) and [(eta(6)-ind)Ru(bipy)Cl][PF(6)] (16) bind only weakly to DNA. DNA may therefore not be the major target for complexes studied here.

We present a new facet of isobenzofuran chemistry which allows for its efficient manipulation to generate biologically relevant entities. This methodology has been successfully applied toward the synthesis of ajudazol A.

A review is presented of the applications of the dSNAP cluster analysis software to the analysis of structural geometries extracted from the Cambridge Structural Database.

Automated cluster analysis is used to examine the conformation and configuration of pyranose sugars. Previous findings on this issue are confirmed, importantly from an analysis that requires no prior knowledge of the significant factors determining the conformational classification. The findings on the conformations adopted in the crystalline solid state are found to be different to existing quantum chemical calculations performed for D-glucose in the gas phase, but consistent with empirically determined conformations in the solution state. The use of this clustering analysis in studying chirality in the determined structures is discussed, as is the ability of this type of method to examine higher dimensions within the metric multi-dimensional scaling formalism.

Understanding the conformations adopted by the sulfonamide group is essential to the understanding of the way that sulfa drugs act upon the body. The relative energies of these conformations in the solid state are estimated from the Cambridge Structural Database (CSD) using cluster analysis, and are used to confirm earlier findings that many high-level ab initio calculations do not reproduce the observed solid-state structure. These conformational studies have been extended to the adjacent torsion angles, and it has been shown that the sulfonamide group significantly affects the form adopted. The relative energies of the observed forms in the solid state have been estimated using data available in the CSD.

We report on the templated growth of 2:1 benzoic acid/isonicotinamide co-crystal on a benzoic acid subphase. The molecular basis for the template, registry between the phases, is presented. The template growth of behavior of the title compound was contrasted with that from melt and solution. This approach may be,applicable as a precursor for the synthesis of bulk composite crystals.

We report the convenient synthesis of a pyrrole-functionalized tetracationic cyclophane, [2]rotaxane, and [2]catenane. X-ray crystallography has confirmed the interlocked structure of the catenane. We have investigated the solution properties of these systems using solution electrochemistry, NMR, and UV–vis spectroscopy. We have also demonstrated that it is possible to immobilize these systems onto a platinum working electrode surface. We have shown that films of the cyclophane have the ability to undergo complexation with a dialkyloxynaphthalene derivative.

A method of validating organic and organometallic crystal structures solved using powder diffraction data is presented. It uses searches and comparisons with structures in the Cambridge Structural Database coupled with multivariate analysis and Clustering techniques. An example using sulphonamides is presented. The associated software (dSNAP) is available as a free download.

The synthesis and characterisation by single crystal X-ray diffraction of 1:2 host-guest assemblies formed between the tetra-amine macrocycle 1,4,7,10-tetraazacyclododecane (cyclen) and diphenylphosphinic acid or 4-tert-butylbenzoic acid are reported. In each case strong hydrogen bonds associated with proton transfer from the acid species to two (trans) amino groups in the cyclen ring are observed. Both adducts are also associated with complex hydrogen bonded networks involving the secondary amines and water molecules, with each crystal structure containing five water molecules per asymmetric unit.

The crystal structure of the ionic complex of 1,8-bis(dimethylamino)naphthalene (DMAN) and 4,5-dichlorophthalic acid has been investigated using a multi-temperature X-ray diffraction approach. The two short intramolecular hydrogen bonds exhibit different behaviors, with the [O···H···O]- hydrogen bond appearing approximately centered throughout the experiment. The [N···H···N]+ hydrogen bond, on the other hand, exhibits a complicated temperature-dependent behavior, with disordered electron density being observed at lower temperatures, with apparent migration at higher temperatures. This continuum can be explained simply in terms of the changing local environment of the [N···H···N]+ hydrogen bond induced by lattice expansion. The related complex of DMAN with 3,4-furandicarboxylic acid shows no equivalent effects; this is consistent with the explanation proposed.

Cluster analysis can be an effective tool for analysing large quantities of data. Here it has been applied to the conformational analysis of enones and enimines in the crystalline solid state, using structural information mined from the Cambridge Structural Database. The forms that are common in the gaseous state and in solution are already known from spectroscopic studies. These forms are also found to be the most common conformations observed in the solid state; however, the clustering method highlights those structures that do not conform to the expected geometries. The study is supported by ab initio gas phase calculations on simple enone and enimine fragments.

Two crystal structures, each containing a 4-dimethylaminobenzoic acid dimer (4-DABA), have been studied by multitemperature X-ray diffraction methods. In form I of pure 4-DABA, temperature-dependent proton disorder is observed. In the molecular complex with 3,5-dinitrobenzoic acid, no such disorder is observed in the 4-DABA dimer but is observed in the 3,5-dinitrobenzoic acid dimer. The effect of the crystal environment perturbing the local symmetry of apparently similar molecular structures is discussed in relation to this change in observed proton disorder.

Clustering and multivariate analysis is used to analyse all the intermolecular interactions between carboxylic acids and secondary amides from structures mined from the Cambridge Structural Database.