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Abstract Elves are a class of transient luminous events, with a radial extent typically greater than 250 km, that occur in the lower ionosphere above strong electrical storms. We report the observation of 1,598 elves, from 2014 to 2016, recorded with unprecedented time resolution (100 ns) using the fluorescence detector (FD) of the Pierre Auger Cosmic‐Ray Observatory. The Auger Observatory is located in the Mendoza province of Argentina with a viewing footprint for elve observations of 3·106 km 2, reaching areas above the Pacific and Atlantic Oceans, as well as the Córdoba region, which is known for severe convective thunderstorms. Primarily designed for ultrahigh energy cosmic‐ray observations, the Auger FD turns out to be very sensitive to the ultraviolet emission in elves. The detector features modified Schmidt optics with large apertures resulting in a field of view that spans the horizon, and year‐round operation on dark nights with low moonlight background, when the local weather is favorable. The measured light profiles of 18% of the elve events have more than one peak, compatible with intracloud activity. Within the 3‐year sample, 72% of the elves correlate with the far‐field radiation measurements of the World Wide Lightning Location Network. The Auger Observatory plans to continue operations until at least 2025, including elve observations and analysis. To the best of our knowledge, this observatory is the only facility on Earth that measures elves with year‐round operation and full horizon coverage.

The observation of ultrahigh energy neutrinos (UHEνs) has become a priority in experimental astroparticle physics. UHEνs can be detected with a variety of techniques. In particular, neutrinos can interact in the atmosphere (downward-going ν) or in the Earth crust (Earth-skimming ν), producing air showers that can be observed with arrays of detectors at the ground. With the surface detector array of the Pierre Auger Observatory we can detect these types of cascades. The distinguishing signature for neutrino events is the presence of very inclined showers produced close to the ground (i.e., after having traversed a large amount of atmosphere). In this work we review the procedure and criteria established to search for UHEνs in the data collected with the ground array of the Pierre Auger Observatory. This includes Earth-skimming as well as downward-going neutrinos. No neutrino candidates have been found, which allows us to place competitive limits to the diffuse flux of UHEνs in the EeV range and above.

The syntheses and crystal structures of four hydrothermally prepared organo–zinc phosphites, viz. poly[[(2-amino-3-methylpyridine)-μ3-phosphonato-zinc] hemihydrate], {[Zn(HPO3)(C6H8N2)]·0.5H2O}n, (I), poly[(2-amino-4-methylpyridine)-μ3-phosphonato-zinc], [Zn(HPO3)(C6H8N2)]n, (II), poly[(2-amino-5-methylpyridine)-μ3-phosphonato-zinc], [Zn(HPO3)(C6H8N2)]n, (III), and poly[bis(2-amino-4-methylpyridinium) [tetra-μ3-phosphonato-trizinc] monohydrate], {(C6H9N2)2[Zn3(HPO3)4]·H2O}n, (IV), are described. Compounds (I)–(III) are constructed from vertex-sharing ZnO3N tetrahedra (the organic molecule acting as a ligand) and HPO3 pseudo pyramids in a 1:1 ratio to generate the same motif of infinite 4-ring `ladder' chains propagating in the [010], [101] and [100] directions, respectively, whereas (IV) consists of (010) layers of vertex-sharing ZnO4 and HPO3 units in a 3:4 ratio with the protonated organic molecule acting as a template. When an excess of HCl is used in the synthesis, the simple hydrated molecular salt, bis(2-amino-3-methylpyridinium) tetrachlorozincate monohydrate, (C6H8N2)2[ZnCl4]·H2O, (V), arises. Compounds (I)–(V) feature extensive networks of hydrogen bonds, both classical (N—H...O, N—H...Cl, O—H...O) and non-classical (C—H...O, C—H...Cl) in nature, which help to consolidate the extended structures.

Low-level easterly winds encircling Antarctica help drive coastal currents which modify transport of circumpolar deep water to ice shelves, and the formation and distribution of sea ice. Reanalysis datasets are especially important at high southern latitudes where observations are few. Here, we investigate the representation of the mean state and short-term variability of coastal easterlies in three recent reanalyses, ERA5, MERRA-2 and JRA-55. Reanalysed winds are compared with summertime marine near-surface wind observations from the Advanced Scatterometer (ASCAT) and surface and upper air measurements from coastal stations. Reanalysis coastal easterlies correlate highly with ASCAT (r= 0.91, 0.89 and 0.85 for ERA5, MERRA-2 and JRA-55, respectively) but notable wind speed biases are found close to the coastal margins, especially near complex orography and at high wind speeds. To characterise short-term variability, 12-hourly reanalysis and coastal station winds are composited using self-organising maps (SOMs), which cluster timesteps under similar synoptic and mesoscale influences. Reanalysis performance is sensitive to the flow configuration at stations near steep coastal slopes, where they fail to capture the magnitude of near-surface wind speed variability when synoptic forcing is weak and conditions favour katabatic forcing. ERA5 exhibits the best overall performance, has more realistic orography, and a more realistic jet structure and temperature profile. These results demonstrate the regime behaviour of Antarctica's coastal winds and indicate important features of the coastal winds which are not well characterised by reanalysis datasets.

The isostructural compounds caesium decasodium tetrazirconium nonaarsenate, CsNa10Zr4(AsO4)9, and caesium decasodium tetrahafnium nonaarsenate, CsNa10Hf4(AsO4)9, arose as unexpected single-crystal products from the reactions of Na2CO3, MO2 (M = Zr, Hf) and As2O5 in a eutectic flux of NaCl and CsCl. They consist of MO6 octahedra and AsO4 tetrahedra sharing vertices to generate three-dimensional polyhedral networks encapsulating the caesium and sodium ions. The MO6 groups share all their vertices with adjacent As atoms but the As atoms have one or two `terminal' O atoms not bonded to Zr or Hf. The Cs+ ion adopts a squashed octahedral geometry and the coordination polyhedra of the partially occupied sodium ions are variously trigonal bipyramidal, tetrahedral, square pyramidal and trigonal pyramidal. Site symmetries: Cs \overline{3}; M 3; As 1 and 2; O 1; Na 1, 2 and 3. The M = Zr crystal was refined as an obverse/reverse rhombohedral twin.

Abstract Oxidative condensation of three p‐phenylenediamines with 3‐hydroxy‐2‐methyl‐N‐(phenylamino)benzene gives new coloured aposafranones. 2‐Methylresorcinol is easy to convert into the asymmetric building block 3‐hydroxy‐2‐methyl‐N‐(phenylamino)benzene with aniline. The aposafranones are sterically crowded because of the 1‐methyl and N‐phenyl groups. The UV/Vis absorption maxima are in the range 530–545 nm.

BackgroundThe design of personal protective equipment (PPE) may affect well-being and clinical work. PPE as an integrated item may improve usability and increase adherence by healthcare professionals. Human factors design and safety may reduce occupational-acquired diseases. As an integrated PPE, a lightweight protective air-purifying respirator (L-PAPR) could be used during health procedures where healthcare professionals are exposed to airborne pathogens. The human factors affecting the implementation of alternative PPE such as L-PAPR have not been thoroughly studied. The population of interest is health care professionals, the intervention is the performance by PPE during tasks across the three PPE types 1.) N95 respirators and face shields, 2.)traditional powered air-purifying respirator(PAPR), and 3.) L-PAPR. The outcomes are user error, communications, safety, and end-user preferences. ObjectiveThis study will assess whether the L-PAPR improves health care professionals’ comfort in terms of perceived workload and physical and psychological burden during direct patient care when compared with the traditional PAPR or N95 and face shield. This study also aims to evaluate human factors during the comparison of the use of L-PAPR with a combination of N95 respirators plus face shields or the traditional PAPRs. MethodsThis is an interventional randomized crossover quality improvement feasibility study consisting of a 3-site simulation phase with 10 participants per site and subsequent field testing in 2 sites with 30 participants at each site. The 3 types of respiratory PPE will be compared across medical tasks and while donning and doffing. We will evaluate the user’s perceived workload, usability, usage errors, and heart rate. We will conduct semistructured interviews to identify barriers and enablers to implementation across each PPE type over a single continuous wear episode and observe interpersonal communications across conditions and PPE types. ResultsWe expect the research may highlight communication challenges and differences in usability and convenience across PPE types along with error frequency during PPE use across PPE types, tasks, and time. ConclusionsThe design of PPE may affect overall well-being and hinder or facilitate clinical work. Combining 2 pieces of PPE into a single integrated item may improve usability and reduce occupational-acquired diseases. The human factors affecting the implementation of an alternative PPE such as L-PAPR or PAPR have not been thoroughly studied. International Registered Report Identifier (IRRID)PRR1-10.2196/36549

Semi-passive bioremediation is a promising strategy to mitigate persistent low volume mine-impacted wastewater containing high sulphate concentrations. Building on the proof of concept demonstration of the hybrid linear flow channel reactor (LFCR), capable of simultaneous biological sulphate reduction and partial sulphide oxidation with elemental sulphur recovery, the impact of key operating parameters, such as temperature, on process performance is critical to real-world application. Temperature fluctuates seasonally and across the diurnal cycle, impacting biological sulphate reduction (BSR) and partial sulphide oxidation. The process is reliant on the metabolic activity and synergistic interactions between sulphate-reducing (SRB) and sulphide-oxidising (SOB) microbial communities that develop within discrete oxic and anoxic microenvironments within the hybrid LFCR. In this study, the impact of operating temperature on process performance was evaluated by decreasing temperature with time from 30 to 10°C in each of three laboratory-scaled hybrid LFCR units operating in pseudo-steady state at 1 g/L sulphate. Using lactate as a carbon source, two reactor sizes (2 and 8 L) were considered, while the impact of lactate vs. acetate as carbon source was evaluated in the 2 L reactors. On incremental decrease in temperature from 30 to 10°C, a decrease in volumetric sulphate reduction rate was observed: from 0.144 to 0.059 mmol/L.h in the 2 L lactate-fed reactor; from 0.128 to 0.042 mmol/L.h in the 8 L lactate-fed reactor; and from 0.127 to 0.010 mmol/L.h in the 2 L acetate-fed reactor. Similarly, sulphate conversion efficiency decreased (2 L lactate-fed: 66% to 27%; 8 L lactate-fed: 61% to 20%; 2 L acetate-fed: 61% to 5%). A decrease in temperature below the critical value (15°C) led to considerable loss in metabolic activity and overall BSR performance. Sessile and planktonic microbial communities were represented by bacterial phyla including Proteobacteria, Synergistetes, Bacteroidetes, and Firmicutes. A diverse group of putative SRB (Deltaproteobacteria) and SOB, including Alpha, Beta, Gamma, and Epsilonproteobacteria phylotypes, were prevalent and shifted in relative abundance and community composition in response to decreasing temperature. Specifically, the decrease in the relative abundance of Deltaproteobacteria with decreasing temperature below 15°C corresponded with a loss of BSR performance across all three reactors. This study demonstrated the impact of low temperature on the physiological selection and ecological differentiation of SRB and SOB communities within the hybrid LFCR and its implications for real-world process performance.

Biological sulfate reduction (BSR) is an attractive approach for the bioremediation of sulfate-rich wastewater streams. Many sulfate-reducing microorganisms (SRM), which facilitate this process, have been well-studied in pure culture. However, the role of individual members of microbial communities within BSR bioreactors remains understudied. In this study we investigated the performance of two up-flow anaerobic packed bed reactors (UAPBRs) supplemented primarily with acetate and with lactate, respectively, during a hydraulic retention time (HRT) study set up to remediate sulfate-rich synthetic wastewater over the course of 1,000 + days. Plug-flow hydrodynamics led to a continuum of changing volumetric sulfate reduction rates (VSRRs), available electron donors, degrees of biomass retention and compositions of microbial communities throughout these reactors. Microbial communities throughout the successive zones of the reactors were resolved using 16S rRNA gene amplicon sequencing which allowed the association of features of performance with discrete microorganisms. The acetate UAPBR achieved a maximum VSRR of 23.2 mg.L−1. h−1 at a one-day HRT and a maximum sulfate conversion of the 1 g/L sulfate of 96% at a four-day HRT. The sulfate reduction reactions in this reactor could be described with a reaction order of 2.9, an important observation for optimisation and future scale-up. The lactate UAPBR achieved a 96% sulfate conversion at one-day HRT, corresponding with a VSRR of 40.1 mg.L−1. h−1. Lactate was supplied in this reactor at relatively low concentrations necessitating the subsequent use of propionate and acetate, by-products of lactate fermentation with acetate also a by-product of incomplete lactate oxidation, to achieve competitive performance. The consumption of these electron donors could be associated with specific SRM localised within biofilms of discrete zones. The sulfate reduction rates in the lactate UAPBR could be modelled as first-order reactions, indicating effective rates were conferred by these propionate- and acetate-oxidising SRM. Our results demonstrate how acetate, a low-cost substrate, can be used effectively despite low associated SRM growth rates, and that lactate, a more expensive substrate, can be used sparingly to achieve high VSRR and sulfate conversions. We further identified the preferred environment of additional microorganisms to inform how these microorganisms could be enriched or diminished in BSR reactors.

Abstract Studies have been performed aimed at the synthesis of N‐heteroacenes via substitution reactions of 4,5‐difluoro‐1,2‐dinitrobenzene with a diamine. The fluorine atoms are displaced first, followed by an activated nitro group. Two intermediates have been characterised by X‐ray single‐crystal structure determinations. Their intermolecular interactions were examined by Hirshfeld surfaces to assess their suitability for organic molecular electronics. The high reactivity of the phenazine, which is prone to oxidise and rearrange, as are displacement products prepared from it, is explained by the formation of a cis‐aci‐nitro form from the secondary amine of the phenazine and a nitro group.

Abstract Cytochrome P450 reductases (CPRs) are diflavin oxidoreductases that supply electrons to type II cytochrome P450 monooxygenases (CYPs). In addition, it can also reduce other proteins and molecules, including cytochrome c, ferricyanide, and different drugs. Although various CPRs have been functionally and structurally characterized, the overall mechanism and its interaction with different redox acceptors remain elusive. One of the main problems regarding electron transfer between CPRs and CYPs is the so-called “uncoupling”, whereby NAD(P)H derived electrons are lost due to the reduced intermediates’ (FAD and FMN of CPR) interaction with molecular oxygen. Additionally, the decay of the iron-oxygen complex of the CYP can also contribute to loss of reducing equivalents during an unproductive reaction cycle. This phenomenon generates reactive oxygen species (ROS), leading to an inefficient reaction. Here, we present the study of the CPR from Candida tropicalis (CtCPR) lacking the hydrophobic N-terminal part (Δ2–22). The enzyme supports the reduction of cytochrome c and ferricyanide, with an estimated 30% uncoupling during the reactions with cytochrome c. The ROS produced was not influenced by different physicochemical conditions (ionic strength, pH, temperature). The X-ray structures of the enzyme were solved with and without its cofactor, NADPH. Both CtCPR structures exhibited the closed conformation. Comparison with the different solved structures revealed an intricate ionic network responsible for the regulation of the open/closed movement of CtCPR.

The syntheses and crystal structures of five 2-benzylidene-1-benzosuberone [1-benzosuberone is 6,7,8,9-tetrahydro-5H-benzo[7]annulen-5-one] derivatives, viz. 2-(4-methoxybenzylidene)-1-benzosuberone, C19H18O2, (I), 2-(4-ethoxybenzylidene)-1-benzosuberone, C20H20O2, (II), 2-(4-benzylbenzylidene)-1-benzosuberone, C25H22O2, (III), 2-(4-chlorobenzylidene)-1-benzosuberone, C18H15ClO, (IV) and 2-(4-cyanobenzylidene)-1-benzosuberone, C19H15NO, (V), are described. The conformations of the benzosuberone fused six- plus seven-membered ring fragments are very similar in each case, but the dihedral angles between the fused benzene ring and the pendant benzene ring differ somewhat, with values of 23.79 (3) for (I), 24.60 (4) for (II), 33.72 (4) for (III), 29.93 (8) for (IV) and 21.81 (7)° for (V). Key features of the packing include pairwise C—H...O hydrogen bonds for (II) and (IV), and pairwise C—H...N hydrogen bonds for (V), which generate inversion dimers in each case. The packing for (I) and (III) feature C—H...O hydrogen bonds, which lead to [010] and [100] chains, respectively. Weak C—H...π interactions consolidate the structures and weak aromatic π–π stacking is seen in (II) [centroid–centroid separation = 3.8414 (7) Å] and (III) [3.9475 (7) Å]. A polymorph of (I) crystallized from a different solvent has been reported previously [Dimmock et al. (1999) J. Med. Chem. 42, 1358–1366] in the same space group but with a packing motif based on inversion dimers resembling that seen in (IV) in the present study. The Hirshfeld surfaces and fingerprint plots for (I) and its polymorph are compared and structural features of the 2-benzylidene-1-benzosuberone family of phases are surveyed.

Abstract The synthesis of a Cu4(OH)4 cube which is coordinated by four molecules of the dipyridyl ligand 1,6‐[di(pyridin‐4‐yl)hex‐3‐ene] is reported. This compound has a trans double bond which restricts the conformational freedom of the ligand and favours coordination within a unique copper cube. The structure was solved by an X‐Ray single crystal structure determination and low temperature magnetic susceptibility measurements examined its magnetic properties. The cube classification corresponds to the type I classification of Mergehenn and Haase and the short/long distribution of Cu ⋅⋅⋅ Cu separations in the cube as defined by Ruiz. The magnetic susceptibility measurements show paramagnetic behaviour down to 50 K but below this the copper cube shows weak ferromagnetic exchange interactions. The low temperature magnetic susceptibility characteristics are examined in detail then modelled and compared to other similar Cu4O4 copper cubes.

The syntheses and crystal structures of three hybrid perovskites, viz. poly[1-methylpiperizine-1,4-diium [tri-μ-bromido-potassium] hemihydrate], {(C5H14N2)[KBr3]·0.5H2O}n, (I), poly[1-methylpiperizine-1,4-diium [tri-μ-bromido-rubidium] hemihydrate], {(C5H14N2)[RbBr3]·0.5H2O}n, (II), and poly[1-methylpiperizine-1,4-diium [tri-μ-bromido-caesium] hemihydrate], {(C5H14N2)[CsBr3]·0.5H2O}n, (III), are described. These isostructural (space group Amm2) phases contain a three-dimensional, corner-sharing network of distorted ABr6 octahedra (A = K, Rb, Cs) with the same topology as the classical perovskite structure. The doubly protonated C5H14N22+ cations occupy interstices bounded by eight octahedra and the water molecules lie in square sites bounded by four octahedra. N—H...Br, N—H...(Br,Br), N—H...O and O—H...Br hydrogen bonds consolidate the structures.

Abstract Two similar molecular building blocks, which both contain a hydrogen‐bonded nitro group, have been prepared and crystallised. One structure has more flexibility with a butyl side chain which allows an open framework organic zeolite to form with large 10 Å diameter pores, whereas the other structure has less flexibility with an aryl side chain and is close packed. The pore size is comparable with those of the aluminophosphate VPI‐5 (12 Å). It is concluded that some flexibility in the design of the building block for porous organic molecular materials was beneficial.

The crystal structures of (E)-1-methyl-5-nitro-1H-imidazole-2-carbaldehyde O-benzyloxime, C12H12N4O3, (I), (E)-1-methyl-5-nitro-1H-imidazole-2-carbaldehyde O-(4-fluorobenzyl) oxime, C12H11FN4O3, (II), and (E)-1-methyl-5-nitro-1H-imidazole-2-carbaldehyde O-(4-bromobenzyl) oxime, C12H11BrN4O3, (III), are described. The dihedral angle between the ring systems in (I) is 49.66 (5)° and the linking Nm—C—C=N (m = methylated) bond shows an anti conformation [torsion angle = 175.00 (15)°]. Compounds (II) and (III) are isostructural [dihedral angle between the aromatic rings = 8.31 (5)° in (II) and 5.34 (15)° in (III)] and differ from (I) in showing a near-syn conformation for the Nm—C—C=N linker [torsion angles for (II) and (III) = 17.64 (18) and 8.7 (5)°, respectively], which allows for the occurrence of a short intramolecular C—H...N contact. In the crystal of (I), C—H...N hydrogen bonds link the molecules into [010] chains, which are cross-linked by very weak C—H...O bonds into (100) sheets. Weak aromatic π–π stacking interactions occur between the sheets. The extended structures of (II) and (III) feature several C—H...N and C—H...O hydrogen bonds, which link the molecules into three-dimensional networks, which are consolidated by aromatic π–π stacking interactions. Conformational energy calculations and Hirshfeld fingerprint analyses for (I), (II) and (III) are presented and discussed.

BackgroundAnesthesiologists who have finished formal training and want to learn ultrasound-guided regional anesthesia (UGRA) commonly attend 1 day workshops. However, it is unclear whether participation actually changes clinical practice. We assessed change implementation after completion of a 1 day simulation-based UGRA workshop.MethodsPracticing anesthesiologists who participated in a 1 day UGRA course from January 2012 through May 2014 were surveyed. The course consisted of clinical observation of UGRA procedures, didactic lectures, ultrasound scanning, hands-on perineural catheter placement, and mannequin simulation. The primary outcome was the average number of UGRA blocks per month reported at follow-up versus baseline. Secondary outcomes included preference for ultrasound as the nerve localization technique, ratings of UGRA teaching methods, and obstacles to performing UGRA.ResultsSurvey data from 46 course participants (60% response rate) were included for analysis. Participants were (median [10th–90th percentile]) 50 (37–63) years old, had been in practice for 17 (5–30) years, and were surveyed 27 (10–34) months after their UGRA training. Participants reported performing 24 (4–90) blocks per month at follow-up compared to 10 (2–24) blocks at baseline (P < 0.001). Compared to baseline, more participants at follow-up preferred ultrasound for nerve localization. The major obstacle to implementing UGRA in clinical practice was time pressure.ConclusionsParticipation in a 1 day simulation-based UGRA course may increase UGRA procedural volume by practicing anesthesiologists.

The crystal structures of (3S,4aS,8aS)-2-[(2R,3S)-3-benzamido-2-benzoyloxy-4-phenylbutyl]-N-tert-butyldecahydroisoquinoline-3-carboxamide, C38H47N3O4, (I), and (3S,4aS,8aS)-2-[(2R,3S)-3-(2,5-dichlorobenzamido)-2-(2,5-dichlorobenzoyloxy)-4-phenylbutyl]-N-tert-butyldecahydroisoquinoline-3-carboxamide, C38H43Cl4N3O4, (II), are described. Despite their chemical similarity, they adopt different conformations in the solid state: (I) features a bifurcated intramolecular N—H...(N,O) hydrogen bond from the tert-butylamide NH group to the piperidine N atom and the benzoate O atom, whereas (II) has an intramolecular N—H...O link from the benzamide NH group to the tert-butylamide O atom. In the crystal of (I), molecules are linked by C(4) amide N—H...O hydrogen bonds into chains propagating in the [010] direction, with both donor and acceptor parts of the benzamide group. In the extended structure of (II), C(11) N—H...O chains propagating in the [010] direction arise, with the donor being the tert-butylamide NH group and the acceptor being the O atom of the benzamide group.

Five new Lanthanide(III) complexes of malonic acid (HOOC-CH2-COOH); {[Gd(C3H2O4)(H2O)4]·NO3}n (1), {[Tb(C3H2O4)(H2O)4]·NO3}n (2), {[Ho(C3H2O4)(H2O)4]·NO3}n (3), [Er(C3H2O4)(C3H3O4)(H2O)2]n (4), and {[Eu2(C3H2O4)2(C3H3O4)2(H2O)6]·4H2O}n (5) were synthesized and characterized by elemental, infrared spectral, and thermal analyses. The structures of compounds 1–5 were determined by single crystal X-ray diffraction technique. The X-ray analysis reveals that compounds 1, 2, and 3 are isostructural and crystallized in the orthorhombic space group Pmn21. The lanthanide(III) ions are coordinated by four carboxylate and four water oxygen atoms adopting a distorted square antiprism geometry. The LnO8 square antiprisms are linked into infinite layers by malonate (C3H2O42-) dianions sandwiching sheets of nitrate counter ions. Compound 4 contains ErO8 square antiprisms linked into a two-dimensional network by hydrogen malonate (C3H3O4-) anions and malonate dianions. The europium complex, 5 is dinuclear having the two europium(III) ions (Eu1 and Eu2) bridged by carboxylate groups of hydrogen malonate ligands. The europium ions in 5 are nine-coordinate and exhibit a distorted monocapped square antiprism geometry. All the structures are consolidated by O–H⋯ O hydrogen bonds. The photoluminescence spectra of 1–5 exhibit characteristic emissions in the visible region. The IR spectra and thermal data are consistent with the structural results. The room-temperature effective magnetic moments for 1–4 are in good agreement with those expected for the free ions, while the data for 5 indicates that low-lying excited states contribute to the observed moment. The compound 1 was further subjected to quantum computational calculations to explore its optoelectronic properties including; density of states (DOS), dielectric function, refractive index, extinction coefficient, and absorption spectrum, to highlight the possible applications of such materials in the optoelectronics.

The title compounds, C14H12O, (I), and C15H11BrO2, (II), were prepared and characterized as part of our studies of potential new photo-acid generators. In (I), which crystallizes in the orthorhombic space group Pca21, compared to P21/n for the previously known monoclinic polymorph [Cornella & Martin (2013). Org. Lett. 15, 6298–6301], the dihedral angle between the aromatic rings is 4.35 (6)° and the OH group is disordered over two sites in a 0.795 (3):0.205 (3) ratio. In the crystal of (I), molecules are linked by O—H...π interactions involving both the major and minor –OH disorder components, generating [001] chains as part of the herringbone packing motif. The asymmetric unit of (II) contains two molecules with similar conformations (weighted r.m.s. overlay fit = 0.183 Å). In the crystal of (II), both molecules form carboxylate inversion dimers linked by pairs of O—H...O hydrogen bonds, generating R22(8) loops in each case. The dimers are linked by pairs of C—H...O hydrogen bonds to form [010] chains.

The gel-mediated syntheses and crystal structures of [N′-(pyridin-2-ylmethylidene-κN)benzohydrazide-κ2N′,O]tris(thiocyanato-κN)praseodymium(III) monohydrate, [Pr(NCS)3(C13H11N3O)2]·H2O, (I), and aqua(nitrato-κ2O,O′)[N′-(pyridin-2-ylmethylidene-κN)benzohydrazide-κ2N′,O](thiocyanato-κN)neodymium(III) nitrate 2.33-hydrate, [Nd(NCS)(NO3)(C13H11N3O)2(H2O)]NO3·2.33H2O, (II), are reported. The Pr3+ ion in (I) is coordinated by two N,N,O-tridentate N′-(pyridin-2-ylmethylidene)benzohydrazide (pbh) ligands and three N-bonded thiocyanate ions to generate an irregular PrN7O2 coordination polyhedron. The Nd3+ ion in (II) is coordinated by two N,N,O-tridentate pbh ligands, an N-bonded thiocyanate ion, a bidentate nitrate ion and a water molecule to generate a distorted NdN5O5 bicapped square antiprism. The crystal structures of (I) and (II) feature numerous hydrogen bonds, which lead to the formation of three-dimensional networks in each case.