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Topological spin textures, such as magnetic skyrmions observed in certain chiral magnets, are one of the most interesting ordered phases in condensed matter. A skyrmion is a swirling spin structure carrying a topological quantum number. Skyrmions were first observed in MnSi, in 2009, and later observed in Cu 2 OSeO 3 , a chiral antiferromagnet with T N = 58 K that can be synthesized by reacting CuO and SeO2 at 600 ° C . Using a transport agent (typically ammonium chloride) in a chemical vapour transport reaction, single crystals can be grown. As skyrmion lattices may find use in nanotechnological devices, such as data storage systems and in other applications, the magnetic properties of nano-sized compounds deserve to be investigated. The following work presents the synthesis and magnetic studies of the nanocrystalline form of Cu 2 OSeO 3 obtained by an alternative route, thermal decomposition of CuSeO3·2 H2O. This procedure afforded nanostructured samples of reasonable purity ( > 95 % ) . Structural, morphological and magnetic characterization of these samples are reported, aiming to study the effect of nanostructuring on the magnetic phases, in particular the presence and stability of the skyrmionic lattice.

Major-league magnetostriction Magnetoelectric materials polarize in response to either electric or magnetic fields, making them attractive for data-storage applications. Long et al. discovered a ytterbium-based molecular magnetoelectric material with high magnetoelectric coupling (see the Perspective by Zhou and Han). An applied magnetic field strains the material, which changes its electrical properties. The required field is much lower than other magnetoelectric materials, and this work highlights the potential for using molecular materials in devices. Science , this issue p. 671 ; see also p. 627

The conformational space of 5-acetic acid hydantoin {5AAH; [2-(2,5-dioxoimidazolidin-4-yl)acetic acid]} was investigated by quantum chemical calculations performed at the DFT(B3LYP)/6-311++G(d,p) level of theory. A total of 13 conformers were located in the potential energy surface of the molecule, six of them bearing the carboxylic group in the

A new phosphonic acid, (2-oxo-2-(thiophen-2-yl)ethyl) phosphonic acid (OTEPA), was synthesized and its molecular and crystal structures investigated using several experimental techniques complemented by different types of calculations. The experimental techniques used include infrared and Raman spectroscopies and single crystal X-ray crystallography. Calculations were performed at both molecular mechanics and DFT(B3LYP)/6–311++G(d,p) levels of approximation, for the isolated molecule. The conformational space of OTEPA was investigated and the most stable conformers characterized both structurally and spectroscopically. It was found that in the lower energy conformers of OTEPA an intramolecular H-bond exists between one of the OH groups of the phosphonic acid fragment and the carbonyl oxygen atom. The two lowest energy conformers have the sulphur atom of the thiophene ring eclipsed with the carbonyl oxygen atom, allowing for the establishment of an O⋯S stabilizing contact, similar to the N⋯S type contact found previously in other molecular systems. Noteworthy, in the crystalline phase the OTEPA molecules do not assume one of the most stable conformations for the isolated molecule, but exist in a conformation similar to that of high-energy conformers, which have predicted energies relative to the conformational ground state higher than 13 kJ mol−1. The infrared spectra of the monomeric molecules of the compound isolated in a low temperature solid argon matrix and of the crystal of the neat compound were also investigated and assigned, together with the Raman spectrum of the crystalline compound.

A new polymorph of a thioimidazole disulfide (2-[(1H-imidazol-2-yl) disulfanyl]-1H-imidazole; IDI) was prepared, which exhibits a rare crystal structure with 4 symmetry independent molecules (Z′ = 4; Z = 16) and all possible conformers predicted for the isolated molecule within the crystal unit cell. The crystal structure is non-centrosymmetric, Ia monoclinic space group, with cell parameters: a = 7.45910(10) A, b = 44.1680(8) A, c = 11.3522(2) A, and β = 103.0240(10)°. The four symmetry independent molecules establish an extensive hydrogen bond network involving NH groups as proton donors and N atoms of neighboring molecules as acceptors. A computational structural investigation of the isolated molecule of the compound was performed at the DFT(B3LYP)/6-311++G(d,p) level of theory in order to characterize in detail its conformational space, and these results were taken into account to evaluate the role of conformational flexibility and intermolecular interactions in the observed crystal packing. The excep...

Topological insulators are a quantum state of matter that has recently created a great interest among the scientific community, with Bi 2 Se 3 being one of the most extensively studied materials. Here, we demonstrate that polycrystalline nanostructured samples of Bi 2 Se 3 preserve the existence of topological surface states, where electrons cannot be localised. The nanosheet crystals were synthesised by a microwave-assisted method and their structure, composition and morphology thoroughly characterised. The transport properties of a textured polycrystalline sample with strong preferred orientation along the c-axis were measured, showing the presence of the weak anti-localisation effect and Shubnikov-de Haas oscillations. These features are robust against the presence of non-magnetic impurities and structural defects.

Pyrenes bear a propensity to form fluorescent excimers, and thus this chromophore is often found in sensors and fluorescent probes. 2-FunctionaIized pyrenes are of particular interest, however the preparation of these scaffolds is not trivial, involving synthetic routes that require 4,5,9,10-tetrahydropyrene as a key intermediate. Herein, the development and optimization of routes for the synthesis of 2-functionalized pyrene-derived building blocks, with potential to be used as tags in the preparation of fluorescent probes, is described. Additionally, the crystal structures of ethyl 4,5,9,10-tetrahydro-2-pyrene-5-oxopentanoate and 2-acetyl-4,5,9,10-tetrahydropyrene revealed distinct conformations of the saturated tetrahydropyrene rings. (C) 2017 Elsevier Ltd. All rights reserved. FEDER [PTDC/QUI-BIQ/112943/2009, PTDC/MAR-BIO/4132/2014, UID/Multi/04326/2013, UID/FIS/04564/2016] Fundacao para a Ciencia e a Tecnologia (FCT), Portugal info:eu-repo/semantics/publishedVersion

Furans were explored as scaffold for the synthesis of a range of heterocyclic compounds, exploring the dienophilic behaviour towards nitroso- and azoalkenes as the first step. Acid-catalysed rearrangements of these cycloadducts, 4a,7a-dihydro-4H-furo[2,3-e][1,2]oxazines and 1,4,4a,7a-tetrahydrofuro[3,2-c]pyridazines, were studied. Using 1 equivalent of TFA, the bicyclic heterocycles derived from furan and 2-methylfuran, are converted into furans bearing side-chains incorporating oxime and hydrazone groups by ring-opening of the six-membered ring with the concomitant aromatization of the furan ring. The use of TFA as solvent can lead to rearrangements via the generation of spirocyclic intermediates followed by furan ring-opening to afford functionalized isoxazoles or pyrazoles. Furthermore, furo-oxazines derived from 2,5-dimethylfuran, where furan aromatization is precluded, are converted efficiently into 6H-1,2-oxazines via a furan ring-opening reaction upon thermolysis in presence of a catalytic amount of p-toluenesulfonic acid. Tetrahydrofuro[3,2-c]pyridazines derived from furan and dimethylfuran undergo acid-catalyzed addition reaction, leading to 6-substitued-hexahydrofuro[3,2-c]pyridazines, when in presence of alcohols or water.

Cu4O(SeO3)3 is a copper-oxo-selenite belonging to the CuxO(SeO3)(x–1) family of the topological chiral magnet Cu2OSeO3. We report magnetometry and specific heat data measured in a monoclinic Cu4O(SeO3)3 single crystal grown through a Chemical Vapour Transport (CVT) reaction. Our study shows a typical antiferromagnetic behaviour, with a Néel temperature TN = 58 K, similar to that of the Cu2OSeO3 and an additional transition at 13 K. The effective magnetic moment per Cu atom is 1.84 μB, close to the expected theoretical value for Cu2+. The low-temperature M(H) curves, show a transition starting at Hc1 ~ 400 Oe at 1.8 K shifting to a lower value of ~ 280 Oe at 30 K, likely from a helical into a conical intermediate phase, and a second transition at Hc2 ~ 1 kOe, above which the net moment increases linearly with applied field. The magnetisation moment value in a 90 kOe field is 0.053 μB/Cu at 1.8 K and attains a maximum value of 0.061 μB at 13 K. Low-temperature specific heat measurements confirm the presence of the magnetic transition at 13 K, slightly shifting to lower temperatures under an applied magnetic field.

The synthesis of a new hydrazone, 2-oxoacenaphthylen-1(2H)-ylidene nicotinohydrazide, and its structural and spectroscopic characterization is reported. The obtained powder was recrystallized from DMSO and ethanol that afforded small crystals used for single-crystal X-ray diffraction studies. The compound was found to crystallize in two polymorphs, depending on the crystallization conditions. One of the polymorphs (form I) crystallizes in the centrosymmetric P21/c monoclinic space group, the other (form II) crystallizes in the non-centrosymmetric, but achiral, orthorhombic space group P212121. Conformation of the molecules is similar in both polymorphs, but the network of weak intermolecular interactions determining the crystal packing is different. In form II an additional C-H⋯O bond connects molecules related by the screw-axis running parallel to the a-axis. Crystals of both polymorphs were also screened by FT-IR and Raman microscopy; a detailed analysis of the spectra and comparison with those of the isolated molecule calculated by ab-initio HF/MP2 and DFT/B3LYP methods using a correlation consistent cc-pVDZ basis set is presented. In addition, UV-vis and NMR studies were performed in solution.

Three novel copper(I) complexes with three methyl 4-aryl-6-methyl-3,4-dihydropyrimidine-2(1H)-thione-5-carboxylate ligands were synthesized and fully characterized by elemental analysis, magnetic susceptibility, molar conductivity, ESI-MS, FTIR, UV–Vis and NMR. The difference between the three ligands is located in the aryl group: 4-(tert-butyl)phenyl (HL1), 2,6-dichlorophenyl (HL2) and 2,4-dichlorophenyl (HL3). Two ligands and complex 2 were characterized by single-crystal X-ray diffraction. The complex [CuCl(HL2)2]·dmso exhibits an almost perfect trigonal planar coordination geometry crystallizing in a space group P21/n, through the two sulfur atoms of the ligands, one chlorine atom bonded to the copper(I) and solvated with one molecule of dimethyl sulfoxide. The anticancer activity was evaluated in vitro against human colorectal cancer (CRC) cell line (Caco-2). The complexes have cytotoxic effect with IC50 values of 28.46, 25.03 and 38.83 μM respectively. Moreover, complexes 1 and 2 are able to strongly induce apoptosis in this CRC in vitro model.

The sodium salt of 5-acetic acid hydantoin (5AAH) was synthesized, and its crystal structure determined by single crystal X-ray diffraction. The material was found to exhibit rather unusual structural features. Firstly, contrarily to what is most common for hydantoins, the 5AAH molecules in the crystal bind the sodium ions through coordination via its oxygen atoms (instead of via a deprotonated ring nitrogen). In second place, the molecular formula of the salt is Na(5AAH)2, i.e., the formal charge of the hydantoin in the crystal is −0.5 e. Finally, the conformation adopted by the 5AAH molecules in the crystal of the salt is neither the most stable conformer for the isolated molecule (and observed before in the gas phase of the compound), nor that present in the neat crystalline compound (most stable polymorph at room temperature). These results show that 5AAH is a structurally very versatile molecule, which is able to participate in strong intermolecular interactions that can supersede the intrinsic higher structural stability of the individual molecules and lead to selection of different higher energy conformers on formation of a crystalline phase. The Raman spectrum of the newly synthesized salt was also obtained and used to extract further structural details of the crystal, in particular on the prevalent intermolecular interactions. The results (both structural and spectroscopic) obtained for the studied sodium salt of 5AAH are also compared with those relative to the neat 5AAH most stable crystalline polymorph at room temperature. To help the interpretation of the spectra, DFT(B3LYP)/6–311++G(d,p) calculations were undertaken on simple models based on the structural elements of the crystals.

Reports showing that the copper concentration is considerably higher in neoplasms than in normal tissues prompted the need to develop selective copper chelators. We disclosed recently that some N-linked tetrazole-saccharinates bind selectively to copper, forming complexes that are highly cytotoxic towards cancer cells. Because tetrazole-saccharinates are photolabile, due to the photoreactivity of tetrazoles, we proposed thiadiazolyl-saccharinates as an alternative. Herein we describe the synthesis, structure, and monomeric photochemistry of a sulphanyl-bridged thiadiazolyl-saccharinate, 3-[(5-methyl-1,3,4-thiadiazol-2-yl)sulphanyl]-1,2-benzothiazole 1,1-dioxide (MTSB). The monomeric structure, charge density analysis, and characteristic infrared spectrum of MTSB were investigated theoretically, using quantum chemical calculations, and also experimentally, using matrix-isolation infrared spectroscopy. The crystal structure was investigated by combining X-ray crystallography with infrared and Raman spectroscopies. Results show that the structure of isolated MTSB is similar to that found in the crystal, with an S⋅⋅⋅N interaction clearly contributing to the structure of the molecule and of the crystal. Matrix irradiation revealed a high photostability of MTSB, compared to parent tetrazole-saccharinates and to the 5-methyl-1,3,4-thiadiazole building block, emphasizing the photostabilizing effect of the saccharyl system. Finally, in vitro toxicity assays of MTSB showed a copper concentration-dependent toxicity against cancer cells, without affecting normal cells. In particular, MTSB was most effective towards the hepatic (HepG2), neuroblastoma (SH-SY5), and lymphoma cell lines (U937). Thus, MTSB represents a promising lead for cancer chemotherapy based on chelating agents.

New copper(I) complexes of four methyl 4-aryl-6-methyl-3,4-dihydropyrimidine-2(1H)-thione-5-carboxylate ligands, where the aryl group is phenyl (HL1), 1-naphthalenyl (HL2), 2-bromophenyl (HL3) and 2-chlorophenyl (HL4), have been synthesized. Structural characterization was carried out using different techniques, such as elemental analysis, mass spectrometry, molar conductivity, magnetic susceptibility, FTIR, UV–Vis/luminescence and NMR spectroscopies, and allowed us to propose the general formula [CuCl(HL)2] for all complexes. Furthermore, X-ray studies of ligands HL2 and HL3 and the complex [CuCl(HL2)2]·3dmso have been performed. The complex crystallizes in the triclinic space group P 1 ¯ and adopts a less common, almost perfect, trigonal planar coordination geometry, through the two sulfur atoms of the ligands and one chlorine atom bonded to the metal. The intramolecular hydrogen bonds between the chlorine and the N1H stabilize the structure of the complex. Evaluation of the in vitro activity against human breast cancer representatives of hormonal receptor positive (MCF7) and triple negative (HCC1806) tumors revealed a higher activity in the complexes than in the ligands. Considering particularly HCC1806 cells for which no targeted treatment is available, complexes [CuCl(HL1)2] and [CuCl(HL3)2] exhibited IC50 values of 5.51 and 5.30 μM, respectively, which are lower than the currently used chemotherapeutic drugs.

WOS: 000361161500008, In this work, we report the synthesis of a novel quinoline derivative, ethyl 4-chloro-7-iodoquinoline-3-carboxylate (CIQC), and its structural, conformational and vibrational characterization. The compound was studied in its neat solid phases (crystalline and low-temperature amorphous phases) and as an isolated species in a cryogenic argon matrix (at similar to 15 K). Infrared spectroscopy and single crystal X-ray diffraction were the chosen experimental techniques. The conformational space and the vibrational spectra of the isolated molecules of the compound were also investigated theoretically at the B3LYP/LANL2DZ-Fcc-pVDZ level of approximation. The CIQC molecule exists in four different conformers, with predicted populations of 4225:17:16% at room temperature (rt). The rt equilibrium conformational mixture was successfully trapped in an argon matrix, at 15K, and the vibrational signatures of the conformers were determined. Upon annealing of the matrix of the compound at higher temperatures (similar to 40 K), conversion of the higher energy forms into the most stable conformer was found to take place, in consonance with the low predicted barriers for conformational isomerization. Sublimation of the host matrix argon atoms (at similar to 43 K) led to production of a low-temperature amorphous state of CIQC, containing the lowest but also the higher energy conformers. At T similar to 233-243 K, the amorphous rearranged to the crystalline state, whose molecular unit corresponds to the most stable CIQC conformer, as shown both by infrared spectroscopy and single crystal X-ray diffraction. At room temperature CIQC crystallizes in the hexagonal P6(3)/m space group, with a=b=17.7928(2) angstrom, and c=6.9830(1) angstrom. The molecules lie on a crystallographic mirror plane and are stacked in layers along the c-axis. The main packing motif consists of a group of three molecules, related by a three-fold rotation, joined together by weak C-H ... O hydrogen bonds, Fundacao para a Ciencia e a Tecnologia (FCT) [PEst-OE/QUI/UI0313/2014, PEst-CCMAR/Multi/04326/2013]; QREN-COMPETE-UE; FCT [SFRH/BPD/88372/2012, RECI/BBB-BQB/0230/2012]; [SFRH/BD/81821/2011], The authors gratefully acknowledge Fundacao para a Ciencia e a Tecnologia (FCT), through the projects PEst-OE/QUI/UI0313/2014 (Coimbra Chemistry Centre) and PEst-CCMAR/Multi/04326/2013 (Center of Marine Sciences, CCMAR), cofunded by QREN-COMPETE-UE. Financial support has also been provided within the framework of the FCT post-doctoral grant SFRH/BPD/88372/2012 (N. K.) and the doctoral grant SFRH/BD/81821/2011 (P. H.). NMR spectrometers used are part of The National NMR Facility, supported by FCT (RECI/BBB-BQB/0230/2012).

The reactivity of 2,2-bis(furan-2-yl)propane towards nitroso- and azoalkenes was explored. The expected hetero-Diels–Alder adducts, 4a,7a-dihydro-4H-furo[2,3-e][1,2]oxazines and 4a,7a-dihydrofuro[3,2-c]pyridazines, were obtained in good yield. The furo-oxazines were easily converted into the corresponding bis(furan-2-yl)methanes bearing an open-chain oxime. Interestingly, the synthesized furo-pyridazines showed a different chemical behavior. In the presence of HCl, they underwent a rearrangement giving 6-(2-oxobutyl)-1,6-dihydropyridazine derivatives in a process having as its key step a furan ring-opening reaction. The synthesis of 4a,7a-dihydrofuro[3,2-c]pyridazines from 2-methylfuran and the subsequent acid-catalysed rearrangement to the corresponding 6-(2-oxopropyl)-1,6-dihydropyridazines was also achieved.

Thermal reactions of 1-(thiophene-2-yl)-1H-tetrazoles are reported for the first time. The solution thermolysis of 1-(thiophene-2-yl)-1H-tetrazoles under conventional heating and microwave irradiation afforded the unexpected new thieno[2,3-d]pyrimidines incorporating two thiophene rings, which were obtained as major or only product. The synthesis of these heterocycles was rationalized considering the initial nitrogen elimination to generate imidoylnitrene followed by rearrangement to the corresponding carbodiimide and subsequent cyclization triggered by the nucleophilic attack of the in situ generated 2-aminothiophene. The flash vacuum pyrolysis and solution thermolysis of 1-(thiophene-2-yl)-1H-tetrazoles also gave thieno[2,3-d]imidazoles via intramolecular formal insertion into a C–C bond of the corresponding imidoylnitrene intermediate.

In a previous study [Nogueira, B.A.; Ildiz, G.O.; Canotilho, J.; Eusebio, M. E. S.; Fausto, R. J. Phys. Chem. A, 2014, 118, 5994-6008], two different polymorphs of 1-methylhydantoin (1-MH, C4H6N2O2) were identified using infrared spectroscopy, differential scanning calorimetry and polarized-light thermal microscopy. Unfortunately, at that time it was not possible to structurally characterize in detail the second polymorph (polymorph II) of the compound, due to lack of suitable crystals for X-ray diffraction structure determination. In this article, a throughout investigation of the polymorphism of 1-MH is presented. Screening for polymorphs was performed by recrystallization from different solvents, and the structure of polymorph II was determined for the first time by single crystal X-ray diffraction. The spectroscopic characterization of this polymorph was also undertaken, by Raman spectroscopy, which was also used to follow the phase transition between the two polymorphs (the well-known polymorph I, and the newly described polymorph II), showing that even though their structures are significantly distinct, the transition is a non-destructive one. (C) 2017 Elsevier B.V. All rights reserved.

The molecular structure, vibrational spectra and photochemistry of 5-methylhydantoin (C4H6N2O2; 5-MH) were studied by matrix isolation infrared spectroscopy and theoretical calculations at the DFT(B3LYP)/6-311++G(d,p) theory level. The natural bond orbital (NBO) analysis approach was used to study in detail the electronic structure of the minimum energy structure of 5-MH, namely the specific characteristics of the sigma and pi electronic systems of the molecule and the stabilizing orbital interactions. UV irradiation of 5-MH isolated in argon matrix resulted in its photofragmentation through a single photochemical pathway, yielding isocyanic acid, ethanimine, and carbon monoxide, thus following a pattern already observed before for the parent hydantoin and 1-methylhydantoin molecules. The investigation of the thermal properties of 5-MH was undertaken by differential scanning calorimetry (DSC), polarized light thermal microscopy (PLTM) and Raman spectroscopy. Four different polymorphs of 5-MH were identified. The crystal structure of one of the polymorphs, for which it was possible to grow up suitable crystals, was determined by X-ray diffraction (XRD). Two of the additional polymorphs were characterized by powder XRD, which confirmed the molecules pack in different crystallographic arrangements.

Recent studies directed to the design of compounds targeting the bc(1) protein complex of Plasmodium falciparum, the parasite responsible for most lethal cases of malaria, identified quinolones (4-oxo-quinolines) with low nanomolar inhibitory activity against both the enzyme and infected erythrocytes. The 4-oxo-quinoline 3-ester chemotype emerged as a possible source of potent bc(1) inhibitors, prompting us to expand the library of available analogs for SAR studies and subsequent lead optimization. We now report the synthesis and structural characterization of unexpected ethyl 6-methyl-7-iodo-4-(3-iodo-4-methylphenoxy)quinoline-3-carboxylate, a 4-aryloxy-quinoline 3-ester formed during attempted preparation of 6-methyl-7-iodo-4-oxo-quinoline-3-carboxylate (4-oxo-quinoline 3-ester). We propose that the 4-aryloxy-quinoline 3-ester derives from 6-methyl-7-iodo-4-hydroxy-quinoline-3-carboxylate (4-hydroxy-quinoline 3-ester), the enol form of 6-methyl-7-iodo-4-oxo-quinoline-3-carboxylate. Formation of the 4-aryloxy-quinoline 3-ester confirms the impact of quinolone/hydroxyquinoline tautomerism, both on the efficiency of synthetic routes to quinolones and on pharmacologic profiles. Tautomers exhibit different cLogP values and interact differently with the enzyme active site. A structural investigation of 6-methyl-7-iodo-4-oxo-quinoline-3-carboxylate and 6-methyl-7-iodo-4-hydroxy-quinoline-3-carboxylate, using matrix isolation coupled to FTIR spectroscopy and theoretical calculations, revealed that the lowest energy conformers of 6-methyl-7-iodo-4-hydroxy-quinoline-3-carboxylate, lower in energy than their most stable 4-oxo-quinoline tautomer by about 27 kJ mol(-1), are solely present in the matrix, while the most stable 4-oxo-quinoline tautomer is solely present in the crystalline phase. Fundacao para a Ciencia e Tecnologia (FCT - Portugal) [UID/Multi/04326/2013]; QREN-COMPETE-UE; CCMAR; FCT [SFRH/BD/81821/2011, RECI/BBB-BQB/0230/2012, UI0313/QUI/2013, UID/FIS/04564/2016]; FEDER/COMPETE-UE; [PTDC/QEQ-QFI/3284/2014 - POCI-01-0145-FEDER-016617] info:eu-repo/semantics/publishedVersion

Quantum effects such as weak-antilocalisation (WAL) behavior and Shubnikov-de Haas (SdH) oscillations in the electrical transport properties of topological insulators, measured on nanostructured polycrystalline samples and single-crystals of a series of bismuth chalcogenide compounds (Bi2(SexTe1-x)3, 0 ≤ x ≤ 1 and BiSbTe3), are presented and discussed.

The molecular structure and photochemistry of 5-thiosaccharyl-1-methyltetrazole (TSMT) were studied by means of matrix-isolation FTIR spectroscopy, X-ray crystallography, and theoretical calculations. The calculations predicted two conformers of TSMT that differ in energy by more than 15 kJ mol(-1). The infrared spectrum of TSMT isolated in solid argon was fully assigned on the basis of the spectrum calculated (O3LYP/6-311++G(3df,3pd)) for the most stable conformer. In the crystal, TSMT molecules were found to assume the same conformation as for the isolated molecule, with each molecule forming four hydrogen bonds with three neighboring molecules, leading to a network of TSMT oligomers. Upon UV (λ = 265 nm) irradiation of the matrix-isolated TSMT, two photodegradation pathways were observed, both arising from cleavage of the tetrazolyl ring. Pathway a involves cleavage of the N1-N2 and N3-N4 bonds with extrusion of N2, leading to photostable diazirine and thiocarbodiimide derivatives. The photostability of the photoproduced diazirine under the conditions used precluded its rearrangement to the nitrile imine, as reported for 5-phenyltetrazole by Bégué et al. ( J. Am. Chem. Soc. 2012 , 134 , 5339 ). Pathway b involves cleavage of the C5-N1 and N4-N3 bonds, leading to a thiocyanate and methyl azide, the latter undergoing subsequent fragmentation to give CNH.

A new sodium salt, sodium triphenylacetate has been synthesized and characterized by single-crystal X-ray diffraction: triclinic, P-1 with a = 8.3846(2) angstrom, b = 13.5992(3) angstrom, c = 15.5288(3) angstrom, a = 76.7270(11)degrees, b = 74.4500(11)degrees, c = 84.7410(13)degrees, M-W = 656.65, V = 1659.42(6) angstrom(3), Z = 2. The triphenylacetic molecules bridge the metallic ions forming an infinite columnar structure. Calorimetric data does not support the existence of a mesophase induced by temperature.

(1H-Tetrazol-5-yl)-allenes have been prepared for the first time, and their reactivity toward aziridines explored. Reaction of a (1-benzyl-1H-tetrazol-5-yl)-phosphonium chloride and acyl chlorides in the presence of triethylamine afforded the target allenes via Wittig reaction of the in situ generated phosphorus ylide and ketenes. 1-(1-Benzyl-1H-tetrazol-5-yl)propa-1,2-diene and 3-methyl-, 3-ethyl- and 3-benzyl derivatives undergo microwave-induced formal [3 + 2] cycloaddition with cis-N-benzyl-2-benzoyl-3-phenylaziridine, through C-N bond cleavage, to give selectively tetrasubstituted pyrroles. In contrast, with (1H-tetrazol-5-yl)-allenes bearing bulkier substituents at C-3, such as i-propyl or a tert-butyl, 4-methylenepyrrolidines were obtained exclusively via [3 + 2] cycloaddition of the in situ generated azomethine ylide. The latter allenes also gave 4-methylenepyrrolidines on reacting with cis-2-benzoyl-N-cyclohexyl-3-phenylaziridine, whereas with the other allenes, pyrroles were obtained as major products together with the formation of 4-methylenepyrrolidines. All the studied (1H-tetrazol-5-yl)-allenes reacted with N-benzyl-cis-3-phenylaziridine-2-carboxylate to give the corresponding 4-methylenepyrrolidines exclusively.

A new ternary uranium intermetallic compound, U2Fe3Ge, was synthesized and investigated. This compound crystallizes in the MgZn2-type structure ( a = 5.1870 ( 3 ) A and c = 7.8501 ( 5 ) A , space group P 6 3 / m m c ), with uranium–uranium distances well below the Hill limit. Magnetization measurements indicate a ferromagnetic-type transition at 55(1) K. Mossbauer studies show that the magnetic ordering is due only to the uranium sub-lattice, pointing to U2Fe3Ge as a new exception to Hill’s rule.

The role of copper in the proliferation of cancer cells is under investigation and has been explored in the context of cancer chemotherapy. The evidence that proliferation of cancer cells requires a higher abundance of Cu(II) than their normal counterparts has prompted the development of new copper chelators that can avidly bind copper ions, forming redox active metal complexes that ultimately lead to harmful reactive oxygen species (ROS) in neoplasms. In this context, the mandatory properties of the chelators for medical applications are safety (neglectable cytotoxicity), high binding affinity and selectivity towards Cu(II). We report the synthesis, structure (calculations and single crystal X-ray diffraction), spectroscopic (IR; UV-Vis) and magnetic properties of two novel copper(II) complexes based on 5-(3-aminosaccharyl)-tetrazoles (TS and 2MTS), as well as their in vitro cytotoxicity against the human hepatic carcinoma cell line HepG2. Quite interestingly, we found that the saccharinate-tetrazoles tested exhibit strong binding selectivity to Cu(II), over Fe(II) and Ca(II). Additionally, the corresponding copper complexes have shown a huge increase in the in vitro cytotoxicity against tumoral cells, compared to the corresponding nontoxic ligands. Thus, the new ligands may be viewed as potential precursors of selective cytotoxic agents, acting as non-cytotoxic pro-drugs that can be activated inside neoplastic cells, known to be richer in Cu(II) than the corresponding normal cells.

The reactivity of 2,2-bis(furan-2-yl)propane towards nitroso- and azoalkenes was explored. The expected hetero-Diels–Alder adducts, 4a,7a-dihydro-4H-furo[2,3-e][1,2]oxazines and 4a,7a-dihydrofuro[3,2-c]pyridazines, were obtained in good yield. The furo-oxazines were easily converted into the corresponding bis(furan-2-yl)methanes bearing an open-chain oxime. Interestingly, the synthesized furo-pyridazines showed a different chemical behavior. In the presence of HCl, they underwent a rearrangement giving 6-(2-oxobutyl)-1,6-dihydropyridazine derivatives in a process having as its key step a furan ring-opening reaction. The synthesis of 4a,7a-dihydrofuro[3,2-c]pyridazines from 2-methylfuran and the subsequent acid-catalysed rearrangement to the corresponding 6-(2-oxopropyl)-1,6-dihydropyridazines was also achieved.

The synthesis and reactivity of tetrazol-5-yl-phosphorus ylides towards N-halosuccinimide/TMSN3 reagent systems was explored, opening the way to new haloazidoalkenes bearing a tetrazol-5-yl substituent. These compounds were obtained as single isomers, except in one case. X-ray crystal structures were determined for three derivatives, establishing that the non-classical Wittig reaction leads to the selective synthesis of haloazidoalkenes with (Z)-configuration. The thermolysis of the haloazidoalkenes afforded new 2-halo-2-(tetrazol-5-yl)-2H-azirines in high yields. Thus, the reported synthetic methodologies gave access to important building blocks in organic synthesis, vinyl tetrazoles and 2-halo-2-(tetrazol-5-yl)-2H-azirine derivatives.

Thermal reactions of 1-(thiophene-2-yl)-1H-tetrazoles are reported for the first time. The solution thermolysis of 1-(thiophene-2-yl)-1H-tetrazoles under conventional heating and microwave irradiation afforded the unexpected new thieno[2,3-d]pyrimidines incorporating two thiophene rings, which were obtained as major or only product. The synthesis of these heterocycles was rationalized considering the initial nitrogen elimination to generate imidoylnitrene followed by rearrangement to the corresponding carbodiimide and subsequent cyclization triggered by the nucleophilic attack of the in situ generated 2-aminothiophene. The flash vacuum pyrolysis and solution thermolysis of 1-(thiophene-2-yl)-1H-tetrazoles also gave thieno[2,3-d]imidazoles via intramolecular formal insertion into a C–C bond of the corresponding imidoylnitrene intermediate.

The isothermal section at 900 °C of the U–Fe–Ge ternary system was assessed using experimental results from X-ray diffraction and observations by scanning electron microscopy coupled with energy dispersive X-ray spectroscopy chemical analysis. The phase diagram at this temperature is characterized by the formation of fourteen stable phases: four homogeneity ranges and ten intermetallic compounds. Among these, there is an extension of the binary compound UFe2 into the ternary system (UFe2−xGex, x

The isothermal section at 900 °C of the phase diagram of the U—Fe—Ge ternary system is investigated by melting and annealing the elements for 4 weeks prior to quenching in H2O.

WOS: 000366877900036, PubMed ID: 26551438, Recent publications report in vitro activity of quinolone 3-esters against the bc(1) protein complex of Plasmodium falciparum and the parasite. Docking studies performed in silica at the yeast Q(o) Site established a key role for the 4-oxo and N-H groups in drug-target interactions. Thus, the possibility of 4-oxoquinoline/4-hydroxyquinoline tautomerism may impact in pharmacologic profiles and should be investigated. We describe the synthesis, structure, photochemistry, and activity against multidrug-resistant P. falciparum strain Dd2 of ethyl 4-oxo-7-methylquinoline-3-carboxylate (7Me-OQE) and ethyl 4-hydroxy-5-methylquinoline-3-carboxylate (5Me-HQE), obtained from diethyl 2-[((3-methylphenyl)amino)methylene]malonate. Theoretically (B3LYP/6-311+ +G(d,p)), 5Me-HQE and 7Me-OQE show clear preference for the hydroxyquinoline form. The difference between the lowest energy hydroxyquinoline and quinolone forms is 27 and 38 kJ mol(-1), for 5Me-HQE and 7Me-OQE, respectively. Calculations of atomaticity indexes show that in 5Me-HQE,both rings are aromatic, while in the corresponding oxo tautomers the nitrogen-containing ring is essentially non-aromatic. The structure of monomeric 5Me-HQE was studied using matrix-isolation coupled to FTIR spectroscopy. No traces of 4-oxoquinoline tautomers were found in the experimental IR spectra, revealing that:the species present in the crystal, 5Me-HQE center dot HCl, was lost HCl upon sublimation but did not tautomerize. Continuous broadband irradiation (lambda > 220 nm; 130 min) of the matrix led to only partial photodecomposition of 5Me-HQE (ca. 1/3)., Fundacao para a Ciencia e a Tecnologia (FCT), Portugal [PEst-C/MAR/LA0015/603 2013]; QREN-COMPETE-UE; CCMAR; FCT [PEst-OE/QUI/UI0313/2014, SFRH/BD/81821/2011, SFRH/BPD/88372/2012]; Engineering and Physical Sciences Research Council [EP/K039687/1], The authors gratefully acknowledge Fundacao para a Ciencia e a Tecnologia (FCT), Portugal (Project PEst-C/MAR/LA0015/603 2013), cofounded by QREN-COMPETE-UE and CCMAR for generous financial support. The Coimbra Chemistry Centre (CQC) is also supported by FCT through Project PEst-OE/QUI/UI0313/2014. P.H. acknowledges FCT for the award of a doctoral grant (SFRH/BD/81821/2011). N.K acknowledges FCT for the award of a postdoctoral grant (SFRH/BPD/88372/2012). NMR spectrometers used are part of The National NMR Facility, supported by Fundacao para a Ciencia e a Tecnologia (RECI/BBB-BQB/0230/2012).

This work reports on highly fluorescent and superparamagnetic bimodal nanoparticles (BNPs) obtained by a simple and efficient method as probes for fluorescence analysis and/or contrast agents for MRI. These promising BNPs with small dimensions (ca. 17 nm) consist of superparamagnetic iron oxide nanoparticles (SPIONs) covalently bound with CdTe quantum dots (ca. 3 nm). The chemical structure of the magnetic part of BNPs is predominantly magnetite, with minor goethite and maghemite contributions, as shown by Mossbauer spectroscopy, which is compatible with the x-ray diffraction data. Their size evaluation by different techniques showed that the SPION derivatization process, in order to produce the BNPs, does not lead to a large size increase. The BNPs saturation magnetization, when corrected for the organic content of the sample, is ca. 68 emu g-1, which is only slightly reduced relative to the bare nanoparticles. This indicates that the SPION surface functionalization does not change considerably the magnetic properties. The BNP aqueous suspensions presented stability, high fluorescence, high relaxivity ratio (r 2/r 1 equal to 25) and labeled efficiently HeLa cells as can be seen by fluorescence analysis. These BNP properties point to their applications as fluorescent probes as well as negative T 2-weighted MRI contrast agents. Moreover, their potential magnetic response could also be used for fast bioseparation applications.

WOS: 000342396100008, PubMed ID: 25144919, The crystal structure of 3-quinolinecarboxaldehyde (3QC) has been solved, and the compound has been shown to crystallize in the space group P2(1)/c (monoclinic) with a = 6.306(4), b = 18.551(11), c = 6.999(4) angstrom, beta = 106.111(13)degrees, and Z = 4. The crystals were found to exhibit pseudomerohedral twinning with a twin law corresponding to a two-fold rotation around the monoclinic (100) reciprocal lattice axis (or [4 0 1] in direct space). Individual molecules adopt the syn conformation in the crystal, with the oxygen atom of the aldehyde substituent directed toward the same side of the ring nitrogen atom. In the gas phase, the compound exists in two nearly isoenergetic conformers (syn and anti), which could be successfully trapped in solid argon at 10 K, and their infrared spectra are registered and interpreted. Upon in situ irradiation of matrix-isolated 3QC with UV light (lambda > 315 nm), significant reduction of the population of the less stable anti conformer was observed, while that of the conformational ground state (syn conformer) increased, indicating occurrence of the anti -> syn isomerization. Upon irradiation at higher energy (lambda > 235 nrn), the syn -> anti reverse photoreaction was observed. Interpretation of the structural, spectroscopic, and photochemical experimental data received support from quantum chemical theoretical results obtained at both DFT/B3LYP (including TD-DFT investigation of excited states) and MP2 levels, using the 6-311++G(d,p) basis set., Fundacao para a Ciencia e a Tecnologia (FCT), Portuguese Agency for Scientific Research [PEst-OE/QUI/UI0313/2014, PEst-OEFIS/UI0036/2014]; FCT [SFRH/BPD/88372/2012]; QREN-Mais Centro Project [ICT_2009_02_012_1890]; Academic Computer Center "Cyfronet", Krakow, Poland [KBN/SGI_ORIGIN 2000/UJ/044/1999], CQC and CEMDRX are supported by the Fundacao para a Ciencia e a Tecnologia (FCT), Portuguese Agency for Scientific Research, through Projects PEst-OE/QUI/UI0313/2014 and PEst-OEFIS/UI0036/2014. N.K. acknowledges FCT for the award of a postdoctoral grant (SFRH/BPD/88372/2012). Access to XRD facilities of TAIL-UC funded under QREN-Mais Centro Project ICT_2009_02_012_1890 is gratefully acknowledged. The authors also thank Dr. Agnieszka Kaczor and the Academic Computer Center "Cyfronet", Krakow, Poland (Grant KBN/SGI_ORIGIN 2000/UJ/044/1999), for providing us the required computing time to undertake the most demanding calculations reported in the present work.

A new ternary compound, U 9 Fe 7 Ge 24 , was synthesized by arc-melting the elements, followed by annealing at 900 °C. This compound was characterized by single crystal and powder X-ray diffraction, magnetization, specific heat and electrical transport measurements. It crystallizes in an original tetragonal structure type (space group I4/mmm ), with lattice parameters a = 12.3789(2) A and c = 18.2881(3) A. Three uranium, eighth germanium, and three iron crystallographic sites exist in this structure, with the atoms making a stacking of infinite chains along the a and b axis. From their interatomic distances strong interactions between the uranium and germanium atoms can be predicted. The magnetic and specific heat measurements down to 2 K do not show any magnetic transition. The Curie–Weiss behaviour with a negative paramagnetic Curie temperature θ p = −94 K and reduced effective magnetic moment of μ eff = 2.13 μ B /U indicate that the compound is rather far from onset of magnetism, presumably due to a strong hybridisation of the 5 f and ligand states. The electrical transport measurements show a metallic behaviour.

The angular dependent magnetoresistance of the superconducting ferromagnet UCoGe is studied in detail at 40 mK to fields of 18 T in a single crystal sample with a low residual resistivity ratio [R(300 K)/R(1 K)=RRR=5]. A ferro-to-ferrimagnetic transition near 9 T that depends only on the field component along the uniaxial magnetic c axis is observed in both transport and susceptibility. Reverse hysteresis in the magnetoresistance in the critical field region indicates a coupling of the superconductivity to the magnetization for fields aligned closely to the ab plane. These results corroborate and advance previous findings on higher residual resistivity ratio samples.

This contribution focuses on the structural and physical properties of U-based Laves phases. It starts with the structural description of the different type of Laves phases, followed by a brief description of the factors that affect their stability. The majority of the uranium Laves phases show a weakly paramagnetic behaviour. The reason is the compact structure of the phases that leads to small a U-U spacing as well as very high coordination numbers, regarding both the uranium and the ligands sublattices, which brings a strong hybridization with non-f states. However, there are some exceptions of uranium Laves phases that do order magnetically (UFe2, UNi2 and the recently discovered U2Fe3Ge compound). These exceptions are discussed in more detail in the present manuscript.