Horizontal flux growth as an efficient preparation method of CeRh2As2 single crystals.

We report an efficient method to obtain CeRh2As2 single crystals with the use of a bismuth flux growth method in a horizontal configuration. Based on our numerous attempts, we found this technique to be scalable and repeatable. The crystals thus obtained are characterized by much sharper phase transitions and distinctly higher characteristic temperatures Tc and T0, compared to previous reports. Moreover, based on our specific heat studies of the obtained single crystals, we also indicate a clear connection between both transition temperatures.

Rearrangement of thiazolidine derivatives - a synthesis of a chiral fused oxathiane-γ-lactam bicyclic system.

Reaction of L-cysteine with carbonyl compounds leads to thiazolidine derivatives which undergo a stereoselective conversion to two types of chiral bicyclic products bearing two or three stereogenic centers, including the first fused oxathiane-γ-lactam system.

An efficient one-pot synthesis of pyrazole complexes formed in situ: synthesis, crystal structure, Hirshfeld surface analysis and in vitro biological properties.

The molecular crystals of monomeric and dimeric pyrazole complexes were prepared via one-pot syntheses. These are dichloridobis(3,5-dimethyl-1H-pyrazole-κN1)cobalt/zinc(0.2/0.8), [Co0.20Zn0.80Cl2(C5H8N2)2] or [Co0.2Zn0.8Cl2(3,5-dmp)2] (1), and bis(µ-3,5-dimethyl-1H-pyrazole)-κ2N1:N2;κ2N2:N1-bis[bromido/chlorido(0.7/0.3)bis(3,5-dimethyl-1H-pyrazole-κN1)cobalt/zinc(0.1/0.9)], [Co0.20Zn1.80Br1.40Cl0.60(C5H7N2)2(C5H8N2)2] or [Co0.1Zn0.9Br0.7Cl0.3(µ-3,5-dmp)(3,5-dmp)]2 (2). The isolated complexes contain 3,5-dimethylpyrazole (3,5-dmp) ligands formed in situ from the decomposition of 1-hydroxymethyl-3,5-dimethylpyrazole. In both isolated complexes, some positional disorder is observed at the metal ions and halogen ligands. The molecular crystals of 1 and 2 are centrosymmetric, with the space groups C2/c and P-1, respectively. Additionally, in the dinuclear complex, the pyrazole ring has a bridging coordination function with respect to the metal ions. Both complexes have good biological activities against cancer cells. The results of an in vitro cytotoxicity study indicated that compounds 1 and 2 showed significant cytotoxicity for cancer cell lines, including hepatic (HepG2 cells), lung (A549 cells) and colon cancer cells (SW 480 and SW 620). Based on the calculated IC50 values against human cancer cell lines, it was found that both complexes demonstrated potent antiproliferative activity combined with great selectivity towards cancer cells. Complex 2 was a more effective cytotoxic agent which, at the same time, exhibited high cytocompatibility. The obtained data are very encouraging and could be useful for anticancer drug discovery.

Structural and theoretical analysis of 2-chloro-4-nitroaniline and 2-methyl-6-nitroaniline salts.

The crystal structures of five new salts of 2-chloro-4-nitroaniline (2Cl4na) and 2-methyl-6-nitroaniline (2m6na) with inorganic acids, namely, 2-chloro-4-nitroanilinium bromide, C6H6ClN2O2+·Br- (1), 2-chloro-4-nitroanilinium hydrogen sulfate, C6H6ClN2O2+·HSO4- (2), 2-methyl-6-nitroanilinium bromide, C7H9N2O2+·Br- (3), 2-methyl-6-nitroanilinium triiodide, C7H9N2O2+·I3- (4), and 2-methyl-6-nitroanilinium hydrogen sulfate, C7H9N2O2+·HSO4- (5), were determined by single-crystal X-ray diffraction. Theoretical calculations of the relaxed potential energy surface (rPES) revealed that the energy barriers for the rotation of the nitro group for isolated H2Cl4na+ and H2m6na+ cations are 4.6 and 11.6 kcal mol-1, respectively. The ammonium group and respective anions form hydrogen bonds which are the most important interactions and are arranged in zero- (in 3), one- (in 1 and 4) or two-dimensional (in 2 and 5) networks. Hydrogen-bonding patterns were analyzed by means of mathematical relationships between graph-set descriptors and compared with previously reported nitroaniline salts. Hirshfeld surface analysis indicates that the nitro group plays a dominant role among the weak interactions, i.e. C-H...O(NO2), NO2...π(Ar) and O(NO2)...π(NO2). The frequency of the νsNO2 vibration is correlated with the type of interaction in which the NO2 group is involved. Analysis of the νsNO2 band observed in the IR and Raman spectra allowed an assessment of its shift in the sequence (H2m6na)I3 (4) < (H2m6na)HSO4 (5) < (H2m6na)Br (3) < (H2Cl4na)Br (1) < (H2Cl4na)HSO4 (2).

Biaryl Sulfonamides Based on the 2-Azabicycloalkane Skeleton-Synthesis and Antiproliferative Activity.

In a search for new, selective antitumor agents, we prepared a series of sulfonamides built on bicyclic scaffolds of 2-azabicyclo(2.2.1)heptane and 2-azabicyclo(3.2.1)octane. To this end, aza-Diels-Alder cycloadducts were converted into amines bearing 2-azanorbornane or a bridged azepane skeleton; their treatment with sulfonyl chlorides containing biaryl moieties led to the title compounds. The study of antiproliferative activity of the new agents showed that some of them inhibited the growth of chosen cell lines with the IC50 values comparable with cisplatin, and some derivatives were found considerably less toxic for nonmalignant cells.

Aminophosphonates and aminophosphonic acids with tetrasubstituted stereogenic center: diastereoselective synthesis from cyclic ketimines.

New chiral tetrasubstituted aminophosphonic acid derivatives of hexahydroquinoxalin-2(1H)-one were synthesised via highly diastereoselective hydrophosphonylation of the corresponding imines with tris(trimethylsilyl) phosphite as phosphorus nucleophile. High asymmetric induction, good yields, mild reaction conditions, and ease of purification of the final products are the key advantages of the presented protocol.

Structural, theoretic and spectroscopic analysis of 2-methyl-5-nitroaniline salts with various inorganic acids.

Crystal structures of six new salts of 2-methyl-5-nitroaniline with inorganic acids [(H2Me5NA)Br, (H2Me5NA)I, (H2Me5NA)NO3, (H2Me5NA)Cl, (H2Me5NA)HSO4 and (H2Me5NA)I3·0.5H2O] are determined by single-crystal X-ray diffraction. The most important hydrogen-bonding patterns are formed by the ammonio group and respective anions composing 1D or 2D networks. The patterns are analysed using the graph-set approach and mathematical interrelations between graph-set descriptors are shown for comparative purposes. Analysis of IR spectra enables the strength of hydrogen bonds in the crystals to be assessed. The frequency of N-H and O-H stretching vibrations and NH3 group libration indicates that the strongest hydrogen bonds are present in (H2Me5NA)HSO4, whereas the weakest ones occur in (H2Me5NA)I3·0.5H2O. Hirshfeld surface analysis reveals that apart from obvious N-H...anion hydrogen bonds, the molecules are also connected to each other by exclusive C-H...ONO2 interactions. The opposite occurs in the crystal structure of 2-methyl-4-nitroaniline salts, where a variety of ONO2...π(N)NO2 non-hydrogen bonding interactions are observed.

Phase transition in polar 2-nitroanilinium nitrate. Graph-set approach of hydrogen bonding patterns and analysis of vibrational spectra.

A phase transition in new compound 2-nitroanilinium nitrate, (H2NA)NO3, was found. A symmetry lowering from orthorhombic, Pmn21, to monoclinic one, P21, at 249 K is observed. During the phase transition, the H2NA+ and nitrate ions displace from the mirror plane in high-temperature phase. As a result, hydrogen bonding network constructed by the ammonio group and NO3- anion is changed. Especially, a bifurcated hydrogen bond disappears. Mathematical operations using both elementary and hydrogen bond graph-set descriptors were used for the first time to describe a mechanism of phase transition. Changes in hydrogen bonding network were also studied by means of vibrational spectroscopy. Band shift associated with stretching and bending vibrations of the ammonio group indicates that the energy of intermolecular interactions rises along with temperature decrease. SHG response for the studied compound is higher than KDP, I(H2NA)NO3 = 1.1·IKDP, although a decay of the signal was observed due to instability of the sample.

Magnetic field driven complex phase diagram of antiferromagnetic heavy-fermion superconductor Ce3PtIn11.

We present the results of our comprehensive investigation on the antiferromagnetic heavy-fermion superconductor Ce3PtIn11 carried out by means of electrical transport, heat capacity and ac magnetic susceptibility measurements, performed on single-crystalline specimens down to 50 mK in external magnetic fields up to 9 T. Our experimental results elucidate a complex magnetic field - temperature phase diagram which contains both first- and second-order field-induced magnetic transitions and highlights the emergence of field stabilized phases. Remarkably, a prominent metamagnetic transition was found to occur at low temperatures and strong magnetic fields. In turn, the results obtained in the superconducting phase of Ce3PtIn11 corroborate an unconventional nature of Cooper pairs formed by heavy quasiparticles. The compound is an almost unique example of a heavy fermion system in which superconductivity may coexist microscopically with magnetically ordered state.

Comparison of hydrogen bonds and diverse weak interactions of the nitro group in 2-methyl-4-nitroanilinium nitrate, bisulfate and two hexafluoridosilicates: elementary graph-set approach.

Crystal structures of (H2m4na)NO3 (1), (H2m4na)HSO4 (2), (H2m4na)2SiF6 (3) and (H2m4na)2SiF6·2H2O (4), where 2m4na = 2-methyl-4-nitroaniline, are presented. Two layers of interactions occur in the structures, N-H...O/F hydrogen bonds and interactions with the nitro group. Although diverse, hydrogen-bonding patterns are compared with each other by means of interrelations among elementary graph-set descriptors and descriptors of hydrogen-bonding patterns. Using mathematical relations, the gradual expansion of the ring patterns was shown in the crystal structures. Parallel and perpendicular arranged nitro groups form weak π(N)NO2...π(O)NO2 and π(N)NO2...ONO2 interactions, respectively. The πNO2...πring interaction has an impact to the stabilization of parallel oriented nitro groups. Generally, weak interactions constructed by the nitro group occur in the studied crystals as follows: π(N)NO2...π(O)NO2, πring...πring, C-H...O (1); π(N)NO2...π(O)NO2, π(N)NO2...ONO2 (2); π(N)NO2...π(O)NO2, π(N)NO2...ONO2 (3); C-H...O (4).

Variable-temperature X-ray diffraction study of structural parameters of NH---S hydrogen bonds in triethylammonium and pyridinium silanethiolates.

Two hydrogen-bonded, well defined compounds were synthesized from tris(2,6-diisopropyl)phenoxysilanethiol (TDST) and triethylamine (TDST-TEA) or pyridine (TDST-py). The crystalline compounds were characterized in the solid state by variable-temperature X-ray diffraction measurements and ATR FT-IR spectroscopy. The toluene solutions of TDST-TEA and TDST-py were studied by NMR spectroscopy. The total hydrogen-bond energies and FT-IR spectra were calculated with the use of BLYP-D/TZP and B3LYP/6-31G(d,p)/GD3BJ methods. Thermochemical parameters and potential energy scans were calculated at the B3LYP/6-31G(d,p)/GD3BJ level. All results point to the higher energy of bonding in TDST-TEA both in the solid state and in solution. At the same time the potential energy scan reveals a very broad double-well hydrogen bond in TDST-py, indicating good stabilization of the system for a wide range of D-H...A distances.

Accidental formation of Gd4(SiO4)2OTe: crystal structure and spectroscopic properties.

Designing new functional materials with increasingly complex compositions is of current interest in science and technology. Complex rare-earth-based chalcogenides have specific thermal, electrical, magnetic and optical properties. Tetragadolinium bis[tetraoxidosilicate(IV)] oxide telluride, Gd4(SiO4)2OTe, was obtained accidentally while studying the Gd2Te3-Cu2Te system. The crystal structure was determined by means of single-crystal X-ray diffraction. The compound crystallizes in the space group Pnma. Three symmetry-independent gadolinium sites were determined. The excitation and emission spectra were collected at room temperature and at 10 K. Gd4(SiO4)2OTe appears to be a promising optical material when doped with rare-earth ions.

X-ray, vibrational and theoretical studies of weak hydrogen bonds in bis(4-nitroanilinium) hexachloridostannate.

Crystal structure of bis(4-nitroanilinium) hexachloridostannate, (H4NA)2SnCl6, was determined by means of X-ray single crystal diffraction. In the crystal structure, weak N-H…Cl hydrogen bonds are present. These interactions were taken into consideration in calculations of vibrational spectra for the [(H4NA)Cl4O](5-) anion. Very good agreement between theoretical and experimental frequencies was achieved. The calculations were done at the B3LYP/6-311+G(2d,1p) level including Grimme's correction for dispersion. The relaxed potential energy surface indicated that the energy of H4NA(+) ion is approximately independent upon rotation of the ammonio group. The energy barrier is 0.01 kcal/mol. Therefore the position of the ammonio group can be easily modified the other interacting molecules during molecular self-assembly and crystal growth processes. The energy of the H4NA(+) ion significantly depends on the relative position of the nitro group towards the aromatic ring. The energy barrier of the nitro group is 4.35 kcal/mol.

Vibrational spectra of the ortho-nitroanilinium cation in torsional space. Theoretical studies vs. experimental data of ortho-nitroanilinium chloride.

Crystal structure of the ortho-nitroanilinium chloride, (HoNA)Cl, was re-determined by means of X-ray single crystal diffraction. Hydrogen atoms of the ammonio form intra- and intermolecular hydrogen bonds which are arranged in chain and ring patterns. The patterns are described by the mathematical relations of the elementary graph-set descriptors. Since the interactions have a weak nature, the interpretation of the vibrational spectra was carried out with the help of theoretical calculations of the spectra for the HoNA+ ion. In order to properly assign experimental bands, theoretical spectra were calculated at the B3LYP/6-31G(d,p) level of theory for the geometry of global minimum of HoNA+ ion as a reference and for the other conformations, including in-crystal geometry of the ion, changing the relative position of the ammonio and nitro groups. Overall, the 89 spectra were analyzed as a two-dimensional dependence of each of 45 normal modes of the HoNA+ ion on two dihedral angles, dih(HNCC) and dih(ONCC). Additionally, calculations were done for the in-crystal conformation of the (HoNA)Cl3(2-) anion. Great increase of frequency is observed for the ν7 (641 cm(-1)), where the H1C atom is involved in, because the intramolecular N-H1C⋯O hydrogen bond weakens upon rotation of the NH3+ group. PED analysis shows that also the modes of vibrations changes upon rotation. The mode of vibrations for the (HoNA)Cl3(2-) anion differs from the HoNA+ ion, especially for the ν(N-H) vibrations. Besides, when three chloride anions where included in the calculations, only then the experimental spectra were well reproduced.

Weak hydrogen bonds in bis(3-nitroanilinium) hexachloridostannate monohydrate. X-ray, vibrational and theoretical studies.

Crystal structures of bis(3-nitroanilinium) hexachloridostannate monohydrate, (H3NA)2SnCl6·H2O, was determined by means of X-ray single crystal diffraction. Relaxed potential energy surface of the H3NA(+) ion was calculated at the B3LYP/6-31(d,p) level. The energy of the H3NA(+) ion is approximately independent upon rotation of the ammonio group. It significantly depends on relative position of the nitro group towards aromatic ring. Theoretical spectra were calculated for the [(A-H3NA)Cl5·H2O](4-) and [(B-H3NA)Cl5](4-) anions, and thus hydrogen bonds of the ammonio group with the nearest neighboring atoms were included. PED results revealed that no coupling among all of the N-H oscillators exists. They vibrate separately because each hydrogen atom of the ammonio group of A- and B-H3NA(+) ions has different surroundings of the acceptors. Overall, very good agreement between theoretical and experimental frequencies was achieved.

3-Amino-1,2,4-triazolium ion in [24(3at)]Cl and [24(3at)]2SnCl6·H2O. Comparative X-ray, vibrational and theoretical studies.

Crystal structures of 3-amino-1,2,4-triazolium chloride and bis(3-amino-1,2,4-triazolium) hexachloridostannate monohydrate were determined by means of X-ray single crystal diffraction. The route of protonation of organic molecule and tautomer equilibrium constants for the cationic forms were calculated using B3LYP/6-31G* method. The most stable protonated species is 2,4-H(2)-3-amino-1,2,4-triazolium ion, 24(3at)(+). Very good agreement between theoretical and experimental frequencies was achieved due to very weak interactions existing in studied compounds. Significantly weaker intermolecular interactions are found in [24(3at)](2)SnCl(6)·H(2)O than in [24(3at)]Cl. The differences in strength of interactions are manifested in red and blue shifts for stretching and bending motions, respectively. PED calculations show that for 24(3at)(+) ion the stretching type of motion of two N(ring)H bonds is independent, whereas bending is coupled.

Synthesis, crystal structure, spectroscopic, magnetic, theoretical, and microbiological studies of a nickel(II) complex of L-tyrosine and imidazole, [Ni(Im)2(L-tyr)2]·4H2O.

The [Ni(Im)(2)(L-tyr)(2)]·4H(2)O (1) complex was obtained in crystalline form as a product of interaction of L-tyrosine sodium salt, imidazole, and NiSO(4). The X-ray structure was determined, and the spectral (IR, FIR, NIR-vis-UV, HF EPR) and magnetic properties were studied. The Ni(2+) ion is hexacoordinated by the N and O atoms from two L-tyrosine molecules and by two N atoms of imidazole, resulting in a slightly distorted octahedral [NiN(2)N(2)'O(2)] geometry with a tetragonality parameter T = 0.995. The bands observed in the electronic spectra were ascribed to the six spin-allowed electronic transitions (3)B(1g) → (3)E(g) and (3)B(2g), (3)B(1g) → (3)A(2g) and (3)E(g), and (3)B(1g) → (3)A(2g) and (3)E(g). The spin Hamiltonian parameters g, D, and E, which were determined from high-field HF EPR spectra, excellently reproduced the magnetic properties of the complex. Calculation of the zero-field splitting in the S = 1 state of nickel(II) using DFT and UHF was attempted. The biological activity of the complexes has been tested for antifungal and antibacterial effects against Aspergillus flavus, Fusarium solani, Penicillium verrucosu, Bacillus subtilis, Serratia marcescens, Pseudomonas fluorescens, and Escherichia coli.

Silver(I) complexes with hydantoins and allantoin: synthesis, crystal and molecular structure, cytotoxicity and pharmacokinetics.

Coordination polymers [Ag(L(1,3))](n) (L(1)=hydantoin, L(3)=5,5-dimethylhydantoin), {[Ag(L(2))](.)0.5H(2)O}(n) (L(2)=1-methylhydantoin) and [Ag(NH(3))(L(4))](n) (L(4)=allantoin) were prepared and characterized by elemental analysis, spectroscopic (IR, FTIR and NMR), thermal and mass spectrometry methods. The crystal structure of {[Ag(1-methylhydantoin)]·0,5H(2)O}(n) was determined and analyzed. Three 1-methylhydantoinate ligands create a T-shape (CN=3) coordination sphere around the Ag(+) ion. Additionally, a short Ag⋯Ag distance of 2.997Å was found in the structure resulting in the expanded [3+2] environment of a distorted square shape. The [Ag(L(2))] entities are bound to each other by the bridging organic ligands. Thus a two-dimensional coordination polymer is created with water molecules located between the layers. In contrast to hydantoins, the allantoin complex contains an additional ammonia molecule in the coordination sphere. Moreover, in the Ag-alla complex the M-organic ligand binding site is shifted to the N-atom of the ureid chain. Free ligands are cytotoxically inactive against human MCF-7 and A549 cancer cell lines and mouse fibroblasts Balb/3T3. The silver hydantoin complexes exhibit a very strong activity against these lines. (The introduction of the methyl groups to the ring slightly increases resistance only against the A549 cell line.) In contrast, the silver complex of allantoin shows only a weak activity which may be related to the presence of the cytotoxic ammonia group in the composition of the compound and/or the different binding site of the ligand. Calculated in silico physiochemical parameters are promising for the future application of the complexes as drugs.

Ln3M(1-delta)TX7--quasi-isostructural compounds: stereochemistry and silver-ion motion in the Ln3Ag(1-delta)GeS7 (Ln = La-Nd, Sm, Gd-Er and Y; delta = 0.11-0.50) compounds.

The crystal structures of the Ln3Ag(1-delta)GeS7 (Ln = La-Nd, Sm, Gd-Er, Y; delta = 0.11-0.50, space group P6(3)) compounds were determined by means of X-ray single-crystal diffraction and the similarities among the crystal structures of all Ln3M(1-delta)TX7 (space group P6(3); Ln--lanthanide element, M--monovalent element; T--tetravalent element and X--S, Se) compounds deposited in the Inorganic Crystal Structure Database (ICSD) are discussed. Substitutions of each element in Ln3M(1-delta)TX7 result in a different structural effect. On the basis of the data deposited in the ICSD the large family of the Ln3M(1-delta)TX7 compounds was divided into three groups depending on the position of the monovalent element in the lattice. This position determines what kind of stereoisomer is present in the structure, either the ++ enantiomer or the +- diastereoisomer. Since the silver ions can occupy a different position and the energy barriers between positions are low the ions can move through the channel. It was shown that this movement is not a stochastic process but a correlated one.

Crystal architecture of R(2)SnS(5) (R = Pr, Nd, Gd and Tb): crystal structure relationships in chalcogenides.

The crystal structure of the R(2)SnS(5) (R = Pr, Nd, Gd and Tb) compounds has been investigated using X-ray single-crystal diffraction. Crystal architecture and structural relationships among U(3)S(5), Y(2)HfS(5), R(2)SnS(5) compounds are discussed and a structural origin is determined. It is shown that the complex architecture of the crystal structure of Eu(5)Sn(3)S(12) is a result of interweaving of the simple crystal structures. The location of the copper ions in the non-stoichiometric compound Y(2)Cu(0.20)Sn(0.95)S(5) is proposed on the basis of comparative analysis of the R-S interatomic distances in the R(2)SnS(5) series of compounds.