Structures and syntheses of layered and framework amine-bearing uranyl phosphate and uranyl arsenates

Two hydrated uranyl arsenates and a uranyl phosphate were synthesized by hydrothermal methods in the presence of amine structure-directing agents and their structures determined: (N₂C₆H₁₄)[(UO₂)(AsO₄)]₂(H₂O)₃, DabcoUAs, {NH(C₂H₅)₃}[(UO₂)₂(AsO₄)(AsO₃OH)], TriethUAs, and (N₂C₄H₁₂)(UO₂)[(UO₂)(PO₄)]₄(H₂O)₂, PiperUP. Intensity data were collected at room temperature using MoKα X-radiation and a CCD-based area detector. The crystal structures were refined by full-matrix least-squares techniques on the basis of F² to agreement indices (DabcoUAs, TriethUAs, PiperUP) wR₂=5.6%, 8.3%, 7.2% for all data, and R₁=2.9%, 3.3%, 4.0%, calculated for 1777, 5822, 9119 unique observed reflections (|F_o|?4σ_F), respectively. DabcoUAs is monoclinic, space group C2/m, Z=2, a=18.581(1), b=7.1897(4), c=7.1909(4) Å, β=102.886(1)°, V=936.43(9) Å³, D_calc=3.50 g/cm³. TriethUAs is monoclinic, space group P2₁/n, Z=4, a=9.6359(4), b=18.4678(7), c=10.0708(4) Å, β=92.282(1)°, V=1790.7(1) Å³, D_calc=3.41 g/cm³. PiperUP is monoclinic, space group Pn, Z=2, a=9.3278(4), b=15.5529(7), c=9.6474(5) Å, β=93.266(1)°, V=1397.3(1) Å³, D_calc=4.41 g/cm³. The structure of DabcoUAs contains the autunite-type sheet formed by the sharing of vertices between uranyl square bipyramids and arsenate tetrahedra. The triethylenediammonium cations are located in the interlayer along with two H₂O groups and are disordered. Both TriethUAs and PiperUP contain sheets formed of uranyl pentagonal bipyramids and tetrahedra (arsenate and phosphate, respectively) with the uranophane sheet-anion topology. In TriethUAs, triethlyammonium cations are located in the interlayer. In PiperUP, the sheets are connected by a uranyl pentagonal bipyramid that shares corners with phosphate tetrahedra of adjacent sheets, resulting in a framework with piperazinium cations and H₂O groups in the cavities of the structure.     

Versicolactones A and B: total synthesis and structure revision

To further determine absolute configurations of versicolactones A and B, total synthesis of versicolactones A and B and their six stereoisomers were reported in this Letter. The ¹H and ¹³C NMR spectra of the synthetic erythro-stereoisomers matched perfectly with those of the natural products. Combined with the comparison of the specific rotations, the absolute configuration of versicolactones A and B were revised as (4Z,6R,7S)- and (4E,6R,7S)- from the corresponding (4Z,6R,7R)- and (4E,6R,7R)-6,7-dihydroxyocta-2,4-dien-4-lactone, respectively.     

Antioxidant activity and phenolic compounds of buckwheat and barley by the data of spectrophotometry and HPLC

The antioxidant activity of buckwheat and barley extracts by reaction with 1,1-diphenyl-2-picrylhydrazyl and the total of phenolic compounds have been determined using the Folin-Ciocalteu reagent. It has been found that water-ethanol extracts of buckwheat are characterized by higher antioxidant activity (6.2 ± 0.5 μM-eq. of Trolox/g) and concentration of phenolic compounds (4.41 ± 0.07 mg-eq. of rutin/g) compared to barley extracts (4.2 ± 0.3 μM-eq. of Trolox/g and 2.4 ± 0.1 mg-eq. of rutin/g, respectively). A series of phenolic compounds have been identified by HPLC with UV detection and mass spectrometric detection with electrospray ionization. The main phenolic compounds-antioxidants in buckwheat extracts are rutin, catechin and epicatechin, 1-O-caffeoyl-O-rutinoside (m/z 487), and epicatechin-O-3,4-dimethylgallate (m/z 469), and in the barley extract, catechin, prodelphinidin B3 (m/z 593), procyanidin B3 (m/z 577), and procyanidin C2 (m/z 865).     

Chemical Composition and Antifungal Activity of Myrcia multiflora and Eugenia florida Essential Oils

The essential oils of three specimens of Myrcia multiflora (A, B and C) and Eugenia florida were extracted by hydrodistillation, and the chemical compositions from the essential oils were identified by gas chromatography and flame ionization detection (CG/MS and CG-FID). The fungicide potential of the EOs against five fungicide yeasts was assessed: Candida albicans INCQS-40175, C. tropicalis ATCC 6258, C. famata ATCC 62894, C. krusei ATCC 13803 and C. auris IEC-01. The essential oil of the specimen Myrcia multiflora (A) was characterized by the major compounds: α-bulnesene (26.79%), pogostol (21.27%) and δ-amorphene (6.76%). The essential oil of the specimen M. multiflora (B) was rich in (E)-nerolidol (44.4%), (E)-γ-bisabolene (10.64%) and (E,E)-α-farnesene (8.19%), while (E)-nerolidol (92.21%) was the majority of the specimen M. multiflora (C). The sesquiterpenes seline-3,11-dien-6-α-ol (12.93%), eremoligenol (11%) and γ-elemene (10.70%) characterized the chemical profile of the EOs of E. florida. The fungal species were sensitive to the essential oil of M. multiflora (B) (9–11 mm), and the lowest inhibitory concentration (0.07%) was observed in the essential oil of M. multiflora (A) against the yeasts of C. famata. Fungicidal action was observed in the essential oils of M. multiflora (A) against C. famata, with an MIC of 0.78 µL/mL and 3.12 µL/mL; C. albicans, with an MFC of 50 µL/mL and M. multiflora (C) against C. albicans; and C. krusei, with a MFC of 50 µL/mL.     

Synthesis and thermal study of polyamides and polyaspartimides

Copolymers were synthesized by polyaddition reactions of aromatic diamine (4,4′-sulphonyl dianiline) and aliphatic diamines (1,2-diaminoethane and 1,3-diaminopropane) with N,N′-arylenebismaleimides (N,N′-m-phenylene-N,N′-p-phenylene-, and N,N′-benzidine-). They were characterized by elemental analysis, i.r. spectra and viscosity. The thermal behaviour of copolymers was studied using Thermogravimetric Analysis (TGA). All the copolymers are stable up to 270°. Polyamides are less stable than polyaspartimides.     

Conformations and steric and stacking interactions of trisubstituted ureas and thioureas with alkyl and phenyl groups

The monomeric ν(N—H) vibrations of various trisubstituted ureas of the R₂UPh type and -thioureas of the R₂TUPh type have been studied. The trans—out isomerism in the former and the trans—out—cis isomerism in the latter are discussed from the point of view of steric effect. The monomeric ν(N—H) vibrations of RPhUPh and RPhTUPh are also examined. The single band appearing in the spectrum of both ureas is characteristic of the cis form; this suggests the existence of phenyl—phenyl interaction (the stacking interaction proposed by Galabov et al. [10]). Behavior of ν(N—H) vibrations at several concentrations is shown to be clearly different in the three forms (trans, out and cis). The presence of the cis form is confirmed by solvent effect experiments.     

Synthesis and odor of optically active trans-2,2,6-trimethylcyclohexyl methyl ketones and their related compounds

The synthesis characterized by cationic olefin cyclizations accomplished using ketone enol esters and odor of novel (1R,6S)- and (1S,6R)-2,2,6-trimethylcyclohexyl methyl ketones (5) are described. The stereoselective syntheses of (E)-(1R,6S)- and (E)-(1S,6R)-1-(2,2,6-trimethylcyclohexyl)-2-buten-1-one (6) and (1R,6S)-ethyl 2,2,6-trimethylcyclohexylcarboxylate (7), useful raw materials for flavor and fragrance, starting from the (1R,6S)- and (1S,6R)-5 are also described.     

Chiral derivatives of Butenafine and Terbinafine: synthesis and antifungal activity

Two series of allylamines/benzylamines have been synthesised and evaluated for their antifungal activity towards Cryptococcus neoformans. All compounds are chiral derivatives of Butenafine and Terbinafine, having additional substituents at the carbon connected to the central nitrogen atom. In both series, the antifungal activity was strongly dependent on both the steric bulk and the electronic nature of the substituents. Compared to the parent compounds (Butenafine and Terbinafine), the activity was maintained when the hydrogen was replaced with a methyl group. Lower activity was observed for ethyl, whereas introduction of -CH₂F, -CHF₂, -CF₃ or -CN substituents removed all antifungal activity. Testing of (R)- and (S)-N-(4-tert-butylbenzyl)-N-methyl-1-(naphthalen-1-yl)ethanamine against C. neoformans, Cryptococcus diffluens and Trichosporon cutaneum revealed that most of the activity resides in the (R)-enantiomer. The (R)-enantiomer performed as well as, or better (lower MIC values) than Butenafine against each test strain, suggesting that antimycotics based on this compound might be an improvement of existing Butenafine-based formulations.     

Stereochemical studies-XXXIII. Saturated heterocycles-IX: Synthesis and conformations of stereoisomeric cis- and troans-tetramethylene- and pentamethylenedihydro-1,3-oxazines

By the reaction of cis- and trans-2-aminomethylcyclohexanol (1, 2), cis- and trans-2-hydroxymethyl-cyclohexylamine (3,4) and the homologous cycloheptane derivatives (5-8) with ethyl p-chlorobenzimidate (11), cis- and trans-5,6-tetramethylene- and pentamethylene-2,3,5,6-tetrahydro-4H-1,3-oxazines (12,13,16,17) and cis- and trans-4,5-tetramethylene- and pentaimethylene-4,5-dihydro-6H-1,3-oxazines (14, 15, 18, 19) were prepared. The amidine intermediate of the ring-closure reaction was isolated, and the mechanism of the acid-catalysed reaction is discussed. It follows from the ¹H NMR data that in the preferred conformations of the cis-tetramethylene-tetrahydrooxazines the methylene group of the hetero ring is equatorial and the hetero atom (O or N) axial. In contrast, the conformation equilibria of the cis pentamethylene derivatives, in accordance with earlier X-ray analysis, are shifted towards the conformer containing the methylene group in isoclinal and the hetero atom in equatorial position. The preferred conformations 12a and 14a of the tetramethylene derivatives 12 and 14 were also determined by X-ray crystal analysis.     

Synthesis and structural study of tetrahydroindazolones

Multinuclear magnetic resonance spectroscopy allowed us to characterize four 1(2),5,6,7-tetrahydro-4H-indazol-4-one derivatives (1-4) and establish the most stable tautomer in each case. The crystal structure of 6,6-dimethyl-1(2),5,6,7-tetrahydro-4H-indazol-4-one (2) (orthorhombic space group P2(1)2(1)2(1), a=10.1243(8), b=21.526(2), c=24.992(2) Å, Z=4, 293 K) presents two different trimers, bonded through N-H?N hydrogen bonds involving tautomers 1H and 2H. In crystalline 3,6,6-trimethyl-2,5,6,7-tetrahydro-4H-indazol-4-one (4) (monoclinic space group P2(1)/c, a=5.9827(7), b=16.494(2), c=11.012(1) Å, β=93.464(2)°, Z=4, 293 K) only tautomer 2H exists forming a hydrogen-bonded network through the 4-oxo group and a water molecule.     

Synthesis and characterization of new thiazolidinones containing coumarin moieties and their antibacterial and antioxidant activities

New coumarin derivatives, namely (2-(4-methyl-2-oxo-2H-chromen-7-yloxy)-N-(4-oxo-2-phenylthiazolidin-3-yl)acetamide, N-(2-(3-methoxyphenyl)-4-oxothiazolidin-3-yl)-2-(4-methyl-2-oxo-2H-chromen-7-yloxy)acetamide, 2-(4-methyl-2-oxo-2H-chromen-7-yloxy)-N-(4-oxo-2-(2,3,4trimethoxyphenyl)thiazolidin-3-yl)acetamide and N-(2-(4-bromophenyl)-4-oxothiazolidin-3-yl)-2-(4-methyl-2-oxo-2H-chromen-7-yloxy)acetamide) were synthesized starting from 4-methyl-7-hydroxycoumarin. The structures of the obtained compounds were confirmed by analytical IR and NMR spectra to elucidate the different positions of protons and carbons and as well as theoretical studies (DFT/B3LYP). The new compounds were screened for antibacterial activity. Most of them are more active against E. coli S. aureus and B. subtilis than standard references.     

Synthesis and investigation of anti-inflammatory and anticonvulsant activities of novel coumarin-diacylated hydrazide derivatives

A number of novel coumarin derivatives synthesized by the reaction of 3-carbonyl chloride coumarin with some substituted aryl acid hydrazides to investigate their anti-inflammatory and anticonvulsant activities. Carrageenan (0.1 ml of 1%, w/v) was injected subplantarly in the right paw of rats to induce an acute model of inflammation. Anti-inflammatory efficacy was evaluated for 5 hours at 3 different dosages 5, 10, 25 mg/kg. After that, the changes in the level of paw edema volumes and percentage inhibition of all groups were observed and the most effective coumarin derivative was found as N'-(2-hyroxybenzoyl)-2-oxo-2H-chromene-3-carbohydrazide. In addition, N’-(2-oxo-2H-chromene-3-carbonyl)nicotinohydrazide, (E)-N’-(3-(4-hydroxyphenyl)acryloyl)-2-oxo-2H-chromene-3-carbohydrazide, and N’-(5-amino-2-hydroxybenzoyl)-2-oxo-2H-chromone-3-carbohydrazide showed their anti-inflammatory effects in a dose-dependent manner. On the other hand, pentylenetetrazole (PTZ, 80 mg/kg, i.p.)-induced seizure model was used to investigate the anticonvulsant activities of six newly synthesized coumarin derivatives in mice. Hybrid compound of salicylic acid hydrazide and 3-carbonyl chloride coumarin (8d) was found the most promising anticonvulsant agent among all treatment groups according to the onset of seizure and survival rate. Moreover, (E)-N'-cinnamoyl-2-oxo-2H-chromene-3-carbohyrazide (8b) and (E)-N'-(3-(4-hyroxyphenyl)acryloyl)-2-oxo-2H-chromene-3-carbohydrazide (8c) has potential anticonvulsant efficiency in low doses (30 mg/kg). The anticonvulsant effect of these coumarin derivatives may be through enhanced GABA-mediated inhibition in the brain.     

Comprehensive DFT and MO studies on glyoxilic acid oxime and related ions in gas phase and solution: Conformations,basicities and acidities

Density functional (BLYP, B3LYP and BHLYP) and highly correlated MP2 and CCSD(T) calculations have been performed to investigate conformers, energy barriers, intramolecular H-bond strength, gas-phase basicity and deprotonation energies of glyoxilic acid oxime (gao) and related ions in gas phase and in aqueous solution (SCRF-PCM method). BHLYP/6-311G(d,p) and B3LYP/6-31++G(d) predictions for the global minimum conformer of gao were consistent with experiment. BLYP level overestimated the H-bond and stabilized incorrectly the H-bonded conformer. The calculations in solution indicated destabilization of H-bonded conformers due to the small polarizability and weaken of the H-bond. The same global minimum structures in gas phase and aqueous solution were found for gao-neutral (ectt) and gao-dianion (e⁻²), whereas they were different for gao-anion because of the strong decrease of the conformational energies in solution. The global minimum structures of the neutral, anion and dianion of gao, obtained in solution, are in agreement with experiment. The gas-phase basicity (GB) and molecular electrostatic potential (MEP) calculations revealed the same sites for electrophilic attack, supported by the nature of HOMO: the carbonylic oxygen for the neutral, the carboxylic oxygen for the anion and the oxime nitrogen for the dianion. MEP results in gas phase and in solution suggested a region between the two atoms, but not on one atom in accordance with bidentate binding of gao ions to a metal. The BHLYP/6-31++G(d,p) molecular properties of gao were in best consistent with CCSD(T) results. The thermodynamical properties (GB and bond deprotonation energy) of gao were better estimated at B3LYP level.     

Relative cross-sections of charge transfer and ionization processes between multiply-charged ions and He at low and intermediate energies

The relative cross-sections of double (DI) to single ionization (SI) σ_DI/σ_SI, transfer ionization (TI) to single capture (SC) σ_TI/σ_SC and double capture (DC) to single capture σ_DC/σ_SC of helium by multiply-charged ions A^q+ (q = 2–5) at low and intermediate energies are calculated by considering the distribution of target electron and the interaction time between the projectile and the target electron. The calculated results are compared with published experimental data by our group and others.     

Synthesis and conformational and configurational studies of diastereoisomeric O-protected 4-(arylsulfonimidoyl)butane-1,2,3-triols

Chiral sulfoximines have applications as transition-state mimicking enzyme inhibitors, as peptide isosteres and as chiral auxiliaries in synthesis. To access the required O-protected 4-(arylsulfonimidoyl)butane-1,2,3-triols, 4S,5S-di(hydroxymethyl)-2,2-dimethyl-1,3-dioxolane (prepared from diethyl R,R-tartrate) was converted into its monobenzyl ether. Mitsunobu-like coupling with thiophenols gave 4S,5R-4-(benzyloxymethyl)-2,2-dimethyl-5-(arylthiomethyl)-1,3-dioxolanes. Sulfoxidation and S-imination (trifluoroacetamide, iodosobenzene diacetate, rhodium acetate) proceeded without stereoselectivity, giving inseparable diastereomeric mixtures of 4S,5R,S(±)-4-(benzyloxymethyl)-2,2-dimethyl-5-(N-(trifluoroacetyl)arylsulfonimidoylmethyl)-1,3-dioxolanes. Removal of the trifluoroacetyl protection allowed chromatographic separation of the diastereomeric 4S,5R,S(±)-4-(benzyloxymethyl)-2,2-dimethyl-5-(arylsulfonimidoylmethyl)-1,3-dioxolanes. The configurations at sulfur were determined by X-ray crystallography and some analysis of the solution and solid-state conformations was carried out. The resulting O-protected 4-(arylsulfonimidoyl)butane-1,2,3-triols are of use in developing enzyme inhibitors.     

Positional Order and Disorder of Symmetric and Unsymmetric BEDT-STF Salts

The symmetric (s-) and unsymmetric (us-) BEDT-STF (=bis(ethylenedithio)diselenadithia-fulvalene) salts were prepared, and their crystal structures and electrical resistivities were investigated. Four us-BEDT-STF salts have the positional disorder of the Se atoms in the STF framework in crystals, whereas three s-BEDT-STF salts have no disorder. When κ-(us-BEDT-STF)₂GaCl₄ and κ-(cis-s-BEDT-STF)₂GaCl₄ are compared, the latter without the positional disorder of the Se atoms is more conductive than the former one with the disorder.     

The preparation and crystal structures of dicarbonylcyclopentadienylnitrosylchromium and dicarbonylfluorenylnitrosylchromium

The X-ray-crystal structures of both (η⁵-C₅H₅)Cr(CO)₂(NO) (I) and (η⁵-C₁₃H₉)Cr(CO)₂(NO) (II, η⁵-C₁₃H₉ = η⁵-9H-fluorenyl) are described. I crystallizes in the monoclinic space group P2₁/n with lattice constants a 10.998(4), b 7.066(3), c 11.940(4) Å, β 116.37(4)°, and ?_calc 1.63 g cm^?3 for Z = 4. II belongs to the orthorhombic space group Pnma with a 6.463(4), b 15.512(6), c 12.916(6) Å, and ?_calc 1.55 g cm^?3 for Z = 4. Least-squares refinement gave final conventional R values of 0.037 based on 1081 independent observed reflections for I, and 0.042 with 630 reflections for II. The carbonyl and nitrosyl groups are disordered in I, but the nitrosyl ligand in II occupies a position “trans” to the electron-rich C(9) of the fluorenyl system. Photolysis of II in liquid olefins (L) or acetyleness leads to substituted derivatives of the type (η⁵-C₁₃H₉)Cr(CO)(NO)L (L = cyclooctene, cycloocta-1,5-diene, norbornene, norbornadiene, phenylacetylene).     

Synthesis and characterization of chiral mono N-heterocyclic carbene-substituted rhodium complexes and their catalytic properties in hydrosilylation reactions

Different chiral mono-substituted N-heterocyclic carbene complexes of rhodium were prepared, starting from [Rh(COD)Cl]₂ (COD = cyclooctadiene) by addition of free N-heterocyclic carbenes (NHC), or an in-situ deprotonation of the corresponding iminium salt. All new complexes were characterized by spectroscopy methods. In addition, the structures of chloro(η⁴-1,5-cyclooctadiene)(1,3-di-[(1R,2R,3R,5S)-2,6,6-trimethylbicyclo[3.1.1]hept-3-yl] imidazolin-2-ylidene)rhodium(I) (5a), chloro(η⁴-1,5-cyclooctadiene)(1,3-di-[(1R,2S,5R)-2-isopropyl-5-menthylcyclohex-1-yl]imidazol-2-ylidene)rhodium(I) (5b) and chloro(η⁴-1,5-cyclooctadiene)(1,3-di-[(2R,4S,5S)-2-methyl-4-phenyl-1,3-dioxacyclohex-5-yl]imidazolin-2-ylidene)rhodium(I) (5i) were analyzed by DFT-calculations. The enantioselective hydrosilylation of acetophenone, ethylpyruvate and n-propylpyruvate with diphenylsilane and hydrolysis was carried out with chiral C₂-symmetrical mono-substituted N-heterocyclic carbene rhodium complexes giving for the first time an enantioselective excess of up to 74% ee in the case of the n-propylpyruvate.     

A P,N ligand with central and axial chiral elements: synthesis and application in allylic alkylation

Two epimers of 4-({5-[(diphenylphosphino)methyl]-2,2-dimethyl-1,3-dioxolan-4-yl}methyl)-4,5-dihydro-3H-dinaphtho[1,2-e:2′,1′-c]azepine were prepared starting from (2S,3S)-4-amino-2,3-O-isopropylidenebutane-1,2,3-triol and (R)- and (S)-binaphthol. These ligands, in association with Pd(0) gave enantioselectivities up to 89% (S) and 36% (R) ee for the (S_A,4S,5R) and the (R_A,4S,5R) ligands in the alkylation of racemic 1,3-diphenylprop-2-enyl acetate with dimethyl malonate, showing that the binaphthyl moiety is the most important structure in the enantioselective creation of the new stereogenic center.     

Microwave spectra and stable conformations of exo- and endo-norborneols

The microwave spectra of exo- and endo-norborneols and their isotopic species deuterated in the hydroxyl group have been investigated over the frequency range 8–40 GHz. Conventional Stark spectroscopy and microwave—microwave double resonance were used to assign Q and R-branch rotational transitions. From the measured transition frequencies the rotational constants A = 3605.9374(9) MHz, B = 1935.4207(8) MHz and C = 1752.3947(8) MHz have been fitted for exo-norborneol and A = 3151.4865(15) MHz, B = 2095.2483(24) MHz and C = 1914.7057(25) MHz for endo-norborneol. Quantitative measurements of the Stark splittings of selected transitions yielded the dipole components μ_a = 0.53(9) D, μ_b = 1.22(6) D and μ_c = 0.294(4) D and the total dipole moment μ = 1.36(9) D of exo-norborneol. The spectroscopic constants of the deuterated species -were used to deduce the orientation of the hydroxyl group of the only conformer found for each isomer of norborneol.