CuO metallic aerogels with a tailored nodular morphology.

This work reports, for the first time, an efficient and fast microwave-based method for the preparation of CuO aerogels. For that, CuCl2, glyoxylic acid and sodium carbonate are employed as reagents. Different experimental conditions such as synthesis temperature, synthesis time and concentration of the precursor solution are investigated to design CuO aerogels with customizable nodular morphologies. The resulting aerogels exhibit well-defined three-dimensional structures and nodular sizes, and therefore, textural properties vary according to the experimental parameters applied in their synthesis.

(Na, Zr) and (Ca, Zr) Phosphate-Molybdates and Phosphate-Tungstates: I-Synthesis, Sintering and Characterization.

Submicron-grade powders of Na1-xZr2(PO4)3-x(XO4)x compounds (hereafter referred to as NZP) and Ca1-xZr2(PO4)3-x(XO4)x compounds (hereafter, CZP), X = Mo, W (0 ≤ x ≤ 0.5) were obtained by sol-gel synthesis. The compounds obtained were studied by X-ray diffraction phase analysis and electron microscopy. An increase in the W or Mo contents was shown to result in an increase in the unit cell volume of the NZP and CZP crystal lattices and in a decrease in the coherent scattering region sizes. Thermal expansion behavior at high temperatures of synthesized NZP and CZP compounds has been investigated. The dependencies of the parameters a and c on the heating temperature, as well as the temperature dependence of the crystal lattice unit cell volume V in the range from the room temperature up to 800 °C, were obtained. The dependencies of the average thermal expansion coefficient (αav) and of the volume coefficient (ß) on the W and Mo contents in the compositions of NZP and CZP compounds were studied. Ceramics Na1-xZr2(PO4)3-x(XO4)x with relatively high density (more than 97.5%) were produced by spark plasma sintering (SPS). The increase in the W or Mo contents in the ceramics leads to an increase in the relative density of NZP and to a decrease of the optimum sintering temperature. The mean grain size in the NZP ceramics decreases with increasing W or Mo contents. The study of strength characteristics has revealed that the hardness of the NZP ceramics is greater than 5 GPa, and that the minimum fracture toughness factor was 1 MPa·m1/2.

Sonochemical synthesis, characterization, and effects of temperature, power ultrasound and reaction time on the morphological properties of two new nanostructured mercury(II) coordination supramolecule compounds.

Two new mercury(II) coordination supramolecular compounds (CSCs) (1D and 0D), [Hg(L)(I)2]n (1) and [Hg2(L')2(SCN)2]·2H2O (2) (L=2-amino-4-methylpyridine and L'=2,6-pyridinedicarboxlic acid), have been synthesized under different experimental conditions. Micrometric crystals (bulk) or nano-sized materials have been obtained depending on using the branch tube method or sonochemical irradiation. All materials have been characterized by field emission scanning electron microscope (FESEM), scanning electron microscopy (SEM), powder X-ray diffraction (PXRD) and FT-IR spectroscopy. Single crystal X-ray analyses on compounds 1 and 2 show that Hg2+ ions are 4-coordinated and 5-coordinated, respectively. Topological analysis shows that the compound 1 and 2 have 2C1, sql net. The thermal stability of compounds 1 and 2 in bulk and nano-size has been studied by thermal gravimetric (TG), differential thermal analyses (DTA) for 1 and differential scanning calorimetry (DSC) for 2, respectively. Also, by changing counter ions were obtained various structures 1 and 2 (1D and 0D, respectively). The role of different parameters like power of ultrasound irradiation, reaction time and temperature on the growth and morphology of the nano-structures are studied. Results suggest that increasing power ultrasound irradiation and temperature together with reducing reaction time and concentration of initial reagents leads to a decrease in particle size.

Influences of temperature, power ultrasound and reaction time on the morphological properties of two new mercury(II) coordination supramolecular compounds.

Nanoparticles of two new coordination compounds, [Hg2(L)2(Br)4]n (1) and [Hg(L')(SCN)2] (2), (L=2-amino-4-methylpyridine, L'=2,6-pyridinedicarboxlic acid), have been synthesized by use of a sonochemical process and characterized by scanning electron microscopy (SEM), field emission scanning electron microscopy(FESEM), X-ray powder diffraction (XRPD), Fourier transform infrared spectroscopy (FTIR) spectroscopy and elemental analyses. The single crystal X-ray data of compounds 1 and 2 imply that the Hg(II) ions are four and five coordinated, respectively. Topological analysis shows that 1D and 0D coordination networks of 1 and 2 can be classified as underlying nets of topological types 2C1 and 1,3M4-1, respectively. The thermal stability of compounds has been studied by thermal gravimetric (TG) and differential thermal analyses (DTA). The role of temperature, reaction time and ultrasound irradiation power on the size and morphology of "nano-structures" 1 and 2, has been investigated. Results claim that an increase of temperature, sonication power and decrease in reaction time leads to a decrease of particle size.

Conformational analysis, X-ray crystallographic, FT-IR, FT-Raman, DFT, MEP and molecular docking studies on 1-(1-(3-methoxyphenyl) ethylidene) thiosemicarbazide.

Conformational analysis, X-ray crystallographic, FT-IR, FT-Raman, DFT, MEP and molecular docking studies on 1-(1-(3-methoxyphenyl) ethylidene) thiosemicarbazide (MPET) are investigated. From conformational analysis the examination of the positions of a molecule taken and the energy changes is observed. The docking studies of the ligand MPET with target protein showed that this is a good molecule which docks well with target related to HMG-CoA. Hence MPET can be considered for developing into a potent anti-cholesterol drug. MEP assists in optimization of electrostatic interactions between the protein and the ligand. The MEP surface displays the molecular shape, size and electrostatic potential values. The optimized geometry of the compound was calculated from the DFT-B3LYP gradient calculations employing 6-31G (d, p) basis set and calculated vibrational frequencies are evaluated via comparison with experimental values.

Crystallographic, experimental (FT-IR and FT-RS) and theoretical (DFT) investigation, UV-Vis, MEP, HOMO-LUMO and NBO/NLMO of (E)-1-[1-(4-Chlorophenyl)ethylidene]thiosemicarbazide.

Crystallographic, experimental (FT-IR and FT-RS) and theoretical density function theory (DFT) and UV-Vis spectra of (E)-1-[1-(4-Chlorophenyl)ethylidene]thiosemicarbazide) (ECET) are investigated. The optimized geometry of the compound was calculated from the DFT-B3LYP gradient calculations employing 6-31G (d,p) basis set and calculated vibrational frequencies are evaluated via comparison with experimental values. Molecular stability has been analyzed using Natural Bond Orbital (NBO) and Natural Localized Molecular Orbital (NLMO) analysis and the limits of the molecular electrostatic potential observed. The calculated HOMO and LUMO energies show the charge transfer occurs within the molecule.

Structures of relevant ammonium salts in fertilizers.

The crystal structures of two double salts of ammonium nitrate (AN) and ammonium sulfate (AS) are reported. The double salts 2NH(4)NO(3).(NH(4))(2)SO(4) (2AN.AS) and 3NH(4)NO(3).(NH(4))(2)SO(4) (3AN.AS) show a very similar crystal structure packing with alternating layers of anions and cations. The solid-state ionic distribution is controlled by an extensive hydrogen-bonding network with ammonium groups as the donors and O atoms acting as the acceptors. Crystallographic studies were conducted at both room temperature (293 K) and 100 K. Increasing the temperature involves shortening the b axis in the case of the 3AN.AS salt. Quantification of fertilizer mixtures using the Rietveld method was also carried out by means of the structural models reported in this paper for both salts.

Antibacterial studies, DNA oxidative cleavage, and crystal structures of Cu(II) and Co(II) complexes with two quinolone family members, ciprofloxacin and enoxacin.

Nine coordination compounds of Cu(II) and Co(II) with Ciprofloxacin (HCp) and Enoxacin (HEx) as ligands have been prepared and characterized. Single crystal structural determinations of [Cu(HCp)2(ClO4)2].6H2O (1) and [Co(HEx)2(Ex)]Cl.2CH(3)OH.12H2O (4) are reported. The crystal of 1 is composed of [Cu(HCp)2(ClO4)2] units with the two perchlorate anions semicoordinated, and uncoordinated water molecules. The copper ion, at a crystallographic inversion centre, is in a tetragonally distorted octahedral environment. The structure of 4 consists of cationic monomeric [Co(HEx)2(Ex)]+ units, chloride anions, and uncoordinated methanol and water molecules. The complex is six-coordinate, with a slightly distorted octahedral environment around the metal centre. Some complexes of ciprofloxacin and enoxacin were screened for their activity against several bacteria, showing activity similar to that of the corresponding free ligands. All compounds tested were more active against Gram-negative bacteria than against Gram-positive bacteria. Ciprofloxacin hydrochloride and its complexes were more active than enoxacin and its complexes. In addition, the bactericidal studies against Staphylococcus aureus ATCC 25923 reveal that one complex exhibits the "paradoxical effect" (diminution in the number of bacteria killed at high drug concentration), which has been described and related to the mechanism of action of quinolones, but three other complexes do not, suggesting different mechanisms of bactericidal action. The ability of Cu(HCp)2(NO3)2.6H2O to cleave DNA has been determined. The results show that the complex behaves as an efficient chemical nuclease with ascorbate/hydrogen peroxide activation. Mechanistic studies using different inhibiting reagents reveal that hydroxyl radicals are involved in the DNA scission process mediated by this compound.

Rhodium(I) and Rhodium(III) complexes containing the chiral ligand 2,6-bis[4'(S)-isopropyloxazolin-2'-yl]pyridine (pybox): an unprecedented monohapto coordination of pybox.

The complex [Rh(kappa(3)-N,N,N-pybox)(CO)][PF(6)] (1) has been prepared by reaction of the precursor [Rh(mu-Cl)(eta(2)-C(2)H(4))(2)](2), 2,6-bis[4'(S)-isopropyloxazolin-2'-yl]pyridine (pybox), CO, and NaPF(6). Complex 1 reacts with monodentate phosphines to give the complexes [Rh(kappa(1)-N-pybox)(CO)(PR(3))(2)][PF(6)] (R(3) = MePh(2) (2), Me(2)Ph (3), (C(3)H(5))Ph(2) (4)), which show a previously unseen monodentate coordination of pybox. Complex 1 undergoes oxidative addition reactions with iodine and CH(3)I leading to the complexes [RhI(R)(kappa(3)-N,N,N-pybox)(CO)][PF(6)] (R = I (5); R = CH(3) (6)). Furthermore, a new allenyl Rh(III)-pybox complex of formula [Rh(CH=C=CH(2))Cl(2)(kappa(3)-N,N,N-pybox)] (7) has been synthesized by a one-pot reaction from [Rh(mu-Cl)(eta(2)-C(2)H(4))(2)](2), pybox, and an equimolar amount of propargyl chloride.

Interactions of metal ions with two quinolone antimicrobial agents (cinoxacin and ciprofloxacin). Spectroscopic and X-ray structural characterization. Antibacterial studies.

Several novel metal-quinolone compounds have been synthesized and characterized by analytical, spectroscopic and X-ray diffraction methods. The crystal structure of the four compounds, Na(2)[(Cd(Cx)3)(Cd(Cx)3(H2O))].12H2O, [Co(Cp)2(H2O)2].9H2O, [Zn(Cp)2(H2O)2].8H2O and [Cd(HCp)2(Cl)2].4H2O, is presented and discussed: HCx=1-ethyl-1,4-dihydro-4-oxo(1,3)-dioxolo(4,5-g)cinnoline-3-carboxylic acid and HCp=1-cyclopropyl-6-fluoro-1,4-dihydro-4-oxo-7-(1-piperazinyl)-3-quinoline carboxylic acid. In all these compounds the quinolone acts as a bidentate chelate ligand that binds through one carboxylate oxygen atom and the exocyclic carbonyl oxygen atom. Complexes of ciprofloxacin were screened for their activity against several bacteria, showing activity similar to that of the ligand. In addition, the number of bacteria killed after 3 h of incubation with the ligand, [Co(Cp)2(H2O)2].9H2O, Ni(Cp)2.10H2O and Cu(Cp)2.6H2O, was determined against S. aureus ATCC25923. There is a direct relationship between the growth rate and the lethal rate. Against growing bacteria, the ligand is the most bactericidal and Cu(Cp)2.6H2O is the less bactericidal. On the contrary, against non-dividing bacteria, the complexes were more bactericidal than the ligand, with Cu(Cp)(2).6H(2)O the most bactericidal compound.

Total synthesis of (+)-ampullicin and (+)-isoampullicin: two fungal metabolites with growth regulatory activity isolated from Ampulliferina sp. 27.

The total synthesis of the growth regulators (+)-ampullicin 1 and (+)-isoampullicin 2 from (R)-(-)-carvone 5 was accomplished by application of an 18-step sequence with 4.5% overall yield. The crucial step of the synthetic strategy lies on the internal displacement of tosylate 13 by means of the lactone enolate. In this way, access was opened to the tricyclic core present in these biologically active sesquiterpenic amides. A Horner-Emmons reaction between the carbaldehyde 16 and the phosphonate 22 led us to the stereoselective preparation of (+)-ampullicin 1. Standard transformation of 1 into the thermodynamically more stable geometric isomer (+)-isoampullicin 2 was trivial. The absolute configuration of both amides was established by X-ray analysis of a sample of synthetic (+)-isoampullicin 2.

New approach to the chemistry of polysulfides using diphosphanylmethanide complexes of manganese(I).

The study of the nucleophilic degradation of S8 by the methanide complex [Mn(CO)4[(PPh2)2CH]] (2) has led to the preparation of a unique class of polysulfide derivatives of formula [(CO)4Mn[(PPh2)2C-Sn-C(PPh2)2]-Mn(CO)4]. The structures of 3 (n = 6), 4 (n = 2), and 7 (n = 1) have been determined by X-ray crystallography, whereas those polysulfides with the sulfur chains S7, S5, S4, and S3 have been detected by spectroscopic methods. The polysulfides with n > 2 lose sulfur spontaneously, a process that can be accelerated by treatment with PPh3 or Na/Hg. Complexes 3, 4, and 7 were protonated at the two methanide carbon atoms to give the cationic dinuclear derivatives [(CO)4Mn[(PPh2)2C(H)-Sn-C(H)-(PPh2)2]Mn(CO)4]2+ (8, n=6; 9, n=2; 10, n = 1). The 1H NMR spectrum of 9 suggests the existence of intramolecular C-H...S interactions, in agreement with the X-ray structural determination of this complex. By treatment of 4 and 7 with one equivalent of HBF4 it is possible to selectively protonate just one methanide carbon atom, which allows the isolation of the mixed cationic derivatives R(CO)4Mn[(PPh2)2C(H)-Sn-C(PPh2)2]Mn(CO)4]+ (11, n = 2; 6, n = 1). Additionally, heterometallic complexes containing a bridging disulfide unit, of general formula [(CO)4Mn[(PPh2)2C(AuPPh3)S-SC-(AuPPh3)(PPh2)2]Mn(CO)4]2+ (12) and [(CO)4Mn[(PPh2)2C(H)S-SC(AuPPh3)-(PPh2)2]Mn(CO)4]+ (13), were prepared by reaction of 4 and 11, respectively, with [AuCl(PPh3)] in the presence of TlPF6.

Diastereo- and enantioselective cyclopropanation with chromium fischer carbene complexes: alkenyl oxazolines as useful achiral and chiral substrates.

The cyclopropanation reaction of chromium Fischer carbene complexes with alkenyl oxazolines has been studied in both racemic and enantioselective fashions. The oxazolinyl group acts as both electron-acceptor substituent and chiral auxiliary. Achiral (4,4-dimethyloxazolin-2-yl)alkenes derived from trans-crotonic and trans-cinnamic acids 2a,b undergo the cyclopropanation reaction to give 4a-d,g with excellent diastereoselectivity (trans/cis ratio between 93:7 and >97:3), while those derived from acrylic and metacrylic acids 2c,d give the cyclopropanes 4e,f,h with much lower selectivity (trans/cis ratio between 68:32 and 83:17). The homogeneous catalytic hydrogenolysis of 4 leads in a selective manner to 5 or 6, depending on the nature of the R3 substituent. The removal of the oxazoline moiety is achieved by carboxybenzylation/hydrolysis and ester reduction, yielding monoprotected 1,4- and 1,3-diols 9 and 11, respectively. The alkenes derived from enantiopure (S)-valinol and (S)-tert-leucinol 3 led to cyclopropanes trans-12 with high relative and absolute stereocontrol. Using tert-leucinol as the auxiliary permits attaining total facial stereoselectivity (>98% ee). Reductive cleavage of the cyclopropane ring and removal of the auxiliary afford the enriched alcohols (3S,4S)-9 and (S)-11. The stereochemical outcome of the cyclopropanation reaction is rationalized by a trans approach of the s-cis conformer of the alkenyl oxazoline to the carbene complex involving the less hindered face of the oxazoline auxiliary and the re-face of the carbene complex.

Novel silicate anion: Si(8)O(22)(12-). Hydrothermal synthesis and X-ray powder structure of three new niobium silicates.

A sodium niobium(V) tetrasilicate, Na(2)H(NbO)Si(4)O(11).1.25H(2)O (1), was synthesized hydrothermally at 190 degrees C from a mixture of silicic acid, NaOH, NbCl(5), and H(2)O(2) and added hydrochloric acid. The successive treatment of 1 with nitric acid yielded HNb(H(2)O)Si(4)O(11).H(2)O (2). Contact of 2 with cesium hydroxide solutions converted it to the partially exchanged Cs(+) phase Cs(0.66)H(0.33)Nb(H(2)O)Si(4)O(11) (3). The three structures were solved from X-ray powder diffraction data. All compounds crystallize in the monoclinic space group P2(1)/m with Z = 2, containing the Si(8)O(22)(12-) anion. This new silicate anion type is related to the Si(4)O(11)(6-) unit, which is present in the amphibole series. The difference between both anion types lies in the chain periodicity: two for amphiboles or four for the new niobium silicates. These niobium silicates have framework structures enclosing tunnels in which the alkali cations reside.

Formation of cyclopentadienyl and ruthenacyclopentadienyl derivatives through ynenyl-diyne and ynenyl-alkyne couplings onto a triruthenium cluster core.

The compound [Ru3(mu-H)(mu3-eta2-ampy)(CO)9] (1; Hampy =2-amino-6-methylpyridine) reacts with diynes RC4R in THF at reflux temperature to give the ynenyl derivatives [Ru3(mu3-eta2-ampy)(mu-eta3-RC...CC-CHR)(mu-CO)2-(CO)6] (2: R=CH2OPh; 3: R=Ph). These products contain a 1,4-disubstituted butynen-3-yl ligand attached to two ruthenium atoms. The compound [Ru3(mu-eta2-ampy)[mu3-eta6-PhCC5(C...CPh)-HPh2](CO)7] (4), which contains an eta5-cyclopentadienyl ring and a bridging carbene fragment, has also been obtained from the reaction of 1 with diphenylbutadiyne. This compound arises from a remarkable [3+2] cycloaddition reaction of a preformed 1,4-diphenylbutynen-4-yl ligand with a triple bond of a second diphenylbutadiyne molecule. The reactivity of the ynenyl derivatives 2 and 3 with diynes and alkynes has been studied. In all cases, compounds of the general formula [Ru3(mu-eta2-ampy)[mu3-eta5-C(=CHR)C=CRCR1=CR2](CO)7] (5-17) have been obtained. They all contain a ruthenacyclopentadienyl fragment formed by coupling of the coordinated ynenyl ligand of 2 (R = CH2OPh) or 3 (R = Ph) with a triple bond of the new reagent (the CR1=CR2 fragment results from the incoming diyne or alkyne reagent). While most of the products derived from 2 have the alkenyl C=CHR fragment with a Z configuration (R cis to Ru), all the compounds obtained from 3 have this fragment with an E configuration. Except 2 and 3, all the cluster complexes described in this article have a five-electron donor ampy ligand attached to only two metal atoms, a coordination mode unprecedented in cluster chemistry.

The first synthesis of enantiopure alpha-amino ketimines and amino aziridines.

Chiral 1-aminoalkyl chloromethyl ketimines 2 are synthesized in enantiomerically pure form starting from 1-aminoalkyl chloromethyl ketones 1 and different amines. Reduction of amino ketimines 2 and subsequent spontaneous cyclization affords aminoalkyl aziridines 3 with high diastereoisomeric excess and without detectable racemization.

A new vector-search rotation function: image-seeking functions revisited in macromolecular crystallography.

A new rotation function in Patterson space is described. An image-seeking function can be defined as a criterion of fit between the observed Patterson map and a suitable vector set extracted from a specially calculated Patterson map of the search model. The behaviour of image-seeking functions has appeared to be heavily dependent on certain relations between some statistical parameters of both maps. A new algorithm, which carries out the crucial step of selecting the appropriate vector set from the search model, has been established. As a consequence of the combination of these two preceding results, a new vector-search rotation function has been proposed and tested.