RESUMEN
Zinc borates are very important industrial materials with applications that include fire retardants and preservatives in wood. In this work, we report the preparation of three novel zinc borates: [Zn(NH3)3B4O5(OH)4]·H2O (ZB1), Zn3(H2B3O7)2·2NH3·4H2O (ZB2), and [Zn(NH3)4][B4O5(OH)4]·4H2O (ZB3). The solid phases were characterized by elemental analysis, X-ray diffraction, infrared and Raman spectroscopy, scanning electron microscopy and thermal analysis. The crystal structures of ZB1 (monoclinic, Cc, a = 12.1972(8), b = 7.8314(5), c = 12.1441(8) Å and ß = 107.404(5)°) and ZB3 (orthorhombic, Pbca, a = 15.0796(9), b = 11.8853(5) and c = 16.7606(8) Å) were determined. They are novel neutral Zn-polyborate complexes [Zn(NH3)3B4O5(OH)4] hydrate and [Zn(NH3)4][B4O5(OH)4] tetrahydrate salt, respectively. The complete assignment of infrared and Raman spectra was performed theoretically using DFT calculations. For ZB2 (obtained as a polycrystalline phase), powder X-ray diffraction confirmed a single phase and allowed the determination of the unit cell parameters and lattice type (rhombohedral, a = 36.78076 (6), c = 12.20052 (3) Å) with an expected formula Zn3(H2B3O7)2·2NH3·4H2O suggesting that this compound is a complex triborate. Furthermore, a low-cost scalable synthetic procedure for ZB1 starting from zinc oxide and boric acid in ammonia solution with a high yield is also reported.
RESUMEN
AIM: We sought to determine variations in fiber organization at the molecular level using x-ray diffraction analyses on human blood vessel specimens after cryopreservation processes. MATERIALS AND METHODS: Diffractometric profiles were performed on aortic and carotid cryopreserved-thawed vessel samples (CVS) versus the same fresh vessel samples (FVS). X-ray diffraction was performed on vascular tissues from 17 cadaveric donors after informed consent. Measurements utilized a Seifert Scintag PAD-II powder diffractometer with CuK(a) radiation; lambda = 1.5418 A. Scans were evaluated in the 5 degrees to 60 degrees range in theta -2theta mode, in the 5 degrees to 60 degrees range in 2-theta, with steps 0.1 degrees and 10 seconds per step. Ten aortic and 8 carotid diffractometric profiles were analyzed, using differential planimetric surfaces measured under x-ray diffraction curve. Diffractographic profiles were analyzed according to intervals based upon the ages of the donors. An ordering profile coefficient (OPC) was obtained as the quotient between the differential planimetric surface (DPS) of FVS versus CVS vessel ordering diffraction. RESULTS: There was a decreased ordering profile according to age: older donors showed less ordering than younger ones. Clear peaks at d-spacing of 2.86 A and 2.15 A (2-theta = 31.3 degrees and 42.0 degrees , respectively) were always confirmed despite the different profiles of samples. OPC showed a higher ordering profile among the CVS than FVS: 70% aortas and 62.5% carotids. CONCLUSION: The cryopreserved-thawed procedure does not damage the fibrillar organization of vessels.
Asunto(s)
Aorta , Vasos Sanguíneos , Arterias Carótidas , Criopreservación/métodos , Adulto , Cadáver , Humanos , Masculino , Persona de Mediana Edad , Donantes de Tejidos , Difracción de Rayos XRESUMEN
Three cis nickel-dithiocyanate (SCN) complexes with different N,N'-bidentate bases have been prepared and their crystal structures determined: bis(2,2'-bipyridine-N,N')bis(-ato-N)nickel(II), [Ni(SCN)(2)(C(10)H(8)N(2))(2)], bis(1,10-phenanthroline-N,N')bis(thiocyanato-N)nickel(II), [Ni(SCN)(2)(C(12)H(8)N(2))(2)], and bis(2,9-dimethyl-1,10-phenanthroline-N,N')bis(thiocyanato-N)nickel(II) monohydrate, [Ni(SCN)(2)(C(12)H(8)N(2))(2)].H(2)O. Distortions due to ligand size are discussed.
RESUMEN
The structures and absolute stereochemistries of two chamigrene-type metabolites (spiro[5.5]undecane derivatives) isolated from the red algae Laurencia scoparia are described. One, a non-sesquiterpene named mailione (8-bromo-9-hydroxy-7,7-dimethyl-11-methylenespiro[5.5]undec-1-en-3-one), C(14)H(19)BrO(2), was detected previously in Laurencia cartilaginea, while the other, the sesquiterpene isorigidol (8-bromo-3,7,7-trimethyl-11-methylenespiro[5.5]-undec-1-ene-3,9-diol), C(15)H(23)BrO(2), is a new isomer of rigidol, first isolated from Laurencia rigida. The A rings of these spirocyclic compounds show the same carbon skeleton. However, the relative stereochemistry of the 8-Br and 9-OH substituents is different. While mailione displays the usual syn (or cis) relative stereochemistry of the bromohydroxy vicinal group, isorigidol shows an anti (or trans) arrangement. The 8-Br and 9-OH groups are both in equatorial positions in isorigidol, while the 9-OH group is axial in mailione, as in most chamigrenes. The absolute configurations of the chiral centers were determined as 6S, 8S and 9R in mailione, and 3R, 6S, 8S and 9S in isorigidol.
Asunto(s)
Alquenos/química , Rhodophyta/química , Sesquiterpenos/química , Compuestos de Espiro/química , Animales , Aplysia/química , Cristalografía por Rayos X , Modelos Moleculares , Conformación MolecularRESUMEN
Eleven sesquiterpenes (1-11) and one long chain aldehyde (12) have been isolated from the dichloromethane extract of the red alga Laurencia scoparia. Four of them are new natural products. Scopariol (1) is a new natural product with an unusual rearranged chamigrane-type structure. The other three are beta-chamigrenes: isorigidol (2), (+)-3-(Z)-bromomethylidene-10 beta-bromo-beta-chamigrene (3), and (-)-3-(E)-bromomethylidene-10 beta-bromo-beta-chamigrene (4). The in vitro activity of compounds 1-12 against the parasitant stage of Nippostrongylus brasiliensis (L4) has been studied.
Asunto(s)
Antihelmínticos/aislamiento & purificación , Nippostrongylus/efectos de los fármacos , Rhodophyta/química , Sesquiterpenos/aislamiento & purificación , Compuestos de Espiro/aislamiento & purificación , Animales , Antihelmínticos/química , Antihelmínticos/farmacología , Brasil , Cromatografía en Capa Delgada , Técnicas In Vitro , Conformación Molecular , Estructura Molecular , Resonancia Magnética Nuclear Biomolecular , Sesquiterpenos/química , Sesquiterpenos/farmacología , Espectroscopía Infrarroja por Transformada de Fourier , Compuestos de Espiro/química , Compuestos de Espiro/farmacología , Estereoisomerismo , Relación Estructura-ActividadRESUMEN
Several new 1,2,5-oxadiazole N-oxide derivatives were synthesized to be tested both as potential selective hypoxic cell cytotoxins and as DNA-binding agents. The compounds prepared included bis(1,2,5-oxadiazole N-oxide) derivatives and oxadiazole rings linked to naphthyl residues. The compounds were tested for their cytotoxicity in oxia and hypoxia and they proved to be non-selective and less active than the parent compounds 3-formyl-4-phenyl-1,2,5-oxadiazole N2-oxide (3) and 3-chloromethyl-4-phenyl-1,2,5-oxadiazole N2-oxide (4). The DNA-affinity assays showed that the compounds tested have poor affinity for this biomolecule.
Asunto(s)
Hipoxia de la Célula/fisiología , Supervivencia Celular/efectos de los fármacos , Citotoxinas/síntesis química , ADN/química , Oxadiazoles/síntesis química , Oxadiazoles/farmacología , Óxidos/síntesis química , Óxidos/farmacología , Aerobiosis , Animales , Hipoxia de la Célula/efectos de los fármacos , Línea Celular , Células Clonales , Citotoxinas/química , Citotoxinas/farmacología , Modelos Moleculares , Conformación Molecular , Estructura Molecular , Oxadiazoles/química , Óxidos/química , Relación Estructura-ActividadRESUMEN
The title macrocycle, C(31)H(30)O(5), is comprised of two bibenzyl ether moieties linked cyclically by spacers which each consist of two-carbon alkyl chains. The observed conformation of the macrocycle may be partly stabilized by intramolecular C-H.O close contacts. The packing appears to be directed by van der Waals forces. This work explains the occurrence of a signal found in the (1)H NMR spectra of both marchantinquinone and marchantin M trimethyl ether at delta = 5. 49 and 5.56 p.p.m., respectively. The shift in the position of the expected peak can be explained by the proximity of an H atom belonging to one of the aromatic rings to another ring in the same molecule.
RESUMEN
Trichlorooxo[1,3-propanediylbis(diphenylphosphine)-P,P ']rhenium(V), [ReCl(3)O(C(27)H(26)P(2))], crystallizes with four formula units per unit cell. The crystal structure consists of neutral complexes of [ReOCl(3)(dppp)] [dppp is 1,3-bis(diphenylphosphino)propane] packed by H.pi-ring interactions. The Re atom is octahedrally coordinated to the oxo anion, three Cl atoms and two P atoms from the dppp ligand. The six-membered ring formed by the bidentate dppp ligand and the rhenium metal centre is in a chair conformation. The title compound is an intermediate in the synthesis of bis(dppp) complexes of rhenium.
Asunto(s)
Compuestos Organometálicos/química , Cristalografía por Rayos X , Modelos Moleculares , Conformación MolecularRESUMEN
As part of an ongoing program on the chemistry and biological activity of N-oxide-containing molecules, a number of novel 1,2, 5-oxadiazole N-oxide, benzo[1,2-c]1,2,5-oxadiazole N-oxide, and quinoxaline N,N'-dioxide derivatives were synthesized and evaluated for their herbicidal activity. Many of these compounds exhibited moderate to good herbicidal pre-emergence activity against Triticum aestivum. Dose-response studies were done on the more representative compounds (12, 20, and 26). The most active compound, butylcarbamoylbenzo[1,2-c]1,2,5-oxadiazole N-oxide, 26, displayed herbicidal activity at concentrations as low as 24 g/ha.
Asunto(s)
Herbicidas/síntesis química , Óxidos/síntesis química , Relación Dosis-Respuesta a Droga , Herbicidas/farmacología , Modelos Químicos , Modelos Moleculares , Conformación Molecular , Óxidos/farmacologíaRESUMEN
The structures of two absorption furosemide prodrugs, hexanoyloxymethyl 4-chloro-N-furfuryl-5-sulfamoyl-anthranilate (C19H23CIN2O7S), (I), and benzoyloxymethyl 4-chloro-N-furfuryl-5-sulfamoylanthranilate (C20H17CIN2O7S), (II), are described in this paper and compared with furosemide and four other prodrugs. The molecular conformations of both compounds are similar to those of the other prodrugs; the packing and the crystal system are the primary differences. Compound (I) crystallizes in the trigonal space group R3 and compound (II) in the monoclinic space group P2(1)/n. The packing of both structures is stabilized by a three-dimensional hydrogen-bond network.
Asunto(s)
Cristalografía por Rayos X , Furosemida/farmacocinética , Absorción Intestinal , Profármacos/farmacocinética , Enlace de Hidrógeno , Modelos MolecularesRESUMEN
Synthesis and biological evaluation of new 1,2,5-oxadiazole N-oxide derivatives with potential cytotoxic effects are described. From the series of compounds tested, compounds 2 and 6 proved to be very active, although non-selective.
Asunto(s)
Antineoplásicos/síntesis química , Óxidos N-Cíclicos/síntesis química , Oxadiazoles/síntesis química , Animales , Antineoplásicos/química , Antineoplásicos/farmacología , Hipoxia de la Célula/efectos de los fármacos , Cricetinae , Cricetulus , Óxidos N-Cíclicos/química , Óxidos N-Cíclicos/farmacología , Ensayos de Selección de Medicamentos Antitumorales , Modelos Moleculares , Oxadiazoles/química , Oxadiazoles/farmacología , Células Tumorales Cultivadas , Difracción de Rayos XRESUMEN
The synthesis of a series of 2-amino-4-hydroxy-delta-valerolactam derivatives is described (compounds 4 to 10). These compounds showed a high anthelmintic in vitro activity against the Nippostrongylus brasiliensis model.