Butane-1,4-diyl bis-(pyridine-3-carboxyl-ate)

Mol­ecules of the title compound (alternative name: butane-1,4-diyl dinicotinate), C16H16N2O4, lie on a inversion centre, located at the mid-point of the central C—C bond of the aliphatic chain, giving one half-mol­ecule per asymmetric unit. The butane chain adopts an all-trans conformation. The dihedral angle between the mean plane of the butane-3-carboxyl­ate group [for the non-H atoms, maximum deviation = 0.0871 (15) Å] and the pyridine ring is 10.83 (7)°. In the crystal, mol­ecules lie in planes parallel to (122). The structure features weak π–π inter­actions with a centroid–centroid distance of 3.9281 (11) Å

Propane-1,3-diyl bis­(pyridine-4-carboxyl­ate)

The title compound. C15H14N2O4, (I), has a gauche–gauche (O/C/C/C—O/C/C/C or GG) conformation and is a positional isomer of propane-1,3-diyl bis­(pyridine-3-carboxyl­ate), (II). The mol­ecule of (I) lies on a twofold rotation axis, which passes through the central C atom of the aliphatic chain, giving one half-mol­ecule per asymmetric unit. There is excellent agreement of the geometric parameters of (I) and (II). The most obvious differences between them are the O/C/C/C—O/C/C/C torsion angles [56.6 (2)° in (I) and 174.0 (3)/70.2 (3)° in (II) for GG and TG conformations, respectively] and the dihedral angle between the planes of the aromatic rings [80.3 (10)° in (I) and 76.5 (3)° in (II)]. The crystal structure is stabilized by weak C—H ... N and C—H ... O hydrogen bonding

17-Acetoxymulinic acid

The title compound, [systematic name: 5a-acetoxymethyl-3-isopropyl-8-methyl-1,2,3,3a,4,5,5a,6,7,10,10a,10b-dodecahydro-7,10-endo-epidioxycyclohepta[e]indene-3a-carboxylic acid], C22H32O6 (I), is closely related to methyl 5a-acetoxymethyl-3-isopropyl-8-methyl-1,2,3,3a,4,5,5a,6,7,10,10a,10b-dodecahydro-7,10-endo-epidioxycyclohepta[e]indene-3a-carboxylate, (II) [Brito et al., (2008 [triangle]). Acta Cryst. E64, o1209]. There are two molecules in the asymmetric unit, which are linked by two strong intramolecular O—H ... O hydrogen bonds with graph-set motif R 2 2(8). In both (I) and (II), the conformation of the three fused rings are almost identical. The five-membered ring has an envelope conformation, the six-membered ring has a chair conformation and the seven-membered ring has a boat conformation. The most obvious differences between the two compounds is the observed disorder of the acetoxymethyl fragments in both molecules of the asymmetric unit of (I). This disorder is not observed in (II). The crystal structure and the molecular conformation is stabilized by intermolecular C—H ... O hydrogen bonds. The ability to form hydrogen bonds is different in the two compounds. The crystal studied was a non-merohedral twin, the ratio of the twin components being 0.28 (1):0.72 (1

Trithia­cyanuric acid: a second triclinic polymorph

The title compound, C3H3N3S3, is a triclinic modification. The other reported modification crystallizes with just one mol­ecule in the asymmetric unit, [Guo et al. (2006 ▶). Cryst. Growth Des. 6, 846–848] and was solved by power X-ray diffraction data. The present modification has Z′ = 2. In the crystal, mol­ecules are linked by strong intra­molecular N—H⋯S hydrogen bonds with set graph-motif R 2 2(8). In both mol­ecules, all of the N atoms and two of the S atoms are involved in hydrogen bonding, with an average H⋯S distance of 2.58 Å and N—H⋯S angles in the range 163–167°. π–π stacking inter­actions are not observed. In the solid state, the mol­ecules exist in the thione form. The mol­ecular and supra­molecular properties are similar in both polymorphs

Poly[[μ-ethane-1,2-diyl bis­(pyridine-3-carboxyl­ate)](μ-tetra­fluorido­borato)silver(I)]

In the title compound, [Ag(BF4)(C14H12N2O4)]n, the coordination of the Ag+ ion is trigonal–bipyramidal with the N atoms of two ethane-1,2-diyl bis­(pyridine-3-carboxyl­ate) ligands in the apical positions and three F atoms belonging to different tetra­fluorido­borate anions in the equatorial plane. The material consists of infinite chains of [Ag(C14H12N2O4)] units running along [001], held together by BF4 − bridging anions

Propane-1,3-diaminium bis­(pyridine-4-carboxyl­ate) monohydrate

The asymmetric unit of the title compound, C3H12N2 2+·2C6H4NO2 −·H2O, consists of half of a doubly protonated propane-1,3-diammonium dication, a pyridine-4-carboxyl­ate anion and half of a solvent water mol­ecule; the dication and the solvent water are located on a twofold rotation axis which passes through the central C atom of the dication and the water O atom. The carboxyl­ate group of the anion appears to be delocalized on the basis of the C—O bond lengths. In the crystal, the components are linked by inter­molecular N—H⋯O, N—H⋯N and O—H⋯O hydrogen bonds

Luminescent and Scintillating Properties of Lanthanum Fluoride Nanocrystals in Response to Gamma/Neutron Irradiation: Codoping with Ce Activator, Yb Wavelength Shifter, and Gd Neutron Captor

A novel concept for detection and spectroscopy of gamma rays, and detection of thermal neutrons based on codoped lanthanum fluoride nanocrystals containing gadolinium is presented.The trends of colloidal synthesis of the mentioned material, LaF3 co-doped with Ce as the activator, Yb as the wavelength-shifter and Gd as the neutron captor, is reported. Nanocrystals of the mentioned material were characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDS), optical absorption, and photoluminescence spectroscopy. Gamma detection and its potential spectroscopy feature have been confirmed. The neutron detection capability has been confirmed by experiments performed using a 252Cf neutron source.Comment: 5 figures, 16 page

Influence of demolition waste fine particles on the properties of recycled aggregate masonry mortar

The final publication is available at Springer via http://dx.doi.org/10.1007/s40999-017-0280-xThis paper analyses the influence of the fine fraction of two types of construction and demolition waste (CDW1 and CDW2) on the properties of recycled aggregates (RA) and masonry mortars. The CDW1’s main component was ceramic while the CDW2 were concrete. Three different kinds of fine RA were produced from each source of CDW; the first type was produced by only using the fraction finer than 4.76 mm, the second one by employing only the coarser fraction than 4.76 mm, and the third type was a mix of both fractions of CDW. The masonry mortars were produced employing the 100% substitution of natural aggregates. The results show that all the recycled mortars achieved a higher water retentivity capacity than that of the conventional mortars. However, the sole use of the fine fraction of the CDW was found to have a deleterious effect over the hardened mortar properties, thus making it only adequate for the rendering or bonding of interior walls at or above ground level. In contrast a combination of both the fine fraction and coarse fraction of the CDW in the production of the RA achieved all the minimum requirements for rendering and bonding masonry mortar.Peer ReviewedPostprint (author's final draft

Analysis of the properties of masonry mortars made with recycled fine aggregates for use as a new building material in Cuba

This paper details the research work carried out on masonry mortars produced employing recycled aggregates in 100% substitution for natural sand aggregates. The main objective of the work being the validation of the resulting recycled aggregate mortar for use as a new construction material in Cuba. The recycled aggregates were acquired from the crushing of demolition material obtained from four different houses of distinct construction types. The work was carried out in two experimental stages. In stage 1, mortars with different percentages of recycled aggregates were produced and analysed. The analysis was carried out in order to achieve the optimal mix dosage, while employing the largest usable volume of recycled aggregates and in compliance with the functional requirements established by Cuban regulations. In stage 2, all mortars were produced employing the defined optimal mix proportion The fresh state properties (water retentivity) and hardened state (flexural, compression and bond strengths and capillary absorption capacity) were evaluated in the mortars produced with the other three mixed recycled aggregates of different compositions. It was concluded that the mortars produced with recycled aggregates needed less filler than that of the control mortar in order to obtain adequate properties in their fresh state. However, these recycled aggregate mortars obtained lower mechanical properties and higher capillary absorption that those of the control mortar. Nevertheless they were in compliance with the minimum requirements established in the Cuban regulation.Postprint (published version