Herman Potgieter

Micron- and nanosized FAU-type zeolites from fly ash for antibacterial applications

The development of procedures for the synthesis of nanosized zeolites from cheap sources in the absence of organic templates is of great industrial importance. In this work, the size of FAU-type zeolites was decreased from micron- to nano-dimensions by reducing the amount of distilled water added to fly ash after alkali fusion. The fly ash zeolites showed high antimicrobial activity after introduction of Cu and Ag, which was associated with the release of Cu/Ag into the medium. This activity of Cu-containing zeolites from fly ash was similar to the activity of Cu-containing zeolites prepared by conventional methods but lower than that of Ag-containing zeolites.

Comparison of the structural motifs and packing arrangements of six novel derivatives and one polymorph of 2-(1-phenyl-1H-1,2,3-triazol-4-yl)pyridine.

The crystal structures of a new polymorph and seven new derivatives of 2-(1-phenyl-1H-1,2,3-triazol-4-yl)pyridine have been characterized and examined along with three structures from the literature to identify trends in their intermolecular contact patterns and packing arrangements in order to develop an insight into the crystallization behaviour of this class of compound. Seven unique C-H···X contacts were identified in the structures and three of these are present in four or more structures, indicating that these are reliable supramolecular synthons. Analysis of the packing arrangements of the molecules using XPac identified two closely related supramolecular constructs that are present in eight of the 11 structures; in all cases, the structures feature at least one of the three most common intermolecular contacts, suggesting a clear relationship between the intermolecular contacts and the packing arrangements of the structures. Both the intermolecular contacts and packing arrangements appear to be remarkably consistent between structures featuring different functional groups, with the expected exception of the carboxylic acid derivative 4-(4-(pyridin-2-yl)-1H-1,2,3-triazol-1-yl) benzoic acid (L11), where the introduction of a strong hydrogen-bonding group results in a markedly different supramolecular structure being adopted. The occurrence of these structural features has been compared with the packing efficiency of the structures and their melting points in order to assess the relative favourability of the supramolecular structural features in stabilizing the crystal structures.

Toxicological and analytical assessment of e-cigarette refill components on airway epithelia

There are over 2.6 million users of e-cigarettes in the United Kingdom alone as they have been promoted as a safer alternative to traditional cigarettes. The addition of flavours and aromas has also proven to be popular with younger generations. In this review, we survey the range of studies in the short timeframe since e-cigarettes reached the market to draw attention to the health associated risks and benefits of their introduction. We complement this review with a case study reporting on the composition of selected e-cigarette refills with particular emphasis on the toxicological activity of its components on lung cells.

2-(4-Isobutyl-phen-yl)-N'-[(3Z)-2-oxoindolin-3-yl-idene]propano-hydrazide.

In the title compound, C21H23N3O2, the indolin-2-one group is essentially planar, with a maximum deviation of 0.016 (2) Å for the N atom, and makes a dihedral angle of 84.38 (14)° with the benzene ring. The =N—N(H)—C(=O)—C– torsion angle is 0.9 (3)°. In the crystal, molecules are linked into a three-dimensional network via N—H⋯O and C—H⋯O hydrogen bonds. In addition, a C—H⋯π interaction was observed.

Crystal structure of 1H-imidazol-3-ium 2-(1,3-dioxoisoindolin-2-yl)acetate

The title salt, C3H5N2 +·C10H6NO4 −, was obtained during a study of the co-crystallization of N′-[bis(1H-imidazol-1-yl)methylene]isonicotinohydrazide with (1,3-dioxoisoindolin-2-yl)acetic acid under aqueous conditions. The 1,3-dioxoisoindolinyl ring system of the anion is essentially planar [maximum deviation = 0.023 (2) Å]. In the crystal, cations and anions are linked via classical N—H⋯O hydrogen bonds and weak C—H⋯O hydrogen bonds, forming a three-dimensional network. Weak C—H⋯π interactions and π–π stacking interactions [centroid–centroid distances = 3.4728 (13) and 3.7339 (13) Å] also occur in the crystal.

Formation of polymeric assemblies of six-coordinate metal complexes with mixed bridges of dicarboxylato-azido moieties

New biscarboxylato zwitterionic ligands, namely bis(N-carboxylatoethyl)-4,4′-dipyridinum) L1 and bis(N-carboxylatopropyl)-)-4,4′-dipyridinum) L2, were synthesized from the reaction of 4,4′-dipyridine with 3-bromopropanoic acid and 4-bromobutanoic acid, respectively. The reaction of these ligands and the azido coligand with some metal ions resulted in the formation of polymeric complexes of general formulae [Cr2(Ln)(N3)4]Cl2·H2O and [M2(Ln)(N3)4] xH2O, where (M=Mn (II), Fe(II), Co(II), Ni(II), Cu(II), Zn(II) and Cd(II); n=1, 2; x=1, 1, 1, 1, 0, 1, and 1, respectively.) The oxygens of the carboxylato group are coordinated to the metal ion in a bidentate fashion. The mode of bonding and overall geometry of the complexes were determined through IR, UV–VIS, NMR and mass spectral studies, magnetic moment measurements, elemental analysis, metal content, chloride content and conductance. These studies revealed the formation of polymeric assemblies of six-coordinate complexes with distorted octahedral geometries about metal centers.

A new polymorph of N-(2-{N'-[(1E)-2-hy-droxy-benzyl-idene]hydrazinecarbon-yl}phen-yl)benzamide.

The title compound, C21H17N3O3, is a new polymorph of an already published structure [Shashidhar et al. (2006 ▶). Acta Cryst. E62, o4473–o4475]. The previously reported structure crystallizes in the monoclinic space group C2/c, whereas the structure reported here is in the tetragonal space group I41/a. The bond lengths and angles are similar in both structures. The molecule adopts an extended conformation via intramolecular N—H⋯O and O—H⋯N hydrogen bonds; the terminal phenyl ring and the hydroxylphenyl ring are twisted with respect to the central benzene ring by 44.43 (7) and 21.99 (8)°, respectively. In the crystal, molecules are linked by N—H⋯O hydrogen bonds, weak C—H⋯O hydrogen bonds and weak C—H⋯π interactions into a three-dimensional supramolecular network.

4-Chloro-N′-[(E)-2-chloro­benzyl­idene]benzohydrazide monohydrate

The title compound, C14H10Cl2N2O·H2O, has a nearly planar extended conformation [C—N—N—C = −173.66 (15)°]. The dihedral angle between the aromatic rings is 4.6 (2)°. The water molecules alternate with benzohydrazide molecules in chains formed by O—H⋯O hydrogen bonds which run parallel to the a axis. These chains are linked to neighboring chains through N—H⋯O and C—H⋯O interactions, forming a layer parallel to (001).

N'-[(E)-2-Chloro-benzyl-idene]-2-(6-meth-oxy-naphthalen-2-yl)propano-hydrazide.

In the title compound, C21H19ClN2O2, the benzene ring and the naphthalene ring system are oriented at a dihedral angle of 65.24 (10)°. In the crystal, N—H⋯O, C—H⋯N and C—H⋯O hydrogen bonds link the molecules, forming chains along the b-axis direction. Further C—H⋯O hydrogen bonds link the chains, forming corrugated sheets lying parallel to (10-1).

(6Z)-4-Bromo-6-{[(2-hy-droxy-eth-yl)amino]-methyl-idene}cyclo-hexa-2,4-dien-1-one.

The title molecule, C9H10BrNO2, excluding methylene H atoms and the C—OH group, is essentially planar, with a maximum deviation of 0.037 (2) Å for the N atom. The N—C—C—O torsion angle is −63.1 (3)°. The molecular structure is stabilized by a weak intramolecular N—H⋯O(carbonyl) hydrogen bond, forming an S(6) motif. In the crystal, molecules are linked by O—H⋯O and C—H⋯O hydrogen bonds, forming a three-dimensional network.