Anion-controlled networks of intermolecular interactions in the crystal structure of 9-aminoacridinium salts

A series of salts, with the 9-aminoacridinium cation (9-AA) and aromatic carboxylic acid: benzoate (1), ortho-phthalate (2), and salicylate (3) anions have been synthesized and characterized using X-ray diffraction. In the crystal packing, the ions are linked via N-H?O, O-H?O, and C-H?O hydrogen bonds. Analysis of the hydrogen bonds in the crystal lattices of the title compounds shows that the cations and anions form tetramers. The ions in these tetramers are linked via N(amino)-H?O(carboxy) hydrogen bonds forming R₂²(8) (1 and 3) or R₂⁴(15) (2) hydrogen bond ring motifs. The cations interact through π-π interactions in the ABBA (1), AB (2) or ABA (3) arrangement to form columns (1 and 2) or chains (3).     

Enantioselective oxidation of sulfides with hydrogen peroxide catalyzed by vanadium complex of sterically hindered chiral Schiff bases

Sterically hindered chiral Schiff base ligands 4a-d were prepared from an aldehyde derived from BINOL. The vanadium complexes of the ligands catalyze an efficient, enantioselective H₂O₂-promoted sulfoxidation of alkyl aryl sulfides, and enantioselectivities as high as 98-99% ee are observed in the sulfoxidation of benzyl aryl sulfides.     

Crystal structure of 1-hydroxy-1,2,3-benzotriazolium diphenyl phosphate reveals strong NHO and OHO hydrogen bonds

The structure of 1-hydroxy-1,2,3-benzotriazolium diphenyl phosphate (HOBt/DPP) has been investigated by X-ray analysis. The compound crystallizes in the monoclinic space group P2₁/n with Z = 4 and the following lattice parameters: a = 11.711(2), b = 12.727(2) and c = 12.794(3) Å, β = 105.12(2)°, V = 1840.9(6) ų. The structure was solved by direct methods and refined on F² to R values of wR2 = 0.084 and R1 = 0.034 for 1985 observed reflections. HOBt/DPP has an ionic structure with very short OHO and NHO hydrogen bonds linking the different ions. Owing to these hydrogen bonds, infinite screw-shaped chains which are twisted parallel to the y-axis are formed.     

Cholesterol complexes with some proton acceptors in benzene and toluene solutions

Abstract  Cholesterol complexes with tri-n-butyl phosphate, tri-n-octylamine, N,N-dimethylacetamide, and cyclohexanone in benzene and toluene solutions were studied using conventional IR spectroscopy. The spectra were recorded in the region of fundamental OH stretching (3,700–3,100 cm⁻¹) at 298 K. The experimental spectra were resolved into bands corresponding to the cholesterol monomer and particular oligomeric and complex species. The formation constants of complexes were determined from the-least squares plots of the linearized expressions of Bjerrum’s formation function. The stoichiometry of complexes was also identified in this way. The identification of the particular resolved bands was performed from their location, and from the dependence of their intensity on the cholesterol monomer and free base concentration. Graphical Abstract        

Concurrent adsorption and complex formation in reversed-phase liquid-liquid chromatography with tri-n-octylphosphine oxide

Summary Reversed-phase liquid-liquid chromatographic systems consisting of an aqueous mobile phase and an organic liquid stationary phase of the proton acceptor tri-n-octylphosphine oxide (TOPO) inn-decane, coated on LiChrosorb RP-8, have been studied. The solutes were hydrophilic aromatic carboxylic acids and phenol. The retention of the carboxylic acids shows a minimum at 10 mM of TOPO, whereas increasingly tailing peaks have been obtained with decreasing concentrations of TOPO. This behaviour is due to a concurrent complex formation by hydrogen bonding with TOPO in the liquid stationary phase and adsorption at the interface between the support and the liquid stationary phase. The adsorption of TOPO, ketones and aromatic acids from hexane on Li-Chrosorb RP-8 has been studied, and seems to be due to residual silanol groups. The adsorption isotherm of TOPO has been determined and can be described by a two-site Langmuir adsorption model. Non polar solutes are not adsorbed. The influence of TOPO on the retention and the peak symmetry of carboxylic acids in the liquid-liquid chromatographic system appears to be due to a competition between TOPO and the acids for the same adsorption sites. No competition was found for phenol.Presented at the 14th International Symposium on Chromatography London, September, 1982     

Extending framework based on the linear coordination polymers: Alternative chains containing lanthanum ion and acrylic acid ligand

One-dimensional alternative chains of two lanthanum complexes: [La(L¹)₃(CH₃OH)(H₂O)₂]·5H₂O (L¹=anion of α-cyano-4-hydroxycinnamic acid ) 1 and [La(L²)₃(H₂O)₂]·3H₂O (L²=anion of trans-3-(4-methyl-benzoyl)-acrylic acid) 2 were synthesized and structurally characterized by single-crystal X-ray diffraction, element analysis, IR and thermogravimetric analysis. The crystal structure data are as follows for 1: C₃₁H₃₆LaN₃O₁₇, triclinic, P-1, , , , α=72.7960(10)°, β=83.3820(10)°, γ=67.1650(10)º, Z=2, R₁=0.0377, wR₂=0.0746; for 2: C₃₃H₃₇LaO₁₄, triclinic, P-1, , , , α=81.145(2)°, β=87.591(2)°, γ=67.345(5)°, Z=2, R₁=0.0869, wR₂=0.220. 1 is a rare example of the alternative chain constructed by syn-syn and anti-syn coordination mode of carboxylato ligand arranged along the chain alternatively. La(III) ions in 2 are linked by two η³-O bridges and four bridges (two η²-O and two η³-O) alternatively. Both of the linear coordination polymers grow into two- and three-dimensional networks by packing through extending hydrogen-bond network directed by ligands.     

Biocidal effects of photocatalytic semiconductor TiO2

Photocatalytic action of the commercial TiO₂ was the subject of study on the destruction of the microbes within the biofilms. The TiO₂ powder was characterized by X-ray diffraction (XRD) for identifying its type and the particle size was determined. The biofilm was allowed to form over TiO₂ coatings over glass slides irradiated with polychromatic light for different time durations and distances. It indicates that a five-fold decrease in bacterial count due to the formation of H₂O₂ at TiO₂/biofilm interface. The formation of H₂O₂ at the TiO₂/biofilm interface is estimated and it does not destroy the entire bacterial population within the biofilm. Bacterial killing effect is supported by FT-IR analysis.     

Hydrogen peroxide bleaching of cotton in ultrasonic energy

It is well known that, conventional hydrogen peroxide bleaching process is an important and a specific step for wet processors; however it has some problems such as long time, high energy consumption. On the other hand, using ultrasonic energy in bleaching is an alternative method for the conventional processes.

In this work, 100% cotton materials of different forms such as raw fibre, ring-spun yarns and knitted fabrics produced from these cottons, were treated with hydrogen peroxide in two different concentrations (5 mL/L and 10 mL/L), at three different temperatures (20 °C, 30 °C, 40 °C) and times (20 min, 30 min, 60 min). Whiteness Index of the samples were then measured spectrophotometrically and the overall results were compared.     

Diguanidinium hydrogenarsenate monohydrate and its deuterated analogue vibrational, DSC and X-ray investigations

The crystal structure of diguanidinium hydrogenarsenate monohydrate has been found to belong to the P42(1)/c space group of the tetragonal system, with Z = 8, a = 17.114(2) A, c = 7.3500(10) A. In this complex, a network of hydrogen bonds links water molecules and hydrogenarsenate ions. The hydrogenarsenate ions form hydrogen-bonded chains along the crystallographic c-axis. Detailed vibrational studies have been carried out (FTIR and FT-Raman on powder samples, polarized FTIR microscope on a small single crystal at room temperature). The vibrational spectra are discussed in relation to the crystal structure. Calorimetric (DSC) studies have been performed, but no phase transition was found in the temperature range 100-350 K.     

Polymeric Ordering by H-bonds. Mimicking Nature by Smart Building Blocks

Summary. Functional macromolecules can self assemble into regular structures yielding biological structures. The present review assembles recent literature on the formation of supramolecular polymers via hydrogen bonding forces and functional aggregates derived therefrom.This revised version was published online in February 2005. In the previous version the issue was not marked as a special issue, and the issue title and the editor was missing