Ultrathin functional films of titanium(IV) oxide

Chemistry and physics of thin semiconducting layers of various types are subjects of intense research. Especially when nanotechnology methods such as self-assembly are involved, amazing structural and/or functional properties may appear. Also modern physical methods using variously organized plasma arrangements are able to produce uniform structures with distinctive functionality. In this review, based virtually on our own work, discussions on the preparation, structure, morphology, and function of titanium(IV) oxide nanoscopic thin films are presented. It was shown that structurally and functionally similar titanium(IV) oxide films can be prepared via completely different preparation techniques. Function tests were arranged as “primary”, covering the assessment of the light induced charge separation efficiency, and “secondary”, based on photocatalytic surface oxidations.     

A new platinum–bromine cyclohexanediamine complex from the family of cancer cytostatics

Another new substance from the family of Pt‐based coordination complexes with potential use in cancer chemotherapy has been synthesized, crystallized and structurally characterized. In this compound {systematic name cis‐dibromido[(1R,2R)‐cyclohexane‐1,2‐diamine‐κ²N,N′]platinum(II)}, cis‐[PtBr₂(C₆H₁₄N₂)], there are two molecules with very similar conformations in the asymmetric unit. The component species interact by way of N—H...Br and C—H...Br hydrogen bonds to give two‐dimensional networks which lie parallel to the (100) plane.     

[11]Anthrahelicene on TiO2 surfaces

Helicenes are carbon-rich materials with an ordered structure that possess interesting and remarkable electronic, chiroptical, mechanical and magnetic properties either in bulk or as single molecule devices. We report on the first attempt to anchor and organize [11]anthrahelicene ([11]AH) molecules onto a metal oxide surface. Molecular structures obtained on the (110) and (011) faces of rutile titania are characterized using scanning probe microscopy. On the (110) surface, [11]AH molecules form islands that are comprised of small domains of two types that are mirror reflections of each other and have an ordered quasi-hexagonal lattice. In contrast, molecules form unordered clusters on the (011) surface. Single molecules on both faces are imaged with sub-molecular resolution.     

Three-Stage Extraction of Gelatines from Tendons of Abattoir Cattle: 2—Properties of Gelatines

The subject of our previous paper (part 1) was three-stage extraction of gelatines from short cattle tendons. In this paper, we studied influence of extraction conditions on quality of produced gelatines??protein content, ash content, rigidity of gelatine gels, viscosity, and distribution of molecular weights. Ash content of gelatines ranged in limits 3.5?C10.5?%. Rigidity of the gels was influenced by extraction conditions and by elastin content in gelatines; highest-quality gels display rigidity of 213 Bloom. Viscosity of gelatines ranged from 2.47 to 12.11?mPa?s. Molecular weights of gelatines display a proportion of fractions from 20 to 36?kDa, a quite high proportion of fractions from approximately 50 to 100?kDa, in some cases even fractions above 200?kDa appear. It was found that transition temperature and melting temperature of gelatines extracted from tendons are in accord with data on gelatines obtained by traditional extraction techniques from skins and bones. With respect to efficiency of the whole extraction process and to quality of extracted gelatine, we may recommend extraction conditions as follows: in the 1st processing stage, shaking degreased starting material with water in ratio 1:10 at 25?°C for 5?h; in the 2nd stage, treating the swelled material with 5?% (w/w) added proteolytic enzyme at 40?°C for 25?h; in 3rd stage, extracting gelatine while boiling for 16?min.     

In-syringe magnetic-stirring-assisted liquid–liquid microextraction for the spectrophotometric determination of Cr(VI) in waters

A fully automated method for the determination of chromate is described. It is based on the selective reaction of Cr(VI) with diphenylcarbazide in acidic media to form a colored complex of Cr(III) with the oxidation product diphenylcarbazone. The reaction was performed within the syringe of an automatic burette containing a magnetic stirrer for homogenization of the sample and the required reagents. In-syringe stirring was made possible using a specially designed driving device placed around the syringe barrel to achieve a rotating magnetic field in the syringe, forcing the stirrer to spin. In a second step, the reaction mixture in the syringe was neutralized to allow in-syringe magnetic-stirring-assisted dispersive liquid–liquid microextraction of the complex into 125 μL of n-hexanol. After phase separation by droplet flotation over 30 s, the organic phase was propelled into a coupled spectrophotometric detection cell. The entire multistep procedure including in-system standard preparation was done within 270 s. The method was used for the analysis of natural waters, achieving average analyte recovery of 103 %, a limit of detection of 0.26 μg L^-1, and a repeatability of less than 4 % relative standard deviation.     

Green chromatography separation of analytes of greatly differing properties using a polyethylene glycol stationary phase and a low-toxic water-based mobile phase

A simple, rapid, and environmentally friendly HPLC method was developed and validated for the separation of four compounds (4-aminophenol, caffeine, paracetamol, and propyphenazone) with different chemical properties. A “green” mobile phase, employing water as the major eluent, was proposed and applied to the separation of analytes with different polarity on polyethylene glycol (PEG) stationary phase. The chromatography separation of all compounds and internal standard benzoic acid was performed using isocratic elution with a low-toxicity mobile phase consisting of 0.04 % (v/v) triethylamine and water. HPLC separation was carried out using a PEG reversed-phase stationary phase Supelco Discovery HS PEG column (15?×?4 mm; particle size 3 μm) at a temperature of 30 °C and flow rate at 1.0 mL min^?1. The UV detector was set at 210 nm. In this study, a PEG stationary phase was shown to be suitable for the efficient isocratic separation of compounds that differ widely in hydrophobicity and acid–base properties, particularly 4-aminophenol (log P, 0.30), caffeine (log P, ?0.25), and propyphenazone (log P, 2.27). A polar PEG stationary phase provided specific selectivity which allowed traditional chromatographic problems related to the separation of analytes with different polarities to be solved. The retention properties of the group of structurally similar substances (aromatic amines, phenolic compounds, and xanthine derivatives) were tested with different mobile phases. The proposed green chromatography method was successfully applied to the analysis of active substances and one degradation impurity (4-aminophenol) in commercial preparation. Under the optimum chromatographic conditions, standard calibration was carried out with good linearity correlation coefficients for all compounds in the range (0.99914–0.99997, n?=?6) between the peak areas and concentration of compounds. Recovery of the sample preparation was in the range 100?±?5 % for all compounds. The intraday method precision was determined as RSD, and the values were lower than 1.00 %.

Properties of two amide‐based hydrophilic interaction liquid chromatography columns

Hydrophilic interaction liquid chromatography is a separation technique suitable for the separation of moderately and highly polar compounds. Various stationary phases (SPs) for hydrophilic interaction liquid chromatography are commercially available. While the SPs based on the same type of ligand are available from different providers, they can display a distinct retention characteristics and separation selectivity. The current work is focused on characterization and comparison of the separation systems of two amide‐based HPLC columns from two producers, i.e. XBridge Amide column and TSK gel Amide‐80 column. Several characterization procedures (tests) were used to investigate the differences between these columns. The chromatographic behavior of selected analytes indicates that multimodal interactions are responsible for retention and separation on these columns. Multiple testing approaches were used in order to reveal subtle differences between the SPs. Both amide‐based columns showed certain differences in retention, selectivity, and plate counts. Based on the tests used in this study, we conclude that the investigated columns provide a different degree of H‐bonding interactions.     

Palladium-catalysed Claisen rearrangement of 6-allyloxypurines

6-Allyloxypurines readily undergo palladium-catalysed Claisen rearrangement under mild conditions affording N ¹-substituted hypoxanthines. In contrast with the previously reported protocol, the Claisen rearrangement can be performed using Pd(PPh₃)₄ or Pd(dba)₂/dppf in dry THF at 60°C. The reaction can accommodate variously substituted allyl fragments to position N ¹ of the hypoxanthine skeleton with high yields. Retention of the double bond configuration during rearrangement was observed.     

Combining ferrocene,thiophene and a boronic acid: a hybrid ligand for reagentless electrochemical sensing of cis-diols

A redox-active affinity ligand suitable for reagentless sensing of cis-diols was synthesised and characterised. 4-[(Ferrocenylamino)methyl]thiophene-3-boronic acid (FcTBA) was allowed to interact with the model cis-diol, sorbitol. A discrete, cathodic shift of the redox potential was observed upon interaction of FcTBA with sorbitol thus providing simultaneous differentiation between the free and bound forms of this sensor molecule. Similar behaviour was observed also for FcTBA co-immobilised with thiophene in a mixed self-assembled monolayer on a gold electrode.     

Rapid determination of RMSDs corresponding to macromolecular rigid body motions

Finding the root mean sum of squared deviations (RMSDs) between two coordinate vectors that correspond to the rigid body motion of a macromolecule is an important problem in structural bioinformatics, computational chemistry, and molecular modeling. Standard algorithms compute the RMSD with time proportional to the number of atoms in the molecule. Here, we present RigidRMSD, a new algorithm that determines a set of RMSDs corresponding to a set of rigid body motions of a macromolecule in constant time with respect to the number of atoms in the molecule. Our algorithm is particularly useful for rigid body modeling applications, such as rigid body docking, and also for high‐throughput analysis of rigid body modeling and simulation results. We also introduce a constant‐time rotation RMSD as a similarity measure for rigid molecules. A C++ implementation of our algorithm is available at http://nano‐d.inrialpes.fr/software/RigidRMSD . © 2014 Wiley Periodicals, Inc.