Spectroscopy and crystal structure of anabasine salts

The anabasinium hydrochloride, hydriodide and perchlorate were characterized by IR and NMR spectroscopy as well as by X-ray diffraction. Anabasinium hydrochloride crystallizes with three independent ionic pairs in the asymmetric part of the orthorhombic unit cell, while anabasinium hydriodide and perchlorate crystals, being isostructural, are hexagonal and contain only one symmetry independent ionic pair. Despite these differences in the crystal data, both types of crystals display very similar helical solid-state patterns. The reported results combined with the CSD searches indicate an inherent tendency of anabasinium salts to crystallize with multiple asymmetric units, and to form folded arrangements in crystals. In the solid state the anabasinium cations predominantly adopt either synperiplanar or antiperiplanar conformations with respect to the mutual orientation of C^*–H and pyridine C–C(N) bonds, with deformations towards, respectively, (+) synclinal or (+) anticlinal rotamers.     

Clinical Trials and Basic Research in Photodynamic Diagnostics and Therapies from the Center for Laser Diagnostics and Therapy in Poland

The purpose of this review is to present an overview of the development of photodiagnostic and photodynamic therapy (PDD and PDT) techniques in Poland. The paper discusses the principles of PDD, including fluorescent techniques in determining precancerous conditions and cancers of the skin, digestive tract, bladder and respiratory tract. Methods of PDT of cancer will be discussed and the current state of knowledge as well as future trends in the development of photodynamic techniques will be presented, including the possibility of using photodynamic antimicrobial therapy. Research pioneers in photodynamic medicine such as Thomas Dougherty are an inspiration for the development of methods of PDD and PDT in our Clinic. The Center for Laser Diagnostics and Therapy in Bytom, Poland, promotes the propagation of PDD and PDT through the training of clinicians and raising awareness among students in training and the general public. Physicians at the Center are engaged in photomedical research aimed at clinical implementation and exploration of new avenues in photomedicine while optimizing existing modalities. The Center promotes dissemination of clinical results from a wide range of topics in PDD and PDT and serving as representative authorities of photodynamic medicine in Poland and Europe.     

Separation of Some Aromatic Amino Acid Enantiomers with Pressurized Planar Electrochromatography and TLC

Influence of buffer pH, buffer concentration and ratio of methanol to acetonitrile in ternary mobile phase on migration distance of enantiomers of phenylalanine, tyrosine and DOPA in pressurized planar electrochromatography (PPEC) and thin-layer chromatography (TLC) systems is presented and compared. The applied operating variables in PPEC system more strongly influence on separation selectivity of investigated solutes than those in TLC one. Higher separation efficiency of PPEC system relative to TLC one is also demonstrated.     

Fluorescent Turn-On Probes for the Development of Binding and Hydrolytic Activity Assays for mRNA Cap-Recognizing Proteins

The m⁷G cap is a unique nucleotide structure at the 5′-end of all eukaryotic mRNAs. The cap specifically interacts with numerous cellular proteins and participates in biological processes that are essential for cell growth and function. To provide small molecular probes to study important cap-recognizing proteins, we synthesized m⁷G nucleotides labeled with fluorescent tags via the terminal phosph(on)ate group and studied how their emission properties changed upon protein binding or enzymatic cleavage. Only the pyrene-labeled compounds behaved as sensitive turn-on probes. A pyrene-labeled m⁷GTP analogue showed up to eightfold enhanced fluorescence emission upon binding to eukaryotic translation initiation factor 4E (eIF4E) and over 30-fold enhancement upon cleavage by decapping scavenger (DcpS) enzyme. These observations served as the basis for developing binding- and hydrolytic-activity assays. The assay utility was validated with previously characterized libraries of eIF4E ligands and DcpS inhibitors. The DcpS assay was also applied to study hydrolytic activity and inhibition of endogenous enzyme in cytoplasmic extracts from HeLa and HEK cells.     

Strain in Platonic fullerenes

Platonic fullerenes are those structures, either closed or open ones, covered by a single type of polygonal face. Excepting the graphite sheet, all the other nano-structures show non-zero strain energy. In this study, Platonic nanostructures, covered by polygonal faces f _k , k = 5–7, are designed and optimized at Hartree–Fock HF and DFT levels of theory. Next, their stability, in terms of total energy and HOMO–LUMO gap, strain energy (by POAV theory), HOMA index of aromaticity, and Kekulé structure count, is discussed. Vibrational spectra for the open fullerenes are also given.     

Precipitated silica as filler for polymer electrolyte based on poly(acrylonitrile)/sulfolane

The aim of the present work was to perform a preliminary study of the physicochemical properties of hybrid organic–inorganic gel electrolytes for Li-ion batteries based on the PAN/TMS - poly(acrylonitrile)/sulfolane - polymeric matrix and surface-modified precipitated silicas. Modifications were done by means of the so-called dry method using silane U-511 3-methacryloxypropyltrimetoxysilane. Scanning electron microscopy (SEM), noninvasive back scattering method (NIBS), specific surface area (BET), the degree of modification of the silica fillers—Fourier-transform infrared spectroscopy (FT-IR), impedance analysis, and charging/discharging were carried out. It is found that the silica fillers were homogeneously dispersed in the polymeric matrix, which enhanced conductivity and electrochemical stability of porous polymer electrolytes. Applicability of the prepared gel electrolytes for the Li-ion technology was estimated on the basis of specific conductivity measurements. It was shown that modification of the silica surface by the silane causes an increase in the gel-specific conductivity by about 2 orders of magnitude as compared to gel with unmodified silica.     

Solvent Effect on the Chemiluminescence of Acridinium Thioester: A Computational Study

Chemiluminescent labelling, which is one of the promising procedures of modern immunodiagnostics, is increasingly carried out using acridinium derivatives, an oxidant, and an alkaline aqueous environment. However, the efficiency of the chemiluminescence of luminol or acridinium esters is higher in non-aqueous solvents such as dimethyl sulfoxide or acetonitrile. Therefore, the search for a new environment for the chemiluminescence reaction, especially the one characterized by a higher quantum yield of chemiluminescence, is one of the aims of current research. Using computational methods (DFT and TD DFT with PCM model of solvent), we examined thermodynamic and kinetic data concerning the chemiluminescence and competitive dark pathways. Our results suggest that better characteristics of the chemiluminescence reaction of acridinium thioester are observed in nonpolar solvents, such as methylcyclohexane, n-hexane and n-pentane, than in aqueous media used so far. Further experimental verification is necessary to confirm the possible application of proposed nonpolar solvents in chemiluminescent labelling and hence in immunodiagnostics.     

Stages of thermal decomposition of sodium oxo-salts of sulphur

Thermal behaviour of sodium oxo-salts of sulphur: Na₂SO₄, Na₂S₂O₇, Na₂S₂O₆, Na₂SO₃, Na₂S₂O₅, Na₂S₂O₄, Na₂S₂O₃, Na₂S₃O₆ and of sulphides Na₂S and Na₂S₂ was studied on heating up to 1000°C. The experiments were performed with anhydrous compounds obtained from commercial products by recrystallisation and dehydration. The stage mechanisms of decomposition of anionic sub-lattices of the salts have been proposed basing on the Górski’s morphological classification of simple species. The thermal stability and the stage decomposition mechanisms were correlated with the structure and the potential chemical properties of the salt anions. The thermal decomposition processes were studied by means of thermal analysis, and the decomposition products were identified by means of X-ray phase analysis.     

Star-Shaped Poly((9-carbazolyl)methylthiirane): A New Polymer for Optoelectronic Applications

Summary: The polymerization of (9-carbazolyl)methylthiirane in the presence of cyclic oligo(potassium glycidoxide) as the macroinitiator activated 18-crown-6 leads to polythioether with the molecular masses relatively near to the calculated ones. This polythioether dispersed in a commercially available transparent polymer gives a new blue photoluminescent material.     

Compensation voltage shifting in high-field asymmetric waveform ion mobility spectrometry-mass spectrometry

The separation and ion focusing properties of High-Field Asymmetric Waveform Ion Mobility Spectrometry (FAIMS) depend on desolvated ions entering the device, leading to a compound-specific, reproducible compensation voltage (CV) for each ion. This study shows that the conditions identified for stable spray and satisfactory ion desolvation in normal electrospray ionization mass spectrometry (ESI-MS) operation might significantly differ from those required for FAIMS-MS. In a typical setup with high-flow electrospray conditions, ions could be incompletely desolvated, resulting in the formation of unidentified clusters with differing behavior in a FAIMS environment. This causes compound-specific shifts of as much as 10 V in CV values when the mobile phase composition and/or flow rate are varied. The shifts diminish and finally disappear when the flow rate of methanol, used as mobile phase, is reduced to 40 microL/min and that of acetonitrile to 20 microL/min. The reproducibility of the observed CV was determined by scanning the CV while infusing a five-component mixture into a 400 microL/min flow of methanol or 50:50 acetonitrile/water. The relative standard deviation (RSD) for these multiple scans ranged from 0.7% to 6%. Therefore, under a constant set of experimental parameters, the CV does not shift appreciably. These observations have an impact on method development strategies. High flow rates can be used with the FAIMS device, since the CV values are reproducible, but it is likely that clusters are forming. Therefore, CV scans should be performed under conditions which mimic the chromatographic elution or flow injection analysis conditions, including matrix composition, to minimize errors in CV determination. An alternative approach is to determine the liquid flow rate at which the CV becomes compound-specific and to split the mobile phase stream accordingly. These experimental results may be specific to the setup used for this study and may not be directly applicable to other instrument FAIMS devices.