Electrospray mass spectrometric studies of noncovalent complexes of buspirone hydrochloride and other serotonin 5-HT(1A) receptor ligands containing arylpiperazine moieties

Noncovalent complexes consisting of two protonated amines and a chloride anion were observed under electrospray ionization mass spectrometry (ESI-MS) conditions. The observed phenomenon was investigated for the hydrochlorides of buspirone, a well-known anxiolytic drug, and 23 other arylpiperazine derivatives that had been developed as serotonin 5-HT(1A) receptor ligands. Due to the major role of ionic interactions in a vacuum, it was proposed that the detected complexes were formed by NH(+)---Cl(-)---NH(+) bridges. It was found that complexation depended on structural features of the analyzed compounds. For derivatives with a shorter linker (three methylene groups) containing a terminal cyclic amide fragment, complex ions were not observed. It was postulated that, in the latter case, steric hindrance due to a terminal group could disturb ionic bridge formation. Since both the observed complexation and ligand-binding processes are driven by noncovalent forces, and a qualitative relationship between them was found (compounds with a 4-carbon chain always display higher affinity for 5-HT(1A) receptors than do their 3-carbon analogues), such ESI-MS studies may yield valuable information on ligand-receptor interactions.     

Separation of matrix by means of biosorption for flow-injection chemiluminescent determination of trace amounts of Pt(IV) in natural waters

A novel flow-injection chemiluminescent (CL) method of determination of trace amounts of Pt(IV) based on its catalytic effect on the reaction of oxidation of luminol in alkaline solution is proposed. The method employs on-line separation of analyte on the column containing green algae Chlorella vulgaris immobilized on Cellex-T support. The application of biosorption process for elimination of interferences resulted in the increase in the tolerable matrix ions concentration by several orders of magnitude. The influence of dissolved organic matter on chemiluminescence of luminol was eliminated by means of a reversed phase C₁₈ column. Under optimized conditions the suitable selectivity, good sensitivity, and low limit of detection (LOD = 0.057 ng mL^− 1) of the method were obtained. The method was applied to the analysis of spiked river water samples.     

Synthesis of Chiral 2,4-Chiral 2,4-Dichloro-6-menthoxy-1,3,5-triazines and 2-Chloro-4, 6-Dimenthoxy-1,3,5-triazines as Enantiodifferentiating Coupling Reagents. An X-ray Study on 2,4,6-Trimenthoxy-1,3,5-triazine

Chiral mono-di-and trimenthoxy-1,3,5-triazines ware obtained from natural menthol and cyanuric chloride and applied as enantioselective coupling reagents in the synthesis of dipeptides.     

Mid‐ and Near‐Infrared Spectroscopic Determination of Carbon in a Diverse Set of Soils from the Brazilian National Soil Collection

Abstract

Calibrations for soil carbon content measured by combustion (total carbon, TC) and chromate oxidation by a modified Walkley‐Black method (Walkley‐Black carbon, WBC) from the Brazilian National Soil Collection were made using Fourier‐transform near (1100 to 2500 nm; NIRS) and mid‐infrared diffuse reflectance (2,500 to 25,000 nm; DRIFTS) spectroscopy combined with partial least squares (PLS). Calibration sets of sample populations of different carbon ranges, soil taxonomic classes, and soil textural groups were established. These are for TC ranges between 0.4 to 555.0, 0.4 to 99.1, and 0.4 to 39.9 g kg^?1: for WBC 0.2 to 401.0, 0.2 to 66.0, and 0.2 to 66.0, and 0.2 to 30.0 g kg^?1: for soil taxonomic classes Ferralsols and Acrisols; and for soil textural groups very clayey, clayey, and medium textures were examined. Calibrations obtained for the largest TC and WBC ranges were better compared to the lower ones, but lower root mean squared deviation (RMSD) and relative difference (RD=RMSD/mean value) were found for the lower carbon ranges. Taxonomic soil class was not an adequate criterium for calibration set formation. Soil texture had effect on calibrations, especially using NIR, because of the particle size effect to which NIR was more sensitive than mid‐IR. In general, DRIFTS showed better performance than NIRS. NIRS only outperformed DRIFTS when used with calibration set fairly homogeneous in its particle size distribution. Results demonstrated that while calibrations can be developed using either DRIFTS or NIRS for even a very diverse set of soil samples, which will determine C over a wide range of concentrations inherent in such a diverse set, it is desirable to seperate sample populations by soil textural properties and choose the adequate spectral range (NIR or mid‐IR) based on the textural group, for calibration development to achieve more accurate results.     

Analysis of Some Antihistamine Drugs in Normal-Phase Chromatographic Systems

JPC – Journal of Planar Chromatography – Modern TLC - The selectivity of the separation of five antihistamines has been investigated by TLC on silica gel 60 F254 and on aluminium oxide...     

Addendum zu Einige neue Thiaspirane

Ohne ZusammenfassungMh. Chem.108, 885 (1977).     

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.