Selective complex formation of some chromogenic calix[4]arene derivatives detected by Fourier transform infrared spectroscopy 2. Solid experiments

Two chromogenic calix[4]arene derivatives having identical coordination sphere (consisting of ester groups) but different chromogenic units (pyridinium type and dinitro-phenyl type) were the subject of structural studies with sodium(I) and thallium(I) ions in solid state, both as bulk and surface complexes. Their diffuse reflectance infrared Fourier transform (DRIFTS) spectra were recorded and the characteristic changes of the vibrational spectra due to complex formation were analysed based on curve fitting.     

Interaction of monovalent cationic drugs with montmorillonite

The aim of this study was to compare the adsorption of various organic drugs and a well-studied surfactant. The organic drugs used were promethazine chloride [10-(2-dimethylammonium) propylfenothiazine chloride] and buformin hydrochloride (1-butylbiguanidine chloride). The surfactant was benzalkonium chloride (N-tridecyl-N-benzyl-N,N-dimethylammonium chloride). Different amounts of drug solutions were added to montmorillonite suspensions, either separately (simple system) or in combination (competitive system) under the same conditions, and the organocomplexes formed were investigated. The organic molecule with the short alkyl chain adsorbed to yield monolayer coverage, whereas the aromatic molecule and the surfactant formed a pseudotrimolecular arrangement. In the competitive system, the larger organic molecules (having the same charge) displaced the smaller one from the interlayer space. The intercalation of molecules in the interlayer space was investigated by X-ray diffraction measurements. Received: 30 November 2000 Revised: 20 December 2001 Accepted: 26 October 2001     

1H and 7Li NMR Study on the Complex Formation of Lithium Cations with Pyridinium Derivatives of Calix[4]arenes

Complexation of lithium ions by three chromoionophoric calix[4]arenes has been studied by ¹H and ⁷Li NMR spectroscopy. The signalling unit of the chromoionophores is the N-methylpyridinium(methyleneimino) group in conjugation with a phenolic group of the calixarene ring while the coordination spheres contain esteric (ethoxycarbonylmethoxy) or etheric (ethoxy, propoxy) units. ¹H NMR and NOESY measurements suggest the dominance of cone conformations of the calixarene rings with slight, solvent-dependent distortions. Complexation occurs only in the presence of a weak base. The interaction with lithium ions causes a broadening of both the ¹H and ⁷Li NMR signals. Analysis of the chemical shifts in the three complexes indicates a different coordination environment for the lithium with the calixarene containing esteric groups from those having etheric groups. This explains the differences in the stabilities of the lithium complexes of the two types of calixarenes.     

Convenient Synthesis of 1,2,3,4-Tetrahydroisoquinoline-1-carboxylic Acid Derivatives via Isocyanide-Based,Three-Component Reactions

The three-component reactions of 3,4-dihydroisoquinolines, isocyanides, and benzyl chloroformate furnished 2-benzyloxycarbonyl-1,2,3,4-tetrahydroisoquinoline-1-carboxamides in moderate to good yields. Hydrogenolysis or selective hydrolysis of the benzyloxycarbonyl group provided 1,2,3,4-tetrahydroisoquinoline-1-carboxamides, further hydrolysis of which resulted in the corresponding 1,2,3,4-tetrahydroisoquinoline-1-carboxylic acids.     

Kinetics and mechanism of the photoinitiated autoxidation of sulfur(IV) in the presence of iodide ion

The kinetics and mechanism of the photoinitiated and iodide ion-catalyzed aqueous autoxidation of sulfur(IV) has been studied in a diode-array spectrophotometer using the same light beam for excitation and detection. Light absorption of both the iodide ion and sulfur(IV) contribute to the initiation of a highly efficient radical chain reaction, the overall rate of which depends on the reactant and catalyst concentrations, the pH, and the light intensity in a complex manner. To interpret all the experimental findings, an elaborate scheme is proposed, in which the chain carriers are SO3-*, SO4-*, SO5-*, I*, and I2-*. There are three termination steps, each of them is second-order with respect to the chain carriers. Model calculations and nonlinear fitting have been used to show that the proposed scheme gives an excellent quantitative interpretation of the experimental results.     

Vibrational spectroscopy of resveratrol

In this article the authors deal with the experimental and theoretical interpretation of the vibrational spectra of trans-resveratrol (3,5,4'-trihydroxy-trans-stilbene) of diverse beneficial biological activity. Infrared and Raman spectra of the compound were recorded; density functional calculations were carried out resulting in the optimized geometry and several properties of the molecule. Based on the calculated force constants, a normal coordinate analysis yielded the character of the vibrational modes and the assignment of the measured spectral bands.     

A Combined Petrographic and Micro-Raman Study of Meteoritic Microdiamond in ALH-77257 Ureilite and ALH-78113 Aubrite

ABSTRACT

Two diamond-bearing meteorites (ALH-77257 and ALH-78113) were investigated by petrographic microscope and micro-Raman spectroscopy. The meteoritic diamonds can be found in fractures or veins cross-cutting the original minerals (olivine, pyroxene, feldspar) and inside the host minerals. The micro-Raman spectral features of microdiamonds in two studied meteorites are very similar to each other. The diamond peak was found at 1329 in ALH-77257 and 1332 cm^?1 in ALH-78113. Hexagonal diamond was not present. However, we observed the D and G bands of graphite or amorphous carbon at 1322 and 1582 cm^?1 wavenumbers, indicating an origin of the meteoritic microdiamonds by magmatic processes.     

Effect of Thyme (Thymus vulgaris L.) Essential Oil and Its Main Constituents on the Outer Membrane Protein Composition of Erwinia Strains Studied with Microfluid Chip Technology

Changes in the composition of bacterial outer membrane proteins may result in antibiotic resistance and in altered invasive ability. A rapid method (microfluid chip technology) was used in this study to analyze the outer membrane protein profile changes of Erwinia strains under antibiotic effect and to compare it with the effect of essential oil and its constituents. Streptomycin, gentamicin and thyme essential oil were capable of significantly changing the protein profile. Neither of the main constituents of the essential oil (thymol and carvacrol) can be exclusively responsible for the changes induced. Quantitative changes in the protein profile may contribute to the explanation of antibacterial effect of thyme oil on pathogenic Erwinia. strains.     

Mass spectra of tetrahydroisoquinoline-fused 1,3,2-O,N,P- and 1,2,3-O,S,N-heterocycles: influence of ring size and fusion, of present heteroatoms, substituent effects and of the stereochemistry on fragmentation

The electron ionization (EI) mass spectra of a variety of stereoisomeric tricyclic 1,3,2-oxazaphosphino[4,3-a]isoquinolines (1-4), 1,2,3-oxathiazino[4,3-a]isoquinoline-4-oxides (5-7) and the -4,4-dioxides (8-10) of oxazaphospholo- and oxathiazolo[4,3-a]- (11, 12, 15 and 16) and -[3,4-b]isoquinolines (13, 14 and 17) were recorded. Ring size and fusion, the different heteroatoms (P and S) and substituents on the ring systems strongly influence the mass spectra. In addition, mass spectra of the stereoisomers of compounds 1, 2 and 13, 14 revealed stereochemically relevant differences which are not observed for the other pairs of isomers.     

Complex formation between aliphatic amines and chromogenic calix[4]arene derivatives studied by FT-IR spectroscopy

Complex formation of two calix[4]arene derivatives - containing two ethoxycarbonylmethoxy groups or a bridge including two carboxamide moieties in the coordination sphere - with aliphatic amines (n-octylamine, OA and triethylamine, TEA) were the subject of FT-IR studies. Two nitrophenyl type auxochromic moieties were also present in both of the ligands. Solvent effects were studied in chloroform, diiodomethane and dichloromethane. Presumably, in these reactions, the reactants undergo phenol-amine type interactions and, simultaneously, coordinative interaction takes place between the carbonyl group of the ligand and the protonated form of the aliphatic amine. Complex formation of calixarene 1a with n-octylamine was complete resulting in drastic changes in the FT-IR spectra. Moreover, the possibility of the formation of a new compound by the reaction between the ester type functionalities and octylamine was precluded. The expected ligand was synthesized and its spectra were compared with those of calixarene 1a. In most of the cases of calixarene 1b, the amide moiety of the carboxamide bridge does not participate in the complex formation with the exception of complexes formed in diiodomethane solution and of the 1b-TEA complex observed in dichloromethane.