Mercuric cyanide as a receptor of pyrene

Cocrystallization of pyrene with Hg(CN)₂ gives a new clathrate, namely bis[dicyanidomercury(II)] pyrene solvate, [Hg(CN)₂]₂·C₁₆H₁₀, with molecules of pyrene embedded in cavities of the slightly deformed structure of the mercuric salt; the weak intermolecular N...Hg interactions present in pure Hg(CN)₂ are maintained in the cocrystal. The X‐ray analysis of the resulting compound reveals unusual organic–inorganic interactions. One molecule of Hg(CN)₂ lies on a crystallographic mirror plane, while in the other, only the Hg atom is on the mirror plane. The molecule of pyrene is cut by a mirror plane perpendicular to the plane of the molecule.     

1‐(1,2,3‐triazol‐4‐yl)‐benzimidazolones,a new series of heterocyclic derivatives

New 1‐(1,2,3‐triazol‐4‐yl)‐benzimidazolone derivatives were obtained on pursuing research about new tricyclic derivatives of medicinal interest, bearing a 1,2,3‐triazole ring fused with another heterocyclic ring. 1‐[(5‐Carboxamido)‐1,2,3‐triazol‐4‐yl]‐benzimidazolone was prepared by four different chemical routes and it was unequivocally confirmed by spectroscopic methods. Its chemical behaviour, was evaluated by some common chemical reactions such as hydrolysis, esterification, decarboxylation, nitration and N‐methylation.     

A facile “one pot” synthesis of 2,9-disubstituted 8-azapurin-6-ones (3,5-disubstituted 7-hydroxy-3H-1,2,3-triazolo[4,5-d]pyrimidines)

A series of title compounds have been synthesized by utilising benzylazide, cyanoacetamide, ethyl or methyl esters of aliphatic or aromatic carboxylic acids and sodium ethoxide as catalyst.     

Voice quality after carbon dioxide laser and conventional surgery for T1A glottic carcinoma

The different types of small vocal fold tumor therapy allow the preservation of respiration and deglutition; the quality of phonation is the most important criterion for the patient. The aim of the study is to compare vocal function after treatment of T1a tumors by conventional and laser cordectomy. Fifty-seven male patients were included in the study: 27 underwent conventional cordectomy using an external approach, and 30 underwent an endoscopic microscopic laser cordectomy. Videolaryngoscopy was performed for each subject, and the maximal phonation time was measured. Spectrograms were recorded, and a perturbation analysis was performed if a clear harmonic structure was visible. Voices were perceptually rated by two experienced phoniatricians using the GRBAS scale. Even though a slightly better voice was found after conventional surgery throughout the data, no statistically significant difference was measured in the two groups. The data on voice outcome per se do not indicate the selection of one surgical approach over another.     

Phase behavior of modified montmorillonite– poly(ϵ‐caprolactone) nanocomposites

The thermal behavior and overall isothermal crystallization kinetics of a series of organophilic modified montmorillonite–poly(?‐caprolactone) nanocomposites were investigated. In general, the thermal behavior was influenced more by the type of dispersion than by the clay content. For nanocomposites in which silicate platelets were predominantly dispersed in the polymer matrix to give exfoliated structures, the thermal properties were improved with respect to those of neat poly(?‐caprolactone), whereas in those cases in which simply intercalated structures were attained, the thermal properties regularly decayed as the clay content increased. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 1321–1332, 2004     

13C magnetic resonance studies of reduced proaporphine alkaloids

The natural abundance ¹³C magnetic resonance spectra of reduced proaporphines are reported, with complete assignments based on peak multiplicity and empirical calculations of chemical shifts. The chemical shift values of C-8, C-12 and C-7 are found to be strongly diagnostic of the spiro carbon configuration.     

A method for correcting the reverberation times of enclosures as a function of humidity and temperature

The decay rate of sound within large enclosures depends on air humidity and temperature. This phenomenon must be taken into account in most problems of architectural acoustics; generally, the measurement data obtained in actual humidity and temperature conditions should be normalized to standard conditions. In this paper a simple procedure for correcting the measured reverberation time and the related program, implemented on a Texas Instruments T1–59 personal calculator, are presented.     

Evaluation of departure from stoichiometry of gallium arsenide crystals

A method is described for determining arsenic in gallium arsenide. In order to avoid the conventional pre-reduction process, arsenic is directly titrated iodimetrically as As(V) in acidic solution. The determination is made with an automatic titrator and potentiometric detection of the equivalent point. Pure arsenic is used as a reference substance. Deviations from the stoichiometric composition of the order of 10^?3-10^?4% with a standard deviation of about 0.06% can be determined. The limits of chemical analysis for controlling the stoichiometry of the semiconductor are discussed.     

13C-NMR of some ajmalane alkaloids

The ¹³C-NMR spectra of the alkaloid ajmaline ($\text{1}$) and its stereoisomers isoajmaline ($\text{2}$), sandwichine ($\text{3}$) and isosandwichine ($\text{4}$) are reported. The different stereochemistry at C (17), C(20) and C(21) of the four isomers can be directly ascertained by chemical shifts data.     

Determination of glycoalkaloids and relative aglycones by nonaqueous capillary electrophoresis coupled with electrospray ionization-ion trap mass spectrometry

Glycoalkaloids are naturally occurring nitrogen-containing compounds present in many species of the family Solanaceae, including cultivated and wild potatoes (Solanum spp.), tomatoes (Lycopersicon spp.), etc. These compounds have pharmacological and toxicological effects on humans due to their significant anticholinesterase activity and disruption of cell membranes. Herein is reported the development of a capillary electrophoresis (CE) method using nonaqueous (NA) separation solutions in combination with ion trap mass spectrometry (MS and MS/MS) detection for the identification and quantification of glycoalkaloids and their relative aglycones. A mixture 90:10 v/v of MeCN-MeOH containing 50 mM ammonium acetate and 1.2 M acetic acid (applied voltage of 25.5 kV) was selected as a good compromise for the separation and detection of these compounds. The electrospray MS measurements were carried out in the positive ionization mode using a coaxial sheath liquid, methanol-water (1:1) with 1% of acetic acid at a flow rate of 2.5 microL/min. Under optimized experimental conditions, the predominant ion was the protonated molecular ion ([M+H](+)) of solanidine (m/z = 398), tomatidine (m/z = 416), chaconine (m/z = 852), solanine (m/z = 868), and tomatine (m/z = 1034). MS/MS experiments were carried out systematically by changing the relative collisional energy and monitoring the intensities of the fragment ions that were not high enough to allow better quantification than with the mother ions. The method was used for analyzing glycoalkaloids in potato extracts.