Solid state and solution fine tuning of the linear and nonlinear optical properties of (2-pyrene-1-yl-vinyl)pyridine by protonation-deprotonation reactions.

The unexpected and acido-triggered reversible luminescence and nonlinear optical properties of (2-pyrene-1-yl-vinyl)pyridine, a simple and highly transparent chromophore, are studied both in solution and in the solid state. Remarkably, for the first time the acidomodulation of the NLO response of a poled thin film is reported.

Identification and estimation of the levo isomer in raw materials and finished products containing atropine and/or hyoscyamine.

The belladonna alkaloids atropine sulfate and hyoscyamine sulfate, occasionally used as anticholinergic and antimuscarinic agents, have identical molecular formulas but different stereo configurations. Hyoscyamine sulfate contains almost 100% of the levo isomer, whereas atropine sulfate is composed of equal parts of dextro and levo isomers. It is believed that the therapeutic properties of these alkaloids are due exclusively or primarily to the levo isomer. Currently available methods determine only the total amount of atropine (hyoscyamine) sulfate. A method has been developed and is reported for the identification and estimation of the levo and dextro isomers of atropine and hyoscyamine. Reference solutions are prepared in methanol at the following weights per 100 mL: 8.0 mg atropine sulfate; 4.0 mg hyoscyamine sulfate; 7.0 mg scopolamine hydrobromide; and 10.0 mg homatropine methylbromide. Samples of raw materials are similarly prepared in methanol, commercial products are also extracted or diluted with methanol, and solutions are filtered. Liquid chromatography is used for separations on a 25 cm Chirobiotic T2 column. The mobile phase is prepared by mixing 3.0 mL acetic acid and 2.0 mL triethylamine with 1000 mL methanol. The injection volume is 100 or 200 microL; the flow rate is about 0.35 mL/min. Fluorescence detection is at 255 nm excitation and 285 nm emission. Scopolamine hydrobromide and hyoscyamine eluted after 20 and 60 min, respectively. Atropine sulfate generated 2 peaks after 60 and 65 min. Homatropine methylbromide also produced 2 peaks after 70 and 85 min. Samples tested in this study included raw materials and commercial tablets or injections containing belladonna alkaloids. In all cases, the percentage calculated was that of the levo isomer relative to the total amount of atropine (hyoscyamine) present.

Thermal transformations and stability of organometallic materials with electrical and optical properties: the case of polycrystalline cis-[Ir(CO)2Cl(C5H5N)].

In this paper the solid-state transformations under heating of cis-[Ir(CO)2Cl(C5H5N)] are discussed. The complexity of the transformations was revealed by integrating infrared spectroscopy, conventional and bidimensional X-ray diffraction, thermal analysis, and hot stage optical microscopy. During heating anisotropic expansion of the lattice along the Ir-Ir stacking takes place. Then cis-[Ir(CO)2Cl(C5H5N)] undergoes an irreversible solid-solid phase transition to a lattice of higher symmetry followed by a reversible transition into the amorphous phase. Under proper cooling a partial recrystallization takes place. Experiments in the presence of oxygen must be carried out in short time periods to avoid oxidation from Ir(I) to Ir(III).

Determination of atropine (hyoscyamine) sulfate in commercial products by liquid chromatography with UV absorbance and fluorescence detection: multilaboratory study.

A liquid chromatographic (LC) method with 2 detection systems for determining atropine (hyoscyamine) sulfate in commercial products was tested in a multilaboratory study. Depending on the type of product, sample solutions are prepared in methanol or methanol-water (1 + 1). The standard solution contains about 1.0 mg atropine sulfate/100 mL and is prepared in the same solvent used in sample preparation. LC separations are performed on a 7.5 cm Novapak silica column. The mobile phase is prepared by mixing 970 mL methanol with 30 mL of a 1% aqueous solution of 1-pentanesulfonic acid, sodium salt. Detection is by 2 systems, UV absorbance detection at 220 nm and fluorescence detection with excitation at 255 nm and emission at 285 nm. The injection volume is 100 or 200 microL. The following materials were used for the study: 2 separate samples of tablets labeled to contain 0.4 mg atropine sulfate, 2 separate samples of extended-release tablets labeled to contain 0.375 mg hyoscyamine sulfate, one sample of atropine sulfate injection labeled to contain 2 mg/mL, and one sample of 1% (v/v) atropine sulfate ophthalmic. Eight participants analyzed 2 separate portions of the 6 samples by both detection systems. A ninth participant analyzed the samples in duplicate but only by UV absorbance detection because of the unavailability of a fluorescence detector. The relative standard deviation (RSD) between laboratories ranged from 1.4 to 3.3% for samples of tablets and injections but higher for ophthalmic solutions (5.1-5.2%). A linearity study was conducted in the originating laboratory before the multilaboratory study with 5 solutions ranging in concentration from 0.80 to 1.20 mg atropine sulfate in 100 mL. Average recoveries were 100.0% by UV absorbance detection and 99.9% by fluorescence detection; the RSDs were 1.1 and 1.2%, respectively.