Polymeric organosilicon systems. XVII. Synthesis and photochemical and conducting properties of poly[o-and m-(disilanylene)phenylene]s

Poly[o-(tetramethyldisilanylene)phenylene] ( 2a ), poly[o-(1,2-dimethyldiphenyldisilanylene)-phenylene] ( 2b ), poly[m-(tetramethyldisilanylene)phenylene] ( 2c ), and poly[m-(1,2-dimethyldiphenyldisilanylene)phenylene] ( 2d ) were prepared by the sodium condensation reaction of the corresponding 1,2-and 1,3-bis (chlorosilyl)benzenes in toluene. Irradiation of thin films of 2a-2d in air resulted in a rapid decrease of absorption maxima in the ultraviolet region. The photolysis of 2b and 2d in benzene afforded photodegradation products with low molecular weights. When thin films of 2b and 2d were doped with antimony pentafluoride vapor, films which have conductivities of semi-conductor level were obtained. © 1993 John Wiley & Sons, Inc.     

Reflective mode of deformed-helix ferroelectric liquid crystal cells for sensing applications

We present a detailed theoretical and experimental study of the reflectance response of a deformed-helix ferroelectric (DHF) liquid crystal (LC) cell to an applied voltage under cross-polarisers. Using a model based on the effective dielectric tensor approximation, we derive simple analytical formulas to design a LC cell with maximum modulation depth and optimal linearity of the electro-optical response intensity versus the electric field. Our experimental results show that the cell works at frequencies up to 10 kHz and exhibits excellent linearity, with a total harmonic distortion as low as ?70 dB. These findings suggest that DHF-LCs can be exploited to develop simple and accurate optical sensors.     

Pharmacokinetic study of intraperitoneally administered troglitazone in mice using ultra-performance liquid chromatography/tandem mass spectrometry

A rapid and sensitive ultra-performance liquid chromatography/tandem mass spectrometry (UPLC/MS/MS) method was developed and validated for the determination of troglitazone in mouse plasma. Troglitazone and its internal standard (IS), rosiglitazone, were separated on an ACQUITY UPLC BEH C(18) column (1.7 microm particle size, 50 x 2.1 mm i.d.) by gradient elution with water and methanol at a flow rate of 0.5 mL/min. The cycle time of each analysis was 2.5 min. Rosiglitazone and troglitazone eluted at 1.13 and 1.57 min, respectively, and were chromatographically resolved from the ion suppression and enhancement zones due to the biological matrix effect. Quantitation of the analytes was performed in electrospray negative ionization mode (ESI -ve) using multiple reaction monitoring (MRM) experiments. The weighted (1/x) calibration curve was quadratic over the plasma concentration range 1-2500 ng/mL with a correlation coefficient (r(2)) of 0.9966. The limit of quantitation (LOQ) of troglitazone in mouse plasma was lower than 1 ng/mL. The inter- and intra-day variations of the assay were lower than 12.1%; the overall accuracy ranged from 86.4-110.2% and recovery from spiked plasma was more than 60%. The developed method was successfully applied to determine troglitazone in mouse plasma after intraperitoneal administration.     

Competitive electron impact induced methylene imine elimination from methyl- and dimethylamino N-heterocycles. 1—substituted melamines

Competitive intramolecular expulsion of methylene imine is evaluated for heterocyclic methylamino and dimethylamino substituents using selectively labelled N²,N²,N⁴-trimethylmelamine. In this compound methylene imine expulsion from the dimethylamino group is favored by more than 2:1 over loss from the methylamino group. The effects of other fragmentations and hydrogen randomisation are estimated independently using methylmelamines with each of the groups as the sole source of methylene imine loss.