EXCITED STATES OF DNA AND ITS COMPONENTS AT ROOM TEMPERATURE—III. SPECTRA, POLARISATION AND QUANTUM YIELDS OF EMISSIONS FROM ApA AND poly rA*

Abstract— Corrected normalised emission spectra from 300 to 480 nm and their polarisation are reported for neutral and poly rA at room temperature. Yields are 4 times (ApA) and 6 times (poly rA) greater than the monomer. Comparison of emission spectra and polarisation spectra demonstrates heterogeneity of emission and, following attempts at spectral synthesis, comparison with experimental reference spectra allows the observed total emission spectra to be resolved into four components assigned as I monomer-like emission, II excimer fluorescence, HI monomer phosphorescence, IV excimer phosphorescence; the polarisation of the excimer fluorescences of ApA and poly rA are deduced. The observations can be understood quantitatively using a simple stacking model with excimer emissions originating in the stacked components. Quantitative differences between ApA and poly rA are due to their different hypochromism and extent of stacking. Differences of polarisation are attributed to different stacking geometries, and the directional properties of the transition moment suggest that the excimer fluorescence is largely charge-resonance in nature.     

Catalytic asymmetric carbohydroxylation of alkenes by a tandem diboration/Suzuki cross-coupling/oxidation reaction

[reaction: see text] Chiral nonsymmetric 1,2-diboron adducts are generated by catalytic enantioselective diboration. Oxidation of these adducts provides 1,2-diols in good yield. Alternatively, 1,2-diboron compounds may be reacted, in situ, with aryl halides wherein the less hindered C-B bond participates in cross-coupling. The remaining C-B bond is then oxidized in the reaction workup thereby allowing for net asymmetric carbohydroxylation of alkenes in a tandem one-pot diboration/Suzuki coupling/oxidation sequence.     

Treatment of the transplantable FANFT induced bladder tumors with the purpurin SnET2 and red light emitted by a pulsed frequency doubled Nd:YAG laser

Photodynamic therapy of transplantable N-[4-(5-nitro-2-furyl)-2-thiazolyl] formamide-induced tumors engrafted onto Fischer CDF (F-344)/CrlBR rats that had been sensitized with the photosensitizer tin (ll) etiopurpurin dichloride was performed in combination with visible light (approximately equal to 660 nm) emitted by either a continuous wave argon-dye laser or a pulsed, frequency-doubled Nd:Yag laser. Tumor control was assessed either by tumor dry-weight 12 days after treatment or by the palpatory absence of tumor at 60 days after treatment. Both laser sources were effective in creating the desired photodynamic effect. This study demonstrates the potential for the use of a solid-state pulsed laser for photodynamic therapy when used in combination with the tumor sensitizer tin (ll) etiopurpurin dichloride.     

High-performance liquid chromatographic analysis of vancomycin in plasma, bone, atrial appendage tissue and pericardial fluid

Solid-phase extraction coupled with reversed-phase high-performance liquid chromatography and UV detection was employed for the analysis of the antibiotic vancomycin in patient plasma, bone, atrial appendage, and pericardial fluid. Vancomycin was quantitated in samples from patients undergoing cardiac surgery. Calibrations were linear in the range 3-100 micrograms/ml vancomycin; the lower limit of detection was approximately 3 micrograms/ml in fluids with an absolute limit of detection in bone samples of 0.75 microgram per injection.     

METALLOPURPURINS and LIGHT: EFFECT ON TRANSPLANTABLE RAT BLADDER TUMORS and MURINE SKIN

Purpurins are modified chlorins with photodynamic properties. Their strong absorption in the red region of the visible spectrum makes them candidates for use in photodynamic cancer therapy. A series of metal derivatives of the free base purpurins have been synthesized and shown to cause tumor necrosis in transplantable tumors when exposed to visible light. In the following set of experiments, the effects of two metallo-derivatives (tin and zinc) of two purpurins, octaethylpurpurin (NT2) and etiopurpurin (ET2), and light on the N-[4-(5-nitro-2-furyl)-2-thiazolyl] formamide transplantable tumors in Fischer CDF(F344)/CrlBr rats were studied. The photodynamic activity was assessed by a short term assay using tumor dry weight 12 days after purpurin-PDT as a criterion of response. From these experiments it appears that SnET2 greater than SnNT2 greater than ZnET2 greater than ZnNT2 in photodynamic activity. SnET2 was further characterized by attempting to determine the time interval after systemic injection at which maximum therapeutic effect occurred. These studies shown that 24 h after metallopurpurin injection was the optimum time for treatment of tumors with visible light. In a final set of experiments, the effect of solar light on the skin of hairless mice injected with SnET2 was found to be much less injurious than with hematoporphyrin derivative.     

Solvatochromism and piezochromism of pentacyanoferrate(II) complexes in binary aqueous solvent media

Summary The solvatochromic behaviour of a number of pentacyano-ferrates (II), [Fe^II(CN)₅L] ^n-, is described, for solutions in H₂O-alcohol, -Me₂CO and -DMSO mixtures. The strong dependence of solvent sensitivity on the nature of the ligand L is particularly fully documented for H₂OMeOH mixtures (0–100% MeOH). The piezochromic behaviour of seven pentacyanoferrates(II) has been established, in aqueous solution. The connection between piezochromism and solvatochromism is detailed, and the solvatochromic results discussed in terms of (preferential) solvation.