Michael R. Detty

Synthesis of 1,3-ditellurole and ditellurolylium cations

Abstract 1,3-Ditellurole was synthesized and shown to oxidize to the 1,3-ditellurolylium ion, which rearranges to a 1,2-ditellurolylium ion.

Photosensitization of human glioma cells by chalcogenapyrylium dyes

Chalcogenapyrylium (CP) dyes which are specifically activated by red and near infrared light (600–900 nm) were examined as potential photosensitizers for photochemotherapy of malignant gliomas. Eleven CP dyes of varying chemical structure and redox potential were evaluated for selective toxicity against glioma and normal skin fibroblast cell cultures both before and after light activation. Eight of eleven CP dyes exhibited differential toxicity to tumor over fibroblast cells at dye concentrations of 1.0 µM. Dose dependent toxicity was seen both in the dark and after laser light activation. The toxicity of two of the CP dyes was significantly enhanced by photoactivation with 800 nm light.The CP dyes that absorb light maximally between 775 and 850 nm, in the range of excellent light penetration through brain, appear to be promising candidates as photosensitizers for treating malignant brain tumors.

Conducting salts of (telluropyranyl)telluropyrans

Abstract Conducting complexes of (telluropyranyl)telluropyran donors with tetracyanoquinodimethane (TCNQ) and the closed-shell anions tetrafluoroborate and perchlorate were prepared.

Regiochemistry and stereochemistry of oxirane ring-opening with silyl halides

Abstract The ring-opening of various styrene and stilbene oxides with silyl halides was examined. The regiochemistry of ring-opening was independent of the silyl halide used, but the stereochemistry of ring-opening was sensitive to both the choice of halide and the steric bulk of groups attached to silicon.

Trimethylsilyl iodide. preparation from and catalytic behavior with phenylselenotrimethylsilane

Abstract Trimethylsilyl iodide (TMSI) and diphenyldiselenide are produced by the addition of iodine to phenylselenotrimethylsilane. TMSI generated in this manner cleaves a variety of C-O bonds and catalyzes 1,2 and 1,4 additions of phenylselenotrimethylsilane to various carbonyl compounds.

Squarylium dyes based on 2,6-di-tert-butylselenopyrylium or telluropyrylium nuclei

The condensation of 2,6-di-tert-butyl-4-methylselenopyrylium and -telluropyrylium salts with squaric acid gives squarylium dyes with absorption maxima at 847 and 910 nm, respectively, in dichloromethane. The condensation of a 2,6-di-tert-butyl-4-ethylselenopyrylium salt with squaric acid gives the corresponding dimethyl-substituted squarylium dye with an absorption maximum at 906 nm in dichloromethane. Electrochemical reduction and oxidation potentials of these dyes are compared to those of the corresponding squalium dyes based on pyrylium and thiopyrylium nuclei

Rational Design Of Properties In Chalcogenapyrylium Dyes.

The chalcogenapyrylium dyes can be treated as model systems whose properties can be designed by proper choice of substituents. The use of different chalcogen atoms and substituents in the dye chromophore allows control of the wavelength of absorption maxima, redox properties, fluorescence yields, and hydrolytic stability.

Heavy Atom Effects in Tellurapyrylium Dyes Useful in Photodynamic Therapy and Catalytic Generation of H2O2

Abstract The large rate of intersystem crossing between singlet and triplet states of tellurapyrylium dyes leads to efficient generation of singlet oxygen in irradiated airsaturated aqueous solutions containing these dyes. One reaction of tellurapyrylium dyes with singlet oxygen and water is the formation of dihydroxy tellurane [tellurium(IV)] species. We have found that the photochemical generation of dihydroxy telluranes is reversible thermally. The tellurapyrylium dye is regenerated while a molecule of hydrogen peroxide is produced. The thermal generation of hydrogen peroxide coupled with a photochemical generation of singlet oxygen allows a catalytic cycle to be devised for the conversion of oxygen and water to hydrogen peroxide. The dihydroxy telluranes are efficient two-electron oxidizing agents and can be used as catalysts to accelerate reactions using hydrogen peroxide as a two-electron oxidizing agent. Examples of tellurapyrylium dye-mediated reactions of hydrogen peroxide include reactions of le...