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The photophysical properties of the thiopyrylium dye 1-S and the related thio (6-S0 and selenopyrylium (6-Se) analogues in aqueous solution were examined. It was shown that not only the fluorescence yield for the production of [1.sup.O.sub.2] increase upon binding to DAN in these systems but also the quantum yield.

9-Formyljulolidine is oxidized by using a microwave-assisted Willgerodt-Kindler reaction to the N-piperidine or N-morpholine julolidine-9-thioamide. The products are converted to chalcogenoxanthones with phosphorus oxychloride and triethylamine (PO[Cl.sub.3]/[Et.sub.3]N).

The synthesis of chalcogenorhodamines by using dianions generated from 5-bromothiophene-2-carboxylic acid and 3-bromothiophene-2-carboxylic acid through metal-halogen exchange with tert-butyllithium (t-BuLi) are reported. The analysis has shown that the deprotonation is faster than metal-halogen exchange with the bromothiophene-2-carboxylic acids using t-BuLi.

We report on a new sensor strategy that we have termed site selectively templated and tagged xerogels (SSTTX). The SSTTX platform is completely self-contained, and it achieves analyte recognition without the use of biomolecules. To illustrate the SSTTX scheme's potential, we present results for the selective detection and quantification of a model compound, 9-anthrol. The first-generation SSTTX shows the following: (i) exhibits an apparent dissociation constant of (1.8 [+ or -] 0.3) x [10.sup.-4] M for 9-anthrol; (ii) provides 0.3 [micro]M detection limits for 9-anthrol; (iii) yields a 45-s response time (2-[micro]m-thick film); (iv) is completely reversible (6% relative standard deviation after 25 cycles); (v) yields a selectivity factor for 9-anthrol over several structurally similar analogues/ interferences (e.g., anthracene, 9,10-anthracenediol, benzophenone, 2-naphthol, phenol, and pyrene) of between 290 and 520; and (vi) is stable (

Di-n-hexyl telluride, di-p-methoxyphenyl telluride and (S)-2-(1-N,N-dimethylaminoethyl)-phenyl phenyl telluride catalyzed the oxidation of PhSH to PhSSPh with H2O2 in MEOH. The kinetics associated with each step of the catalytic cycle for the thiol peroxidase-like activity of several diorganotellurides using stopped-flow spectroscopy is described.

The bromination of olefins and subsequent debrominations of the vic-dihalides that results from the reaction provides a means of protecting the carbon-carbon double bond during synthesis. The use of iodide and aryltelluride anions, which are strongly nucleophilic debrominating compounds, results in the initiation of vic-dibromide debrominations through a nucleophilic attack at one bromine. Using a less nucleophilic debrominating agent such as dihexyltelluride results in the formation of bromonium ion intermediates by the vic-dibromide.

Research was conducted to examine chalcogen atom effects on the rates of hydrolysis of chalcogenopyrylium dyes. Results indicate that the qualitative ordering of the rates can be rationalized in terms of higher stability of the thiopyrylium ring relative to the selenopyrylium ring. Findings also show that the decreasing electronegativity of the chalcogen atoms as size increases would tend to stabilize the cationic charge inductively, predicting the opposite trend in stability.

Research was conducted to assess the viability of a novel synthetic approach to 2-azetidinones involving the one-pot addition/cyclization of an amine to propenoic acid derivatives having an electron-withdrawing substituent at the 2-position. Evidence suggests that a 2-phenylsulfoxo substituent gives a 95:5 ratio of 1,2- to 1,4-addition whereas a 2-phenylsulfonyl substituent provides a 16:84 ratio of 1,2- to 1,4-addition. Inclusion of electron- withdrawing substituents on the arylsulfonyl group increases the amount of 1,4-addition while the opposite applies to electron-donating substituents.

The modifications to the procedure of H Suzuki, A Kondo and A Osuka which describes a catalytic version of stoichiometric reactions are limited by the reversibility of the process. The procedure is more general for vic-dibromides which worked with at least one benzylic bromide. Results indicate that the more electron-rich diorganotellurides are better debrominating agents than (p-CH3OC6H4)2Te in stoichiometric reactions.

Research was conducted to examine the debrominations of vic-dibromides with diorganotelluries. Several observations were noted including the highly stereoselective reaction, the acceleration of the reaction by more electron-rich diorganotellurides, in more polar solvent and through the adition of carbocation-stabilizing substituents to the carbons. Another finding is the fact that erythro-dibromides were more reactive than threo-dibromides.

The products of the hydrolysis of chalcogenopyrylium dyes at alkaline pH under both anaerobic and aerobic conditions were analyzed. The types of hydrolysis products observed were found strongly dependent on the identity of the chalcogen atoms in the pi-framework and on the presence of molecular oxygen during the hydrolysis. It was found that chalcogenopyranomes produce modest yields in aerobic reactions.

Organotellurium catalysts (1-3) are used to oxidize sodium bromide, sodium chloride and sodium iodide to positive halogens with hydrogen peroxide in two-phase systems of dichloromethane and pH 6 phosphate buffer. Results show that the relative rates of catalysis for for equimolar amounts of 1-3are identical to the relative second-order rate constants of the organotellurium compounds with hydrogen peroxide. This finding suggests that oxidation of the catalysts is the rate-determining step of the process.

Heteroatom scrambling occurs due to the formation of unsymmetrical tris(chalcogenopyramylmethylidene)methanes during the synthesis of unsymmetrical chalcogenopyrylium dyes. The complete chalcogenopyranyl ring is involved during heteroatom scrambling and Reverse aldol reaction with dyes has no significant influence on scrambling mechanism. Dyes have found various applications in optical recording, electrophotography and thermal dye transfer. The experimental procedure for the synthesis of unsymmetrical dyes and tris(chalcogenopyramylmethylidene)methanes is discussed.

4H-thiopyran-4-one 1,1dioxides is synthesized by the use of sodium hydrosulfide hydrate instead of hydrogen sulfide gas. The use of sodium hydrosulfide hydrate provides large quantities of the thiopyran dioxides. The process of synthesis involves the double dehydrogenation of the saturated sulfones by using hetroaryl or aryl substituents.

Condensation of malonitrile having corresponding 4H-1,1-dioxothiopyran-4-one results in the formation of a variety of 4H-1,1-dioxo-4-(dicyanomethylidience)thiopyrans. The thiopyrans thus produced are capable of functioning as electron-transport materials. The x-ray crystal structure of the thiopyrans reveal that these complexes are made of a planar ring which is boat shaped in the tert-butyl-substituted derivatives.

Kinetic studies of the oxidation of glutathione to glutathione disulfide by organotellurium compounds reveal the involvement of two discrete steps, a fast reaction and a slow reaction, in the oxidation. Kinetic data enable the determination of second-order rate constants for both fast and slow reactions. Formation of tellurium(II) compound accompanies the slow reaction. Organoselenium(IV) compounds also exhibit this oxidation behavior, but the rate constants for both steps are significantly lower than those of tellurium analogues.