Thianthrene

Abstract: The electrochemical oxidation of oxalate at a platinum electrode in acetonitrile solutions as studied by cyclic and rotating-ring disk voltammetry and controlled potential coulometry shows an irreversible two-electron oxidation at ca. 0.3 V vs. SCE to CO2 with no intermediates detectable by these techniques. The oxidation of oxalate in the presence of several fluorescers (such as rubrene, 9, IO-diphenylanthracene, and the bipyridyl chelates of ruthenium(l1) and osmium(l1)) does not produce light, but emission characteristic of the fluorescer occurs during the simultaneous oxidation of the additive and oxalate. Studies of the conditions for emission in the presence of thianthrene and naphthalene lead to a mechanism for the oxidation of oxalate and the excitation process based on oxidation of oxalate to CzO4-., which undergoes rapid decomposition to COz and C02--. The C02-e can transfer an electron to the additive molecule to produce a radical anion, which can then undergo an ecl annihilation reaction with the electrogenerated radical cation. There has been much interest in the intense chemiluminescence which results from the reaction of oxalyl chloride or oxalate esters and hydrogen peroxide in the presence of fluorescent compounds in nonaqueous solvents.’-3 In the proposed mechanism for these processes, the reaction between the oxalate ester and H202 produces the dioxetanedione (1) as an

Abstract: Diffuse reflectance and transmission flash photolysis have been used to study the primary reaction intermediates in titanium dioxide (TiO{sub 2}) photosensitized reactions of potassium iodide, 2,4,5-trichlorophenol, methyl viologen dichloride, potassium tetrachloroplatinum(II), tris(1,10-phenanthroline)-iron(II) perchlorate, N,N,N{prime},N{prime}-tetramethyl-p-phenylenediamine, and thianthrene. In the cases where the product of OH radical mediated oxidation is different from that of direct electron transfer oxidation, only products of direct electron transfer oxidation are observed. The products of direct electron transfer and OH radical mediated oxidation of iodide and tetrachloroplatinum are identical. The transient decay kinetics in TiO{sub 2} powder systems appear to be first order with a Gaussian distribution of reaction rate constants reflecting the distribution of particle radii.

Abstract: High refractive aromatic polyimides (PIs) containing a thianthrene-2,7-disulfanyl moiety in their main chain have been developed. The PIs were prepared from a newly developed aromatic diamine 2,7-bis(4-aminophenylenesulfanyl)thianthrene (APTT) and several aromatic dianhydrides by a two-step polycondensation procedure. The relationships between the structures and the thermal, mechanical, and optical properties of the flexible, tough, transparent, and amorphous PI films were established. Introduction of the thianthrene-2,7-disulfanyl group endowed the PIs with good combined properties, including high thermal stability with 10% weight loss temperatures (T10%) higher than 500 °C in nitrogen and the glass transition temperatures (Tgs) higher than 200 °C, good transparency with transmittances higher than 80% at 500 nm, and refractive indices higher than 1.73 at 632.8 nm. Because of higher sulfur content, the refractive indices of the PIs we synthesized are higher than those of PIs derived from the other sulfur-...