Electronic spectra alcohols

The complexes [Ru(bpy)2L]+ (HL = acetylacetone, trifluoroacetylacetone, hexafluoroacetylace-tone, tropolone or dibenzoylmethane) have been prepared and characterized they act as catalysts for the oxidation of alcohols, 3,5-di-tert-butylcatechol and alkanes in the presence of appropriate co-oxidants." Perchlorate salts of [Os(bpy)2L] in which HL = salicylaldehyde, 2-hydroxyaceto-phenone or 2-hydroxynaphthaldehyde, are formed from reactions of [Os(bpy)2Br2] with HL. The structure of the salicylaldehyde derivative has been determined. Chemical and electrochemical oxidations of [Os(bpy)2L]" yield the corresponding low-spin Os species from which [Os(bpy)2L]+ can be regenerated." " [Ru(bpy)2L]" (HL = salicylic acid) has been prepared and structurally characterized as the tetrahydrate. Absorptions at 590 nm, 400 nm, and 290 nm in the electronic spectrum have been assigned to Ru bpy CT transitions electrochemical oxidations of the complex have been investigated." ... 

For the experiments that measure the solvation of the electron in an alcohol, different neat alcohols were placed in a flow cell and the kinetics at different wavelengths and the evolution of the spectra were observed [15-17]. Kinetics were determined to the blue side of the solvated electron spectrum. The temperature could be lowered to provide data over a range of temperatures. The lower-temperature experiments all utilized n-propanol or 2-propanol because they have a long liquid range [18]. 

In experiments done by Baxendale [24] and Baxendale and Sharpe [25] in mixed n-propanol-hexane systems, it was found that at low concentrations of alcohol, a solvated species was formed however, it was not the solvated electron. The existence of the solvated species was determined by the decrease in mobility of the electron in the solvent. The mobility never decreased to the level that would be expected for the solvated electron and no evidence of the solvated electron spectrum was detected. 

At least four protonation-deprotonation equilibria have been implicated in catalysis, having p a values 6.4, 7.6, 9.2 and 11.2.562,563 The pKa of 9.2 has been attributed to the deprotonation of the zinc-bound water, and the values of 7.6 and 11.2 to its deprotonation in the binary complexes with NAD+ and NAD(H) respectively.563-565 The pJ a value of 6.4 has been assigned to the deprotonation of the zinc-coordinated alcohol.566 The electronic spectra of Co(c)2Zn(n)2-LADH and its binary complex with NAD+ are pH dependent, with pKa values of around 8 and 9 respectively.567 These have been related to the pKa values of 7.6 and 9.2 reported for the Zn4 enzyme described above. The electronic spectrum of the binary complex of Co(c)2Zn(n)2-LADH with NADH is independent of pH in the range 6 to 9. 

The free ligand is stable to the atmosphere and can be stored indefinitely. It is soluble in nonpolar solvents, for example, benzene, toluene, and halohydro-carbons, and to a lesser extent in acetonitrile. It is insoluble in primary alcohols and water. The nmr spectrum in CDC13 consists of a simple four-line spectrum 2.12 (12H), 4.87 (2H), 6.98 (8H), 12.58 (broad, 2N—H) ppm. The compound melts sharply at 243°. The electronic spectrum contains the following absorptions 340 (emax = 39,700), 269 (emax = 15,100), 255 nm (emax = 18,400). 

VO(tpp)-CH3OH, is slightly soluble in CHC13 and CH2C12, less soluble in pyridine, and insoluble in water and alcohols. The material is stable in the solid state and stable in solution when protected from the light. The electronic spectrum contains bands at 423, 508, 547, and 581 nm with molar absorptivities of 50,100, 4900, 22,500 and 4160, respectively. 

The association constant of pyridazine with ethanol was found to be 4.9 (from electronic absorption spectra) and 6.8 (infrared absorption spectra), and the corresponding values for the strength of the hydrogen bond are 4.2 and 4.6 kcal. The hydrogen-bonded form of P3n-idazine was considered to comprise one alcohol at one azine-nitrogen at small mole ratios of alcohol to azine and to involve the second nitrogen at high mole ratios (an additional shift in the electronic spectrum. The association constants (3.1-3.8) of pyridine, quinoline, and isoquinoline with methanol in carbon tetrachloride have been determined by infrared spectroscopy. 

Abramczyk H, Kroh J. (1992) Near-IR absorption spectrum of the solvated electron in alcohols and deuterated water. Radiat Phys Chem 39 99-104. 

A. Borin-Carlos, M.H.M. Olsson, U. Ryde, B.O. Roos, E. Cedergren-Zeppesauer A. Merli (2000) A theoretical study of the structure and electronic spectrum of Cu-substituted alcohol dehydrogenase , J. Am. Chem. Soc. submitted. 

Pulse radiolysis provides also means to determine the size of chemically prepared CdS clusters in measuring their reaction rate with OH radicals. The mechanisms of such an electron transfer process from the surface of CdS, CdTe and ZnTe, PbS semiconductor particles to OH radicals, and from solvated electrons or alcohol radicals to the particle were studied. The absorption spectrum of CdS with an excess electron is blue-shifted. Colloidal nanoparticles (2 nm) of chalcopyrite CuFeSj are oxidized in their first monolayer by Fe "ions induced by a pulse. 

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