Wurster’s blue perchlorate

THF tetrahydrofuran, NaNap sodium naphthalenide, Na2St disodium stilbene dianion, BP benzoyl peroxide, DME 1,2-dimethoxyethane, TMBD tetramethylbenzidine dication diperchlorate, WBP Wurster s blue perchlorate, LP lauroyl peroxide, FLSPEC fluorescence spectrum obtained, FPSPEC fluorescence and phosphorescence spectrum obtained, FXSPEC fluorescence and eximer spectra obtained, DPAC12 9,10-dichlorO 9,10-dihydro-9,10-diphenylanthracene. 

More recently, charge-transfer emission was anticipated when solutions of hydrocarbon anion radical salts in dimethoxyethane were mixed with Wurster s blue perchlorate.15 Emission was seen in every instance however, with eight anion radicals derived from 3 to 5 ring-fused aromatic hydrocarbons, the emission was derived from the hydrocarbon rather than the complex. Preliminary studies with smaller hydrocarbons, biphenyl and naphthalene, did show emission in the region (18 kK) where charge transfer was expected. The question as to what pairs of ion radicals will be emissive under what conditions has only begun to be considered. Much opportunity for further experimentation exists in this area. 

Nearly all the nonfluorescent emission bands reported in these studies have been found at longer wavelengths than the expected fluorescence. They have been variously ascribed to eximers6,15 or to phosphorescence1315 of the electroactive substance. Some apparently do not arise from the electroactive compound itself.16 On oxidation of the pyrene anion radical with Wurster s blue perchlorate, an emission band was obtained which corresponded closely to the known pyrene eximer emission.15 Several spectra obtained from polycyclic aromatic hydrocarbons by electrochemical treatment at constant applied voltage have... 

Preannihilative electrochemical oxidation of the phenanthrene anion has given a green emission13,64 spectrally nearly identical to the previously reported room-temperature phenanthrene phosphorescence which is a single broad peak.71 Chemical oxidation of the chrysene anion with Wurster s blue perchlorate produced an emission containing three bands at 19,800, 18,600, and 17,400 cm"1 which seem to correspond to the known phosphorescence bands of chrysene (19,500,18,500, and 16,600 cm-1). Chemical oxidation of the radical anion of N-methylcarbazole has possibly led to phosphorescent emission from this triarylamine.7... 

Wood sugar, AE80 Wood sugar oxime, AE93 Wurster s blue perchlorate, AS51... 

D. D. Thomas, H. Keller, and H. M. McConnell, Exciton magnetic resonance in Wurster s blue perchlorate,. Chem. Phys. 39 2321-2329 (1963). 

In fluid solutions, Faulkner and Bard first found the MFEs on the electrogenerated chemiluminescence of anthracence triplet-triplet annihilation [4], The general features of the MFEs were similar to those observed in crystals the intensity of delayed fluorescence was found to decrease with increasing B from 0 T to 0.8 T and to approach as3miptotically a value which was about 4 % below the zero-field intensity. They also found the MFEs on the anthracene fluorescence in the presence of doublet species such as Wurster s Blue perchlorate [5] the fluorescence intensity was found to be quenched by the doublet species, but the quenched intensity was found to be increased by magnetic fields. Their typical results are shown in Fig. 12-2. Although these MFEs observed in fluid solutions were smaller than those in crystals due to rotational motion of triplet molecules, the MFEs in solutions could also be explained by Eqs. (13-3) and (13-9). The magnetically induced decrease in the... 

Wurster s Blue perchlorate has been the subject of many investigations. Its stability as a solid and in solution, its ease of preparation, and its symmetry make it an ideal model in spectroscopic and magnetic susceptibility studies. It was one of the first cation radicals to be shown to exist both as a monomer and as a dimer in solution (Hausscr, 1956 Bolton et al., 1962) and in the solid state (Duffey, 1962 McConnell and Lynden-Bell, 1962), the dimeric form being obtainable reversibly by lowering the temperature. This phenomenon is widespread among cation radicals and is discussed in section 3. 

Formation of dicationic dimers (90) has been longer known than formation of the monocationic type (89), no doubt because of the availability of and interest in the very stable Wurster Salts. Hausser and Murrell (1957) proposed that the long wave-length absorption band (near 800 nm) of Wurster s Blue perchlorate in ethanol at —90° was caused by two associated, cation radicals lying in parallel planes. Since that time a considerable number of workers have explored the dimerization of Wurster and analogous cation radicals, (e.g. Kawamori et al., 1966 Kimura et al., 1968). Not only does Wurster s Blue cation radical (i.e. TMPD +) associate with itself, but it also forms a spin paired dimer with p-phenylenediamine cation radical (PD +). In fact, Takimoto et al. (1968) conclude from absorption spectroscopy that solutions of TMPD + and PD + in ethanol-ether at —195° contain (PD"+)2 and (PD"+-TMPD +)2 but very little of (TMPD +)2. Dimerization of unlike cation radicals is known in other systems too. Perylene" and naphthacene4-each forms an (M"+)2 dimer in sulfuric acid at reduced temperatures (Kimura et al., 1971). Mixtures of the two cation radicals in sulfuric acid leads to a mixed dimer too, (Perylene "+, naphthacene +), the heat of formation of which (—7-7 kcal mole-1) incidentally, lies between that of the perylene"+ (—8-8) and naphthaccne + (— 5 6) dimers (Yamazakiand Kimura, 1972). 

Another, lower-energy type of Peierls transition is possible for magnetic systems (Wurster s Blue Perchlorate, or alkali TCNQ salts). Then one talks about "spin-Peierls" transitions, whose X-ray signature is a 2kp SDW (spin density wave) which, again, is dynamic and diffuse above the ordering temperature, and static (or "pinned") and sharpened below the transition temperature [72]. 

Wurster s blue perchlorate Feiylene cation (98% H2SO4) Tetracene cation (98% H2SO4) p-Benzosemiquinone anion ... 

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