Spectroscopic evidence

It has long been known that bacterial luminescence is intimately associated with the cells (165), and there is yet no certain evidence that luminescence has been observed apart from the living bacteria. Various means of disrupting cell structure—cytolytic agents, osmolysis, autolysis, mechanical grinding, supersonic vibration—apparently destroy the capacity for luminescence (138), although the activity of certain enzyme systems, 

The results of a recent investigation of the effects of radiation on bacterial luminescence have provided extremely interesting and significant data with respect to the system in these organisms and its relation to that of Cypridina. Earlier studies had not indicated that illumination by visible light causes any effect on the intensity of bacterial luminescence (97), although it was known to reduce the luminescence of Cypridina extracts (96), and the inactivation spectrum by ultraviolet radiation (22,76,77,80) had 

430 m/i. These results are in remarkable agreement with the absorption spectrum of purified Cypridina luciferin (43). The absorption at 465 my that appears during the oxidation of the latter evidently represents the oxidation product of luciferin. Consequently, this wave length would not necessarily be important in the inactivation spectrum. Although the inactivation of purified Cypridina luciferin by visible light appears to depend upon the presence of a sensitizer, it remains possible that the effects in bacteria occur in the luciferin directly, in addition to probable effects of the shorter ultraviolet wave lengths on the luciferase. On the basis of the 

The spectroscopic data, together with the fact that bacterial luminescence is evidently imder the control of an enzyme which is readily denatured by heat as well as by certain other agents, constitute substantial evidence for assuming a fundamentally similar luciferin-luciferase system in both bacteria and Cypridina extracts. 

Direct information about the rate of vibration-vibration transfer between molecules with comparatively high vibrational frequencies can be obtained by 

In the optical fluorescence quenching experiments on mixtures of NO( 4 2 +)+ N2, the former was produced in vibrational levels, v = 3,2 and 1, and transfers involving each of these levels were followed. It was found that more than 85 % of the transfers observed involved exchange of a single quantum, e.g. 

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Sulfonation under mild conditions is reported to yield thiazolyl-2-sulfamic acid, which, when heated in H2SO4. rearranges to 2-aminothiazole-5-sulfonic acid (16. 374. 390. 391). Postovskfi. however, reports exactly the opposite rearrangement (367). and spectroscopic evidence supports his conclusion (368) (see Section III.5). 

Other Hydroperoxides. Several hydrotrioxides including alkyl hydrotrioxides, R—OOOH, have been reported (63,64). There is strong spectroscopic evidence that a-cumyl hydrotrioxide [82951-48-2] is produced in the low temperature ozonization of cumene. Homolytic decomposition of a-cumyl hydrotrioxide in cumene/acetone-hindered phenol resulted in cumyl alcohol as the only organic product (65). Based on the... 

Chlorous Acid. The physical properties of HCIO2 have been determined using acidified alkah metal chlorite solutions. The existence of HCIO2 is based on spectroscopic evidence (6,13,97). 

Pyridazines with a hydroxy group at an a- or y-position to a ring nitrogen atom, i.e. 3-and 4-hydroxypyridazines (4) and (5), exist predominantly in the oxo form. This conclusion is based on spectroscopic evidence from UV spectra of unsubstituted compounds and their A-methyl and O-methyl derivatives in alkaline, neutral and acidic solutions. In some instances, as for example for 6-oxo-l,6-dihydropyridazine-3-carboxamide, there is also evidence from X-ray analysis <54AX199, 63AX318). Maleic hydrazide and substituted maleic hydrazides exist in the monohydroxymonooxo form (6). 

FTIR SPECTROSCOPIC EVIDENCE FOR THE BASICITY INDUCED BY ADSORPTION... 

The spectroscopic evidence suggests that on adsorption of CO, an adsorbed ion and a polymeric form of the CO molecule are formed thus... 

In fact, the sun is not a first-generation main-sequence star since spectroscopic evidence shows the presence of many heavier elements thought to be formed in other types of stars and subsequently distributed throughout the galaxy for eventual accretion into later generations of main-sequence stars. In the presence of heavier elements, particularly carbon and nitrogen, a catalytic sequence of nuclear reactions aids the fusion of protons to helium (H. A. Bethe... 

The chloride can be crystallized but the bromide disproportionates. On the basis of mol wt and infrared spectroscopic evidence the proposed structure is ... 

The solubility of AS2O3 in water, and the species present in solution, depend markedly on pH. In pure water at 25°C the solubility is 2.16 g per lOOg this diminishes in dilute HCl to a minimum of 1.56g per lOOg at about 3 m HCl and then increases, presumably due to the formation of chloro-complexes. In neutral or acid solutions the main species is probably pyramidal As(OH)3, arsenious acid , though this compound has never been isolated either from solution or otherwise (cf. carbonic acid, p. 310). The solubility is much greater in basic solutions and spectroscopic evidence points to... 

M-C (T bonds are not strong and, as might be expected for metals with so few d electrons, little help is available from synergic n bonding for instance, of the simple carbonyls only Ti(CO)6 has been reported, and that only on the basis of spectroscopic evidence. However, as will be seen on p. 972, the discovery that titanium compounds can be used to... 

The parent substance, 3,4-dihydroquinazoline, is strongly basic (pKa 9.19) on account of the amidinium resonance present in the cation. Spectroscopic evidence favors this resonance and is illustrated... 

Syntheses of phthalimidines (e.g., 30) do not in themselves constitute syntheses of isoindoles or isoindolenines, since the lactam from shows no tendency to tautomerize, as discerned from spectroscopic evidence, to lactim forms (31 and 32). However, phthalimidines are... 

The quaternization of pyrazine compounds has not been extensively studied, and, therefore, a detailed discussion of the effect of substituents is not possible. Recently Cheeseman has shown, from spectroscopic evidence, that 2-amino- and 2-diethylamino-pyrazine (50, Y = NH2 and NEt2) quatemize at N-4, although protonation occurs at position-1. Other substituted pyrazines from which quaternary salts of structure 51 are formed include 2-chloro- and 2-... 

Spectroscopic evidence indicates that protonation of 2-fluoro-and 2-chloro-quinoline is not appreciable in O.OlJf aqueous hydrochloric acid. Protonation becomes evident in more strongly acidic solution in the case of the chloro compound without any accompanying decomposition, but the fluoro compound hydrolyzes to carbostyril under the latter conditions. The hydrolysis is acid-catalyzed, but it is doubtful whether protonation on the heterocyclic nitrogen is responsible, owing to its low basicity (presumably below that for the chloro compound). An alternative explanation in this case would be hydrogen bond formation with fluorine, Ar—F. .. H-O+H2. 

Dihydroxypteridine was expected to undergo hydration but, a priori, it was difficult to decide whether covalent hydration would occur across the 3,4- or the 7,8-position, or both. Kinetic and spectroscopic evidence now indicate that addition of water occurs much more rapidly across the 3,4-positions (and, hence, that the energy of activation must be less for this site), but the 7,8-water-adduct is thermodynamically the more stable. With time, the concentration of the species hydrated in the 3,4-position reaches a maximum (about 64% of the total concentration). Thereafter, it falls steadily and the concentration of the 7,8-adduct rises until, at equilibrium, the latter accounts for 92% of the total and the 3,4-adduct for only 7.6%. In 2,6-dihydroxy-4-methylpteridine, the methyl group drastically reduces the extent of water addition to the 3,4-position but does not significantly affect 7,8-addition, so that, spectroscopically, only a first-order conversion of anhydrous molecule into the 7,8-water-adduct is observed. ... 

Indeno[l,2-rf]azepin-4-ol and its 10-bromo derivative appear to be in the lactam form 20. In base solution, however, there is UV and HNMR spectroscopic evidence for the 14k fully conjugated anions, e.g. 21.57... 

Similarly, photolysis of l-(2-azidophenyl)-l/f-pyrazole in acetonitrile in the presence of dipropylamine affords AfN-dipropyl-7-(lF/-pyrazol-l-yl)-3//-azepin-2-amine in low yield (4%).192 Surprisingly, however, photolysis of the corresponding 1-(2-azidophenyl)-3,5-dimethyl-l//-pyrazole (84) in cyclohexane in the presence of the base yields 85 which, on the basis of H NMR spectroscopic evidence, has been formulated as a rare example of a stable 2 H-azepine. 

This was a claim that I and several other authors criticized in a number of journals, but unfortunately not in Nature magazine.11 Although the authors of the Orbitals Observed study protested their innocence, it became clear that their claims had been incorrect and exaggerated.12 In a section of the same paper, I discussed the notion that the 4s atomic orbital is occupied before the 3d orbitals. This has subsequently turned out to be incorrect and there is conclusive spectroscopic evidence to the contrary which seemed to have escaped the attention of several authors who have written on this issue, including myself.13... 

The Raman spectroscopic work of Ja-covitz [31], Cornilsen et al. [32, 33], and Audemer et al. [34] is the most direct spectroscopic evidence that the discharge product in battery electrodes, operating of the pi ji cycle, is different from well-crystallized / -Ni(OH)2. The O-H stretching modes and the lattice modes in the Raman spectra are different from those found for well-crystallized Ni(OH)2, prepared by recrystallization from the ammonia complex, and are more similar to those... 

Changes in relative peak intensity and marginal line shifts have been observed for benzene adsorbed on porous glass (26). More significantly, infrared spectroscopic evidence had been found in the appearance of inactive fundamentals for the lowering of molecular symmetry of benzene on adsorption on zeolites (47). 

Equilibrium constants for complex formation (A") have been measured for many donor-acceptor pairs. Donor-acceptor interaction can lead to formation of highly colored charge-transfer complexes and the appearance of new absorption bands in the UV-visible spectrum may be observed. More often spectroscopic evidence for complex formation takes the font) of small chemical shift differences in NMR spectra or shifts in the positions of the UV absorption maxima. In analyzing these systems it is important to take into account that some solvents might also interact with donor or acceptor monomers. 

Bayliss et al. (1963) emphasize that they did not detect the nitrosoacidium ion in spectrophotometrically determinable concentrations. In our opinion, however, it may be more cautious to say that there is no spectroscopic evidence for two species on the more acidic side of that series of spectra with increasing acid concentrations. 

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