Ultraviolet, absorption spectrum

The ultraviolet absorption spectra of 1,7-phenanthroline,19,20,22,64 1,8-phenanthroline,64 1,10-phenanthroline,18-20,23,24,64,92-95 2,7-phen- 

The UV spectra of all ten of the parent phenanthrolines in hexane or heptane solution were taken by Perkampus and Kassebeer.12 Their 

The spectrum of 1,10-phenanthroline in polarized light102 has also been compared with that of phenanthrene.103 

The characteristic ultraviolet absorption spectra of carbazole, 3-methyl-, formyl- and methoxycarbazoles (18) continue to be useful in structure elucidation studies. Uv absorption data of the alkaloids reported after 1977 are detailed in Table 2. 

A strong IR band near 750 cm Ms characteristic of the four adjacent unsubstituted positions in ring A of carbazomycin-B (5) and -A (6) (107), while a carbonyl bond at the unusually low frequency of 1630-1645 cm is diagnostic of a formyl group at C-3 chelated to the hydroxyl at C-2 in various alkaloids. 

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Section A,7, Applications of infrared and ultraviolet absorption spectra to organic chemistry, should provide a brief introduction to the subject. 

The ultraviolet absorption spectra of most new thiazoles currently synthesized have been described and occasionally used for structural... 

TABLE 1-16 ULTRAVIOLET ABSORPTION SPECTRA OF THIAZOLE AND ITS MONOMETHYL DERIVATIVES... 

TABLE 1-17. ULTRAVIOLET ABSORPTION SPECTRA OF SOME TYPICAL derivatives OFTHIAZOLE IN EtOH SOLUTION... 

TABLE 1-19. ULTRAVIOLET ABSORPTION SPECTRA OF THIAZOLIUM TOSYLATES IN EtOH (186) COMPARED WITH CALCULATED TRANSITION ENERGIES (187)... 

FIGURE 4.15 The ultraviolet absorption spectra of the aromatic amino acids at pH 6. 

Methyloxindole and dimethyl acetylenedicarboxylate with me-thanolic sodium methoxide gave two addition products which from their ultraviolet absorption spectra are suspected to be the geo-... 

Pyrazole and its 3,5-dimethyl and 3,4,5-trimethyl derivatives combined with two moles of dimethyl acetylenedicarboxylate giving products of similar ultraviolet absorption spectra to the parent pyrazoles. These products [e.g., (69)] do not possess the strong broad absorption at ca. 3.20 /u, characteristic of the bonded N—H group which is present in the parent pyrazoles and are formed by two successive Michael addition reactions. In the case of 3,5-dimethylpyra-zole, the initial fumarate (68) has been isolated and possessed a more conjugated type of absorption spectrum to those of the dipyrazolyl-... 

The 9ai7-quinolizine structure (82) for the labile adduct from 3,5-dimethylpyridine was clearly established by the nuclear magnetic resonance studies of Richards and Higham, and subsequent work showed the labile adduct from 3-methylpyridine was analogous. As the labile adducts from all the pyridines and benzopyridines so far examined have very similar infrared absorption spectra in the 5-7 yn. (carbonyl and aromatic) region and within quite close limits very similar ultraviolet absorption spectra, it can be concluded that all are derivatives of 9aH-quinolizine,... 

The stable adducts form salts with perchloric acid in methanol and the ultraviolet absorption spectra of these salts fall into two classesd The spectra of the cations from both tetramethyl 4f/-quino-lizine-l,2,3,4-tetracarboxylate and its 7-methyl derivative are very similar and closely resemble that of 3,4-dihydroquinolizinium iodide. This strongly suggests that the proton has added at position 3 yielding cations such as (97). 

The physical properties of the pyridopyrimidines closely resemble those of their nearest A-heteroeyclie neighbors the quinazolines and the pteridines. Thus, in common with the pteridines, the presence of groups capable of hydrogen-bonding markedly raises the melting point and lowers the solubility. - The acid dissociation constants (pif a values) and ultraviolet absorption spectra of all four parent pyridopyrimidines have been determined by Armarego in a comprehensive study of covalent hydration in these heterocyclic systems. The importance of these techniques in the study of covalent hydration, and... 

Treatment of isohortiamine (363) with acid or base leads to a pronounced change in the visible and ultraviolet absorption spectra. The structures shown, in which the 1,2-bond of the jS-carboline moiety... 

That the ind-N atom in the anhydro-bases is the basic center is also obvious from a consideration of the ultraviolet absorption spectra of the anhydro-bases. In aqueous 0.1 A hydrochloric acid as well as in neutral alcoholic solutions each carboline anhydro-base gives rise to an ultraviolet absorption spectrum identical with that of the parent carbolinium salt. In alkaline solutions (pH above 11.5 in the case of the... 

The ultraviolet absorption spectra of the anhydro-bases in acid solution or in protic solvents are those of the 3,4-dihydro-)3-carbolinium ion (Ajnax 355 mp, for 438b and 438c). In alkaline solution and in nonionizing solvents absorption at a shorter wavelength (A ax 315 m/x) is observed. In general, solutions of the anhydro-bases in acid and in protic solvents are more deeply colored than their solutions in basic or in non-ionizing media. 

The third structural possibility, the formulation of the compounds as pseudo-bases (445) was eliminated in the case of the anhydro-bases derived from p /r-iV -alkyl-l-methyl-3,4-dihydro-j8-carbolinium salts on the basis of their ultraviolet absorption spectra. A structure such as 445 demands indole-type absorption (A jax 280 mp) which was not encountered in the spectra of the anhydro-bases under discussion. This is in accord with general experience. Pseudo-bases are generally found only when dehydration to anhydro-bases is structurally impossible Indole-type absorption was indeed found in the case of the product obtained by treatment of 3,4-dihydro-)3-carboline methiodide (452 R = H) with alkali.In acid solution this compound gave the expected absorption (A jax 355 mp). In alkaline solution, however, an indole-type absorption (A jax 285 mp) was observed. On this basis formulation of the product as a derivative of 2-formylindole (454) ( max 315 mp) was rejected. Although the indole-type absorption is in accord with the pseudo-base structure 453 (R = H), the elemental analysis and molecular weight were not compatible with this formulation and the product was regarded as a dimeric anhydro-base (455). 

The ultraviolet absorption spectra of carboline derivatives have been repeatedly recorded. Since the basic jpyr-N in the carbohnes and in 3,4-dihydro-jS-carbolines is part of a conjugated system, protonation affects the electronic absorption spectra significantly. It is unfortunate therefore that the spectra of the protonated, as well as those of the unprotonated, species have not been reported in all instances. Protonation leads to a bathochromic shift of 20-30 mp,. This is illustrated by the absorption of j3-carboline, 1-methyl-jS-carboline, 7-methoxy-l-methyl-jS-carbohne, and the salts of these compounds. 

The ultraviolet absorption spectra of 3,4-dihydro-jS-carboline derivatives exhibit a dependence on pH similar to that shown by the speetra of the fully aromatie compounds. 3,4-Dihydro-/S-carboline and 1-methyl- and 7-methoxy-l-methyl-3,4-dihydro-jS-carbo-line serve as examples. The quaternary 3,4-dihydro-jS-earbolin-ium salts obtained on p /r-A-alkylation of these dihydro-j3-earbo-lines show a bathoehromic shift of 5 mp, eompared to the... 

Ultraviolet absorption spectra of tetrahy dro-1,3-oxazines do not show any maximum. Only after the introduction of a chromophoric group do bands appear. Thus 5-nitro derivatives show a strong maximum near 270 m/A, which is typical for a nitro group, and another one near 200 m(x which is probably also produced by the nitro group.In the instance of 5-nitro-5-hydroxymethyl derivatives, the absorption is much weakened this was explained by Urbanski in terms of a hydrogen bond between the hydroxyl and the nitro group. Other chromophores, such as C=0, C=NH, C—C, also cause the appearance of absorption maxima in the range 210-265 m/A and near 360... 

Ultraviolet absorption spectra were also applied in the investigations on photophysical, photochemical, and photochromic behavior of some... 

Properties. Cypridina luciferin is soluble in water, methanol and other alcoholic solvents, but not in most aprotic solvents. The ultraviolet absorption spectra of luciferin and oxyluciferin are shown in Fig. 3.1.3. Luciferin in neutral solutions is yellow (lmax 432 nm ... 

Visible and ultraviolet absorption spectra are measured in an absorption spectrometer. The source gives out intense visible light or ultraviolet radiation. The wavelengths can be selected with a glass prism for visible light and with a quartz prism or a diffraction grating for ultraviolet radiation (which is absorbed by glass). A typical absorption spectrum, that of... 

Ultraviolet absorption spectra were obtained from a Cary 118C Spectrophotometer. Luminescence measurements were obtained from a Perkin-Elmer Model MPF-3 Fluorescence Spectrophotometer equipped with Corrected Spectra, Phosphorescence and Front Surface Accessories. A Tektronix Model 510N Storage Oscilloscope was used for luminescence lifetime measurements. Fiber irradiation photolyses were carried out in a Rayonet Type RS Model RPR-208 Preparative Photochemical Reactor equipped with a MGR-100 Merry-go-Round assembly. 

The ultraviolet absorption spectra of compounds II from D-glucose and XI from D-fructose show an absorption band at 250 m/j, in accordance with their furan character.9 The product of periodate oxidation (V) and the dimethyl ester of the derived dicarboxylic acid (III) absorb at 285 and 262 m/i, respectively. The anhydrides of the condensates, XXXIV, do not exhibit selective absorption in the ultraviolet region, but the product of their oxidation (XXXVI) with periodic acid shows8 a band at about 270 m/i. 

The ultraviolet absorption spectra of kojic acid and its 5,7-diacetate were determined by Stacey and Turton,83 the characteristic absorption maximum of kojic acid being located at 3150 A. and that of the diacetate at 2550 A. However, Berson and coworkers108a reported that a neutral methanolic solution of kojic acid had its peak absorption at 2690 A. and an alkaline solution showed a bathochromic shift of the peak to 3160 A. 

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