Aqueous absorption spectra

Unfortunately, addition of copper(II)nitrate to a solution of 4.42 in water did not result in the formation of a significant amount of complex, judging from the unchanged UV-vis absorption spectrum. Also after addition of Yb(OTf)3 or Eu(N03)3 no indications for coordination were observed. Apparently, formation of a six-membered chelate ring containing an amine and a ketone functionality is not feasible for these metal ions. Note that 4.13 features a similar arrangement and in aqueous solutions, likewise, does not coordinate significantly to all the Lewis acids that have been... 

The ultraviolet absorption spectrum of thiazole was first determined in 1955 in ethanolic solution by Leandri et al. (172), then in 1957 by Sheinker et al. (173), and in 1967 by Coltbourne et al. (174). Albert in 1957 gave the spectrum in aqueous solution at pH 5 and in acidic solution (NHCl) (175). Nonhydroxylic solvents were employed (176, 177), and the vapor-phase spectrum was also determined (123). The results summarized in Table 1-15 are homogeneous except for the first data of Leandri (172). Both bands A and B have a red shift of about 3 nm when thiazole is dissolved in hydrocarbon solvents. This red shift of band A increases when the solvent is hydroxylic and, in the case of water, especially when the solution becomes acidic and the extinction coefficient increases simultaneously. 

Moreover, solutions of TII3 in MeOH do not show the visible absorption spectrum of I3 and, when shaken with aqueous Na2C03, give a precipitate of TI2O3, i.e. ... 

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... 

In the experiments descrihed above no tendency was found for the (ClOi)- ion to form a molecular ion by combination with Fe+++. The absorption spectrum characteristic of the Fe+++ ion in aqueous solution was therefore determined by studying solutions of FeC104 as a function of the hydroxyl-ion concentration. 

Fig. 9.13 Absorption spectrum of one of the luciferin precursors of Mycena cit-ricolor in methanol (dash-dot line, A.max 369 nm). The absorption and fluorescence emission spectra of the decylamine-activation product of the same precursor in neutral aqueous solution (solid lines abs. Amax 372 nm and fl. Xmax 460 nm), and in ethanol (broken lines abs. Amax 375 nm and fl. Amax 522 nm). The chemiluminescence spectrum of the same activation product (dotted line, A.max 580 nm). The dotted line (7max 320 nm) is the absorption spectrum of M. citricolor natural luciferin reported by Kuwabara and Wassink (1966).

Aqueous geranium extract inhibited TMV starch lesion formation in cucumber cotyledons. Starch lesions were completely inhibited by vacuum infiltrating effective dosages at any time between 1 and 33 hours after virus inoculation. Between 33 and 72 hours, inhibition decreased progressively. The active ingredient in the geranium extract was identified by means of ultraviolet absorption spectrum and... 

Part of the absorption spectrum of an aqueous solution of neodymium(iii) -configuration/ - is shown in Fig. 10-4. The situation shown there is quite typical of the whole of the lanthanoid series i.e. we could have chosen any/" configuration equally well to illustrate the main characteristics of the spectra of lanthanoid complexes. We shall focus on three main features splittings, band widths and absolute excitation frequencies. 

Figure 10-4. Absorption spectrum of an aqueous solution of ions.

Licht et al. [17] developed a method of numerical analysis to describe the above-quoted equilibria of the 11 participating species (including alkali metal cations) in aqueous polysulfide solution, upon simple input to the algorithm of the temperature and initial concentration of sulfur, alkali metal hydroxide, and alkali metal hydrosulfide in solution. The equilibria constants were evaluated by compensation of the polysulfide absorption spectrum for the effects of H8 absorption and by computer analysis of the resultant spectra. Results from these calculations were used to demonstrate that the electrolyte is unstable, and that gradual degradation of polysulfide-based PECs (in the long term) can be attributed to this factor (Chap. 5). 

The absorption spectrum of Ag in aqueous solution has a broad band with a maximum at 340 nm. The Ag atoms rapidly disappear as they react with Ag" " ions to form Ag which absorbs at 310 nm... 

The reversible oxygenation of Fe(DMG)2 (B)2 in aqueous dioxane solution, as monitored by reversible changes in the visible absorption spectrum and manometric oxygen evolution, has been reported (55), but in a more recent study 54) it was not possible to confirm the earlier findings. However it was established that there was a slow irreversible... 

FIGURE 1.2 Absorption spectrum of 52 obtained by LFP of naphthol 50, in aqueous acetonitrile. Source Data taken with permission from Ref. [40]. 

FIGURE 12.4 Lycopene photodegradation in 0.02 M Triton X-100 aqueous solutions illuminated with a 150 W (> 380 nm) filament lamp. Inset evolution of the difference absorption spectrum (AA). 

Fig. 6.2 Absorption spectrum of silver nanoparticles prepared from an aqueous solution (70 ml) of AgN03 (0.2 mM) containing polyethylene glycol (0.1 wt%) and ethylene glycol (0.1 M)...

Henglein A, Ershov BG, Malow M (1995) Absorption spectrum and some chemical reactions of colloidal platinum in aqueous solution. J Phys Chem 99 14129-14136... 

Figure 4. Absorption and emission spectra of Ru(bpy)s2+ and the excited state transient absorption spectrum of Ru(bpy)s2 Key A, absorption spectrum of Ru(bpy)s2V B, absorption spectrum of Ru(bpy)32+ and C, emission spectrum. Conditions room temperature, and aqueous solution. (Reproduced from Ref. 19c. Copyright 1981, American Chemical Society.)...

With this objective, experiments have been made on the dehydration of the polyhydroxyl chain of 2-D-ara6mo-tetrahydroxybutylquinoxaline (L) under relatively mild conditions.38 After heating a solution of the compound in 1% aqueous hydrochloric acid, there may be isolated an appreciable quantity of a crystalline product which is not that (LII) expected by analogy with the dehydrations already described. Its elementary analysis corresponds to the formula C12H8N2O and it is optically inactive. The ultraviolet absorption spectrum of an alcoholic solution shows maxima at 365... 

A stopped-flow methodology using deuterium exchange was employed to study the binding dynamics of 1 with ct-DNA.93 This method relies on the fact that the absorption spectrum of 1 changed upon deuteration, and the rate for deuteration was slowed down when 1 was bound to DNA when compared to the rate in aqueous solution. This method was validated by comparing the rate constant values with... 

The spectrum exhibits maxima at 281 and 223 nm with molar absorptivities of 4,768 and 14,400, respectively. When aqueous potassium hydroxide is added to the methanolic solution of dobutamine hydrochloride the maxima at 281 and 223 shift to 293 (e=6,100) and 240 nm, respectively. These shifts are reversible by addition of hydrochloric acid. When the absorption spectrum of the drug is recorded in water rather than methanol, slight shifts in peak positions and intensities are observed ... 

Figure 3. Ultraviolet Absorption Spectrum of Hydralazine Hydrochloride, 9 9 mg per liter, Aqueous Solution.

UV-visible absorption spectrum in an aqueous bilayer solution... 

Encapsulation of 3,3 -diethyl-thiacarbocyanine iodide (DTCI) with CB7 resulted in a fivefold increase of its quantum yield. The encapsulation decreases the 550 nm peak in the absorption spectrum and increases the shoulder at 510 nm [47]. The fluorescence lifetime for DTCI in aqueous solution is 0.12 ns, but in the presence of CB7 it increased to 1.07 ns. The association constant of 1 1 complexes of DTCI with CB7 was determined to be K = (2.8 0.2) x 104 M-1. 

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