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Spectra, electronic absorption solution

The preceding empirical measures have taken chemical reactions as model processes. Now we consider a different class of model process, namely, a transition from one energy level to another within a molecule. The various forms of spectroscopy allow us to observe these transitions thus, electronic transitions give rise to ultraviolet—visible absorption spectra and fluorescence spectra. Because of solute-solvent interactions, the electronic energy levels of a solute are influenced by the solvent in which it is dissolved therefore, the absorption and fluorescence spectra contain information about the solute-solvent interactions. A change in electronic absorption spectrum caused by a change in the solvent is called solvatochromism. [Pg.435]

The electronic absorption spectra of the products of one-electron electrochemical reduction of the iron(III) phenyl porphyrin complexes have characteristics of both iron(II) porphyrin and iron(III) porphyrin radical anion species, and an electronic structure involving both re.sonance forms Fe"(Por)Ph] and tFe "(Por—)Ph has been propo.sed. Chemical reduction of Fe(TPP)R to the iron(II) anion Fe(TPP)R) (R = Et or /7-Pr) was achieved using Li BHEt3 or K(BH(i-Bu)3 as the reductant in benzene/THF solution at room temperature in the dark. The resonances of the -propyl group in the F NMR spectrum of Fe(TPP)(rt-Pr) appear in the upfield positions (—0.5 to —6.0 ppm) expected for a diamagnetic porphyrin complex. This contrasts with the paramagnetic, 5 = 2 spin state observed... [Pg.248]

Figure 5.7 Room-temperature electronic absorption, excitation and emission spectra for 2 in aqueous solution. The excitation spectrum of 2 was recorded by monitoring emission at 400 nm. Reproduced with permission from [31]. Copyright (2004) Royal Society of Chemistry. Figure 5.7 Room-temperature electronic absorption, excitation and emission spectra for 2 in aqueous solution. The excitation spectrum of 2 was recorded by monitoring emission at 400 nm. Reproduced with permission from [31]. Copyright (2004) Royal Society of Chemistry.
Figure 10.8 Room temperature electronic absorption spectrum recorded on a THF solution of 6. Bands are marked by the nominal Russell-Saunders multiplet to which the excitation occurs. (Adapted from Ref. [34], Copyright (2011) Nature Publishing Group.)... Figure 10.8 Room temperature electronic absorption spectrum recorded on a THF solution of 6. Bands are marked by the nominal Russell-Saunders multiplet to which the excitation occurs. (Adapted from Ref. [34], Copyright (2011) Nature Publishing Group.)...
Dibenzothiophene acts as a 7r-electron donor and readily forms complexes with known electron acceptors. In such cases the electronic spectrum of a solution of the two compounds shows a new absorption band, usually in the visible region. The order of donor strengths of several o,o -bridged biphenyls has been estimated from their respective charge-transfer spectra and found to be carbazole > fluorene > dibenzothiophene >dibenzofuran. Dibenzothiophene forms complexes with tetracy-anoethylene, various polynitro derivatives of fluorenone, > naphthalene-1,4,5,8-tetracarboxylic acid dianhydride, and tetra-methylmic acid. ... [Pg.202]

No zirconium(III) complexes with oxygen donor ligands have been isolated. However, the electronic absorption spectra of aqueous solutions of Zrl3 have been interpreted in terms of the formation of aqua complexes (equation 4).29 The spectrum of a freshly prepared solution of Zrl3 exhibits a band at 24 400 cm-1, which decays over a period of 40 minutes, and a shoulder at 22000 cm-1, which decays more rapidly. The 24400 cm-1 band has been assigned to [Zr(H20)6]3+, and the 22000 cm-1 shoulder has been attributed to an unstable intermediate iodo-aqua complex. If it is assumed that the absorption band of [Zr(H20)6]3+ is due to the 2T 2Ee ligand-field transition, the value of A is 24 400 cm. This corresponds to a A value of 20 300 cm-1 for [Ti(H20)6]3+ 30 and 17 400 cm-1 for the octahedral ZrCl6 chromophore in zirconium(III) chloride.25... [Pg.370]

Figure 15.1 Electronic absorption spectrum of nitrobenzene in aqueous solution at 0.1 mM. (a) Absorbance A as a function of wavelength. (b) Log as a function of wavelength. Figure 15.1 Electronic absorption spectrum of nitrobenzene in aqueous solution at 0.1 mM. (a) Absorbance A as a function of wavelength. (b) Log as a function of wavelength.
Somebody measures the electronic absorption spectrum of an 0.1 mM solution of ni-... [Pg.616]

Only in a few papers has an attempt been made to interpret the electronic absorption spectra of anions and protonated cations of the bases. The absorption spectrum of cytosine in acidic as well as in alkaline aqueous solution differs from that in neutral.104,108 The first... [Pg.299]

Fig. 4.—The electronic absorption spectrum of VOSOrSHsO in aqueous solution (a) complex = 0.0237 M, HsSO - 0.1 M (b) complex = 000237 M, HjSO - O01M. Fig. 4.—The electronic absorption spectrum of VOSOrSHsO in aqueous solution (a) complex = 0.0237 M, HsSO - 0.1 M (b) complex = 000237 M, HjSO - O01M.
The solution of C60H18 has been irradiated inside a quartz reactor with a low pressure mercury lamp having a monochromatic emission at 245 nm. The solution was kept under continuous He blanket to avoid any interference from air. Periodically samples from the irradiated solution were taken to measure the electronic absorption spectrum. [Pg.160]

As shown in Fig. 8.7, the freshly prepared solution of C60H18 in n-hexane is characterized by three distinct maxima at 212, 260 and 340 nm (Palit et al. 1998). A similar spectrum is displayed by the deuterated molecule C60D18 in Fig. 8.8. Since the replacement of hydrogen with deuterium implies only a variation of mass of the substituents but not the electronic properties of the molecule. Thus, the two electronic absorption spectra are in Figs. 8.7 and 8.8 respectively due to C60H18 and its deuterated analogous are necessarily identical. [Pg.160]


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