Toluene absorption spectrum

Sanders (14) has exploited the strong and selective coordination of phosphine donor groups to Ru(II) to construct hetero-dimetallic porphyrin dimers (17, Fig. 5). An alkyne-phosphine moiety introduced on the periphery of a free base or metalloporphyrin (M = Zn or Ni) spontaneously coordinates to a Ru(II)(CO) porphyrin when the two porphyrins are mixed in a 1 1 ratio. Coordination is characterized by a downfield shift of the 31P resonance (A<531P = 19 ppm). There is no evidence of self-coordination of the zinc porphyrin at 10 6 m in toluene, there is no shift in the Soret band in the UV-Vis absorption spectrum. The Ni-Ru dimer was observed by MALDI-TOF mass spectrometry. Heating the Ru(II)CO porphyrin with 2 equivalents of the phosphine porphyrins led to quantitative formation of trimeric assemblies. 

The fluorescence of TPHA 3 is not a mirror image of its absorption spectrum and the emission intensity is sensitive to concentrations greater than 10 M. The excitation profile of 3 also varies with concentration, believed to be due to aggregation of TPHA in solution and only emulates the ultraviolet-visible (UV-Vis) spectrum at concentrations less than 10 M. The Aem decreased from 633 nm in toluene to 619 nm in dimethyl sulfoxide (DMSO), and this is thought to be indicative of a polar ground state and nonpolar excited state <1998JA2989>. 

Several reports have appeared in which the UV absorption spectrum of PS was found to be qualitatively similar to an alkyl benzene model compound. Vala and Rice15> demonstrated the similarity between atactic PS and ethyl benzene this was confirmed for atactic PS in cyclohexane by Hirayama 16) and in tetrahydrofuran by Abuin 17>. Bovey and co-workers20) found that absorbance spectra for isotactic PS, atactic PS, and styrene-methylmethacrylate copolymers in 1,2-dichloroethane were roughly similar to that of toluene. 

Specific examples illustrate that similar principles affect the absorption spectra. For example, as we have pointed out above, the neutral form of the C-2 benzyl ester is red in MeOH and orange in methylene chloride. Thus it has the spectrum of the ionized form in the polar, protic solvent and of the nonionized form in the nonpolar solvent methylene chloride [248]. The tributyl ammonium salt of the C-2 octyl ester is soluble in solvents ranging from ethanol-water to toluene. Its spectrum in an essentially nonionizing solvent such as toluene is that of the ionized xanthene [249], The spectrum of the pyrillium salt in ethanol is concentration dependent. In dilute solution the compound is totally ionized and is red, whereas in concentrated solution the compound is not fully ionized and the orange form predominates, as predicted by the law of mass action. 

A number of other features apparent in the toluene proton spectrum are worthy of note at this stage. Each absorption is accompanied by a number of small satellite peaks equally spaced on either side of the main absorptions. These may be spinning side-bands or 13C satellites (p. 342). The spinning side-bands are caused by inhomogeneities in the magnetic field and in the sample tube. They... 

Figure 6. Absorption spectra of the components in the organic phase obtained after extraction of photogenerated CgV+ from the aqueous phase a) Composite spectrum of CgV+ and CgV in ethylacetate after illumination of the system for 10 minutes b) Spectrum of CgV in ethylaaetate obtained after subtraction of CgV+.spectrum from the composite spectrum (a). Insert is enlarged absorption spectrum of CgV. c) Spectrum of the photoproducts when toluene is used as the organic phase in the two phase system. Spectrum recorded after illumination for 15 minutes corresponds to CgV as major product.

Fig. 3 Change in absorption spectrum of 22 in toluene on irradiation with 405 nm light. Starting from 22E. Concentration (mol dm-3) 8.42 x 10-5. Irradiation time (min) 0, 0.5, 2, 4.2, 7.4, 13, 23, 42, 71 (photostationary state).

Fig. 8.19 Excitation spectrum of the 8 72 complex in toluene monitoring the emission at 740 nm. Inset—corresponding absorption spectrum of 8 72 in toluene...

The UV-vis-NIR absorption spectra of newly isolated EMFs Ce2 C78 and Y2 C84 were recorded between 300 and 1100 nm in toluene solution. The spectrum of Y2 C84 (Fig. 4) is remarkably rich with characteristic absorption bands at 355, 482, 625, 710 and 785 nm. The onset of the absorption spectrum is at 785 nm and corresponds to the lowest energy electronic transition approximately the HOMO-LUMO energy gap. Figure 3 shows the UV-vis spectra of Ce2 C78 with several... 

Fig. 1.27. Normalised UV/VIS absorption (solid lines) and fluorescence excitation spectra of the fullerene emission at 715 nm (dashed lines) of the OPVn-C6o dyads in toluene at 295 K. (a) n = 1, (b) n = 2, (c) n = 3, and (d) n = 4. In each case the fluorescence excitation spectrum shows a close correspondence to the absorption spectrum...

The reaction between Mo(H20)63+, prepared and purified following the procedure of Bowen and Taube (18), and nitrate was followed spec-trophotometrically under strict anaerobic conditions with nitrate in excess. The absorption spectrum of nitrite in 1.0M HPTS (p-toluene sulfonic acid) exhibits a multicomponent band (vibrational fine structure) between 350 and 400 nm which is attributable to the xBi <— 1A1 electronic transition. Purified Mo(H20)63+ in 1.0M HPTS has a low absorption at 293 nm, indicating the purity of the preparation (18). When Mo(H20)63+ is mixed with nitrate (constant concentration in large excess) and the reaction is allowed to go to completion, the nitrite fine structure appears between 350 and 400, concomitant with an increase in absorbance at 293 nm. The molybdenum species resulting from the oxidation of... 

The room temperature solution electronic absorption spectrum of (L-N3) MoO(bdt) is presented in Fig. 6. This spectrum is representative of virtually all (L-A i)MoO(dithiolene) complexes (19, 23) with the possible exception of (L-/Vi)MoO(qdt) (20, 22), where qdt = quinoxaline-2,3-dithiolate, see below. However, the transitions observed for (L-A MoChtdt) (19), where tdt = toluene-1,2-dithiolate, are generally shifted to slightly lower energies relative... 

Figure 8.10. Changes in the absorption spectrum of 21aH+ (R = H) under irradiation of its toluene solution (c = 9 x 10 5 M 16 pi of CF3COOH were added to 1 ml of the solution) at 365 nm 1, before and 2-9, after irradiation for 30, 60, 120, 240, 480, and 960 s.34 (Reproduced with the permission of Gordon and Breach Publishing Group.)...

Identification The infrared absorption spectrum of the sample dissolved in hot toluene and evaporated on a potassium... 

Identification The infrared absorption spectrum of a sample dissolved in hot toluene and evaporated on a potassium bromide plate exhibits relative maxima at the same wavelengths as those of a typical spectrum as shown in the section on Infrared Spectra, using the same test conditions as specified therein. 

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