Vibrational spectra toluene

Baker, J. (2008). A scaled quantum mechanical reinvestigation of the vibrational spectrum of toluene. Journal of Molecular Structure THEOCHEM, 865, 49. 

Figure 14a shows the IR spectrum of a dried silica disc. The sharp band at 3755 cm 1 is consistent with the isolated hydroxyl groups (Type A sites) present, and the broad bands at —1980 and 1860 cm 1 are overtones of the Si-O vibrations. Treatment of the disc with h toluene solu-... 

Because of fortuitous overlap, the bands in the middle of the spectrum (bands 3 and 4) are more difficult to analyze. However, comparison of v3 bands of C02 in spectra of ABP A and ABP 8, as well as kinetic and spectroscopic evidence from other vibrational modes, show that both the single C02 in the presence of methyl benzoate and a differently structured C02 pair in the presence of toluene are found in this region. Band 3 consists of contributions from both types of sites (methyl benzoate and toluene), while band 4 is the lower frequency member of the C02 pair in the presence of toluene. The band from C02 in the presence of methyl benzoate is labeled M. The bands from the C02 pair in this toluene site are named T2 and T3, because in the spectrum of unlabeled ABP, they are the second and third bands from toluene sites. 

Figure 5.4, one can easily understand why the interfacial electron transfer should take place in the 10-100 fsec range because this ET process should be faster than the photo-luminescence of the dye molecules and energy transfer between the molecules. Recently Zimmermann et al. [58] have employed the 20 fsec laser pulses to study the ET dynamics in the DTB-Pe/TiC>2 system and for comparison, they have also studied the excited-state dynamics of free perylene in toluene solution. Limited by the 20 fsec pulse-duration, from the uncertainty principle, they can only observe the vibrational coherences (i.e., vibrational wave packets) of low-frequency modes (see Figure 5.5). Six significant modes, 275, 360, 420, 460, 500 and 625 cm-1, have been resolved from the Fourier transform spectra of ultrashort pulse measurements. The Fourier transform spectrum has also been compared with the Raman spectrum. A good agreement can be seen (Figure 5.5). For detail of the analysis of the quantum beat, refer to Figures 5.5-5.7 of Zimmermann et al. s paper [58], These modes should play an important role not only in ET dynamics or excited-state dynamics, but also in absorption spectra. Therefore, the steady state absorption spectra of DTB-Pe, both in...

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... 

Hydridobis[ s-vinylenebis(diphenylphosphine)] cobalt(l) is a red crystalline solid that is unstable in air both in the solid state and in solution. The complex is soluble in tetrahydrofuran (9.2 X 10-3 mole/L, at 20°), toluene (10.2 X 10 3 mole/L), chloroform (6.3 X 10-3 mole/L), dichloromethane (1.6 X 10-3 mole/ L), and benzene (8.4 X 10-3 mole/L). It is insoluble in ethanol, diethyl ether, acetone, and pentane. The infrared spectrum in Nujol mull shows a band at 1885 (m) cm-1, attributable to the Co-H stretching vibration. 

A solution of Pd(PPhj)4 (767 mg, 0.665 mmol), Af-phenyldiphenylketenimine (2.93 g, 10.9 mmol) and (l-methylethylidene)cyclopropane (2.03 g, 35.6 mmol) in anhyd toluene (30 mL) was placed in a 200-mL stainless steel autoclave. The autoclave was pressurized with 4 MPa of Nj at rt and then heated to 123 °C for 30 h with stirring. After the reaction was complete (most easily monitored by the disappearance of the ketenimine stretching vibration in the IR spectrum), the mixture was filtered through a pad of alumina (EtjO) in order to remove the solid elemental palladium. After removal of the readily volatile components (bp up to 30 C/10" Torr), the brown, vi.scous residue was purified by medium-pressure chromatography (silica gel, CHjClj/cyclohexane 1 1). Under these conditions, most of the impurities were washed off, while the cycloadduct remained on top of the column and was finally eluted with pure Et20 yield 3.3 g (93%) brown needles 98% pure (as determined by GC) mp 148°C (toluene). 

Spectra of proteins and nucleic acids. Most proteins have a strong light absorption band at 280 nm (35,700 cm ) which arises from the aromatic amino acids tryptophan, tyrosine, and phenylalanine (Fig. 3-14). The spectrum of phenylalanine resembles that of toluene (Fig. 23-7)whose 0-0 band comes at 37.32 x 10 cm. The vibrational structure of phenylalanine can be seen readily in the spectra of many proteins (e.g., see Fig. 23-llA). The spectrum of tyrosine is also similar (Fig. 3-13), but the 0-0 peak is shifted to a lower energy of 35,500 cm (in water). Progressions with spacings of 1200 and 800 cm are prominent. The low-energy band of tryptophan consists of two overlapping transitions and The Lb transition has well-resolved vibrational subbands, whereas those of the La transition are more diffuse. Tryptophan derivatives in hydrocarbon solvents show 0-0 bands for both of these transitions at approximately... 

Figure 9. Experimental C Is NEXAFS spectrum of polystyrene (a), and the simulated C Is spectrum of toluene (b). The numbered peaks in (b) correspond to the transitions of different C atoms in the molecule, and spectral broadening and additional spectral features in the experimental spectrum are attributed to the vibrational fine structure. [Reprinted with permission from Elsevier Science from Urquhart et al. (2000), Fig. 3].

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