Indicators, absorption maxima

Figure 6. A composite view of the NO and CN data for the unimolecular decomposition of NCNO. The central trace shows the photodissociation spectrum of jet-cooled NCNO. The NO and CN rotational populations result from dissociation at the indicated absorption maxima. Experimental distributions for the CN rotational quantum number N" and the NO rotational quantum number J" are given as open circles in the upper and lower panels, respectively. The theoretical results are from PST. For a discussion of the calculated versus experimental NO spin-orbit population ratio see Ref. 49. (Reproduced with permission from Ref. 49.)...

The desired pyridylamine was obtained in 69 % overall yield by monomethylation of 2-(aminomethyl)pyridine following a literature procedure (Scheme 4.14). First amine 4.48 was converted into formamide 4.49, through reaction with the in situ prepared mixed anhydride of acetic acid and formic acid. Reduction of 4.49 with borane dimethyl sulfide complex produced diamine 4.50. This compound could be used successfully in the Mannich reaction with 4.39, affording crude 4.51 in 92 % yield (Scheme 4.15). Analogous to 4.44, 4.51 also coordinates to copper(II) in water, as indicated by a shift of the UV-absorption maximum from 296 nm to 308 nm. 

The UV-visible spectra of the H- and nifro-azobenzene dendrimers in chloroform solution showed strong absorption bands within the visible region due to the transitions of azobenzene chromophores (Table 2). Because of the stronger delocalization of n-electrons in nitro-azobenzene, the maximum absorption band is at a longer wavelength compared with that for H-azoben-zene. There was little spectral shift of the absorption maximum for dendrimers with different numbers of azobenzene units, indicating that dendrimers did not form any special intermolecular aggregates. 

The spectra of these highly conjugated betaines are solvent sensitive. The absorption maximum of 144 is 450 nm in carbon tetrachloride and 392nm in dimethylsulfoxide. The spectra of a number of substituted diaryl thiobetaines correlated well with Kossower s Z solvent polarity indicators.227... 

Oxostephasunoline (4) was isolated from the roots of Stephania japonica(4). The UV spectrum of oxostephasunoline (4) showed an absorption maximum at 286 nm, and the IR spectrum depicted bands at 3550,3500, and 1670 cm, indicating the presence of a hydroxyl group and a y-lactam. The mass spectrum (Table VI) exhibited the most abundant ion peak at m/z 258, and the H-NMR spectrum (Table II) revealed the presence of three methoxyl and one N-methyl group. The downfield shift (53.06) of the JV-methyl resonance indicated that oxostephasunoline (4) was a y-lactam, which was further supported by the IR band at 1670 cm 1, significant features of the mass spectrum (Table VI), and the 13C-NMR spectrum (Table III). On exhaustive H-NMR analysis similar to the case of stephasunoline (17), the structure of oxostephasunoline (4) including the stereochemistry was practically proved (4). 

The sol-gel co-immobilization of a non-fluorescent blue indicator bromothymol blue (BTB) with an europium (Ill)-complex intense antenna mediated lanthanide dye represents a new scheme for the fluorescence analysis38. Luminescence spectra of europium (Ill)-complex shown in Figure 12 were found to be independent of pH changes in the range 1-10. Therefore, BTB, a non-fluorescent pH indicator with alkaline absorption maximum close to main europium emission band was added to the sol-gel mixture to shield reversibly the emission of the europium (Ill)-complex at different pH s without quenching of the antenna function. 

Equation (2) indicates that an increase of the tilt angle from 26° to 36° results a small blue shift of the absorption maximum (in wavelength) in the visible region. Spectral observation of the group VI (375 nm) and V (360 nm) is very consistent with the structural estimation from the X-ray diffraction experiments. 

Figure 14.2. UV-Vis spectrum of simple deionized water extract of soil. Absorption maximum is indicated by an arrow. Note that the absorbance is above 1, and therefore the solution should be diluted before attempting to interpret the spectrum.

By comparison of the UV, excitation, and PL spectral data with those of other poly(dialkylsilylene)s, a linear Si chain was inferred. Since poly(dipropylsilylene) is insoluble, the molecular weight could not be measured, but the UV absorption maximum at 345 nm is indicative of a DP of greater than at least 20 repeat units. The photo-CVD... 

The phase transitions for 90 were also evident in the UV-VIS spectra, as seen in Figure 26 M has an absorption maximum at 315 nm, QM at 350 nm, and multiple absorptions with peaks at ca. 315, 350, 365, and 378 nm are evident for phase I and the other phases. Isosbestic points observed between the phases indicate coexistence of two states during structural evolution, and the existence of multiple UV peaks for a phase is considered to indicate the existence of several conformations for that phase. In this report, 0 all structures were modeled with conformations between all-T and all-D thus, the conformational nature of the different phases of (Si-/z-Dec2U is not clear. Similar UV absorptions observed for structurally related polymers, such as PDHS (see below), are suggestive of comparable backbone conformations. 

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