UV-VIS spectral changes

FIGURE 4.2.3 UV-vis spectral changes and AAbs obtained by heating bixin in water ethanol (8 2) at 92°C. Inset shows kinetic profile at several wavelengths, with the solid lines representing the fitting of experimental data from the sum of two exponential functions. From Rios, A.O., Borsarelli, C.D., and Mercadante, A.Z., J. Agric. Food Chem., 53, 2307, 2005. With permission. 

Figure 5.14 UV/Vis spectral changes of [Au2(dcpm)2](Cl04)2 in degassed acetonitrile at room temperature as a function of [NBu4]I concentration. Reproduced with permission from [6b]. Copyright (2001) Wiley-VCH.

This is clearly illustrated by the UV-VIS spectral changes shown in Figure 3. As the irradiation proceeds, the 323 nm absorption maximum of [ReH CPMe Ph) ] shifts to 338 nm, the maximum of [ReH CPMe Ph) ]. Continued photolysis then causes disappearance of all absorption bands below 270 nm as [ReH (PMe2-Ph)9] forms. This sequence of reactions is also evidenced by... 

Exposure of (E)-3a-e, 4a-e in MeCN solutions in the presence of Hg2+ or Pb2+ to visible light, leads to UV-Vis spectral changes typical of AZ-isomcrization [18], The... 

Fig. 14 UV-Vis spectral changes for Mn5j observed using controlled potential electrolysis at potential of process III (—700 mV). Electrolyte = DMF containing 0.1M TBABF4. Electrolysis time was 30 min for each redox process. Reproduced with permission from [14]...

The VPc complexes are reduced at approximately the same potential, Table 2 [30,64,65], The UV-Vis spectral changes observed for the reduction of the OVPc (SCsHii)g complex did not show the typical [15] spectra for ring reduction, Fig. 16. Complexes Zn4m and H24m are readily oxidized because of the deformed nature of the ring [59,66], Table 2. 

Figure 6 UV-Vis spectral changes upon 313- and 366-nm irradiation of glassy nematic films of HMW1. (a) Before irradiation, (b) After irradiation. Residual absorption at ca. 280 nm is attributed to cyclobutane photoproducts. Residual absorption beyond ca. 340 nm is mostly due to photo-Fries rearrangement products. (Reprinted with permission from Creed et al. [23]. Copyright 1990 American Chemical Society.)...

The dependence of the observed second-order rate constant (Atet) on [Sc +] for ET from (AcrH)2 to TolSQ at 233 and 298 K is affected by the formation of TolSQ Sc and TolSQ —(Sc )2 depending on Sc " " concentration. The A et value increases with increasing Sc concentration exhibiting a saturated behavior at low concentrations of Sc + ([Sc ] < 5.0 x 10 M) at both 233 and 298 K, as shown in Fig. 43 (a and b), respectively (115). Such saturated dependence of Atet on [Sc ] is ascribed to a 1 1 complex formation between TolSQ and Sc " " (TolSQ Sc ), which enhances the electron-acceptor ability of TolSQ. The formation constants (ATi) of the TolSQ Sc " " complex at 298 and 233 K were determined from UV-Vis spectral changes of TolSQ in the presence of... 

Figure 25.3 shows the UV-vis spectral change from 1 to 2 in a microcrystalline powder film. The hypsochromic (blue) shift of A,m lx from 510 to 475 nm was... 

Figure 4.2 Thin-layer UV-Vis spectral changes of porphyrin (1) (top) and of the vic-dihydroxychlorin (2) = — CH2-CH2-COO2CH3) (bottom) upon the...

Figure 4.9 Time-dependent UV-Vis spectral changes obtained during the controlled-potential reduction of [(T/ TP)SbCl2] in CH2CI2/O.2 M TRAP (a) during the first 10 s at -0.40 V (vs. SCE), (b) at longer time scales at -0.40 V and (c) at —0.80 V (vs. SCE). With permission from the American Chemical Society, ref. 33.

In Fig. 8, the UV-Vis spectral changes that occurred upon mixing aqueous solutions of 1 and H2O2 in the chamber of the stopped-flow instrument equipped with a rapid scan spectroscopic attachment are reported as a ftmction of time. The final spectrum of the reaction solution is in good agreement with the spectrum of [Ru (edta)0)] Umax=391nm, emax=8000M cm )... 

UV/VIS Spectral Changes upon Interaction with the Surface. . . 361... 

Fig. 6. UV-Vis spectral changes during the reaction of R(P-diketonate)3 with HjiPor). (From Wong 1983 with permission.)...

Fig. 19 UV-VIS spectral change of PPE-SOj as a function of SPG concentration (concentration range of s-SPG 0-6.7 x 10 M). The concentration of PPE-SOj was kept at 1.5 X 10 M. H2O/DMSO = 95/5 (v/v), 1.0 cm cell length, room temperature. Reprinted with permission from [114]...

When solutions of potential tt donors are mixed with those having potential tt acceptors, bathochromic shifts in UV/Vis spectra, and upheld shifts in NMR adsorbances serve as physical evidence that complexation has occurred. Figure 28.19 is representation of the UV/Vis spectral change that occurs when tt acceptor V-methy-3,5-dinitrobenzamide (DNB) is complexed with ether bupivacaine hydrochloride or with its model compound 2,6-dimethylacetanilide. 

Figure 3.12 UV-Vis spectral changes of a chemically prepared PABA thin film as a function of time upon exposure to pH 7.4 PBS over the course of an hour. (Reprinted with permission from Journal of the American Chemical Society, 126, 52. Copyright (2004) American Chemical Society.)...

UV-Vis spectral change of (a) (SP)I and (SP)[Fe"Fe "(dto)3] in KBr pellet at (b) 300 K and (c) 70 K. UV irradiation (350 nm, 40mWcm ) on the pellet was carried out first. After the spectra were saturated, visible-light irradiation (SOOmWcm ) was carried out on the pellet. (Reproduced from Ref. 18 with permission of the American Chemical Society.)... 

Figure 17 (a) Dithienylethene-bridged dinuclear tris(bipyridyl)ruthenium(II) and osmium(II) complexes, (b) UV-vis spectral changes... 

Figure 3.1. Typical UV/Vis spectral changes of the CuBrfPMDETA by UV irradiation at 350 nm. (Reproduced with permission from [TAS 11b]. Copyright 2011 John Wiley Sons)...

After the induction period, the catalyst is oxidized to Co (salen) species as judged by UV-VIS spectral change. This means that the oxidation of Co to Co in the initial stage is essential for the high selective oxygenation. Thus, the use of Co (salen)(X") in... 

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