Absorption bathochromic/hypsochromic shift

ABP = 2-amino-5-bromophenyl(pyridin-2-yl)methanone 226,227 Absorbance, determination of 31 Absorption, measurement of 9,17,31 molar coefficient 36, 40 quantitative relationship 35, 36 recording of spectra 30, 31 -bathochromic/hypsochromic shift 31 -comparison to spectra of solutions 31 scanning curves 17,31,32 ACB = 2-amino-5-chlorobenzophenone 227... 

Behavior of metal complexes of phthalocyanines in supramolecular systems with TX-lOO (Fig. 13.8) is very different from other systems of micellar carriers. Tetra-substituted ZrL Pc, as in other supramolecular systems, has an absorption band with a wavelength of 678 nm corresponding to monomeric of molecules in the micelles. In micellar solutions of SiCl Pc absorption maximum at wavelength of 676 nm is observed only, indicating a completely isolated metal complex in this conditions. Unlike other systems, V=OPc has a well-defined absorption band at 678 mn, which corresponds to the presence of monomers in the system, the band bathochromic shifted to 830 nm, which corresponds to J-aggregates and the absorption band hypsochromic shifted to 630 nm, which corresponds to H-aggregates. Hence, V=OPc molecules interaction with TX-lOO micelles form three different type aggregation states of the molecules. 

Their physical properties closely resemble those of pterin, which has a basic pKt, of 2.20 and an acidic one of 7.86 associated with N-1 protonation and a hypsochromic shift of the long-wavelength absorption band in the UV spectrum, and N-3 deprotonation effecting a bathochromic shift respectively (Table 4). The xanthopterin (4) and isoxanthopterin types... 

Absorption maxima for a wide range of heterocyclic systems are shown in Figure 1.5.2 When the indolyl residue 8a is replaced by other heterocyclic residue, a somewhat small shift in the Xmax occurs. Replacement with a benzothiazoline residue, 8c, results in a bathochromic shift. Comparison between saturated heterocycles 8d-8f and the corresponding benzoderiv-atives 8a-8c shows that the conjugation produced by the benzene nuclei causes a bathochromic shift (ca. 20-50 nm). Replacement of saturated five-membered heterocycles by saturated six-membered heterocycles results in a hypsochromic shift. In the case of the piperidine series (8g) a significant hypsochromic shift occurs, due to steric hindrance in the colored form. 

The of 33 shows a bathochromic shift, compared to that of the corresponding spironaphthopyran [ max 531, 558(s) nm in toluene].78 The substituent effect in 2, 5, 6 - and 5-position of 33 on the absorption band of the colored form has been examined.72,77,7s The donor substituent group in 6 -position, such as piperidino group, gives a hypsochromic shift by 35 nm, but 5 -carbomethoxy substitution results in a bathochromic shift by 20 nm. This may be due to interaction between oxygen atom of the phenolate and methoxy group. 

The x-band in malachite green arises from an NBMO—>n transition, so that 3- and 4-substituents affect the energy of the excited state only and bring about spectral shifts of the first absorption band which vary linearly with the appropriate Hammett substituent constants. Thus, electron-withdrawing groups cause bathochromic shifts of the x-band whereas donor substituents cause hypsochromic shifts (Table 6.6) [64,67]. The 3-band arises from a n—>n transition [68] so that substituent effects are less predictable. As the donor strength of the 4-substituent increases, however, the 3-band moves bathochromically and eventually coalesces with the x-band - at 589 nm in the case of crystal violet (6.164), which possesses two NBMOs that are necessarily degenerate [69]. 

Fig. 3 Typical ICT probes (left) and representative spectroscopic responses toward selected metal ions (right). Color code (left) coordinating atoms in blue, bridgehead atom of the fluorophore that takes part in complexation in orange, formal donor fragment in red, formal acceptor fragment in green (right) hypsochromic shifts in red, bathochromic shifts in green, fluorescence enhancement in violet, fluorescence quenching in blue. Symbols in table Aabs, 7em,

Shifts in absorption spectra due to the effect of substitution or a change in environment (e.g. solvent) will be discussed in Chapter 3, together with the effects on emission spectra. Note that a shift to longer wavelengths is called a bathochromic shift (informally referred to as a red-shift). A shift to shorter wavelengths is called a hypsochromic shift (informally referred to as a blue-shift). An increase in the molar absorption coefficient is called the hyperchromic effect, whereas the opposite is the hypochromic effect. 

Compounds are called solvatochromic when the location of their absorption (and emission) spectra depend on solvent polarity. A bathochromic (red) shift and a hypsochromic (blue) shift with increasing solvent polarity pertain to positive and negative solvatochromism, respectively. Such shifts of appropriate solvatochromic compounds in solvents of various polarity can be used to construct an empirical polarity scale (Reichardt, 1988 Buncel and Rajagopal, 1990). 

To estimate how many dye molecules fit into the dendritic micelles, UV-titra-tion experiments have been employed. In comparison with the spectra of a pure pinacyanol chloride solution in water, the peaks of the absorption maxima of the dye in the presence of the dendrimer are shifted bathochromically due to solvatochromic effects, which indicates the incorporation of the dye within the branches of the dendrimer. At dye-to-dendrimer molar ratios higher than 4 1, in addition to the bathochromic shifts, hypsochromically shifted peaks start to appear, indicating that the dendrimer is not incorporating further dyes. We interpret this as an incorporation of up to four dyes within the branches of the dendrimer. This observation correlates with the calculated available space within the dendrimer, obtained from the molecular simulations. Further studies of the interactions of the dyes within the dendritic micelle are in progress. 

If a structural change, such as the attachment of an auxochrome, leads to the absorption maximum being shifted to a longer wavelength, the phenomenon is termed a bathochromic shift. A shift towards shorter wavelength is called a hypsochromic shift. 

A shift (also known as a red shift ) in a substance s electronic absorption spectrum toward longer wavelengths, as a consequence of a substituent, solvent, environment, or other effect. The opposite of a bathochromic shift is referred to as a hypsochromic shift. 

An effect observed in the spectrum of a chemical species in which a substituent, solvent, change in environment, or other effect causes the electronic absorption spectrum to shift to shorter wavelengths. The opposite effect is referred to as a bathochromic shift. The hypsochromic shift is also known as the blue shift. 

Two differential spectrophotometric methods were used by Chatterjee et al. for the simultaneous analysis of diloxanide furoate and metronidazole in pharmaceutical formulations [24]. The first method involved measurement of the absorbance of a methanolic solution of the two drugs at 259 and 311 nm. Since the absorbance of diloxanide furoate at 311 nm is zero, the concentration of metronidazole is directly measured, and a simple equation based on absorbance ratios is used to calculate the concentration of diloxanide furoate. The second method was a differential spectrophotometric determination based on pH-induced spectral changes, on changing from an acidic to an alkaline solution. A marked bathochromic shift was exhibited by metronidazole, while diloxanide furoate showed a slight hypsochromic shift. The wavelength of maximum absorption difference for diloxanide furoate was 267 nm, where metronidazole did not absorb. Similarly, diloxanide furoate did not interfere with metronidazole at when measured at 322 nm. 

Pyrazoles with nonconjugating substituents show only one region of UV absorption (200-230 nm, log e= 3.1-3.8).14,15,30 Salt formation results in a bathochromic shift in and a small increase in log .8,47 With aryl conjugation there is a large bathochromic shift, and a second band appears.10,15,42,43,45,47 The illustrated examples 57-59,15 60,45 61, 62,47 and 13,8 show the effect of substituents and salt formation. A change of solvent from ethanol to hexane causes a small hypsochromic shift.45,47... 

The UV spectrum of l,2,3-benzotriazin-4-one (10, R = H) consists of two maxima at 223 nm (log e = 3.28) and 278 nm (log e = 2.77)162 and the spectra of a wide variety of 3-alkyl derivatives have been found to be closely similar, with maxima in the ranges 226-244 nm (log e = 4.33-4.49) and 284-289 nm (log e = 3.71-4.03), although only the longer wavelength absorption had been quoted for some compounds. The spectra of the 3-aryl derivatives are also similar to that of 10, R = H,88.89 tjUt significant substituent effects have been noted which depend on the position of the substituent (Me, Ph, MeO, MeCONH, Cl, N02) in the 3-aryl group.88 Thus, relative to 10, R = Ph, the spectra of the o-substituted phenyl derivatives show a strong hypsochromic shift and those of the p-substituted phenyl derivatives show a weak bathochromic shift there is, however, virtually no substituent effect for the m-substituted phenyl derivatives. These effects are almost identical to those found in substituted benzanilides. 

The appearance of the second emission was attributed to (1) strongly bound Ru(bpy) + molecules or (2) a chemical change in Ru(bpy) + during the adsorption process. No significant differences were observed in the diffuse reflectance absorption spectra. A bathochromic shift of the absorption band, a hypsochromic shift of the fluorescence spectrum, and nonexponential luminescence decays are a few other interesting changes observed with these samples. 

For the spironaphthoxazines conjugated with aza-15(18)-crown-5(6)-ether moieties at 6 -position of naphthalene fragment (13a,b) it was found that the addition of Li+ and alkaline earth (Mg2+, Ca2+, Sr2 and Ba2+) metal cations to 13a,b solutions results in a hypsochromic shift of the UV absorption band of the spiro form and a bathochromic shift of the absorption band of the merocyanine form in the visible region [36], In addition, the equilibrium shifts to the merocyanine form, and the lifetime of the photoinduced merocyanine form increases (Scheme 15). The isomerization of crown-containing compound 13a,b to the colored merocyanine form was promoted most strongly by the presence of metal ions, which are expected to be the best recognized by the crown ether ring (Scheme 15). 

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