Effect hypsochromic

Table 30 reports u C=0) for a variety of azolinones containing ring double bonds. The hypsochromic effect of an oxygen atom or CRa group versus the bathochromic effect of NR, S or C=C can readily be traced. 

The mechanism of interaction with DNA is suggested. Ethidium bromide (EB) displacement assay was performed. We determine the binding constant of Tb-E to DNA to be in the order of Ig K = 6.47 0.4. The bathochromic and hypsochromic effects in the absorption spectra of investigated complex were observed and the interaction is assumed to be mainly of the mono-intercalating type. 

An electron-donating group in the 4-position of the pyrazoline ring has a slight hypsochromic effect, but an electron-withdrawing group has a bathochromic effect. 

Heteroatom-containing derivatives of pentalene and azulene are 8- and 10-jr-electron systems, respectively, and have been extensively studied by Hafner and co-workers.301-304 A few examples are presented in Schemes 30, 47, and 86. Electron-rich azapentalenes 247—249305 306 and various aza-azu-lenes 250—252300-302 have intense colors and are stable but oxygen-sensitive compounds. Azulenes with nitrogen heteroatoms placed in positions with high electron density, such as position 5, or positions 5 and 7, present a hypsochromic effect, while a heteroatom in position 6, with low electron density, exerts a bathochromic effect. When both types of positions are substituted by heteroatoms, their effect is canceled out.307 The bond lengths in 252 (Scheme 86), as determined by X-ray, indicate delocalization as in 252a and 252b.308 309... 

Ultraviolet absorption spectra of thiophene derivatives were recorded using isooctane as a solvent (8). An apparent hypsochromic effect caused by the second nitro group in 2,5-dichloro-3,4-dinitro-thiophene was noticed. 

The presence of a CF3 group in 16,16,16-trifluororetinal provokes an hypsochrom effect, probably due to the torsion between the polyenic chain and the cycle. However, this effect is not necessarily accompanied by the translocation of a proton. Conversely, a CF3 group in the 13 position (20,20,20-F) maintains the proton pump... 

In some transitions, the polarity of the chromophore is weaker after absorption of radiation. One case of this is the n — jt absorption due to the carbonyl present in ketones in solution. Before absorption, the C+-0 polarisation stabilises in the presence of a polar solvent whose molecules will be clustered around the solute because of electrostatic effects. Thus, the n —> -rr electronic transition will require more energy and its maximum will be displaced towards a shorter wavelength, contrary to what would be observed in a nonpolar solvent. This is the hypsochromic effect. Because the excited state is readily formed, the solvent shell around the... 

Figure 11.7—Absorption spectrum ofbenzophenone in cyclohexane and ethanol. Note that the bathochromic and hypsochromic effects are reversed for the two types of transitions, depending on the nature of the solvent.

Homonuclear coupling, 143 Horseradish, 337 Hydrogen lamp, 199 Hydrostatic injection, 117 Hyphenated technique, 8 Hypsochromic effect, 195... 

C26H34N2O6, which still contained the carbomethoxy group, and which should be formulated as XLV on the basis of XXXIII for echitamine chloride. The UV-spectrum of this base also showed a hypsochromic effect in acid solution similar to that shown by echitinolide, although in this case conformational change of the type postulated by Conroy was not possible. Other experimental data which were difficult to explain were the resistance of echitinolide to reduction in acid solution, and the comparative reluctance of echitinolide and isoechitinolide to undergo reduction with lithium aluminum hydride under mild conditions. The conformations of the substances involved, i.e.. XXXVIII, XXXVIa, and XXXVII, respectively, revealed no steric factors which could account for this behavior (81). 

Though extension of the n electron system in a homologous series has, in general, a bathochromic effect, there are some exceptions e.g. the series para-benzoquinone, naphtha-1,4-qui-none and anthra-9,io-quinone, where a hypsochromic effect is observed. 

Since many purines exist in lactam and lactim forms (c/. Section 4.09.2.1) the position and intensity of the peaks are often affected by pH and this can be used for pjRTa determinations. In addition the position of substituents affects the spectra by increasing the intensity and causing bathochromic shifts usually in the order 6 < 8 < 2 and of increasing hypsochromic effect 2 > 6 > 8 for the longer wavelength band. The effects of the substituents in polysub-stituted derivatives are not, however, additive. 

Protonation of 4-(5-phenyl-l,2-dithiol-3-ylidene)cyclohexadien-l-one to 5-phenyl-3-(p-hydroxyphenyl)-1,2-dithiolium cation results in a strong hypsochromic effect on the longest wavelength absorption band (530 to 467 nm). ... 

Nicolet and Laurence11 studied the temperature dependence of the wavenumber of the lowest energy absorption band of the relevant probes. In the gas phase the effect was negligible, but not so in both non-EPD solvents (perfluorodecalin, n-heptane and 1,2-dichloroethane) and in EPD/HBA solvents (dibutyl ether, HMPA and triethylamine). The hypsochromic effect noted was 5 to 17 cm-1 K-1 for 8 and 3 to 8 cm-1 K-1 for 7. This magnitude (compared with /iS 7 = 2759 cm-1 at 25 °C for HMPA) is of little consequence for measurements near ambience except for the most precise requirements and is commonly ignored in ordinary work. 

Wetzler and coworkers123 employed 4-aminophthalimide (63) and 4-amino-lV-methyl-phthalimide (64) as solvatochromic (and thermochromic) fluorescent probes in solvent mixtures. A bathochromic shift of the emission spectra was found in mixtures of toluene with ethanol and with acetonitrile123 when the more polar solvent was added to toluene, but raising the temperature causes a relative hypsochromic effect. Mixtures of benzene and acetonitrile were studied by Nevecna and coworkers124 for their polarity by means of the probes 46 and 47 and with respect to the correlation of this with the rate constants of the reaction of triethylamine with ethyl iodide. The fluorescence of the ammonium salt of 4-(l-naphthylsulfonate)aniline (84) in dioxane and water mixtures was studied by Hiittenhain and Balzer125. 

A shift in A,max to shorter wavelength is called a hypsochromic effect, or blue shift, and usually occurs when compounds with a basic auxochrome ionise and the lone pair is no longer able to interact with the electrons of the chromophore. Hypsochromic effects can also be seen when spectra are run in different solvents or at elevated temperatures. Spectral shifts of this type can be used to identify drugs that contain an aromatic amine functional group, e.g. the local anaesthetic benzocaine (see Figure 7.9). 

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