Absorption bands bathochromic shift

Ruthenium(II) complexes of two ligands, pynapy and dinapy, which should be very similar to pq and DMCH have been investigated30. [Ru(pynapy)3]2+ has both absorption and emission bands bathochromically shifted from [Ru(pq)3]2+ by ca. 1600 cm-1, which may account for its shorter emission lifetime than the latter complex. [Ru(dinapy)3]2+ also shows a similar shift from [Ru(DMCH)3]2+ however, the shorter lifetime is difficult to compare with this compound, since different solvents were used. The (presumed) nonplanarity of dinapy certainly is evident in a comparison of [Ru(pynapy)3]2+ and [Ru(dinapy)3]2+, since the half-wave potentials for the (III/II) couple are consistent with greater ruthenium(II) stabilization in the less distorted compound. 

For media of SDS micelles (Fig. 13.7), we observed the formation of various forms metal complex. Molecules of SiCl Pc have absorption bands at 678 mn corresponding to the monomeric state and band bathochromic shift of 200 nm relative to the monomer. This fact demonstrates a formation of SiCl Pc J-aggregates stabilized by SDS micelles. For V=OPc a well-defined band corresponding to J-aggregates at wavelength of 830 nm is observed. Absorption band of H-aggregates at 630 nm is expressed badly and the absorption band of V=OPc monomer is absent. So we can say that the molecules of V=OPc form J-aggregates spontaneously in the majority of supramolecular complexes. Molecules of ZrL Pc have completely isolated state in SDS micelles. 

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. 

Compound 2.6 is noteworthy in that it was the first azo dye reported whose absorption band is shifted beyond the visible region into the near-infrared region of the spectrum, showing a /Lma of 778 nm in dichloromethane. The extreme bathochromicity of this dye may be explained by a combination of the effects discussed throughout this... 

CRBP is distinct from RBP, both immunologically (Ross and Goodman, 1979 Bashor and Chytil, 1975) and by a number of other criteria. It has a lower molecular weight and fails to complex with TTR (Ross and Goodman, 1979 Ong and Chytil, 1978a). CRBP will not bind retinaldehyde, retinoic acid, and retinyl acetate, although these ligands will bind to RBP (Horwitz and Heller, 1974). CRBP has spectroscopic properties that differ from those of RBP. Like free retinol, holo-RBP has a smooth absorption band centered at 330 nm. In CRBP, however, the retinol absorption band is shifted bathochromically to 350... 

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... 

Annelation increases the complexity of the spectra just as it does in the carbocyclic series, and the spectra are not unlike those of the aromatic carbocycle obtained by formally replacing the heteroatom by two aromatic carbon atoms (—CH=CH—). Although quantitatively less marked, the same trend for the longest wavelength band to undergo a bathochromic shift in the heteroatom sequence O < NH < S < Se < Te is discernible in the spectra of the benzo[Z>] heterocycles (Table 17). As might perhaps have been anticipated, the effect of the fusion of a second benzenoid ring on to these heterocycles is to reduce further the differences in their spectroscopic properties (cf. Table 18). The absorption of the benzo[c]... 

Absorption and emission spectra of six 2-substituted imidazo[4,5-/]quinolines (R = H, Me, CH2Ph, Ph, 2-Py, R = H CH2Ph, R = Ph) were studied in various solvents. These studies revealed a solvent-independent, substituent-dependent character of the title compounds. They also exhibited bathochromic shifts in acidic and basic solutions. The phenyl group in the 2-position is in complete conjugation with the imidazoquinoline moiety. The fluorescence spectra of the compounds exhibited a solvent dependency, and, on changing to polar solvents, bathochromic shifts occur. Anomalous bathochromic shifts in water, acidic solution, and a new emission band in methanol are attributed to the protonated imidazoquinoline in the excited state. Basic solutions quench fluorescence (87IJC187). 

The reduced symmetry of the chromophore, which still contains 187t-electrons and is therefore an aromatic system, influences the electronic spectrum which shows a bathochromic shift and a higher molar extinction coefficient of the long-wavelength absorption bands compared to the porphyrin, so that the photophysical properties of the chlorins resulting from this structural alteration render them naturally suitable as pigments for photosynthesis and also make them of interest in medical applications, e.g. photodynamic tumor therapy (PDT).2... 

The introduction of a substituent, especially a free or methylated hydroxyl group, determines a bathochromic shift of band II in the visible region. The 1,4-naphthoquinone absorption bands are at 245, 257, and 335 nm and the bands are at 243, 263, 332, and 405 nm for anthaqninone. The introduction of a substituent (especially a hydroxyl group) in the aromatic ring of a naphthoquinone determines a strong bathochromic effect (up to 100 nm) and some UV bands are shifted into the visible (vis) region. 

A similar effect can be observed in anthaquinones, mainly for the presence of an hydroxyl group. The ionization of hydroxyl groups under basic conditions also undergoes a bathochromic shift. Alizarin has two absorption bands in the vis region, simated at 567 and 609 nm carminic acid has a visible absorption maximum at around 500 nm and kermesic acid at 498 mn. 

Annelation of the benzopyran in spirodibenzopyran series results in remarkably bathochromic shift of the absorption band in the colored form, as shown in Table 4. The of the colored form in 21-23 shifts to longer wavelength of about 80-100 nm, compared to the parent spirodibenzopyran 20. 

Substituent effects on the Vax of the colored form in these series are interesting and are dependent on the pyran component. For compound 20, substitutions at position 3, 6, or 8 (or 3, 6, 8 ) affects the X substantially, i.e., the absorption band lies in a wide range 475-609nm. The 7,7 -, 8,8 -, or 10,10 -dinitro-substituted compounds 21 reveal a somewhat hypso-chromic shift, relative to unsubstituted derivative, whereas the bathochromic shift (1(M0 nm) is observed with dinitro substitution at the same position in compound 22. For compound 23, the pronounced shift is also observed with 8-nitro substitution. Many other spectral data are collected in Ref. 1. 

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. 

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