Excited state intramolecular proton transfer in some tautomeric azo dyes and schiff bases containing an intramolecular hydrogen bond

Joshi, H. C.; Kamounah, Fadhil S.; Gooijer, C.; Zwan, Gert van der; Antonov, L.

doi:10.1016/s1010-6030(02)00155-7

Cited by 116 publications

(87 citation statements)

References 22 publications

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“…Excitation spectra (data not shown) recorded at different wavelengths of observation show that the emitting structure originates from encapsulated trans-AZO. At 485 nm, where trans-HYZ absorbs, a very weak absorption band is recorded in agreement with a previous report on phenyl-substituted 1-(arylazo)-2-naphthols in solution (23). The large Stokes shift (Ϸ8,700 cm Ϫ1 ) of the emission relatively to the absorption of the encapsulated trans-AZO suggests the production of an excited-state IPT in the caged trans-AZO to produce an encapsulated trans-HYZ.…”

Section: Resultssupporting

confidence: 90%

“…H-O structures, depending on the phenyl derivative (21,22). Furthermore, a recent photophysical study of similar molecules in solution has shown the occurrence of a photoinduced proton-transfer reaction in AZO to give HYZ structure with a very low emission quantum yield (10 Ϫ7 ) (23). The inclusion complexes of OII and CDs have been studied by several groups showing the formation of a 1:1 entity (24)(25)(26)(27)(28)(29)(30)(31)(32)(33)(34)(35).…”

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confidence: 99%

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Femtochemistry of orange II in solution and in chemical and biological nanocavities

Douhal

Sanz

Tormo

2005

Proc. Natl. Acad. Sci. U.S.A.

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In this work, we report on studies of the nature of the dynamics and hydrophobic binding in cyclodextrins and human serum albumin protein complexes with orange II. With femtosecond time resolution, we examined the proton-transfer and trans-cis isomerization reactions of the ligand in these nanocavities and in pure solvents. Because of confinement at the ground state, the orientational motion in the formed phototautomer is restricted, leading to a rich dynamics. Therefore, the emission lifetimes span a large window of tens to hundreds of picoseconds in the cavities. Possible H-bond interactions between the guest and cyclodextrin do not affect the caged dynamics. For the protein-ligand complexes, slow diffusional motion (Ϸ630 ps) observed in the anisotropy decay indicates that the binding structure is not completely rigid, and the embedded guest is not frozen with the hydrophobic pocket. The ultrafast isomerization and decays are explained in terms of coupling motions between N-N and C-N stretching modes of the formed tautomer. We discuss the role of confinement on the trans-cis isomerization with the cavities and its relationships to frequency and time domains of nanostructure emission.cyclodextrins ͉ protein ͉ H-bond ͉ twisting ͉ anisotropy F emtosecond (fs) studies of caged molecules in nanocavities provide direct information on the relationship between time and space domains of molecular relaxation (1). Therefore, simple and complex (in concept) molecular systems have been studied using cyclodextrins (CDs), proteins, micelles, pores, and zeolites as nanohosts, demonstrating the confinement effect of the hydrophobic nanocavities on the spectroscopy and dynamics of the guests (2-13). Relevant information on the ultrafast dynamics of caged wavepackets involving breaking͞making chemical bonds, and solvation has been acquired.Orange II (OII) (Fig. 1), also called acid orange 7, is a molecule that has O-H . . . N and NAN bonds and may show photoinduced intramolecular proton-transfer (IPT) and transcis isomerization reactions. It is widely used in the dyeing of textiles, food, and cosmetics and thus is found in the wastewaters of the related industries (14). It has been reported that it exists under azoenol (AZO) and ketohydrazone (HYZ) forms (Fig. 1) (15-20). In a water solution, for example, the H-atom within the O-H . . . N intramolecular H-bond is shifted to the nitrogen site, making HYZ structure the most stable one (Ϸ95%) (20). In DMSO, the HYZ population decreases to 70%, and in solid state it becomes the only populated structure (20). Recent x-ray studies of phenyl substituted 1-(arylazo)-2-naphthols showed that this kind of molecules displaying HYZ-AZO tautomerism can form intramolecular resonance-assisted H-bonds from pure N-H . . . O to pure N . . . H-O structures, depending on the phenyl derivative (21, 22). Furthermore, a recent photophysical study of similar molecules in solution has shown the occurrence of a photoinduced proton-transfer reaction in AZO to give HYZ structure with a very low emission qu...

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Section: Resultssupporting

confidence: 90%

mentioning

confidence: 99%

Femtochemistry of orange II in solution and in chemical and biological nanocavities

Douhal

Sanz

Tormo

2005

Proc. Natl. Acad. Sci. U.S.A.

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“…2-Hydroxy Schiff base ligands are of interest mainly due to the existence of (O-H···N and N-H···O) type hydrogen bonds and tautomerism between the enol-imine and keto-enamine forms (Scheme 1). Tautomerism in 2-hydroxy Schiff bases both in solution and in the solid state was investigated using different spectroscopic techniques [7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23]. In the spectra of solutions of these compounds different Schiff bases have been studied in both polar and non-polar solvents [5,6,8,9,11,13,16,20].…”

Section: Introductionmentioning

confidence: 99%

“…The results indicate that the absorption band at greater than 400 nm belongs to the keto-enamine form of the Schiff base; the enol form has no appreciable absorbance in this region. Different explanations for the source of this band have been proposed [5,8,15,17,20]. It was suggested that this new band is due to the keto form in salicylidene anilines (Scheme 1).…”

Section: Introductionmentioning

confidence: 99%

Synthesis of Some New Anils: Part 1. Reaction of 2-Hydroxy-benzaldehyde and 2-Hydroxynaphthaldehyde with 2-Aminopyridene and 2-Aminopyrazine

Asiri¹,

Badahdah²

2007

Molecules

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“…The pKa values were calculated from Eq. (3) and the results are given in Tables 3 and 4. pKa = m. Hx ½ (H x = Ho, H_ and pH) (3) In this equation, Hx 1/2 represents half of the protonation value. This equation can be mathematically expressed as a straight line (y = m. x + n) with a slope of ‛m' for log I -pH.…”

Section: The Determination Of Acidity Constantsmentioning

confidence: 99%

Synthesis, Characterization and Spectroscopic Studies on Azo-Hydrazone Tautomerism and Acidity Constants of Certain 4-(Phenyldiazenyl) Benzene-1,3-Diol Derivatives

Berber¹,

Ateş²,

Özkütük³

2016

BTDB

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In this study, monoazo dyes were synthesized through the diazotization of several substituted aminobenzenes and couplings with benzene-1,3-diols. The chemical structures of these compounds were characterized using spectroscopic techniques. The tautomeric properties of the 4-(phenyldiazenyl)benzene-1,3-diol derivative compounds were examined using UV-Vis. spectrophotometry in pure polar or apolar media (dimethyl sulfoxide, ethanol, chloroform, benzene and cyclohexane) under acidic and basic conditions at 25±1 °C, 35±1 °C and 45±1 °C. The percentage of the azo-hydrazone tautomers was calculated for all of the compounds. The UV-Vis. analysis reveals that the azo form is dominant in the presence of azo-hydrazone tautomerism for all azo dyes. Concurrently, the acidity constants for these derivatives were determined using a UV-Vis. spectroscopic technique at 25 °C (0.1 °C).

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Excited state intramolecular proton transfer in some tautomeric azo dyes and schiff bases containing an intramolecular hydrogen bond

Cited by 116 publications

References 22 publications

Femtochemistry of orange II in solution and in chemical and biological nanocavities

Femtochemistry of orange II in solution and in chemical and biological nanocavities

Synthesis of Some New Anils: Part 1. Reaction of 2-Hydroxy-benzaldehyde and 2-Hydroxynaphthaldehyde with 2-Aminopyridene and 2-Aminopyrazine

Synthesis, Characterization and Spectroscopic Studies on Azo-Hydrazone Tautomerism and Acidity Constants of Certain 4-(Phenyldiazenyl) Benzene-1,3-Diol Derivatives

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