Substituent and solvent effects on the proton transfer equilibrium in anils and azo derivatives of naphthol. Multinuclear NMR study and theoretical calculations

Alarcón, Sergio H.; Olivieri, Alejandro C.; Sanz, Dionísia; Claramunt, Rosa M.; Elguero, José

doi:10.1016/s0022-2860(03)00208-4

Cited by 85 publications

(52 citation statements)

References 19 publications

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“…As reported earlier (44,45), in 2-arylazo-1-naphthols, but not in 4-arylazo-1-naphthols, there is a strong intramolecular hydrogen bonding both in the hydroxyazo and ketohydrazone forms (Scheme 5). In many cases, a factor which contributes to the explanation of the predominance of the hydrazone isomer is that in this form the intramolecular hydrogen bonding is significantly stronger than the azo form.…”

Section: Synthesis Of Azo Dyes Based On 1-naphtholsupporting

confidence: 68%

Environmentally green approach to synthesize azo dyes based on 1-naphthol using nano BF₃·SiO₂under solvent-free conditions

Bamoniri

Mirjalili

Moshtael-Arani

2014

Green Chemistry Letters and Reviews

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A series of azo dyes were efficiently synthesized by mixing aromatic amines and NaNO 2 in the presence of nano silica supported boron trifluoride (nano BF 3 ·SiO 2 ) and then diazo coupling with 1-naphthol under solvent-free conditions at room temperature. The present methodology has proven to be simple, rapid, environmentally benign, green, and cost-effective compared with previous synthetic methods. Also, by using this procedure, aryl diazonium salts supported on nano BF 3 ·SiO 2 were very stable to be kept at room temperature for several months without any special conditions.

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Section: Synthesis Of Azo Dyes Based On 1-naphtholsupporting

confidence: 68%

Environmentally green approach to synthesize azo dyes based on 1-naphthol using nano BF₃·SiO₂under solvent-free conditions

Bamoniri

Mirjalili

Moshtael-Arani

2014

Green Chemistry Letters and Reviews

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“…It has been reported that it exists under azoenol (AZO) and ketohydrazone (HYZ) forms ( Fig. 1) (15)(16)(17)(18)(19)(20). In a water solution, for example, the H-atom within the O-H .…”

mentioning

confidence: 99%

“…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). So far, the CD inclusion complex studies have considered that OII in water solutions exists under AZO tautomer, contrary to many studies in solutions where OII coexists under AZO and HYZ forms (5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20). Recently, ultrafast transient lens technique with a response function of Ϸ300 fs has been used to study the dynamics of OII in CD (36).…”

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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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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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“…23 Tautomeric forms can be identified from their spectral properties 24 and the stability of such forms in solution may be influenced by the nature of the substituents present in the molecules. 25 Incorporation of an azo group into 2-hydroxy-1,4-naphthoquinone has led to promising antimalarial and anticancer agents, in which metal complexation with copper(II) resulted in increased cytotoxicity. 26,27 The derivatives can be represented by several tautomeric structures illustrated in Figure 1: 3-(2-R-phenylhydrazono)-naphthalene-1,2,4-triones, Ia and Ib, 3-R-arylazo-4-hydroxy-1,2-naphthoquinones, IIa and IIb, and 3-R-arylazo-2-hydroxy-1,4-naphthoquinone III.…”

Section: Introductionmentioning

confidence: 99%

Theoretical studies of the tautomerism in 3-(2-R-Phenylhydrazono)-naphthalene- 1,2,4-triones: synthesis of copper(II) complexes and studies of antibacterial and antitumor activities

Francisco

Vargas

Fragoso

et al. 2010

J. Braz. Chem. Soc.

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Cálculos teóricos utilizando os funcionais B3LYP e PBE1PBE e as bases 6-31G(d) e 6-311+G(2d,p) para o sistema 3-(2-fenil-hidrazona)-naftaleno-1,2,4-triona, em solução (dmso) e em fase gasosa, evidenciaram, em ambos os casos, a maior estabilidade da forma ceto-hidrazona (rotâmeros Ia e Ib) comparada às formas enol-azo (rotâmeros IIa/IIb, por volta de 14 kcal mol -1 ) e III (aproximadamente 6 kcal mol -1 ). A natureza do substituinte no grupo fenil não influenciou a estabilidade relativa dos tautômeros. Estes resultados foram confirmados por dados espectroscópicos dos derivados HL1-HL13, sintetizados a partir da 2-hidroxi-1,4-naftoquinona e arilaminas (R = 4-OMe, 4-N 2 -C 6 H 5 , 4-Cl, 4-I, 3-I, 2-I, 4-COOH, 3-COOH, 4-CN, 3-CN, 4-NO 2 , 3-NO 2 , 2-NO 2 ). A avaliação da atividade anticâncer in vitro (contra linhagens de células cancerosas SF-295, HCT-8, MDAMB-435 e HL-60) e bactericida (Bacillus cereus, Bacillus subtilis, Enterococcus faecalis, Staphylococcus aureus, Escherichia coli, Klebsiella pneumonia e Pseudomonas aeruginosa) dos compostos HL1-HL13 e dos seus respectivos complexos de cobre(II), 2 ], foi avaliada. Em geral a atividade bactericida foi baixa, exceto para o derivado HL5 (R = 3-I), mais ativo do que o controle; entretanto, seu complexo não foi ativo. Por outro lado, a complexação levou, em geral, ao aumento da atividade antitumoral dos pré-ligantes. O complexo [Cu(L13) 2 ] (R = 3-NO 2 ) apresentou moderada citotoxicidade contra leucemia humana (HL-60).DFT calculations using the B3LYP and PBE1PBE functionals with the standard 6-31G(d) and 6-311+G(2d,p) basis sets were carried out for the 3-(2-phenylhydrazone)-naphthalene-1,2,4-trione system in solution (dmso) and in the gas phase, and showed the keto-hydrazone forms (rotamers Ia and Ib) to be more stable than the enol-azo forms (rotamers IIa and IIb, by about 14 kcal mol ), independently of the nature of the substituent in the phenylene ring. These results were confirmed by spectroscopic data on the derivatives HL1-HL13, obtained from 2-hydroxy-1,4-naphthoquinone and arylamines (R = 4-OMe, 4-N 2 -C 6 H 5 , 4-Cl, 4-I, 3-I, 2-I, 4-COOH, 3-COOH, 4-CN, 3-CN, 4-NO 2 , 3-NO 2 , 2-NO 2 ). The in vitro antitumor (against SF-295, HCT-8, MDAMB-435 and HL-60 cancer cell lines) and antibacterial activities (Bacillus cereus, Bacillus subtilis, Enterococcus faecalis, Staphylococcus aureus, Escherichia coli, Klebsiella pneumonia and Pseudomonas aeruginosa) of compounds HL1-HL13 and of their respective copper(II) complexes, ) 2 ], were tested. In general, these compounds exhibited low antibacterial activity, except for HL5 (R = 3-I), more active than the control; however, the corresponding complex was inactive. In contrast, increased cytotoxicity was observed upon complexation. Complex [Cu(L13) 2 ] (R = 3-NO 2 ) presented moderate cytotoxicity against human leukemia (HL-60).Keywords: naphthoquinones, copper(II) complexes, tautomerism, hydrazone compounds, antibacterial activity, antitumor activity Theoretical Studies of the Tautomerism in 3-(2-R-Phenylhydrazono)...

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Substituent and solvent effects on the proton transfer equilibrium in anils and azo derivatives of naphthol. Multinuclear NMR study and theoretical calculations

Cited by 85 publications

References 19 publications

Environmentally green approach to synthesize azo dyes based on 1-naphthol using nano BF₃·SiO₂under solvent-free conditions

Environmentally green approach to synthesize azo dyes based on 1-naphthol using nano BF₃·SiO₂under solvent-free conditions

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

Theoretical studies of the tautomerism in 3-(2-R-Phenylhydrazono)-naphthalene- 1,2,4-triones: synthesis of copper(II) complexes and studies of antibacterial and antitumor activities

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Substituent and solvent effects on the proton transfer equilibrium in anils and azo derivatives of naphthol. Multinuclear NMR study and theoretical calculations

Cited by 85 publications

References 19 publications

Environmentally green approach to synthesize azo dyes based on 1-naphthol using nano BF3·SiO2under solvent-free conditions

Environmentally green approach to synthesize azo dyes based on 1-naphthol using nano BF3·SiO2under solvent-free conditions

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

Theoretical studies of the tautomerism in 3-(2-R-Phenylhydrazono)-naphthalene- 1,2,4-triones: synthesis of copper(II) complexes and studies of antibacterial and antitumor activities

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Environmentally green approach to synthesize azo dyes based on 1-naphthol using nano BF₃·SiO₂under solvent-free conditions

Environmentally green approach to synthesize azo dyes based on 1-naphthol using nano BF₃·SiO₂under solvent-free conditions