Inclusion compounds of cyclodextrin and azo dyes. II. 1H nuclear magnetic resonance and circular dicroism spectra of cyclodextrin and azo dyes with a naphthalene nucleus.

Suzuki, Miyoko; Sasaki, Yoshio

doi:10.1248/cpb.27.1343

Cited by 19 publications

(12 citation statements)

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“…It is especially important to note that, for both 4-nitrophenol and 4-nitrophenolate, it is the nitro end of the guest that enters the cavity. 296b,229,230 Many other guest molecules adopt orientations in the CyD cavity that are reasonably represented by Figure 8: transcinnamic acids; 237 some carboxylates; 238 azo dyes; [239][240][241][242] aromatic amino acids; 243 ephedrine; 244 anilinonaphthalenesulfonates; 245,246 azulene; 247 adamantanes; 248,249 a nonionic surfactant; 250 menthols; 251 and many drug molecules. 252-257 13 C NMR has shown the structure of a 1:2 (SL 2 ) complex of 4-biphenylcarboxylate to possess a head-to-head relationship of the CyD rings, positioned so that hydrogen bonding of the O(2),O-(3) hydroxy group on the two CyDs is possible.…”

Section: B Nuclear Magnetic Resonance Spectroscopymentioning

confidence: 93%

The Stability of Cyclodextrin Complexes in Solution

1997

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Section: B Nuclear Magnetic Resonance Spectroscopymentioning

confidence: 93%

The Stability of Cyclodextrin Complexes in Solution

1997

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“…The inclusion complex of MO and CD has been a subject of NMR and absorption spectroscopy studies and various other measurements in the steady state. [14][15][16][17][18][19][20] In this study, we measured the isomerization dynamics of MO confined in the CD cavity by the ultrafast transient lens method (UTL) and transient absorption spectroscopy (TA). UTL is a technique to detect the ultrafast change of the refractive index of a solution that accompanies the photoexcitation and relaxation processes with picosecond to femtosecond time resolution.…”

Section: Introductionmentioning

confidence: 99%

Femtosecond Time-Resolved Spectroscopy of Photoisomerization of Methyl Orange in Cyclodextrins

et al. 2001

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The photoisomerization of methyl orange (MO) encapsulated in the cavities of R-, -, and γ-cyclodextrins (CDs) was measured by the ultrafast transient lens (UTL) method and transient absorption spectroscopy. The signal for free MO was well-fitted to the sum of two exponential functions, except for the component of the optical Kerr effect (OKE), and their time constants were j1 (τ 1 ) and ∼10 ps (τ 2 ). The UTL signal of the 1:1 complex, in which one MO molecule was included in one CD molecule, was almost the same as that of free MO. On the other hand, MO in two R-CD molecules showed slower relaxation and considerably lower yield of cis isomer. Thus, there were clear confinement effects when MO was capped at both ends by two CD molecules. The observed changes of ultrafast dynamics and yield of the isomer were explained in terms of CD-MO interactions and a steric effect. In the case of γ-CD, which included two MO molecules as a dimer, these confinement effects were also observed even when each MO was capped on only one side (2:1 complex). These results showed that a strong intermolecular interaction was induced between two MO molecules by confinement in a nanospace and this also hindered the isomerization. In particular, the complex with two γ-CD molecules (2:2 complex) showed significantly slower relaxation than the others, and no cis isomer was formed. It seemed that the intermolecular interaction of two MO molecules was further enhanced by photoexcitation in the 2:2 complex and this resulted in the formation of an aggregate-like intermediate in the γ-CD nanocavity.

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“…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). 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).…”

mentioning

confidence: 99%

“…The inclusion of OII under its trans-AZO form into CD proceeds through the naphthol unit ( Fig. 1) (24,25), and the degree of penetration depends on the size of the cavity, being higher in a larger one (24,27,28).…”

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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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Inclusion compounds of cyclodextrin and azo dyes. II. 1H nuclear magnetic resonance and circular dicroism spectra of cyclodextrin and azo dyes with a naphthalene nucleus.

Cited by 19 publications

References 0 publications

The Stability of Cyclodextrin Complexes in Solution

The Stability of Cyclodextrin Complexes in Solution

Femtosecond Time-Resolved Spectroscopy of Photoisomerization of Methyl Orange in Cyclodextrins

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

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