Inclusion complexation of ?-cyclodextrin and 6-O-?-�maltosyl- and 2-O-(2-hydroxypropyl)-?-cyclodextrins �with some fluorescent dyes

Liu, Yu; You, Chang-Cheng

doi:10.1002/1099-1395(200101)14:1<11::aid-poc329>3.0.co;2-7

Cited by 26 publications

(10 citation statements)

References 38 publications

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“…These phenomena suggested that the fluorophore experienced a less polar environment and the inclusion complex was formed by adding host compound. On the other hand, the bridged bis(β-cyclodextrin)s 3 − 5 with long spacers would quench the fluorescence of RhB, which is consistent with the case of β-cyclodextrin or modified β-cyclodextrins . It is unexpected that the bis(β-cyclodextrin) 2 tethered by a shorter linker effectively enhanced the original fluorescence intensity of RhB.…”

Section: Resultssupporting

confidence: 77%

Synthesis of Novel Bis(β-Cyclodextrin)s and Metallobridged Bis(β-Cyclodextrin)s with 2,2‘-Diselenobis(benzoyl) Tethers and Their Molecular Multiple Recognition with Model Substrates

Liu

Zhang

et al. 2002

J. Org. Chem.

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To investigate quantitatively the cooperative binding ability of beta-cyclodextrin dimers, a series of bridged bis(beta-cyclodextrin)s with 2,2'-diselenobis(benzoyl) spacer connected by different lengths of oligo(ethylenediamine)s (2-5) and their platinum(IV) complexes (6-9) have been synthesized and their inclusion complexation behavior with selected substrates, such as Acridine Red, Neutral Red, Brilliant Green, Rhodamine B, ammonium 8-anilino-1-naphthalenesulfonate, and 6-p-toluidino-2-naphthalenesulfonic acid, were investigated by means of ultraviolet, fluorescence, fluorescence lifetime, circular dichroism, and 2D-NMR spectroscopy. The spectral titrations have been performed in aqueous phosphate buffer solution (pH 7.20) at 25 degrees C to give the complex stability constants (K(S)) and Gibbs free energy changes (-DeltaG degrees ) for the inclusion complexation of hosts 2-9 with organic dyes and other thermodynamic parameters (DeltaH degrees and TDeltaS degrees ) for the inclusion complexation of 2-5with fluorescent dyes ANS and TNS. The results obtained indicate that beta-cyclodextrin dimers 2-5 can coordinate with one or two platinum(IV) ions to form 1:1 or 1:2 stoichiometry metallobridged bis(beta-cyclodextrin)s. As compared with parent beta-cyclodextrin (1) and bis(beta-cyclodextrin)s 2-5, metallobridged bis(beta-cyclodextrin)s 6-9 can further switch the original molecular binding ability through the coordinating metal to orientate two beta-cyclodextrin cavities and an additional binding site upon the inclusion complexation with model substrates, giving the enhanced binding constants K(S) for both ANS and TNS. The tether length between two cyclodextrin units plays a crucial role in the molecular recognition with guest dyes. The binding constants for TNS decrease linearly with an increase in the tether length of dimeric beta-cyclodextrins. The Gibbs free energy change (-DeltaG degrees ) for the unit increment per ethylene is 0.32 kJ.mol(-)(1) for TNS. Thermodynamically, the higher complex stabilities of both ANS and TNS upon the inclusion complexation with 2-5 are mainly contributed to the favorable enthalpic gain (-DeltaH degrees ) by the cooperative binding of one guest molecule in the closely located two beta-cyclodextrin cavities as compared with parent beta-cyclodextrin. The molecular binding ability and selectivity of organic dyes by hosts 1-9 are discussed from the viewpoints of the multiple recognition mechanism and the size/shape-fitting relationship between host and guest.

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Section: Resultssupporting

confidence: 77%

Synthesis of Novel Bis(β-Cyclodextrin)s and Metallobridged Bis(β-Cyclodextrin)s with 2,2‘-Diselenobis(benzoyl) Tethers and Their Molecular Multiple Recognition with Model Substrates

Liu

Zhang

et al. 2002

J. Org. Chem.

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“…However, there are some literature reports of such a phenomenon, although the reasons for the fluorescence quenching are not always very clear. − Schuette et al have explained the reduction in the fluorescence of acridine dye in the presence of β-CD in terms of increased intersystem crossing of acridine in the relatively aprotic medium inside the β-CD cavity . Liu et al have attributed the fluorescence quenching of rhodamine B in the presence of β-CD to the preferential complexation of β-CD with the nonfluorescent lactone form of rhodamine B and a conversion of some fluorescent zwitterionic form of the dye to the nonfluorescent lactone form in the presence of β-CD . Very recently, Zhou et al have reported the fluorescence quenching of RF in the presence of CB7, although no explanation was provided for the observed effect .…”

Section: Resultsmentioning

confidence: 99%

A Fluorescence Perspective on the Differential Interaction of Riboflavin and Flavin Adenine Dinucleotide with Cucurbit[7]uril

et al. 2010

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The interaction of the macrocyclic host, cucurbit[7]uril (CB7), with riboflavin (RF) and its derivative, flavin adenine dinucleotide (FAD), has been investigated using absorption and steady-state and time-resolved fluorescence measurements. Interestingly, in the presence of CB7, the fluorescence intensity of RF is quenched, whereas the fluorescence intensity of FAD is enhanced. It is proposed that the fluorescence quenching of RF results from the tautomerization of its isoalloxazine moiety from the lactam to the lactim forms, upon binding to CB7. Such a tautomerization can be brought about since the two lactim forms have higher dipole moments than the lactam form of RF, and thus experience much stronger dipole-dipole interactions (and hence greater binding affinities) with CB7 in the former cases than in the latter. This tautomerization in the presence of CB7 leads to a significant reduction in the observed radiative decay rate and hence a reduction in the fluorescence intensity of RF. Binding of CB7 with RF is confirmed by an increase in the rotational correlation time of RF in the presence of CB7. Geometry optimization studies indicate the formation of an exclusion complex between CB7 and RF, possibly stabilized by H-bonding interactions, as also suggested by the characteristic red shift in the absorption spectra of the CB7-RF system. In the case of FAD, both the isoalloxazine ring and the adenine moiety can interact with the CB7 host. In aqueous solutions, a good fraction of FAD molecules exists in a "closed" conformation with the adenine and isoalloxazine rings stacked together, thus leading to very efficient fluorescence quenching due to the ultrafast intramolecular electron transfer from adenine to the isoalloxazine moiety. Binding of the adenine and/or the isoalloxazine moiety of FAD with CB7 inhibits the stacking interaction and changes the "closed" conformation to the "open" conformation, wherein the adenine and isoalloxazine moieties are widely separated, thus prohibiting the electron transfer process. This reduces the inherent fluorescence quenching of FAD molecule and results in the observed fluorescence enhancement. As observed for RF, the interaction of CB7 with the isoalloxazine ring of FAD should cause fluorescence quenching due to the lactam to lactim tautomerization process. However, in the interplay between the above two opposing effects, the fluorescence enhancement due to the modulation in the conformational dynamics of FAD by the CB7 host predominates. The conformational change is in fact supported by the observation of a long lifetime component in the fluorescence decay of FAD in the presence of CB7. Moreover, at acidic pH, when FAD is already present mainly in the "open" form, the conformational dynamics no longer plays any major role and the fluorescence of FAD is quenched by CB7, as expected, due to the tautomerization at the isoalloxazine moiety.

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“…The lifetimes of aniline (2.7 ns) and N ‐methylaniline (3.7 ns) in the presence of β ‐cyclodextrin are consistent with the above long lifetime. On the other hand, the inclusion complex stabilities of aniline ( K S =61 dm 3 mol −1 ) and N ‐methylaniline ( K S =83 dm 3 mol −1 ) with β ‐cyclodextrin are also in accord with that of ANS 35…”

Section: Resultsmentioning

confidence: 76%

Synthesis and Molecular Recognition of Novel Oligo(ethylenediamino) Bridged Bis(β-cyclodextrin)s and Their Copper(II) Complexes: Enhanced Molecular Binding Ability and Selectivity by Multiple Recognition

Liu

You

2001

Chem. Eur. J.

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Four bridged bis(beta-cyclodextrin)s tethered by different lengths of oligo(ethylenediamine)s have been synthesized and their inclusion complexation behavior with selected substrates elucidated by circular dichroism spectroscopy and fluorescence decay. In order to study their binding ability quantitatively, inclusion complexation stability constants with four dye guests, that is, brilliant green (BG), methyl orange (MO), ammonium 8-anilino-1-naphthalenesulfonic acid (ANS), and sodium 6-(p-toluidino)-2-naphthalenesulfonate (TNS), have been determined in aqueous solution at 25 degrees C with spectrophotometric, spectropolarimetric, or spectrofluorometric titrations. The results obtained indicate that the two tethered cyclodextrin units might cooperatively bind to a guest, and the molecular binding ability toward model substrates, especially linear guests such as TNS and MO, could be extended. The tether length plays a crucial role in the molecular recognition, the binding constants for ANS and TNS decrease linearly with an increase in the tether length of dimeric cyclodextrin. The Gibbs free energy changes (-deltaGo) for the unit increment per ethylene are 0.99 kJ mol(-1) for ANS and 0.44 kJmol(-1) for TNS, respectively. On the other hand, the presence of a copper(II) ion in metallobis(beta-cyclodextrin)s oligo(ethylenediamino) tethers enhances not only the original binding ability, but also the molecular selectivity through triple or multiple recognition, as compared with the parent bis(beta-cyclodextrin)s.

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Inclusion complexation of ?-cyclodextrin and 6-O-?-�maltosyl- and 2-O-(2-hydroxypropyl)-?-cyclodextrins �with some fluorescent dyes

Cited by 26 publications

References 38 publications

Synthesis of Novel Bis(β-Cyclodextrin)s and Metallobridged Bis(β-Cyclodextrin)s with 2,2‘-Diselenobis(benzoyl) Tethers and Their Molecular Multiple Recognition with Model Substrates

Synthesis of Novel Bis(β-Cyclodextrin)s and Metallobridged Bis(β-Cyclodextrin)s with 2,2‘-Diselenobis(benzoyl) Tethers and Their Molecular Multiple Recognition with Model Substrates

A Fluorescence Perspective on the Differential Interaction of Riboflavin and Flavin Adenine Dinucleotide with Cucurbit[7]uril

Synthesis and Molecular Recognition of Novel Oligo(ethylenediamino) Bridged Bis(β-cyclodextrin)s and Their Copper(II) Complexes: Enhanced Molecular Binding Ability and Selectivity by Multiple Recognition

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