A Simple Rule for Predicting Circular Dichroism Induced in Aromatic Guests by Cyclodextrin Hosts in Inclusion Complexes

Kajtár, M.; Horváth-Toró, Csilla; Kuthi, Éva; Szejtli, J.

doi:10.1007/978-94-009-7855-3_22

Cited by 79 publications

(100 citation statements)

References 10 publications

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“…As can be seen from Figure 3, the circular dichroism spectrum of 1 showed a strong positive Cotton effect, which corresponds to the 1 L a band at 241 nm (De = 0.70 dm À3 mol À1 cm À1 ) and a negative Cotton effect for the 1 L b band at 269 nm (De = À0.23 dm À3 mol À1 cm À1 ). According to the pioneering studies of Kajtµr et al [21] and Harata and Uedaira [22] on the ICD phenomena of cyclodextrin complexes, we can deduce that the DPD moiety of 1 has entered into the b-CD cavity with a slightly acclivitous orientation, which is consistent with that seen in the crystal structure of 1. Interestingly, the DPD molecule in the b-CD cavity tethered by a Ni II ion gives an opposite ICD signal: a major negative Cotton effect at 232 nm (De = …”

supporting

confidence: 71%

Polymeric Rotaxane Constructed from the Inclusion Complex of β‐Cyclodextrin and 4,4′‐Dipyridine by Coordination with Nickel(II) Ions

et al. 2003

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supporting

confidence: 71%

Polymeric Rotaxane Constructed from the Inclusion Complex of β‐Cyclodextrin and 4,4′‐Dipyridine by Coordination with Nickel(II) Ions

et al. 2003

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“…[23] From a comparison of the weak ICD spectra obtained for bis(b-cyclodextrin)s 2 ± 5 with that of the reference 6, we deduce that the bipyridine chromophore in 4 and 5 is not embedded in the cavity, while the chromophore in 2 and 3 is either perched on the edge of the cavity or shallowly penetrating into the cavity. Hence, the 1 L a transition of 2 and 3 is deduced to be located in the negative region of the sector rule proposed by Kajtar, [24] Harata, [25] and Kodaka et al, [26] while the weak, positive Cotton effect observed for the 1 L b band of 4 and 5 would be better analyzed as an ordinary CD induced by the two distant chiral cyclodextrin moieties, although a shallow binding or perching model is not rigorously ruled out.…”

Section: Resultsmentioning

confidence: 99%

Cooperative Multipoint Recognition of Organic Dyes by Bis(-cyclodextrin)s with 2,2′-Bipyridine-4,4′-dicarboxy Tethers

Liu¹,

Chen²,

Li³

et al. 2001

Chem. Eur. J.

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A series of novel 6,6'-bis(beta-cyclodextrin)s linked by 2,2'-bipyridine-4,4'-dicarboxy tethers; that is, 2,2'-bipyridine-4,4'-dicarboxy-bridged bis(6-O-beta-cyclodextrin) (2) and N,N'-bis(2-aminoethyl )-2,2'-bipyridine-4,4'-dicarboxamide-bridged (3), N,N'-bis(5-amino-3-azapentyl)-2,2'-bipyridine-4,4'-dicarboxamide-bridged (4) and N,N'-bis(8-amino-3,6-diazaoctyl)-2,2'-bipyridine-4,4'-dicarboxamide-bridged bis(6-amino-6-deoxy-beta-cyclodextrin) (5), has been synthesized as cooperative multipoint-recognition receptor models. The inclusion complexation behavior of 2-5 with organic dyes; that is, ammonium 8-anilino-1-naphthalenesulfonate, Brilliant Green, Methyl Orange, Acridine Red, and Rhodamine B, has been investigated in aqueous phosphate buffer solutions (pH 7.20) at 25 degrees C by means of ultraviolet, fluorescence, and circular dichroism spectrometry as well as by fluorescence lifetime measurements. The spectral titrations gave the complex stability constants (Ks) and Gibbs' free energy changes (deltaG degrees) for the inclusion complexation of 2-5 with the organic dyes and other thermodynamic parameters (deltaH degrees and deltaS degrees) for the inclusion complexation of 2-4 with the fluorescent dyes Acridine Red and Rhodamine B. Bis(beta-cyclodextrin)s 2-5 displayed higher binding abilities toward most of the examined dye molecules than native beta-cyclodextrin 1; this is discussed from the viewpoints of the size/shape-fit concept, the induced-fit interaction, and cooperative, multipoint recognition by the bridging chain and the dual hydrophobic cavities. Thermodynamically, the inclusion complexation of 2-4 with Acridine Red is totally enthalpy driven with a negative or minor positive entropic contribution, but the inclusion complexation with Rhodamine B is mainly entropy-driven with a mostly positive, but occasionally negative, enthalpic contribution; in some cases this determines the complex stability.

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“…According to the rule, a positive ICD signal arises when the electric transition dipole moment is aligned parallel to the axis of the chiral host, but the signal is negative and half as strong when it is oriented in a perpendicular manner ( Figure 5). [18][19][20][21] Recently, a similar rule has also been developed by Kodaka for ICD effects outside the chiral host cavity, where the sign of the ICD signal is opposite to that arising inside the host cavity ( Figure 5). [22] The prolonged irradiation of aqueous R1-alk solution (10 mol solid Na 2 CO 3 were added to the R1 and the isophthalic acid unit was changed to the anionic form) at 335 nm would result in the photoisomerization of the E to Z form and the shuttling of the a-CyD ring from the stilbene unit to the biphenyl unit, which was previously confirmed by 2D ROESY NMR spectrum.…”

Section: Synthesis and Co-conformational Identification Of R4mentioning

confidence: 99%

Unidirectional Threading Synthesis of Isomer‐Free [2]Rotaxanes

Wang

et al. 2006

Chemistry A European J

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The threading of an alpha-cyclodextrin (alpha-CyD) by an unsymmetrical dumbbell generally results in two isomeric [2]rotaxanes differing in the orientation of the alpha-CyD. In this work, two methods have been developed for the unidirectionally threading an alpha-CyD to obtain isomer-free [2]rotaxanes. These methods use the Suzuki coupling of a boronic acid derivative and a halide in aqueous alkaline solution. The conformations of the two unidirectional [2]rotaxanes-R3 and R4 were determined by 2D 1H ROESY NMR spectra. The optical spectral studies revealed that each of the two [2]rotaxanes can proceed with E/Z photoisomerization and shuttling motions of the alpha-CyD ring on the thread under alternating irradiation at 330 and 275 nm, accompanied by fluorescence intensity changes at 530 nm. The induced circular dichroism (ICD) spectra of another two analogous [2]rotaxanes R1 and R2 were also studied. Distinctive ICD signal changes resulting from the photoisomerization with respect to the movements of alpha-CyD were detected. This demonstrates that, besides the fluorescence, ICD signal is another way to identify the shuttling motions of alpha-CyD in these [2]rotaxanes.

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A Simple Rule for Predicting Circular Dichroism Induced in Aromatic Guests by Cyclodextrin Hosts in Inclusion Complexes

Cited by 79 publications

References 10 publications

Polymeric Rotaxane Constructed from the Inclusion Complex of β‐Cyclodextrin and 4,4′‐Dipyridine by Coordination with Nickel(II) Ions

Polymeric Rotaxane Constructed from the Inclusion Complex of β‐Cyclodextrin and 4,4′‐Dipyridine by Coordination with Nickel(II) Ions

Cooperative Multipoint Recognition of Organic Dyes by Bis(-cyclodextrin)s with 2,2′-Bipyridine-4,4′-dicarboxy Tethers

Unidirectional Threading Synthesis of Isomer‐Free [2]Rotaxanes

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