Twisted intramolecular charge transfer emission of dimethylaminobenzonitrile in α-cyclodextrine cavities

Nag, Ashis; Bhattacharyya, Kankan

doi:10.1016/0009-2614(88)85172-8

Cited by 96 publications

(40 citation statements)

References 17 publications

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“…TICT emissions are known to be significantly affected by the polarity in the cavity. [13][14][15] The observation of enhanced TICT emissions indicates that in the complex the DMABN molecule does not remain totally inside the hydrophobic cavity. Therefore, the molecule might be located partially inside the cavity but also project outside, where the molecule is in a polar environment.…”

Section: Resultsmentioning

confidence: 98%

Molecular States of p-Dimethylaminobenzonitrile Coground with .BETA.-Cyclodextrin Investigated Using Solid-State Fluorescence Spectroscopy

Inoue

Hasegawa

Tozuka

et al. 2011

CHEMICAL & PHARMACEUTICAL BULLETIN

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NoteCyclodextrin (CD) molecules with hydrophobic cavities form inclusion complexes with hydrophobic guest molecules.1) b-CD in particular can include a wide range of guest molecules, so b-CD has widely been utilized in formulations for medicines and food.2,3) p-Dimethylaminobenzonitrile (DMABN) is known as a model probe for determining the mechanisms of inclusion in a solution.4) DMABN molecules have been reported to adopt two different conformation, planar and twisted, in a solution. The two structures have been reported to lead to different fluorescence emission peaks, with DMABN molecules in a planar structure producing a fluorescence emission peak at a shorter wavelength, and DMABN molecules in a twisted structure in a twisted intramolecular charge-transfer (TICT) state producing a peak at a longer wavelength. 5,6) TICT state emission has been reported to be caused by an electron transfer of the dimethylamino group from a nitrogen atom to the cyano group, or to the entire benzonitrile group, because of the twist. 7) Since DMABN adopts different structures depending on the molecular environment, e.g. different CD cavity diameters, and DMABN's molecular state is reflected in the fluorescent spectrum, DMABN is an interesting research probe for intermolecular interactions with CDs. 8) As a probe, DMABN was coprecipitated or coground with b-CD in this study to analyze the solid-state fluorescence emission spectrum of the inclusion complexes, as well as the excitation spectrum, and fluorescence lifetime by time-resolved fluorometry, and to examine the changes in DMABN's molecular state. ExperimentalMaterials p-Dimethylaminobenzonitrile (DMABN) was purchased from Tokyo Chemical Industry Co., Ltd. (Japan). b-Cyclodextrin (b-CD) was obtained from Mercian Co., Ltd., Japan. Crystalline cellulose (CC: PH-101) was obtained from Asahi Chemical Industrial Co., Ltd., Japan. b-CD and CC were used after they were dried under reduced pressure at 110°C for 3 h. All other chemicals used were of reagent grade.Preparation of a Physical Mixture and a Ground Mixture A physical mixture of DMABN and b-CD (molar ratio of DMABN/b-CDϭ1/1) or CC (DMABN content 11.4%) was prepared by kneading in a mortar for 10 s. A ground mixture was prepared by grinding the physical mixture (2.0 g) using a vibrating mill (Heiko Seisakusho, TI200, Japan).Preparation of Complexes by Coprecipitation b-CD (2.0ϫ10 Ϫ3 mol) and DMABN (6.0ϫ10 Ϫ3 mol) were dissolved in distilled water and diethyl ether, respectively. The 2 solutions were mixed well. Each solution was slowly cooled to 4.0°C to allow coprecipitation. The coprecipitate obtained in the aqueous phase was filtered out with filter paper and dried under reduced pressure at 120°C for 6 h.Powder X-Ray Diffractometry Powder X-ray diffraction patterns were measured using a Rigakudenki 2027 diffractometer (Japan). The measurement conditions were as follows: target, Cu; filter, Ni; voltage, 30 kV; current, 15 mA; time constant, 0.5 s; scanning speed, 4 degree/min.Thermal Analysis Thermogravimetry-differentia...

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Section: Resultsmentioning

confidence: 98%

Molecular States of p-Dimethylaminobenzonitrile Coground with .BETA.-Cyclodextrin Investigated Using Solid-State Fluorescence Spectroscopy

Inoue

Hasegawa

Tozuka

et al. 2011

CHEMICAL & PHARMACEUTICAL BULLETIN

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“…Knowing that the interiors of the micelles are less polar and protic, the opposite results observed in our case can be explained as follows. The weak TICT emission in water has been attributed to the stabilization of the highly polar TICT state by strong dipole-dipole interactions with water and thus rapid nonradiative transitions to the ground state and/or the low-lying triplet state (19). In the less polar environments of the micelles, the TICT state is destabilized.…”

Section: Discussionmentioning

confidence: 98%

Twisted Intramolecular Charge Transfer Emission of 2-(4′-N,N-dimethylaminophenyl)benzimidazole in Micelles

Krishnamoorthy

Dogra

1999

Journal of Colloid and Interface Science

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“…There have been a number of reports on the effects of hydrogen bonding of TICT states of guests within CD cavities [65][66][67][68][69][70][71][72][73][74][75][76][77]. Nag and Bhattacharyya studied the TICT emission of dimethylaminobenzonitrile (DMABN) in a-CD [65].…”

Section: Cyclodextrinsmentioning

confidence: 99%

“…Nag and Bhattacharyya studied the TICT emission of dimethylaminobenzonitrile (DMABN) in a-CD [65]. They found a significant enhancement of the TICTemission, which they attributed to the reduced polarity of the CD cavity.…”

Section: Cyclodextrinsmentioning

confidence: 99%

Fluorescence Studies of the Hydrogen Bonding of Excited‐State Molecules within Supramolecular Host–Guest Inclusion Complexes

Wagner

2010

Hydrogen Bonding and Transfer in the Excited State

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Twisted intramolecular charge transfer emission of dimethylaminobenzonitrile in α-cyclodextrine cavities

Cited by 96 publications

References 17 publications

Molecular States of p-Dimethylaminobenzonitrile Coground with .BETA.-Cyclodextrin Investigated Using Solid-State Fluorescence Spectroscopy

Molecular States of p-Dimethylaminobenzonitrile Coground with .BETA.-Cyclodextrin Investigated Using Solid-State Fluorescence Spectroscopy

Twisted Intramolecular Charge Transfer Emission of 2-(4′-N,N-dimethylaminophenyl)benzimidazole in Micelles

Fluorescence Studies of the Hydrogen Bonding of Excited‐State Molecules within Supramolecular Host–Guest Inclusion Complexes

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