Effect of solvent polarity on the yield of twisted intramolecular charge transfer (TICT) emission. Competition between formation and nonradiative decay of the TICT state

Nag, Ashis; Kundu, Tapanendu; Bhattacharyya, Kankan

doi:10.1016/0009-2614(89)87592-x

Cited by 37 publications

(23 citation statements)

References 19 publications

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“…1 for 1 at room temperature indicates that, in the nonviscous solvents, the (F LW f /F SW f ) ratio decreases when the solvent polarity increases. This behavior is the opposite of that found for 4-(dimethyl)aminobenzonitrile (DMABN) for which this ratio increases with the polarity of the solvent as demonstrated [46] by increasing the amount of propionitrile in a hexane/propionitrile mixture, the polarity of the later being much higher, 27.2, than that of the former, 1.89. This major difference between 1 and DMABN probably originates from the large difference in dipole moment of their LW* excited states.…”

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confidence: 58%

Temperature-Dependent Behavior of the Dual Fluorescence of 2-(3-Fluorophenyl)-2,3-dihydro-1H-benzo[f]isoindole-1,3-dione

Valat¹,

Wintgens²,

Kossanyi³

et al. 2001

HCA

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Dedicated to Prof. AndreÂ M. Braun on the occasion of his 60th birthdayThe fluorescence behavior of 2-(3-fluorophenyl)-2,3-dihydro-1H-benzo[f]isoindole-1,3-dione (1) was studied in solvents of different polarity and viscosity. Dual luminescence is observed and the short-wavelength emission is found to increase considerably with the solvent polarity. The ratio of the fluorescence quantum yield of the two states emitting, the one (SW*) at short wavelength and the other (LW*) at long wavelength, shows a bell-shaped dependence on the reciprocal of the temperature in diethyl ether, butyronitrile, and propane-1,2,3-triol triacetate (glycerol triacetate; GTA). This has been interpreted as the result of a reversible interconversion between the two states. The enthalpy difference between the SW* and LW* excited states, as deduced from the slope of the ln (F LW f /F SW f ) vs. 1/T curves in the high temperature range, is found to be solvent polarity and solvent viscosity independent as the same value (À 7.3 kJ/mol) is obtained in the three above-mentioned solvents. The independence from polarity is the consequence of a similar difference in dipole moment between the ground-state and the SW* and LW* excited states (4.5 and 4.9 D, respectively, derived from solvatochromy). The activation energy of the SW* 3 LW* step deduced from the low temperature measurements in the nonviscous solvents, increases with solvent polarity (11.6 and 17.5 kJ/mol for diethyl ether and butyronitrile, respectively); they are greater than the viscous-flow activation energy of the solvents indicating that the resolvation of the excited dipole controls the kinetics. In the nonviscous solvents, the LW* state originates from the SW* state, while in the viscous GTA solution, both states are formed simultaneously within the 1-ps laser pulse.

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confidence: 58%

Temperature-Dependent Behavior of the Dual Fluorescence of 2-(3-Fluorophenyl)-2,3-dihydro-1H-benzo[f]isoindole-1,3-dione

Valat¹,

Wintgens²,

Kossanyi³

et al. 2001

HCA

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“…Fromherz, Heilmann and others reported that N,N-dimethyl substituted hemicyanine undergoes internal twisting and a yields a twisted internal charge transfer (TICT) state on photoexcitation [Scheme 7]. 43,44 However, no dual emission was observed in this molecule (HC-3) and the authors hypothesized a non-emissive TICT state. Due to multiple bond rotations producing rotamers in hemicyanine dyes, the ICT states are deactivated.…”

Section: Resultsmentioning

confidence: 98%

Fluorescence phenomena in nerve-labeling styryl-type dyes

Siclovan

Zhang

Cotero

et al. 2016

Journal of Photochemistry and Photobiology A: Chemistry

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Several classes of diversely substituted styryl type dyes have been synthesized with the goal of extending their expected fluorescent properties as much towards red as possible given the constraint that they maintain drug-like properties and retain high affinity binding to their biological target. We report on the synthesis, optical properties of a series of styryl dyes (d1-d14), and the anomalous photophysical behavior of several of these Donor-Acceptor pairs separated by long conjugated π-systems (d7-d10). We further describe an unusual dual emission behavior with two distinct ground state conformers which could be individually excited to locally excited (LE) and twisted intramolecular charge transfer (TICT) excited state in push-pull dye systems (d7, d9 and d10). Additionally, unexpected emission behavior in dye systems d7 and d8 wherein the amino- derivative d7 displayed a dual emission in polar medium while the N,N-dimethyl derivative d8 and other methylated derivatives d12-d14 showed only LE emission but did not show any TICT emission. Based on photophysical and nerve binding studies, we down selected compounds that exhibited the most robust fluorescent staining of nerve tissue sections. These dyes (d7, d9, and d10) were subsequently selected for in-vivo fluorescence imaging studies in rodents using the small animal multispectral imaging instrument and the dual-mode laparoscopic instrument developed in-house.

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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: 99%

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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Effect of solvent polarity on the yield of twisted intramolecular charge transfer (TICT) emission. Competition between formation and nonradiative decay of the TICT state

Cited by 37 publications

References 19 publications

Temperature-Dependent Behavior of the Dual Fluorescence of 2-(3-Fluorophenyl)-2,3-dihydro-1H-benzo[f]isoindole-1,3-dione

Temperature-Dependent Behavior of the Dual Fluorescence of 2-(3-Fluorophenyl)-2,3-dihydro-1H-benzo[f]isoindole-1,3-dione

Fluorescence phenomena in nerve-labeling styryl-type dyes

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

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