Rose bengal and nonpolar derivatives

Lamberts, Joseph J. M.; Neckers, Douglas C.

doi:10.1021/ja00363a056

Cited by 37 publications

(6 citation statements)

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“…Dyes such as rose bengal are known 28 to sensitize oxidation and it is found that singlet oxygen, a very reactive intermediate, is responsible for such processes. 29,30 If the thickness of the rose bengal layer in the device is increased, the oxidation of the aluminum electrode will be enhanced, and thus the insulating Al 2 O 3 layer will grow resulting in a higher R off value. A 2 nm thick Al 2 O 3 layer can be formed by normal oxygen and an even thicker layer will be formed by the more reactive singlet oxygen.…”

Section: Discussionmentioning

confidence: 99%

Resistive switching of rose bengal devices: A molecular effect?

Karthäuser

Lüssem

Weides

et al. 2006

Journal of Applied Physics

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The resistive switching behavior of devices consisting of aluminum top electrode, molecular layer ͑rose bengal͒, and bottom electrode ͑zinc oxide and indium tin oxide͒ is examined. By measuring the current versus voltage dependence of these devices for various frequencies and by systematically varying the composition of the device, we show that the switching is an extrinsic effect that is not primarily dependent on the molecular layer. It is shown that the molecular layer is short circuited by filaments of either zinc oxide or aluminum and that the switching effect is due to a thin layer of aluminum oxide at the zinc oxide/aluminum interface.

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Section: Discussionmentioning

confidence: 99%

Resistive switching of rose bengal devices: A molecular effect?

Karthäuser

Lüssem

Weides

et al. 2006

Journal of Applied Physics

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“…In aqueous solutions, pK a0 ¼ 0.35, pK a1 ¼ 4.00, and pK a2 ¼ 5. 19; the band with l max ¼ 450 nm was attributed to cations H 3 R þ , having a structure analogous to that of 6, but with COOH group instead of COO À . 3d In the ternary solvent mixture studied, the first equilibrium does not Figure 1.…”

Section: Determination Of Ionization Constantsmentioning

confidence: 97%

A dibasic acid with reversed order of the stepwise ionization constants: 2,7‐dichlorofluorescein in the ternary solvent mixture benzene–ethanol–water

Mchedlov‐Petrossyan

Salamanova

Vodolazkaya

et al. 2006

J of Physical Organic Chem

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The ionization constants of 2,7-dichlorofluorescein were determined and the molecular structures of the equilibrium forms were established in the ternary solvent system benzene-ethanol-water (mass ratio 47:47:6) by using visible spectroscopy. In this solvent mixture with relative dielectric constant e r ¼ 12.8 and normalized Reichardt's parameter E N T ¼ 0:587; an inversion of the stepwise ionization constants of the dye, K a1 and K a2 , occurs. The K a1 /K a2 ratio changes from 16 in water and 4.8 in 50 mass % aqueous ethanol to 0.1 in the ternary solvent system with ionic strength of 0.002 mol dm À3 , where pK a1 ¼ 9.23 AE 0.08 and pK a2 ¼ 8.22 AE 0.08 (25 8C). Such an extraordinary interrelation between the K a constants is in line with the molecular structure of ionic and nonionic species of 2,7-dichlorofluorescein deduced from their vis absorption spectra, as well as with the expressed salt effects and the probable ion association. The dianion R 2À (5 in Scheme 1) possesses a band with l max ¼ 512 nm and a molar absorptivity of E ¼ 84.3 Â 10 3 cm À1 mol À1 dm 3 . The tautomeric equilibrium of the neutral form, H 2 R, is strongly shifted toward the colorless lactone (2 in Scheme 1). The (very intensive) absorption band of the HR À species singled out from the vis spectra at different acidity, is red-shifted by Dl % 20 nm against the band of the dianion R 2À . Hence, the monoanion HR À is found to be completely converted into the 'phenolate' tautomer 4 with groups -COOH and -O À , while in aqueous solutions the 'carboxylate' tautomer 3 with groups -COO À and -OH predominates. In 50 mass % aqueous ethanol, the two tautomers 3 and 4 exist in commensurable concentrations. Emission and fluorescence excitation spectra and fluorescence quantum yield of the dianion R 2À in the ternary solvent mixture were determined.

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“…The phenolate centers are not active in this reaction. [19] The polymer was soluble in water, methanol, acetone, and THF.…”

Section: Polymer Characterizationmentioning

confidence: 99%

Polymeric Photosensitizers, 5. Synthesis and Photochemical Properties of Poly[(N-isopropylacrylamide)-co-(vinylbenzyl chloride)] Containing Covalently Bound Rose Bengal Chromophores

Nowakowska¹,

pczyński

browska

2001

Macromol. Chem. Phys.

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The new polymeric photosensitizer poly[(N‐isopropylacrylamide)‐co‐(vinylbenzyl chloride/Rose Bengal)] for singlet oxygen production was synthesized and studied. The polymer is soluble in polar solvents, such as methanol and water. It displays a lower critical solution temperature in aqueous solutions at 31.7 ± 0.3°C. The quantum yield of singlet oxygen formation by the Rose Bengal‐polymer bound chromophore in methanol solution is close to that determined for free Rose Bengal. In an aqueous solution of the polymer, the efficiency of singlet oxygen formation is considerably lower. This phenomenon results mainly from the aggregation of the Rose Bengal chromophores.

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Rose bengal and nonpolar derivatives

Cited by 37 publications

References 0 publications

Resistive switching of rose bengal devices: A molecular effect?

Resistive switching of rose bengal devices: A molecular effect?

A dibasic acid with reversed order of the stepwise ionization constants: 2,7‐dichlorofluorescein in the ternary solvent mixture benzene–ethanol–water

Polymeric Photosensitizers, 5. Synthesis and Photochemical Properties of Poly[(N-isopropylacrylamide)-co-(vinylbenzyl chloride)] Containing Covalently Bound Rose Bengal Chromophores

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