Excited-State Processes in 8-Hydroxyquinoline:  Photoinduced Tautomerization and Solvation Effects

Bardez, Élisabeth; Devol, Isabelle; Larrey, B.; Valeur, Bernard

doi:10.1021/jp971293u

Cited by 255 publications

(248 citation statements)

References 51 publications

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“…Initial N-methyl-6-hydroxyquinolinium iodide was prepared using ak nown procedure which is also described in the Supporting Information (SI0). [25,26] Then, equimolar amounts of N-methyl-6-hydroxyquinolinium iodide (287 mg, 1mmol) and silver bis(trifluoromethylsulfonyl)imide (388 mg, 1mmol) were dissolved in 15 mL water each. Thet wo solutions were combined and the reaction mixture was stirred for 15 min.…”

Section: Introductionmentioning

confidence: 99%

Large Stokes Shift Ionic‐Liquid Dye

et al. 2017

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Abstract:We have incorporated the dye N-methyl-6-oxyquinolone [6MQz] in its protonated form as acation into an ionic liquid (IL) and thus to synthesize an IL dye.T he IL dye N-methyl-6-hydroxyquinolinium bis(trifluoromethylsulfonyl) imide [6MQc][NTf 2 ]w as characterized by NMR, ATRI R spectroscopya nd X-ray crystallography.T he fluorescence of the IL dye has al arge Stokes shift of Dl = 116 nm and aq uantum yield of f F = 0.56 in acetonitrile.C haracteristic solvent dependent shifts can be detected in the emission spectra. In other ILs,acetonitrile and THF we observe abathochromic shift of up to 28 nm compared to the pure IL dye at 467 nm. Forstronger polar solvents the fluorescence signals are strongly red-shifted to 650 nm indicating proton transfer to the solvent molecules in the excited state.T his underlines the importance of the IL building block [ MQc] + as photo acid.Fluorescent dyes are important tools in many branches of chemistry related sciences,s uch as biological chemistry, [1][2][3][4][5][6][7][8] materials science, [9][10][11] or solar-energy conversion. [12,13] Attractive fluorescent dyes are characterized by their extended spectral range,h igh emission quantum yields,p hotostability and good solubility in the solvent. Thef luorescent dye N-methyl-6-oxyquinolone [6MQz] was used for studying solvation phenomena. Thec olor of this solvatochromatic dye molecule depends strongly on the polarity of the surrounding,a st he permanent dipole moments strongly change upon excitation from the ground to the excited state.T hus [6MQz] has been used as dye for understanding solvation processes and proton transfer to solvents. [14][15][16][17][18][19][20][21][22] In some cases the polarity probe was incorporated into biomolecules such as sugars or enzymes for probing the chemical environment and providing biocompatibility. [10,11,18,19] Whereas other dyes have been extensively applied to probe the polarity of ionic liquids,t he protonated form of [6MQz] has never been used as moiety of an ionic liquid itself. [23,24] Thus,t he goal of our work was to incorporate the dye N-methyl-6-oxyquinolone [6MQz] in its protonated form as acation into an ionic liquid (IL) and thus to synthesize an IL dye.T he resulting ionic liquid dye N-methyl-6-hydroxyquinolinium bis(trifluoromethylsulfonyl) imide ]involves anion metathesis reaction and is shown in Scheme 1. Initial N-methyl-6-hydroxyquinolinium iodide was prepared using ak nown procedure which is also described in the Supporting Information (SI0). [25,26] Then, equimolar amounts of N-methyl-6-hydroxyquinolinium iodide (287 mg, 1mmol) and silver bis(trifluoromethylsulfonyl)imide (388 mg, 1mmol) were dissolved in 15 mL water each. Thet wo solutions were combined and the reaction mixture was stirred for 15 min. Silver iodide,which precipitates instantly,was filtered off and discarded. Them other liquor was removed on ar otary evaporator and the residue was dissolved in 25 mL ethanol to carry out ah ot-filtration with activated charcoal. After filtration, the solvent wa...

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Section: Introductionmentioning

confidence: 99%

Large Stokes Shift Ionic‐Liquid Dye

et al. 2017

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“…[19] In acetonitrile, 1 shows an absorption band with l max = 301 nm ( Figure 2) and does not absorb light for l > 350 nm;m oreover it exhibits an intense fluorescenceb and with l max = 388 nm ( Figure 2). Upon addition of one equivalent of triflic acid to 1, the protonated form 1H…”

Section: Resultsmentioning

confidence: 99%

“…[21] As underlined in photochemistry textbooks, [19,22] the reabsorption of the emitted light is of great importance in the measuremento fl uminescence quantum yields and the determinationoft he correct spectralshape of an emission band.…”

Section: Resultsmentioning

confidence: 99%

Unconventional Nonlinear Input–Output Response in a Luminescent Molecular Switch by Inner Filtering Effects

Baroncini

Semeraro

2017

ChemPhysChem

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Nonlinear input–output relations are at the basis of the regulation of biochemical processes in living organisms and are important for the development of digital logic circuits based on molecules. In this article we show that a linear change of a chemical input can be translated into an exponential change of a luminescence output in a simple fluorescent acid‐base switch based on 8‐methoxyquinoline. Such unconventional behavior arises from the fact that part of the light emitted by the switch in its basic form is reabsorbed by the acid form, and is made possible by the particular spectroscopic properties of the two forms. Systems of this kind could act as noise filters in analog‐to‐digital conversion, and as control elements to increase the functional complexity of artificial molecular devices.

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“…The stability of the obtained thiacalix[n]arenes 1-5 was computationally investigated using density functional theory (DFT) using dispersion corrected 27 B3LYP functional 28,29 and balanced polarized triple zeta basis set of Ahlrichs and co-workers. 30 The gas-phase thermodynamic enthalpies of formation were determined from harmonic frequency calculations in the same level.…”

Section: Resultsmentioning

confidence: 99%