Effect of ionic liquid on the fluorescence of an intramolecular exciplex forming probe

Abstract

The effects of ionic liquid addition on the spectroscopic properties of a pyrene-tryptophan-containing fluorescent intramolecular complex in polar-aprotic and polar-protic solvents, specifically, acetonitrile and ethanol, are assessed.

The endeavor of vibration-induced emission (VIE) for dynamic emissions

“…Excimer emission [26][27][28]30,31 and emission mechanochromism [114][115][116][117] have been found in the crystalline solids of the VIEactive compound 12-phenyl-12H-benzo[a]phenothiazine (NAS-2, see Fig. 4a and 12).…”

“…Regarding the specific π-conjugated structures and luminescent mechanisms, scientists have made notable achievements with intriguing systems and concepts, such as the excimer/exciplex, 26 – 28 , 30 , 31 fluorescence resonance energy transfer (FRET), 20 – 25 twisted intramolecular charge transfer (TICT), 48 – 55 and excited-state intramolecular proton transfer (ESIPT). 36 – 42 Most of the mechanisms originate from the accidental discovery of a specific fluorescence phenomenon, 62 – 73 after which the excited-state dynamics and the structure–property relationships were extensively studied and well established.…”

“…1a, the dual bands of an individual uorophore can generally be divided into small (normal) and large (abnormal) Stokes-shied emissions. [11][12][13] The overlap of the normal short-wavelength emission with the lowest-lying absorption band originates from the initial emissive state near the Franck-Condon excited state, while the red-shied emission far from the absorption band arises from the structurally transformed emissive state formed by additional excited-state transformations, such as enhanced charge transfer, [14][15][16][17][18][19] energy transfer, [20][21][22][23][24][25] complex formation, [26][27][28][29][30][31] and structural and/or conformational changes. Due to the signicant congurational and/or structural changes in the excited state, the ratio of short-and long-wavelength bands can be manipulated in a controllable and dynamic manner, activating unprecedented multi-colour luminescence.…”

“…Due to the signicant congurational and/or structural changes in the excited state, the ratio of short-and long-wavelength bands can be manipulated in a controllable and dynamic manner, activating unprecedented multi-colour luminescence. 9,[56][57][58][59][60][61] Regarding the specic p-conjugated structures and luminescent mechanisms, scientists have made notable achievements with intriguing systems and concepts, such as the excimer/exciplex, [26][27][28]30,31 uorescence resonance energy transfer (FRET), [20][21][22][23][24][25] twisted intramolecular charge transfer (TICT), [48][49][50][51][52][53][54][55] and excited-state intramolecular proton transfer (ESIPT). [36][37][38][39][40][41][42] Most of the mechanisms originate from the accidental discovery of a specic uorescence phenomenon, [62][63][64][65][66][67][68][69][70][71][72][73]...…”

Electron Transfer Kinetics between an Electron-Accepting Ionic Liquid and Coumarin Dyes

“…The present paper describes the first measurements of diffusionless electron transfer using an ionic liquid as a neat quenching solvent. Pyridinium ionic liquids were chosen for this purpose based on the fact that several groups had previously noted ability of N -alkylpyridinium cations to oxidatively quench the fluorescence of polyaromatic hydrocarbons , and several coumarin dyes. , The particular ionic liquid chosen here is 1-butylpyridinium bis­(trifluoromethanesulfonyl)­imide ([Py 4 ]­[Tf 2 N]), primarily because commercial samples of high optical purity were available. To achieve a wide range of electron transfer driving force, the 12 coumarin laser dyes shown in Figure were selected as photo-excited electron donors.…”