The inclusion of polarizability slows down the computed solvation dynamics due to interactions of induced dipoles, improving agreement to experiment.

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...

Site‐selective Sonogashira cross‐coupling reactions of 1,4‐dibromo‐2‐(trifluoromethyl)benzene have been performed, affording a variety of functionalized alkynyl‐substituted (trifluoromethyl)benzenes. The site selectivity, in favor of position C‐4, was confirmed by 13C NMR and 1H–13C HMBC NMR measurements, X‐ray crystal structure analysis as well as DFT calculations. Furthermore, the mesomorphic properties and optical textures were examined by differential scanning calorimetry and polarized optical microscopy. Several dialkynyl‐substituted (trifluoromethyl)benzenes showed nematic liquid‐crystalline properties over a long phase range. The influence of terminal and lateral substituents on the formation and stability of the molecular network within the liquid‐crystalline phase is explained by the results of DFT calculations. Additionally, the absorption and fluorescence properties were analyzed in detail. The intramolecular influence of electron‐donating or electron‐withdrawing groups and also of solvatochromatism are considered. In this context, time‐dependent B3LYP/6‐31G* (TD‐B3LYP) calculations were carried out to characterize the main absorption bands.