Luminescence and hydrogen bonding in quinoline and isoquinoline

Abstract

Articles you may be interested inEstimation of the degree of hydrogen bonding between quinoline and water by ultraviolet-visible absorbance spectroscopy in sub-and supercritical water A purification scheme has been developed which is capable of separating the two isomers quinoline and isoquino1ine. The emission spectra of the purified compounds were measured at 77 K in a 3-methylpentane (3MP) glass and in a 3MP glass with small amounts of hydrogen bonder added. The hydrogen bonders used were hexafluoroisopropanol (HFIP), trifluoroethanol (TFE), and absolute ethanol (EtOH). An upper limit on the ratio of fluorescence to phosphorescence quantum yields has been set at 20 ppm for quinoline in 3MP, which is 1-2 orders of magnitude smaller than previously reported. Isoquinoline still fluoresces in 3MP, which we believe to be caused by a residual hydrogen bonder not removed by the purification scheme. The excitation and lifetime data obtained suggest that the phosphorescence in these compounds is originating in a non hydrogen-bonded species, while the fluorescence is originating in a hydrogen-bonded species, regardless of solvent. A new emission has also been detected in the presence of small amounts of hydrogen bonder. This violet fluorescence is believed to be the result of an excited state protonation of the heterocycle. The ground state is believed to be nonprotonated, but strongly or "closely" hydrogen bonded. A summary of impurity induced absorption and luminescence data obtained by other authors is included to help clarify the spectral properties of quinoline and isoquinoline.

Estimation of the degree of hydrogen bonding between quinoline and water by ultraviolet–visible absorbance spectroscopy in sub- and supercritical water

“…Spectroscopic research in the past using quinoline was carried out at the equivalent concentration to our experiment. [37][38][39] In this work, we assumed that the solute-solute interactions could be neglected at our experimental concentrations. Figure 2 shows the -* absorption spectra of quinoline in water at various temperatures and 25 MPa.…”

“…Quinoline is the spectral probe that is stable in supercritical water ͑460°C͒ for about 1 h, 36 and the -* absorbance bands are known to be sensitive to hydrogen bond interactions. [37][38][39] …”

A combined experimental and theoretical studies on FT-IR, FT-Raman and UV–vis spectra of 2-chloro-3-quinolinecarboxaldehyde

“…The monomer and intermolecular charge-transfer complexes of 13 different quinoline derivatives with di-iodine were studied using ab initio molecular orbital (MO) and density functional theory (DFT) methods by Kusama et al, [21] and showed that the interaction between the quinoline additives and iodine redox electrolyte is an important factor for controlling dye-sensitized solar cell performance. Mary,F.A., et al, [22] studied luminescence and hydrogen bonding in quinoline and isoquinoline. Recently, quinoline conjugated derivatives have generated considerable interest as blue-emitting materials [23].…”

Efficient Access to C1‐ and C3‐Functionalized Isoquinolines: Towards Potential Lanthanide Ligands

“…As part of a research project on the development of lanthanide complexes as novel probes for optical and magnetic resonance imaging, [18] access to polysubstituted isoquinolines was of primary interest. Indeed, this scaffold shows interesting luminescence properties, [19] and substitution by electron-donating groups (EDG), like methoxy, on its benzene ring could enhance its capacities. [20] Therefore, the isoquinoline core has to bear highly reactive groups at both the C1 and C3 positions for further functionalization (Figure 1).…”