Marcin Szala

Synthesis, spectroscopy and computational studies of selected hydroxyquinolines and their analogues

Synthetic, spectroscopy and mechanistic aspects of preparation of selected hydroxyquinolines and their analogues or derivatives contained methoxy, fluoro, chloro, carboxylic, carbodithioic and phosphinate or dioxaphosphinane groups were elaborated. The multinuclear NMR and five single crystal X-ray characteristics of the series of quinolines have been determined. The molecular orbitals of the selected hydroxyquinolines have been calculated by density functional theory. The X-ray and NMR studies of 8-[(5,5-dimethyl-2-oxido-1,3,2-dioxaphosphinan-2-yl)oxy]-5,7-dibromo-2-methylquinoline and 8-[(5,5-dimethyl-2-oxido-1,3,2-dioxaphosphinan-2-yl)oxy]-5-fluoro-2-methylquinoline indicate the appearance of anomeric effect.

Identification and derivatization of selected cathinones by spectroscopic studies

In this study we identified three novel hydrochloride salts of cathinones 2-(pyrrolidin-1-yl)-1-(5,6,7,8-tetrahydronaphthalen-2-yl)pentan-1-one (1a) (TH-PVP), 2-(methylamino)-1-(2-methylphenyl)-1-propanone (1b) (2-MMC) and 1-(4-chlorophenyl)-2-(methylamino)propan-1-one (1c) (4-CMC). Their properties have been examined through combinations of GC-MS, IR, NMR, electronic absorption spectroscopy and single crystal X-ray diffraction method. NMR solution spectra showed readily diagnostic H-1 and C-13 signals from methyl, N-methyl and carbonyl groups. Additionally the use of thionation and amination reactions for identification of selected cathinones was presented.

Electrochemistry and spectroelectrochemistry of bioactive hydroxyquinolines: a mechanistic study.

The oxidation mechanism of selected hydroxyquinoline carboxylic acids such as 8-hydroxyquinoline-7-carboxylic acid (1), the two positional isomers 2-methyl-8-hydroxyquinoline-7-carboxylic acid (3) and 2-methyl-5-hydroxyquinoline-6-carboxylic acid (4), as well as other hydroxyquinolines were studied in aprotic environment using cyclic voltammetry, controlled potential electrolysis, in situ UV-vis and IR spectroelectrochemistry, and HPLC-MS/MS techniques. IR spectroelectrochemistry showed that oxidation unexpectedly proceeds together with protonation of the starting compound. We proved that the nitrogen atom in the heterocycle of hydroxyquinolines is protonated during the apparent 0.7 electron oxidation process. This was rationalized by the autodeprotonation reaction by another two starting molecules of hydroxyquinoline, so that the overall oxidation mechanism involves two electrons and three starting molecules. Both the electrochemical and spectroelectrochemical results showed that the oxidation mechanism is not influenced by the presence of the carboxylic group in the chemical structure of hydroxyquinolines, as results from oxidation of 2,7-dimethyl-5-hydroxyquinoline (6). In the presence of a strong proton acceptor such as pyridine, the oxidation ECEC process involves two electrons and two protons per one molecule of the hydroxyquinoline derivative. The electron transfer efficiency of hydroxyquinolines in biosystems may be related to protonation of biocompounds containing nitrogen bases. Molecular orbital calculations support the experimental findings.

Rhenium(I) complexes with phenanthrolines bearing electron-withdrawing Cl and electron-donating CH3 substituents – synthesis, photophysical, thermal, and electrochemical properties with electroluminescence ability

Five rhenium(I) tricarbonyl complexes incorporating 1,10-phenanthroline derivatives with electron-withdrawing Cl and electron-donating CH3 substituents were synthesized, and their photophysical, thermal, and electrochemical properties, with electroluminescence ability were examined. The melting temperature of these complexes was found to decrease from 391 to 281 °C upon adding methyl groups and decreasing the number of chlorine atoms. Compounds bearing methyl substituents could form amorphous molecular materials with glass transition temperatures in the range 118–127 °C. Cyclic voltammetry measurements demonstrated that the complexes are electrochemically active with low energy band gaps in the range 2.24–2.46 eV. All complexes are photoluminescent, form films in the solid state, and blend with poly(9-vinylcarbazole) (PVK) and PVK:(2-(4-tert-butylphenyl)-5-(4-biphenylyl)-1,3,4-oxadiazole) (PBD), emitting light with λem from 560 to 599 nm. They exhibited large Stokes shifts of up to 323 nm in solutions and up to 220 nm as film on a glass substrate. They were tested as guests in organic light-emitting diodes. As hosts, PVK and a binary matrix consisting of PVK with PBD were applied. The ability of the investigated complexes to emit light under an applied voltage was shown.

A copper(I) phosphine complex with 5,7-dinitro-2-methylquinolin-8-ol as co-ligand

Abstract5,7-Dinitro-2-methylquinolin-8-ol has been synthesized, and its copper(I) complex has been prepared. Both the free 2-MequinNO2 ligand and its complex were characterized by IR, NMR, and UV–Vis spectra. The structure of the [Cu(2-MequinNO2)(PPh3)2] complex has been determined by single-crystal X-ray analysis. The free 2-MequinNO2 ligand reveals luminescence in contrast to the complex. For 2-MequinNO2, the quantum yield, lifetime of the excited state, and the rate constants of both radiative and non-radiative decay have been determined. The lack of luminescence for the complex has been explained with the use of a quantum chemical study.