Novel dyes based on a 3-formyl-2(1H)-quinolone skeleton were synthesised and characterised using 1 H nuclear magnetic resonance spectroscopy and mass spectrometry. The spectroscopic properties of these dyes, such as their absorption spectra, emission spectra, and quantum fluorescence yields, were also examined. The behaviour of the obtained compounds at a pH of 7.4 in the absence and in the presence of thiol amino acids, such as L-cysteine, L-glutathione, and N-acetyl-L-cysteine, were studied. The spectroscopic responses of the tested dyes towards other amino acids were also investigated. A reference compound was synthesised to understand the reaction mechanism between the thiols and the obtained dyes. The experimental results show that the synthesised dyes have the potential to act as sensors for thiols. Coloration TechnologySociety of Dyers and Colourists 157

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Several dyes based on a carbostyril skeleton were synthesised and characterised using proton nuclear magnetic resonance spectroscopy and electron ionisation mass spectrometry. Their basic spectroscopic properties, such as absorption and emission spectra, were also measured. The behaviour of the obtained dyes in the absence and presence of thiol amino acids and other compounds under various conditions were studied. These dyes contain various moieties in the structure, acting as Michael acceptors. Results show that the studied compounds have the potential to act as colorimetric sensors for thiols, but the benzothioazolium dyes are less effective than dicyanoethylene derivatives.

A series of neutral dyes based on the naphthoylenebenzimidazolone skeleton have been synthesised and evaluated as potential light‐absorbing chromophores for free radical polymerisation. Kinetic studies of photoinitiated polymerisation of methyl acrylate and trimethylolpropane triacrylate with pyridinium salts have proved that these dyes are efficient electron‐donating photoinitiators operating in visible light.

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Several dyes based on the 6,7-dichloro-5,8-quinolinedione skeleton have been synthesised and characterised by proton nuclear magnetic resonance spectroscopy and electron ionisation mass spectrometry. The spectroscopic and electrochemical properties of these dyes were investigated. Photoredox pairs consisting of the synthesised dyes and commercially available hydrogen donors (2-mercaptobenzoxazole, 2-mercaptobenzothiazole, 2-mercaptobenzimidazole, and 2,5-dimercapto-1,3,4-thiadiazole) were tested for use as effective initiator systems for radical polymerisation of trimethylolpropane triacrylate with visible light. The efficiencies of these initiator systems are discussed in terms of the free energy change for the electron transfer process from the dye to the hydrogen donor.

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The sensing properties of dyes based on 2(1H) quinolones containing dicyanoethylene groups towards selected anions such as CN−, F−, I−, Cl−, SCN−, CH3COO−, NO2- and ClO4- were evaluated. The spectroscopic responses of these compounds were investigated in a solution of acetonitrile/water (1:9, v/v) and phosphate buffer at a pH of 7.4. These dyes were found to act as efficient colorimetric and high turn–off fluorescent sensors to cyanide anions. The fluorescence intensity was linearly related to the concentration of CN− from 1 to 10 µmol/L, and the detection limits reached a micromolar level of 6.7, 11.1, 3.8 and 7.2 µmol/L for 1‐4, respectively. The cytotoxic effect of the dyes against human neuroblastoma cells (SH‐SY5Y) was also determined by MTT assay. The examined compounds exhibited slight cytotoxicity against cells under experimental conditions.