As eries of V-shaped luminophores containing electron-withdrawing quinoxalinec ore and arylthienyl donor fragments at positions 2a nd 3h as been successfully synthesized. Their photophysical properties in two solvents as well as halochromism have been studied, and the ability of 4-diethylaminophenyld erivative to function as colorimetric and luminescent pH sensorh as been demonstrated with significant color changes and luminescence switching upon the introductionofa cid.
The synthesis of a series of push–pull aryl and arylethynyl 2‐(thiophen‐2‐yl)quinazoline derivatives is presented. The photophysical properties of the newly generated compounds are also described. Functionalization of the (2‐thienyl)quinazoline fluorophore at the 5′‐position with aryl and arylethynyl moieties was performed using bromination and subsequent palladium‐catalyzed cross‐coupling reactions. Optical studies revealed that 4‐(diethylamino)phenyl and 4‐(diphenylamino)phenyl derivatives emit green light upon irradiation, whereas their 4‐(9H‐carbazol‐9‐yl)phenyl, methoxyphenyl, thienyl and arylethynyl counterparts are characterized by blue light emission capabilities. The effect of protonation has also been studied, and the ability of some of these molecules to function as colorimetric and luminescent pH sensors has been demonstrated with significant color changes and luminescence switching upon the introduction of acid.
Design and synthesis of 2-(aryl/thiophen-2-yl)quinazolin-4(3H)-ones and 4-cyano-2-arylquinazolines with Et2N-, Ph2N- or carbazol-9-yl- electron donating fragment are described. The key photophysical properties of these compounds have been studied by UV/Vis absorption and fluorescence spectroscopy in solvents of different polarity (toluene and MeCN). 2-(Aryl/thiophen-2-yl)quinazolin-4(3H)-ones show fluorescence in blue-green region in toluene solution with quantum yields up to 89% in the case of 2-(4’-N,N-diphenylamino[1,1’-biphenyl]-4-yl)-quinazolin-4(3H)-one. Moreover, triphenylamino derivative based on quinazolin-4(3H)-one with para-phenylene linker displays the highest quantum yield of 40% in powder. The fluorescence QY of Et2N and Ph2N derivatives decrease when going from toluene to MeCN solution, whereas carbazol-9-yl counterparts demonstrate strengthening of intensity that emphasizes the strong influence of donor fragment nature on photophysical properties. 4-Cyanoquinazolines are less emissive in both solvents, as well as, in solid state. The introduction of cyano group into position 4 leads to orange/red colored powder and dual emission bands. Some molecules demonstrate the increase in emission intensity upon addition of water to MeCN solution. According to frontier molecular orbitals (HOMO, LUMO) calculations, the energy gap of 4-cyanoquinazoline decreases by more than 1 eV compared to quinazolin-4-one, that is consistent with experimental data.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.