Syntheses and Fluorescent Properties of 6‐Methoxy‐2‐oxoquinoline‐3,4‐dicarbonitriles and 6,7‐Dimethoxy‐2‐oxoquinoline‐3,4‐dicarbonitriles

Abstract

4‐Chlorocarbostyrils 3, 12, 17, 24, 26 with methoxy substituents in 6, 7, or 6,7‐position react with potassium cyanide in a p‐toluenesulfinate mediated reaction either to the highly fluorescent and stable 2‐oxoquinoline‐3,4‐dicarbonitriles 6, 27, 29, 30 or at slightly lower temperatures to 4‐monocarbonitriles 5, 13, 18. 4‐Chlorocarbostyril 3 and lithium p‐toluenesulfinate gave pure 4‐toluenesulfonylquinolone 4, which reacted with potassium cyanide either to monocarbonitrile 5 or dicarbonitrile 6, depending on the reaction conditions. 4‐Trifluoromethylquinolones 9 and 19 were prepared for fluorescence comparison from the appropriate methoxyaniline and 4,4,4‐trifluoroacetoacetate. The fluorescence properties such as emission wavelengths and quantum yields of 6‐methoxyderivatives 4, 5, 6, 9, 13 were studied and compared with those of 7‐methoxy derivatives 18, 19 and 6,7‐dimethoxyderivatives 27, 28, 29, 30. 6,7‐Dimethoxy derivatives show best results, showing long‐waved fluorescence spectra up to 520 nm and acceptable quantum yields up to 0.46 for 3,4‐dicyano derivative 27 excited at 440 nm in acetonitrile.

Amplification of the Quantum Yields of 2-λ5-Phosphaquinolin-2-ones through Phosphorus Center Modification

“…Alongside the many derivatives of the parent coumarin scaffold, there is the nitrogen-containing structural analogue known as carbostyril (Figure ). − Though not as widely utilized as coumarin, carbostyril is the subject of many structure–property relationship studies, and it shows promise for use in both pharmaceutical discovery and fluorescence imaging applications. , These carbostyril analogues expand on the applications of the coumarin family through modifying the lactone core to a lactam. With further alteration of this core, new applications, functionality, and fluorescent properties are expected from this widely used fluorophore.…”

Bumpy Roads Lead to Beautiful Places: The Twists and Turns in Developing a New Class of PN-Heterocycles

“…That initial report hinted that there was a lot that could be learned about this new moiety and begged the question as to whether phosphaquinolinone optoelectronic properties could be modified in a similar fashion as coumarin and carbostyril, two well-known, well-studied chromophores ( Figure 2). [54][55][56][57][58][59][60][61][62][63][64][65][66][67][68][69][70][71][72] There is an obvious structural relationship between the latter two structures in Figure 2, where the carbonyl in carbostyril is replaced with an isolobal P(OR)=O group to afford the phosphaquinolinone scaffold. Taking inspiration from the structure-property relationships drawn for the coumarin and carbostyril family of fluorophores, Jeremy set out to perform structure-property relationship studies with substituent groups at two different sites upon the backbone.…”

Computational Design of Long-Wavelength Absorbing and Emitting Carbostyrils

“…The most promising carbostyril-based fluorescent dyes so far are 3,4-dicyanoquinolin-2-(1H)-ones substituted in position 6 by electron donor groups, e.g. 3,4-dicyano-6-methoxyquinolin-2-(1H)-one 1 or 3,4dicyano-6,7-dimethoxyquinolin-2-(1H)-one 2 [8,9].…”