Blue-emissive glyoxal monohydrates via selenium-nitric acid oxidation of methyl ketones

An efficient, practical, economically and industrially viable synthetic route has been demonstrated for the synthesis of a library of arylglyoxal monohydrates (AGMHs) (2) in good to quantitative yields (90-99%) from the oxidation of a wide variety of aryl/heteroaryl methyl ketones (1) using a mixture of selenium metal and nitric acid in 1,4-dioxane. Easy to perform, broad substrate scope, good functional group tolerance, shorter reaction times, simple work-up procedure, gram-scale feasibility and products do not require column chromatography purification are the attractive features of the present reported methodology. Most importantly, the selenium metal is recovered simply by filtration and reused successfully for subsequent reaction cycles. Hence, the established procedure for the oxidation of aryl/heteroaryl methyl ketones (1) is a practical and sustainable alternative protocol to the reported methods. The photophysical properties of the synthesized AGMHs (2) were systematically investigated. The results demonstrated that these compounds exhibit blue light emission spanning the purplish-blue to bluish-green spectral region. Notably, compound 2o showed intense blue emission with CIE chromaticity coordinates of x = 0.14 and y = 0.08, closely matching as per the blue color standards of National Television System Committee (NTSC). These results reveal that AGMHs (2) may serve as potential candidates for future studies in optoelectronics.